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Gbobaniyi, Emiola Olabode. "Transferability of regional climate models over different climatic domains." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/4854.
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Includes abstract.Includes bibliographical references (p. 119-144).
In the continuing quest to improve climate model predictions to meet the increasing demand for knowledge on the regional effects of global climate change, it is pertinent to increase our understanding of how the underlying processes of climate are represented in the models we use to make these predictions. Concerted efforts in model evaluations and intercomparison have provided numerous insights into various model biases which plague current state-of-the-art regional climate models (RCMs). Model evaluation and assessment is crucial to model development and understanding how physical processes are represented in models is necessary for improving model parameterizations. This thesis explored model transferability as a new approach for systematic process-based intercomparison of RCMs. It investigated an untested transferability hypothesis which states that “for non-monsoon regions experiencing weak synoptic scale forcing, the height of the cloud base is correlated with the daytime surface fluxes”. An initial transferability experiment was conducted over Cabauw, the Netherlands (51.97°N, 4.93°E) to assess the models’ skill in resolving the diurnal and seasonal cycles and to investigate the simulated connections between surface and hydrometeorological variables over a non-monsoon station. The ability of models to resolve these cycles correctly is a good metric of their predictive capabilities. The data used for the study comprises three-hourly surface observations for the period October 2002 – December 2004 from the Coordinated Enhanced Observing Period (CEOP) measuring campaigns of the Global Energy and Water Cycle Experiment (GEWEX) and three-year simulations (2002 -2004) from five RCMs (CLM, GEMLAM, MRCC, RCA3 and RSM). In simulating seasonal and diurnal cycles of CBH and surface variables, the European models (CLM and RCA3) demonstrate a clear home advantage over the North American models (GEMLAM, MRCC and RSM). Principal component analysis revealed that the models couple the cloud base height with surface fluxes as in observations and that this coupling is not sensitive to changes in wind speed. This study found that summer daytime loadings gave the strongest couplings of variables. Three major processes were identified over Cabauw. First and most dominant is the surface energy process which couples sensible and latent heat with net radiation. The second process is thermodynamic, coupling temperature and surface moisture (specific humidity), and the third is a dynamic process which couples pressure and wind speed. A model intercomparison was then carried out across the six midlatitude domains to test the validity of the Cabauw findings. In observations, CBH is well coupled with the surface fluxes over Cabauw, Bondville, Lamont and BERMS, but coupled only with temperature over Lindenberg and Tongyu. All the models (except GEMLAM) simulated a good coupling with surface fluxes at all stations. In GEMLAM, there is no coupling between CBH and surface fluxes at any station. In less homogenous domains of the study, a very slight decrease in the strength of coupling is seen in most of the models, under strong large scale forcing. This would suggest that the coupling between cloud base height and surface fluxes in the models is possibly more influenced by radiative forcing than by synoptic controls. This second study confirmed the findings at Cabauw that the simulated cloud base is correlated with surface energy fluxes and the sign of the correlations in the models is as in observations. This finding is important for the modeling community as it establishes the fact that the models are actually simulating the direction of influence of surface fluxes and possibly, soil water variability, on cloud processes.
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Sanchirico, Emily. "A Strong Institutional Climate: Regional Trade Networks and Climate Action." Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13410.
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Climate change has been described as a malign, wicked, and super wicked problem. I focus on key characteristics that make international collective action challenging: asymmetry, fear of free riding, scientific uncertainty, and inherent interdependencies. I argue that an institution designed to tackle such a complex problem requires a key set of features: leadership, linkage, quality information, differentiated obligations, monitoring/enforcement, transparency, and flexibility. I assess the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol to determine what aspects are missing. I then ask why the European Union (EU), with incentives to the contrary, set broad unilateral goals. I argue that the framework of political and economic integration made deep cooperation possible. Lastly, I consider whether this experience is specific to the EU and ask whether regional trade networks have a role in the global arsenal of climate change solutions.
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Quaas, Johannes, Martin F. Quaas, Olivier Boucher, and Wilfried Rickels. "Regional climate engineering by radiation management." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-217984.
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Radiationmanagement (RM), as an option to engineer the climate, is highly controversial and suffers from a number of ethical and regulatory concerns, usually studied in the context of the objective to mitigate the global mean temperature. In this article, we discuss the idea that RM can be differentiated and scaled in several dimensions with potential objectives being to influence a certain climate parameter in a specific region. Some short-lived climate forcers (e.g., tropospheric aerosols) exhibit strong geographical and temporal variability, potentially leading to limited-area climate responses. Marine cloud brightening and thinning or dissolution of cirrus clouds could be operated at a rather local scale. It is therefore conceivable that such schemes could be applied with the objective to influence the climate at a regional scale. From a governance perspective, it is desirable to avoid any substantial climate effects of regional RM outside the target region. This, however, could prove impossible for a sustained, long-term RM. In turn, regional RM during limited time periods could prove more feasible without effects beyond the target area. It may be attractive as it potentially provides the opportunity to target the suppression of some extreme events such as heat waves. Research is needed on the traceability of regional RM, for example, using detection and attribution methods. Incentives and implications of regional RM need to be examined, and new governance options have to be conceived.
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Rupper, Summer Burton. "Glacier sensitivity and regional climate : past and present /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6728.
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Pal, Sujan, and Sujan Pal. "Application of High-Resolution Regional Climate Model Product in Climate and Weather Research." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624093.
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Accurate regional and local scale information about seasonal climate variability and its impact on water availability is important in many practical applications like agriculture, water resource planning, long term decision making etc. Presently, the primary source for real-time seasonal climate forecast comes from the CPC within the NOAA-NCEP which uses its model forecast component (CFSv2) of North American Multi-Model Ensemble (NMME). But it has been observed that in comparison to the cool season, the level of skill in warm season seasonal forecasts of precipitation produced by the NMME is much lower (Kirtman et al. 2014) due to the poor climatological representation of warm season convective precipitation. To fully realise the potential in improving warm season seasonal forecasts using a dynamical modeling approach requires dynamical downscaling of NMME models to better improve their representation of convective precipitation at a convective-permitting (3km) grid. A decade-long CFSR (the reanalysis product of CFS) data is dynamically downscaled using WRF to demonstrate the value added of convective permitting modeling in the representation of mean and extreme warm season precipitation over the Southwest United States. The study shows evidence that the use of regional model adds value to the reanalyses in terms to better special and temporal representation which is also consistent with previous studies and appears to be an important initial step towards seasonal to subseasonal (S2S) forecasting.
Empirical observations show that the structure and size of tropical cyclones (TCs) have dramatic impacts at landfall, including wind damage and storm surge. A better understanding of how the large-scale environment affects TC size and size change might be helpful in the predictions of the TC environment to infer how the TC size might change close to landfall. This study investigates the influence of environmental factors on TC size expansions using numerical simulations. Two periods of size change are investigated one in Hurricane Katrina (2005) as it moved through the Gulf of Mexico and one in Igor (2010) as it begins to undergo extratropical transition. Size changes are evaluated using the North Atlantic Hurricane Database second generation (HURDAT2) data set, which contains the maximum radial extent of the 64-, 50- and 34-kt wind in four quadrants. The average 34-kt wind radius (R34) is used as an indicator of the size of the TC. For the purposes of this study, the environment of a TC is investigated if the wind field either expanded or contracted in size at least 15 n mi radially in a 12-hour period. The regional model used is WRF-ARW. The results found from the simulation of Hurricane Katrina support previous results that increased surface fluxes and higher moisture availability is conducive to TC wind expansion and that as the moisture is depleted, the expansion of the wind field is no longer supported. In the case of Hurricane Igor, the influences of the midlatitude westerlies was evident in the increasing deep vertical wind shear, which is known to be detrimental to TC structure and intensity when strong enough.
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Barandiaran, Daniel A. "Investigation into Regional Climate Variability using Tree-Ring Reconstruction, Climate Diagnostics and Prediction." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5024.
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This document is a summary of research conducted to develop and apply climate analysis tools toward a better understanding of the past and future of hydroclimate variability in the state of Utah. Two pilot studies developed data management and climate analysis tools subsequently applied to our region of interest. The first investigated the role of natural atmospheric forcing in the inter-annual variability of precipitation of the Sahel region in Africa, and found a previously undocumented link with the East Atlantic mode, which explains 29% of variance in regional precipitation. An analysis of output from an operational seasonal climate forecast model revealed a failure in the model to reproduce this linkage, thus highlighting a shortcoming in model performance. The second pilot study studied long-term trends in the strength of the Great Plains low-level jet, an driver of storm development in the region’s wet spring season. Our analysis showed that since 1979 the low-level jet has strengthened as shifted the timing of peak activity, resulting in shifts both in time and location for peak precipitation, possibly the result of anthropogenic forcing. Our third study used a unique tree-ring dataset to create a reconstruction of April 1 snow water equivalent, an important measure of water supply in the Intermountain West, for the state of Utah to 1850. Analysis of the reconstruction shows the majority of snowpack variability occurs monotonically over the whole state at decadal to multidecadal frequencies. The final study evaluated decadal prediction performance of climate models participating in the Coupled Model Intercomparison Project 5. We found that the analyzed models exhibit modest skill in prediction of the Pacific Decadal Oscillation and better skill in prediction of global temperature trends post 1960.
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Menon, Surabi. "Role of Sulfates in Regional Cloud-Climate Interactions." NCSU, 1998. http://www.lib.ncsu.edu/theses/available/etd-19981102-133647.
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Aerosols affect the radiation budget of the earth-atmosphere system by directly reflecting or absorbing solar radiation and also indirectly, by altering the cloud albedo through changes in the cloud condensation nuclei concentration (CCN). Increases in CCN concentrations result in an increase in the cloud droplet number concentration (N). Assuming the cloud liquid water content (LWC) stays the same, this will result in smaller cloud droplet sizes. Thus, this will increase cloud reflectance and cloud lifetime as cloud cover also increases. An accurate quantification of the aerosol forcing effect is still not possible due to the complexity involved in understanding aerosol processes and their effects on climate. There has also been a lack of a coordinated effort toward linking surface and in situ observations, as well climate model results and satellite data. Due to the spatial and temporal heterogeneity in aerosol forcing, regional effects are important. In this dissertation, the direct and indirect radiative forcing effects of aerosols - primarily sulfates and to lesser extent soot aerosols at a site located in the southeastern U.S. are investigated by means of surface observations, modeling results and satellite data.During the summers of 1993-96, field experiments were conducted at Mt. Mitchell, North Carolina, at a site representative of the southeastern U.S. to determine the effect of pollutants on the cloud microphysical and optical properties. Analyses of the results from empirical relationships are used to obtain an estimate of the contribution of sulfates to indirect radiative forcing. Concurrent measurements of size resolved chemical concentrations, light scattering and absorption coefficients, aerosol size distribution and optical depth measurements were obtained during the winter of 1997 for cloud-free skies. Data from these measurements are used to investigate the chemical-physical-optical interaction between aerosols and to determine the direct forcing effect of aerosols by means of a column forcing model. Cloud water sulfate concentration is used as a measure of anthropogenic pollution. Back-trajectory analysis is used to identify the source of the air masses classified as polluted continental, continental and marine. The effect of anthropogenic pollution on cloud microphysical properties such as LWC, N, effective radii (Reff), CCN activation spectrum, cloud optical depth and reflectivity are investigated. The relationship between Reff and sulfate for different air masses, as well as the N-sulfate mass relationship, suggests that the counteracting effect of sulfates on greenhouse warming for the southeastern U.S. would be of a magnitude greater than -4.0 W m-2 obtained by previous modeling studies. Acidity variations between cloud droplets of different sizes indicated that on an average, smaller drops are enriched in sulfates, nitrates and ammonium, whereas, larger droplets have higher concentrations of sodium, calcium and magnesium. As part of a closure experiment cloud albedo calculated from in situ measurements was compared to that retrieved from the Advanced Very High Resolution Radiometer data for four years (1993-96). The nonlinear relationships between the cloud microphysical/optical properties and the sulfate content imply the existence of an optimum level for the sulfate concentration that would affect cloud albedo. In terms of the direct forcing effect, wintertime forcing obtained for an internal mixture of sulfate and soot aerosols is much lower than that obtained during summer, due to reduced sulfate concentrations in winter. A quantitative measure of the direct forcing indicates higher magnitudes both for summer and winter than is obtained from previous modeling results. Analyses of the direct and indirect radiative forcing effect of sulfates for the southeastern U.S. indicate that the negative forcing effect is of greater magnitude than is predicted by modeling results. Thus, reduction in sulfate emissions would have a significant impact on climate for the southeastern U.S.
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Holsten, Anne. "Climate change vulnerability assessments in the regional context." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6683/.
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Adapting sectors to new conditions under climate change requires an understanding of regional vulnerabilities. Conceptually, vulnerability is defined as a function of sensitivity and exposure, which determine climate impacts, and adaptive capacity of a system. Vulnerability assessments for quantifying these components have become a key tool within the climate change field. However, there is a disagreement on how to make the concept operational in studies from a scientific perspective. This conflict leads to many still unsolved challenges, especially regarding the quantification and aggregation of the components and their suitable level of complexity.
This thesis therefore aims at advancing the scientific foundation of such studies by translating the concept of vulnerability into a systematic assessment structure. This includes all components and implies that for each considered impact (e.g. flash floods) a clear sensitive entity is defined (e.g. settlements) and related to a direction of change for a specific climatic stimulus (e.g. increasing impact due to increasing days with heavy precipitation). Regarding the challenging aggregation procedure, two alternative methods allowing a cross-sectoral overview are introduced and their advantages and disadvantages discussed. This assessment structure is subsequently exemplified for municipalities of the German state North Rhine-Westphalia via an indicator-based deductive approach using information from literature. It can be transferred also to other regions. As for many relevant sectors, suitable indicators to express the vulnerability components are lacking, new quantification methods are developed and applied in this thesis, for example for the forestry and health sector.
A lack of empirical data on relevant thresholds is evident, for example which climatic changes would cause significant impacts. Consequently, the multi-sectoral study could only provide relative measures for each municipality, in relation to the region. To fill this gap, an exemplary sectoral study was carried out on windthrow impacts in forests to provide an absolute quantification of the present and future impact. This is achieved by formulating an empirical relation between the forest characteristics and damage based on data from a past storm event. The resulting measure indicating the sensitivity is then combined with wind conditions.
Multi-sectoral vulnerability assessments require considerable resources, which often hinders the implementation. Thus, in a next step, the potential for reducing the complexity is explored. To predict forest fire occurrence, numerous meteorological indices are available, spanning over a range of complexity. Comparing their performance, the single variable relative humidity outperforms complex indicators for most German states in explaining the monthly fire pattern. This is the case albeit it is itself an input factor in most indices. Thus, this meteorological factor alone is well suited to evaluate forest fire danger in many Germany regions and allows a resource-efficient assessment. Similarly, the complexity of methods is assessed regarding the application of the ecohydrological model SWIM to the German region of Brandenburg. The inter-annual soil moisture levels simulated by this model can only poorly be represented by simpler statistical approach using the same input data. However, on a decadal time horizon, the statistical approach shows a good performance and a strong dominance of the soil characteristic field capacity. This points to a possibility to reduce the input factors for predicting long-term averages, but the results are restricted by a lack of empirical data on soil water for validation.
The presented assessments of vulnerability and its components have shown that they are still a challenging scientific undertaking. Following the applied terminology, many problems arise when implementing it for regional studies. Advances in addressing shortcomings of previous studies have been made by constructing a new systematic structure for characterizing and aggregating vulnerability components. For this, multiple approaches were presented, but they have specific advantages and disadvantages, which should also be carefully considered in future studies. There is a potential to simplify some methods, but more systematic assessments on this are needed. Overall, this thesis strengthened the use of vulnerability assessments as a tool to support adaptation by enhancing their scientific basis.Die Anpassung von Sektoren an veränderte klimatische Bedingungen erfordert ein Verständnis von regionalen Vulnerabilitäten. Vulnerabilität ist als Funktion von Sensitivität und Exposition, welche potentielle Auswirkungen des Klimawandels darstellen, und der Anpassungsfähigkeit von Systemen definiert. Vulnerabilitätsstudien, die diese Komponenten quantifizieren, sind zu einem wichtigen Werkzeug in der Klimawissenschaft geworden. Allerdings besteht von der wissenschaftlichen Perspektive aus gesehen Uneinigkeit darüber, wie diese Definition in Studien umgesetzt werden soll. Ausdiesem Konflikt ergeben sich viele Herausforderungen, vor allem bezüglich der Quantifizierung und Aggregierung der einzelnen Komponenten und deren angemessenen Komplexitätsniveaus. Die vorliegende Dissertation hat daher zum Ziel die Anwendbarkeit des Vulnerabilitätskonzepts voranzubringen, indem es in eine systematische Struktur übersetzt wird. Dies beinhaltet alle Komponenten und schlägt für jede Klimaauswirkung (z.B. Sturzfluten) eine Beschreibung des vulnerablen Systems vor (z.B. Siedlungen), welches direkt mit einer bestimmten Richtung eines relevanten klimatischen Stimulus in Verbindung gebracht wird (z.B. stärkere Auswirkungen bei Zunahme der Starkregentage). Bezüglich der herausfordernden Prozedur der Aggregierung werden zwei alternative Methoden, die einen sektorübergreifenden Überblick ermöglichen, vorgestellt und deren Vor- und Nachteile diskutiert. Anschließend wird die entwickelte Struktur einer Vulnerabilitätsstudie mittels eines indikatorbasierten und deduktiven Ansatzes beispielhaft für Gemeinden in Nordrhein-Westfalen in Deutschland angewandt. Eine Übertragbarkeit auf andere Regionen ist dennoch möglich. Die Quantifizierung für die Gemeinden stützt sich dabei auf Informationen aus der Literatur. Da für viele Sektoren keine geeigneten Indikatoren vorhanden waren, werden in dieser Arbeit neue Indikatoren entwickelt und angewandt, beispielsweise für den Forst- oder Gesundheitssektor. Allerdings stellen fehlende empirische Daten bezüglich relevanter Schwellenwerte eine Lücke dar, beispielsweise welche Stärke von Klimaänderungen eine signifikante Auswirkung hervorruft. Dies führt dazu, dass die Studie nur relative Aussagen zum Grad der Vulnerabilität jeder Gemeinde im Vergleich zum Rest des Bundeslandes machen kann. Um diese Lücke zu füllen, wird für den Forstsektor beispielhaft die heutige und zukünftige Sturmwurfgefahr von Wäldern berechnet. Zu diesem Zweck werden die Eigenschaften der Wälder mit empirischen Schadensdaten eines vergangenen Sturmereignisses in Verbindung gebracht. Der sich daraus ergebende Sensitivitätswert wird anschließend mit den Windverhältnissen verknüpft. Sektorübergreifende Vulnerabilitätsstudien erfordern beträchtliche Ressourcen, was oft deren Anwendbarkeit erschwert. In einem nächsten Schritt wird daher das Potential einer Vereinfachung der Komplexität anhand zweier sektoraler Beispiele untersucht. Um das Auftreten von Waldbränden vorherzusagen, stehen zahlreiche meteorologische Indices zur Verfügung, welche eine Spannbreite unterschiedlicher Komplexitäten aufweisen. Bezüglich der Anzahl monatlicher Waldbrände weist die relative Luftfeuchtigkeit für die meisten deutschen Bundesländer eine bessere Vorhersagekraft als komplexere Indices auf. Dies ist er Fall, obgleich sie selbst als Eingangsvariable für die komplexeren Indices verwendet wird. Mit Hilfe dieses einzelnen meteorologischen Faktors kann also die Waldbrandgefahr in deutschen Region ausreichend genau ausgedrückt werden, was die Ressourceneffizienz von Studien erhöht. Die Methodenkomplexität wird auf ähnliche Weise hinsichtlich der Anwendung des ökohydrologischen Modells SWIM für die Region Brandenburg untersucht. Die interannuellen Bodenwasserwerte, welche durch dieses Modell simuliert werden, können nur unzureichend durch ein einfacheres statistisches Modell, welches auf denselben Eingangsdaten aufbaut, abgebildet werden. Innerhalb eines Zeithorizonts von Jahrzehnten, kann der statistische Ansatz jedoch das Bodenwasser zufriedenstellend abbilden und zeigt eine Dominanz der Bodeneigenschaft Feldkapazität. Dies deutet darauf hin, dass die Komplexität im Hinblick auf die Anzahl der Eingangsvariablen für langfristige Berechnungen reduziert werden kann. Allerdings sind die Aussagen durch fehlende beobachtete Bodenwasserwerte zur Validierung beschränkt. Die vorliegenden Studien zur Vulnerabilität und ihren Komponenten haben gezeigt, dass eine Anwendung noch immer wissenschaftlich herausfordernd ist. Folgt man der hier verwendeten Vulnerabilitätsdefinition, treten zahlreiche Probleme bei der Implementierung in regionalen Studien auf. Mit dieser Dissertation wurden Fortschritte bezüglich der aufgezeigten Lücken bisheriger Studien erzielt, indem eine systematische Struktur für die Beschreibung und Aggregierung von Vulnerabilitätskomponenten erarbeitet wurde. Hierfür wurden mehrere Ansätze diskutiert, die jedoch Vor- und Nachteile besitzen. Diese sollten vor der Anwendung von zukünftigen Studien daher ebenfalls sorgfältig abgewogen werden. Darüber hinaus hat sich gezeigt, dass ein Potential besteht einige Ansätze zu vereinfachen, jedoch sind hierfür weitere Untersuchungen nötig. Insgesamt konnte die Dissertation die Anwendung von Vulnerabilitätsstudien als Werkzeug zur Unterstützung von Anpassungsmaßnahmen stärken.
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Mashila, Thabang. "Spatial planning for climate change adaptation : developing a climate change local area adaptation plan for Khayelitsha." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13332.
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Includes bibliographical references.Climate change is now widely seen as a major challenge of this time and the future of cities. However, the most vulnerable will be the urban poor particularly those located on the urban fringes in high risk areas with limited access to basic services and economic opportunities. In South Africa, although progress has been made to reduce socio-economic and environmental challenges created by apartheid legislations, inequalities still exist where the privileged live in safer and well located and serviced parts of the city while he poor are still located in settlements created by apartheid in urban fringes. Spatial Planning presents an opportunity to increase resilience to climate change in vulnerable areas of cities. Through integrating planning and climate adaptation actions, future spatial decisions will add to resilience to climate change and enhance wellbeing of people. The dissertation includes a case study that was conducted to learn about the status quo of the study area to effectively recommend relevant interventions that seek to create resilience to climate change in the area. A local area adaptation plan was then formulated including the framework for implementing proposed interventions in a 20 year timeframe.
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Trail, Marcus Alexander. "Impact of climate-responsive controls and land usage on regional climate and air quality." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53441.
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Impacts of Climate-responsive Controls and Land Usage on Regional Climate and Air Quality
Marcus A. Trail
201 pages
Directed by Dr. Armistead G. Russell
Regional air quality impacts public health, visibility and ecosystem health, and is significantly affected by changes in climate, land use and pollutant emissions. Predictions of regional air quality responses to such changes can help inform policy makers in the development of effective approaches to both reduce greenhouse gases and improve air quality. However, major sources of uncertainty exist in predicting future air quality including limitations in the tools used to project future emissions, land use changes and uncertainties associated with predicting future climate. Recently, technical advances in downscaling global climate simulations to regional scales, and, the development of bottom-up operational tools used to forecast emissions have enhanced our ability to account for the complex interactions between population, socio-economic development, technological change, and federal and regional environmental policies.
The results show that emissions reductions strategies will continue to play a vital role in improving air quality over the U.S. while CO2 emission reduction policies can have mixed positive and negative impacts on air quality. However, additional costs will be necessary to reach air quality goals due to climate change because deeper emission reductions will be required to compensate for a warmer climate, even if current efforts are predicted to show improvement. The results of this study also show that regional climate and O3 and aerosol concentrations are highly sensitive to reforestation and cropland conversion in the Southeast and these land use changes should be considered in air quality management plans.
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Karmacharya, Jagadishwor. "Climate processes over the Himalaya : the added value from high resolution regional climate modelling." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:a8cec5ba-b837-49c0-abd4-62c26d71dffd.
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The Himalaya plays a vital role in shaping the hydro-climate of South Asia and beyond, but their climate has not yet been monitored and modelled as well as some other regions. As the summer monsoon is the dominant climate system over South Asia, including the Himalaya, realistic simulation of the South Asian summer monsoon (SASM) should be a prerequisite for the satisfactory simulation of the Himalayan climate. The present research tests the assumption that higher resolution modelling will provide improved representation of the SASM, both regionally and over the Himalaya region. The first part of this research assesses the strength and stability of the temporal relationships between the monsoon rainfall indices (MRIs) and the large-scale monsoon circulation indices (MCIs), as a precursor to using such indices for model evaluation. The remainder of the thesis evaluates model performance in simulating various characteristics of SASM, mainly with regard to precipitation. In particular, the sensitivity of a regional climate model (RCM) simulation to domain size and added value of high resolution RCM simulation are evaluated. For this purpose, the Hadley Centre unified model - HadGEM is utilized in its regional and, in few instances, global configurations. The RCM simulations are performed at 0.44° and 0.11° horizontal resolutions and they are forced by the ERA interim dataset. Results show that i) the MRI-MCI relationship exhibits considerable low-frequency variability, ii) RCM simulation of SASM, particularly precipitation, shows sensitivity to domain size and simulation with a moderately sized domain that partially excludes bias prone equatorial Indian ocean outperform those with larger domains, iii) high resolution RCM simulation adds value in many aspects of SASM precipitation, including the seasonal mean, relative frequency distribution, extremes, and active and break monsoon composites, but the improvements are generally seen over the Indo-Gangetic plain rather than the Himalaya. The findings promote use of a high resolution RCM over a moderate sized domain (~ 25,000,000 sq. km) for the realistic simulation of SASM, but the study needs to be repeated with multiple realizations and different RCMs before arriving at a robust conclusion.
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André, Karin. "Climate change adaptation processes : Regional and sectoral stakeholder perspectives." Doctoral thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-90500.
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This thesis analyses how societal adaptation processes in public and private sectors at the regional to local level in Sweden are enacted. The thesis pays particular attention to critical factors that constrain or enable adaptation by focussing on: who are the stakeholders, how do different stakeholders perceive their capacity to adapt, and the role of stakeholder interaction in facilitating adaptation processes A combination of two analytical perspectives is used where one is based on key concepts within adaptation literature, and the other draws on boundary crossing and transdisciplinary knowledge production (stakeholders, adaptive capacity, and science-based stakeholder dialogues). The study is conducted within the scope of two overall case studies of local adaptation processes within an urban region, and a land-use based sector, the private forestry sector. The cases are setting the scene for the collection of empirical material which is achieved through qualitative methods, primarily focus groups discussions with local and regional, public and private stakeholders with an interest in, and responsibility for adaptation. The focus groups meetings are organized as a series of meetings to which different participatory techniques are applied. The study also builds on a comprehensive stakeholder mapping. First, the results suggest a systematic method for identifying stakeholders in adaptation research, policy, and planning applicable in both sectors and regions that combines top-down knowledge with experience and knowledge based on bottom-up processes. Second, the analysis of perceived adaptive capacities reveal several facilitating and constraining factors that relates both to the characteristics of climate risks, experience of climate variability and extreme weather events, and responsibility- and decision-making structures. Third, the analysis of the interaction between local experts and scientists show that there is potential for the boundary spanning function of science-based stakeholder dialogues in facilitating adaptation through stimulating questions and sharing different knowledge bases and experiences among the participants. However further attention needs to be taken to the institutional environment and the role of so called anchoring devices that help local experts to contextualise, discus and thus anchor scientific knowledge in their own decision-making context. In conclusion, there are both commonalities between adaptation processes in the two case studies and some marked differences, e.g., regarding the concept of adaptation, what type of adaptation actions that are identified, the perceived opportunities for adaptation and degree of complexity.Denna avhandling analyserar hur klimatanpassningsprocesser inom privata och offentliga sektorer på regional till lokal nivå i Sverige initieras, utvecklas och genomförs. Avhandlingen ägnar särskild uppmärksamhet åt identifiering av vilka intressenter (”stakeholders”) som är involverade i att underlätta och genomföra anpassning, uppfattningar om anpassningsförmåga samt vilken roll interaktion mellan olika intressenter kan ha för att underlätta anpassning. En kombination av två analytiska perspektiv används som bygger på tidigare forskning om klimatanpassningsprocesser samt transdisciplinär kunskapsproduktion. Studien genomförs inom ramen för två övergripande fallstudier av anpassningsprocesser i en urban region samt den privata skogssektorn. Fallstudierna utgör grunden för insamlingen av det empiriska materialet som bygger på kvalitativa metoder. Den främsta metoden är fokusgruppsdiskussioner med lokala och regionala, privata och offentliga aktörer med intresse av, eller ansvar för klimatanpassning. Fokusgrupperna organiseras som en serie möten där olika deltagandetekniker tillämpas. Studien bygger också på en omfattande intressentkartläggning. I avhandlingen utvecklas och ges förslag på en stegvis metod för att identifiera intressenter för anpassningsprocesser som kan användas inom forskning och praktik. Studien analyserar också hur olika intressentgrupper upplever förmågan att hantera klimatförändringar. Ett antal möjliggörande och begränsande faktorer identifieras så som karaktären på de upplevda klimatriskerna, erfarenhet av klimatvariationer och extrema väderhändelser, samt ansvar- och beslutsstrukturer. Slutligen, analyseras om och i så fall hur interaktionen mellan lokala experter och forskare som deltar i intressantdialoger (”science-based stakeholder dialogues”) kan underlätta anpassning. Resultaten visar att det finns potential genom att deltagarna ges möjlighet att ställa frågor tillvarandra och dela med sig av sina olika kunskapsbaser och erfarenheter, samt utforska olika anpassningsalternativ. Däremot behövs vidare studier för att undersöka betydelsen av det institutionella sammanhanget samt hur olika verktyg (”anchoring devices”) kan bidra när det gäller att förankra och omsätta kunskap om klimatförändringar i olika beslutskontexter. Avslutningsvis visar denna studie på att det finns både likheter och skillnader i hur anpassningsprocesser kommer till uttryck bland de olika aktörsgrupperna inom fallstudierna, t.ex. när det gäller hur begreppet anpassning används, vilken typ av anpassning som identifieras, upplevda möjligheter för anpassning samt graden av komplexitet.
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Hamman, Joseph, Bart Nijssen, Michael Brunke, John Cassano, Anthony Craig, Alice DuVivier, Mimi Hughes, et al. "Land Surface Climate in the Regional Arctic System Model." AMER METEOROLOGICAL SOC, 2016. http://hdl.handle.net/10150/621720.
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The Regional Arctic System Model (RASM) is a fully coupled, regional Earth system model applied over the pan-Arctic domain. This paper discusses the implementation of the Variable Infiltration Capacity land surface model (VIC) in RASM and evaluates the ability of RASM, version 1.0, to capture key features of the land surface climate and hydrologic cycle for the period 1979-2014 in comparison with uncoupled VIC simulations, reanalysis datasets, satellite measurements, and in situ observations. RASM reproduces the dominant features of the land surface climatology in the Arctic, such as the amount and regional distribution of precipitation, the partitioning of precipitation between runoff and evapotranspiration, the effects of snow on the water and energy balance, and the differences in turbulent fluxes between the tundra and taiga biomes. Surface air temperature biases in RASM, compared to reanalysis datasets ERA-Interim and MERRA, are generally less than 2 degrees C; however, in the cold seasons there are local biases that exceed 6 degrees C. Compared to satellite observations, RASM captures the annual cycle of snow-covered area well, although melt progresses about two weeks faster than observations in the late spring at high latitudes. With respect to derived fluxes, such as latent heat or runoff, RASM is shown to have similar performance statistics as ERA-Interim while differing substantially from MERRA, which consistently overestimates the evaporative flux across the Arctic region.
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Quaas, Johannes, Martin F. Quaas, Olivier Boucher, and Wilfried Rickels. "Regional climate engineering by radiation management: prerequisites and prospects." AGU Publications, 2016. https://ul.qucosa.de/id/qucosa%3A15257.
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Radiationmanagement (RM), as an option to engineer the climate, is highly controversial and suffers from a number of ethical and regulatory concerns, usually studied in the context of the objective to mitigate the global mean temperature. In this article, we discuss the idea that RM can be differentiated and scaled in several dimensions with potential objectives being to influence a certain climate parameter in a specific region. Some short-lived climate forcers (e.g., tropospheric aerosols) exhibit strong geographical and temporal variability, potentially leading to limited-area climate responses. Marine cloud brightening and thinning or dissolution of cirrus clouds could be operated at a rather local scale. It is therefore conceivable that such schemes could be applied with the objective to influence the climate at a regional scale. From a governance perspective, it is desirable to avoid any substantial climate effects of regional RM outside the target region. This, however, could prove impossible for a sustained, long-term RM. In turn, regional RM during limited time periods could prove more feasible without effects beyond the target area. It may be attractive as it potentially provides the opportunity to target the suppression of some extreme events such as heat waves. Research is needed on the traceability of regional RM, for example, using detection and attribution methods. Incentives and implications of regional RM need to be examined, and new governance options have to be conceived.
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Oliveira, Vanessa Bezerra de Menezes. "Soil function and biodiversity: regional variations and climate changes." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11352.
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Doutoramento em BiologiaEmbora o objetivo principal da proteção internacional dos solos seja proteger tanto as funções quanto a estrutura do solo, a atual abordagem trata principalmente da proteção ao nível estrutural. Há uma carência de estudos que contemplem a ligação das funções do solo com os níveis da comunidade. Além disso, é ainda desconhecido se as variáveis ambientais (ex: tipos de solo, condições climáticas) atuam nas funções do solo da mesma maneira que influenciam sua estrutura biológica. Ademais, as alterações climáticas poderão ter sozinhas ou combinadas com os poluentes, um grande efeito nos ecossistemas terrestres. O presente trabalho propõe estudar as funções e a estrutura biológica do solo quando impactados devido a estresse tóxico (poluição por Cu) e/ou alterações a fatores como a temperatura e abundância de organismos, de maneira a simular possíveis variações regionais ou climáticas. Para alcançar os objetivos principais 3 experiências utilizando diferentes densidades de E. crypticus e 2 gerações foram feitas (Capítulos II e III). Duas experiências com mesocosmos (SMS) decorreram durante 3 meses sob uma gama de diversas temperaturas (10 – 29°C), que representam temperaturas médias para Portugal e Dinamarca (Capítulos IV e V). Duas experiências de campo também foram realizadas com intuito de validar os SMSs (Capítulo VI). Resultados demonstraram que os efeitos do Cu na reprodução dos enquitraídeos dependem da densidade inicial de organismos, especialmente na 2ª geração. Entretanto, nos SMSs expostos a Cu, a densidade inicial é menos importante nos resultados finais. O aumento da temperatura alterou majoritariamente a fase inicial de crescimento populacional. Em períodos mais longos, a abundância estabilizou tornando-se menos influenciada pelas temperaturas. Períodos longos de exposição reforçaram os efeitos da temperatura, como por ex: diversas espécies foram similarmente afetadas a 29 ou 26°C quando expostas durante 28 ou 61 dias respectivamente. De forma geral, o Cu reduziu a abundância da maioria das espécies ao longo do tempo, com poucas exceções. Os resultados da decomposição da matéria orgânica (MO) e atividade alimentar associaram-se com a abundância de organismos em baixas temperaturas (10-23°C). Entretanto, com o aumento das temperaturas (19-29°C), este comportamento não foi claro e a abundância de espécies e atividade alimentar diminuíram enquanto a decomposição da MO aumentou. Além disso, os resultados observados nos SMSs foram confirmados no campo. Mais especificamente, alterações ocorreram na fase de crescimento (correspondente à Primavera) e a exposição ao Cu diminuiu os efeitos da temperatura. Metodologias mais complexas (ex: mais gerações e experiências com múltiplas espécies) apresentam muitos benefícios, mas também proporcionam respostas mais complexas, as quais exigem um maior “peso” de evidências para serem comprovadas.
Although the main aim for international soil protection is to protect both the soil structure and the soil function, the current soil protection approach mainly deals with protecting the soil structure level. There is a lack of studies that link the community level with soil function. Additionally, it is unknown if the environmental variables (e.g. soil type, climate conditions) are acting on function in the same way they influence the biological soil structure. On top of this, climate change will alone and in combination with pollution have a strong effect on the terrestrial ecosystem. In the present work the soil biological structure and function were studied when impacted due to a toxic stress (Cu pollution) and due to changes in factors such as organisms’ abundance, and temperature, simulating ecological aspects, regional and climate changes. To achieve the main goals 3 experiments using different densities of E. crypticus and two generations were performed and culminated in two papers (Chapters II & III). Two multispecies experiments (SMS) were conducted until 3 months and under various temperatures (10-29˚C), representing the span of average temperatures for Denmark and Portugal (Chapters IV & V). Two Field experiments were also performed in order to validate the results of the SMSs (Chapter VI). Results showed that the effect of Cu on reproduction does depend on the density, especially so in the succeeding generation. Nevertheless, in the SMS test with Cu, the initial density is less important for the outcome. Increased temperature in the SMSs caused major changes in the abundance, mainly in the initial phase of population growth. At longer exposures the population abundance stabilized and became less influenced by temperatures. The longer exposure enforced the temperature effects, e.g. for several species effects at 29ºC-28 days were similar to 26ºC-61 days. Copper caused a general depression in abundance over time for most species with a few exceptions. The OM decomposition and feeding activity responses at low temperature (10-23°C) were associated with the increase in species abundance whereas this was less clear at high temperatures (19-29°C), here with a decrease in feeding activity and species abundance but increase in OM decomposition. Additionally, responses observed in the SMSs were confirmed in the field. In specific, changes occurred in the growth phase (corresponding to the late spring exposure) and Cu depressed the temperature responses. More complex approaches (i.e. more generations and multispecies approach) has many benefits, but provides also more complex answers that may require more weight of evidence.
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Inthacha, Sujittra. "The climatology of Thailand and future climate change projections using the regional climate model precis." Thesis, University of East Anglia, 2011. https://ueaeprints.uea.ac.uk/36354/.
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The climate of Thailand has not been studied in as much depth as in other parts of continental Southeast Asia. The baseline climate of Thailand during 1961-1990 is first analysed using daily observational data from five surface stations, each representing a different region of Thailand, supplemented by the high resolution 0.5° monthly gridded observational dataset, CRUTS2.1. The latter leads to a deeper understanding of the spatial variation in seasonal cycles of key climate variables in Thailand. Also revealed is an increase in the number of tropical depressions crossing Thailand during La Niña years. It was found that there is a statistically significant intensification (reduction) of precipitation during La Niña (El Niño) years at Surat Thani (Chiang Mai) in southern (northern) Thailand during ON (JJAS). This work facilitates the Regional Climate Model validation work which follows. The Providing REgional Climates for Impact Studies regional climate model, PRECIS, was run for the first time over Southeast Asia to specifically study the climate of Thailand. The first phase is model validation during the 1961-1990 baseline period. An ensemble of RCM runs is undertaken to study the sensitivity to the driving GCM. The added value provided by PRECIS in comparison to the coarser driving models is discussed. The possible causes of model bias are investigated. The model projections for the end of this century are undertaken based on high (SRESA2) and low (SRES-B2) emission scenarios which estimate the range of possible climate change in Thailand. These RCM simulations suggest trends in temperature that are broadly in line with those reported by IPCC. PRECIS A2 and B2 simulations mostly produce small precipitation increases in JJAS and small precipitation increases (decreases) during DJF under the A2 (B2) scenario. Wet season precipitation increases appear to be related to higher rain intensity on fewer rain days.
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Glushak, Ksenia. "Atmospheric circulation and the surface mass balance in a regional climate model of Antarctica." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1729/.
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Understanding the Earth's climate system and particularly climate variability presents one of the most difficult and urgent challenges in science. The Antarctic plays a crucial role in the global climate system, since it is the principal region of radiative energy deficit and atmospheric cooling.
An assessment of regional climate model HIRHAM is presented. The simulations are generated with the HIRHAM model, which is modified for Antarctic applications. With a horizontal resolution of 55km, the model has been run for the period 1958-1998 creating long-term simulations from initial and boundary conditions provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA40 re-analysis. The model output is compared with observations from observation stations, upper air data, global atmospheric analyses and satellite data. In comparison with the observations, the evaluation shows that the simulations with the HIRHAM model capture both the large and regional scale circulation features with generally small bias in the modeled variables. On the annual time scale the largest errors in the model simulations are the overestimation total cloud cover and the colder near-surface temperature over the interior of the Antarctic plateau. The low-level temperature inversion as well as low-level wind jet is well captured by the model.
The decadal scale processes were studied based on trend calculations. The long-term run was divided into two 20 years parts. The 2m temperature, 500 hPa temperature, MSLP, precipitation and net mass balance trends were calculated for both periods and over 1958 - 1998. During the last two decades the strong surface cooling was observed over the Eastern Antarctica, this result is in good agreement with the result of Chapman and Walsh (2005) who calculated the temperature trend based on the observational data. The MSLP trend reveals a big disparity between the first and second parts of the 40 year run. The overall trend shows the strengthening of the circumpolar vortex and continental anticyclone. The net mass balance as well as precipitation show a positive trend over the Antarctic Peninsula region, along Wilkes Land and in Dronning Maud Land.
The Antarctic ice sheet grows over the Eastern part of Antarctica with small exceptions in Dronning Maud Land and Wilkes Land and sinks in the Antarctic Peninsula; this result is in good agreement with the satellite-measured altitude presented in Davis (2005) .
To better understand the horizontal structure of MSLP, temperature and net mass balance trends the influence of the Southern Annual Mode (SAM) on the Antarctic climate was investigated. The main meteorological parameters during the positive and negative Antarctic Oscillation (AAO) phases were compared to each other. A positive/negative AAO index means strengthening/weakening of the circumpolar vortex, poleward/northward storm tracks and prevailing/weakening westerly winds. For detailed investigation of global teleconnection, two positive and one negative periods of AAO phase were chosen. The differences in MSLP and 2m temperature between positive and negative AAO years during the winter months partly explain the surface cooling during the last decades.Eine der dringendsten wissenschaftlichen Herausforderungen besteht darin, das Klimasystem der Erde und die Prozesse zu verstehen, die seine Klimavariabilität bestimmen. Die Antarktis spielt eine entscheidende Rolle im globalen Klimasystem, da sie die wesentliche Energiesenke und atmosphärische Abkühlregion darstellt. In dieser Arbeit wird das regionale Klimamodell HIRHAM zur Untersuchung des Klimas der Antarktis eingesetzt, das dafür speziell angepasst wurde. Mit einer horizontalen Auflösung von 50 km und 25 vertikalen Schichten wurden Simulationen für 40 Jahre von 1958-1998 durchgeführt, wobei die Anfangs- und Randbedingungen durch die ERA40 Daten des ECMWF (European Centre for Medium-Range Weather Forecasts) geliefert wurden. Die Modellergebnisse wurden mit Daten von Beobachtungsstationen, aerologischen Vertikalsondierungen, globalen Analysedaten und Satellitendaten verglichen. Diese Validierung zeigt, dass die HIRHAM Modellsimulationen die globalen und regionalen Zirkulationsmuster mit einem vertretbaren Modellfehler generieren. Auf der jährlichen Zeitskale zeigen sich die größten Modellfehler in einer Überbestimmung der totalen Wolkenbedeckung und der kalten bodennahen Temperaturen der Atmosphäre. Die bodennahen Inversionen und katabatischen Windsysteme werden durch das Modell gut wiedergegeben. Dekadische Prozesse wurden durch Trendberechnungen analysiert. Dazu wurden die 40 Jahre umfassenden Simulationen in zwei 20 Jahre Abschnitte von 1958-1978 und 1979-1998 unterteilt. Die Trends in den 2m Temperaturen, im mittleren Bodenluftdruck, 500 hPa Geopotential, Niederschlag und der Netto Massenbilanz wurden berechnet. In den letzten zwei Dekaden wurde eine starke atmosphärische Abkühlung an der Oberfläche in der Ostantarktis simuliert, die in guter Übereinstimmung mit den Trendanalysen aus Beobachtungen von Chapman und Walsh (2005) steht. Der Trend im mittleren Bodenluftdruck weist deutliche Unterschiede zwischen den ersten Periode 1958-1978 und der zweiten Periode 1979-1998 auf. Insgesamt verstärkt sich über die untersuchten 40 Jahre der zirkumpolare Tiefdruckwirbel und die kontinentale Antizyklone. Die Nettomassenbilanz und der Niederschlag zeigen einen positiven Trend über der Antarktischen Halbinsel, Wilkes Land und Dronning Maud Land. Das antarktische Eisschild wächst im östlichen Teil der Antarktis mit geringen Ausnahmen in Dronning Maud Land und Wilkes Land an und schächt sich über der antarktischen Halbinsel ab. Dieses Resultat befindet sich in Übereinstimmung mit den Akkumulationstrends von Davis (2005) auf der Basis von Satellitendaten. Die horizontalen Strukturen der simulierten antarktischen Trends im mittleren Bodenluftdruck, in der 2m Temperatur und der Netto Massenbilanz wurden mit Trends des globalen Telekonnektionsmusters der Südhemisphäre verglichen. Dazu wurden wesentliche atmosphärische Parameter für positive und negative Phasen der Antarktischen Oszillation (AAO) analysiert. Die positiven/negativen AAO Phasen gehen einher mit einer Verstärkung/Abschwächung des zirkumpolaren Tiefdruckwirbels, verstärkten/reduzierten Stormtracks und verstärkten/abgeschwächten Westwinden. Für eine tiefergehende Untersuchung wurden zwei positive und eine negative AAO Phase miteinander verglichen. Die Unterschiede im Bodenluftdruck und der 2m Temperatur zwischen den positiven und negativen AAO Perioden können den Abkühlungstrend während der letzten Dekaden zu großen Teilen erklären.
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Mundakkara, Ravi Varma. "Validation of the Canadian Regional Climate Model using spectral analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0027/MQ50842.pdf.
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Pfeifer, Susanne. "Modeling cold cloud processes with the regional climate model REMO /." Hamburg : Max-Planck-Inst. für Meteorologie, 2006. http://edoc.mpg.de/get.epl?fid=18331&did=261718&ver=0.
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Mundakkara, Ravi Varma. "Validation of the Canadian Regional Climate Model using spectral analysis." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21611.
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Spectra for various meteorological fields are computed using the two-dimensional Fourier transform technique on a limited-area grid of the Regional finite-element (RFE) model and the Canadian Regional Climate Model (CRCM). Limitations of removing the linear trend from the fields, and thereby removing the large-scale variance, are discussed. The spectra of difference fields are calculated, yielding the error variance for different scales.Spectral methods are used widely in the evaluation of global models. In this study, the same method is used for evaluating the CRCM in its ability to correctly reproduce the mesoscale systems in short-term integrations, when low-resolution GCM-like initial and lateral boundary conditions are provided. Two cases have been chosen for this study, the first one over the Montreal region and second one over the Mackenzie River Basin (MRB). It is found that the relative error variance growth at most scales, particularly the small scales, is less for the MRB region possibly due to the topographic forcing. In both cases and all experiments, the maximum relative error variance is found to be at a wavelength of about 350-km.
Root mean square (rms) error and relative rms error for the geopotential height field for both cases are very small and show little or no growth, when scale decompositions are not made. However, the relative error variance when examined according to scale, show considerable differences. The relative errors at different scales show different growth rates and that of the meso-alpha and synoptic scales are found to be growing with time.
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Burmeister, Johannes [Verfasser]. "Essays on the Economics of Regional Climate Policy / Johannes Burmeister." Kiel : Universitätsbibliothek Kiel, 2019. http://d-nb.info/1190644665/34.
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Kasoar, Matthew. "Local and remote impacts of regional aerosol emissions on climate." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/42501.
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Aerosols are short-lived in the atmosphere, and so their distribution and climate forcing is very inhomogeneous. To understand the behaviour of the climate system in response to inhomogeneous forcing, and to inform emission policy choices, we must investigate how emissions from individual geographic regions affect the climate regionally and globally. I present here the results of two interwoven modelling studies. First, I analyse the simulated temperature response to perturbing sulfur dioxide emissions over a specific region – China – in three current generation climate models. Second, I systematically investigate with a single model the temperature and precipitation responses to black carbon and sulfur dioxide emissions from the United States, Europe, East Asia, and India. These simulations reveal in the first instance that there is very large uncertainty around aerosol-climate interactions in present climate models. Removing SO2 emissions from China results in a six-fold difference in the optical depth and short-wave flux changes over China between different models, and the resulting surface temperature response is poorly constrained. However, the subsequent systematic perturbations indicate that in the event the regional forcing is large, then there are striking features of the climate response that are consistent across different perturbation locations. Emission changes always result not only in a strong local response around the emission region, but also a strong remote response, the pattern of which is insensitive to the original location of emission changes. There is, however, variation in the efficacy with which emissions from different regions force the climate, with US and European sulphur dioxide emission changes having a larger effect than East Asian emission changes. The results presented here are relevant for understanding the effect of potential future emission controls, and also for understanding how the climate responds to different localised forcings, which has not been tested in complex coupled climate models previously.
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Wrzesien, Melissa Leigh. "Estimating North American montane snowpack with regional climate model simulations." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1522762079858684.
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Liao, Kuo-Jen. "Sensitivity and uncertainty analyses of impacts of climate change on regional air quality." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24822.
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Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Armistead G. Russell; Committee Member: Athanasios Nenes; Committee Member: M. Talat Odman; Committee Member: Michael Bergin; Committee Member: Yuhang Wang.
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Pardikes, Nicholas A. "Global Change and Trophic Interaction Diversity| Complex Local and Regional Processes." Thesis, University of Nevada, Reno, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10282934.
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The structure and functioning of ecosystems across the globe are rapidly changing due to several components of global environmental change (GEC). My dissertation aims to illustrate how regional and local aspects of GEC impact diverse assemblages of species and species interactions. All organisms are embedded in complex networks of species interactions, and future efforts to predict and mitigate the impacts of GEC on ecological communities will be facilitated by such studies that incorporate a suite of species and species interactions. This study advances our understanding of how GEC will impact ecological communities by investigating two questions about GEC: 1) How will shifts in global climate cycles (e.g., El Nino Southern Oscillation), as a consequence of global warming, impact a diverse assemblage of butterflies that exist across a heterogeneous landscape? 2) What are the consequences of woody plant encroachment on complex, specialized interactions between plants, insect herbivores, and natural enemies (e.g., insect parasitoids)? Furthermore, I helped develop a tool to identify characteristics of ecological communities that are essential for promoting the diversity of trophic interactions. While the loss of species diversity is well recognized, interactions among species are vanishing at an astonishing rate, yet we know little about factors that determine the diversity of interactions within a community. Using data from a long-term butterfly monitoring dataset, I was able to demonstrate the utility of large-scale climate indices (e.g., ENSO) for modeling biotic/abiotic relationships for migratory butterfly species. Next, I used encroaching juniper woodlands in the Intermountain West to uncover that population age structure of dominant tress, such as juniper, can affect plant-insect dynamics and have implications for future control efforts in the expanding woodlands. Additionally, reductions of understory plant diversity, as a consequence of juniper expansion, resulted in significantly lower parasitism rates and parasitoid species diversity. Finally, simulated food webs revealed that species diversity and, to a lesser degree, consumer diet breadth, promote the diversity of trophic interactions. As ecosystems across the globe experience changes and the loss of species diversity continues, these findings offer insight into how GEC will impact species and species interactions.
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Risbey, James S. (James Sydney). "On the use of climate models to assess the impacts of regional climate change on water resources." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/57652.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.Includes bibliographical references (p. 207-213).
by James Sydney Risbey.
Ph.D.
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Osima, Sarah Emerald. "Understanding a high resolution regional climate model's ability in simulating tropical East Africa climate variability and change." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16716.
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Includes bibliographical referencesThe main aim of this thesis is to investigate the potential benefits of increasing resolution in regional climate models in the simulation of climate variability and change over East Africa. This study is based on two high resolution regional climate simulations with a horizontal resolution of 50km and 10km, respectively. These represent present day climate and a projection of future climate change over East Africa. The regional climate model (RCM) used here is HIRHAM5, which is driven by the global circulation model (ECHAM5). Downscaled ECHAM5 output is used to drive the 50km HIRHAM5 simulation for the period 1950-2100, and output from this simulation is used to drive the 10km simulation for three time slices: 1980-1999, representative for present-day climate and two time slices for near future (2046-2065) and far future (2080- 2099), respectively. HIRHAM5 is evaluated with respect to the observed mean climatologies of rainfall, surface temperature and surface winds over East Africa, and representations of the observed annual cycles and inter-annual variability of rainfall and surface temperature. This study utilizes reanalysis and observational datasets: a hindcast of HIRHAM5 forced with ERA Interim, as well as two observation datasets for temperature and rainfall. Since reanalyses aim to make "best use" of all available observations by making a physically consistent representation continuous in time and space, and since there is a paucity of observations over many parts of Africa, the ERAI reanalysis is also used as a best estimate for model evaluation. Additionally, for evaluation of the bimodal nature of East Africa's rainfall, especially over Tanzania, three stations run by the Tanzania Meteorological Agency were used. The model data used in th is evaluation ranges from 1980 to 2006 iv HIRHAM5 demonstrates reasonable skill in the reproduction of observed patterns of mean climatology of rainfall, surface temperature and winds over East Africa. Moreover, the patterns of annual cycles of rainfall and surface temperature in the bimodal nature of East Africa are well represented. Furthermore, the model showed reasonable skill in the representation of the inter- annual variability and ENSO signals as suggested by the observation. Despite these strengths, HIRHAM5 shows some shortcomings. One weakness of the model is the simulation of the magnitude of a given variable over a specific region. For example, HIRHAM5 driven by ERAI underestimates rainfall and overestimates surface temperature over the entire domain of East Africa. The higher resolution HIRHAM5 (10km resolution) overestimates rainfall over high ground. The model bias could be due in part to the inadequacy of the observation networks in East Africa, represented in this thesis by the CRU and FEWS datasets. However, these two datasets draw on some different sources and neither do they have the same resolution. FEWS is a high resolution data (0.1 o ) gridded satellite-derived precipitation estimate covering the entire African continent while CRU datasets is a relatively low resolution (0.5 o ) dataset based on rain gauge monthly precipitation only; in addition , near surface temperature is also available. As no reliable wind observations exist, wind data was taken from the ERA-Interim reanalysis. The different observational datasets do not agree particularly well, which impedes evaluating the quality of the HIRHAM5 simulations, in particular the high resolution one. So while the higher resolution HIRHAM5 appears to be generally reliable, caution must be exercised in formulating conclusions from the results, especially over high ground and remote areas without adequate observation data. Under these constraints, the results suggest HIRHAM5 may be useful for assessing climate variability and change over East Africa. A weakness of the analysis presented here is that only one combination of GCM and RCM could be investigated in depth due to computer and time constraints. Therefore the results presented here, if used in application for climate change adaptation, should be considered in conjunction with a broader suite of data, such from the CORDEX programme. This has potential to increase the reliability of information about climate variability and change at a regional to local level necessary for impact assessment.
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Chandrasa, Ganesha Tri. "Evaluation of Regional Climate Model Simulated Rainfall over Indonesia and its Application for Downscaling Future Climate Projections." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523464961178694.
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May, Christopher. "The use and application of performance metrics with regional climate models." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59406/.
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This thesis aims to assess and develop objective and robust approaches to evaluate regional climate model (RCM) historical skill using performance metrics and to provide guidance to relevant groups as to how best utilise these metrics. Performance metrics are quantitative, scalar measures of the numerical distance, or ’error’, between historical model simulations and observations. Model evaluation practice tends to involve ad hoc approaches with little consideration to the underlying sensitivity of the method to small changes in approach. The main questions that arise are to what degree are the outputs, and subsequent applications, of these performance metrics robust? ENSEMBLES and CORDEX RCMs covering Europe are used with E-OBS observational data to assess historical and future simulation characteristics using a range of performance metrics. Metric sensitivity is found in some cases to be low, such as differences between variable types, with extreme indices often producing redundant information. In other cases sensitivity is large, particularly for temporal statistics, but not for spatial pattern statistics. Assessments made over a single decade are found to be robust with respect to the full 40-year time period. Two applications of metrics are considered: metric combinations and exploration of the stationarity of historical RCM bias characteristics. The sensitivity of metric combination procedure is found to be low with respect to the combination method and potentially high for the type of metric included, but remains uncertain for the number of metrics included. Stationarity of biases appears to be highly dependent on the potential for underlying causes of model bias to change substantially in the future, such as the case of surface albedo in the Alps. It is concluded that performance metrics and their applications can and should be considered more systematically using a range of redundancy and stationarity tests as indicators of historical and future robustness.
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Ummenhofer, Caroline C. Mathematics & Statistics Faculty of Science UNSW. "Southern hemisphere regional precipitation and climate variability : extrems trends and prdictability." Awarded by:University of New South Wales. Mathematics & Statistics, 2008. http://handle.unsw.edu.au/1959.4/41253.
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This PhD thesis investigates the relative importance of oceanic and atmospheric influences on extremes, long-term trends, and seasonal to interannual variability of precipitation for different regions in the Southern Hemisphere in observations, reanalysis data, and output from general circulation models (GCM). Examination of interannual rainfall extremes over southwest Western Australia (SWWA) reveals a characteristic dipole pattern of Indian Ocean sea surface temperature anomalies (SSTA). This coincides with a large-scale reorganization of the wind field over the tropical/subtropical Indian Ocean changing SSTA, via anomalous Ekman transport in the tropical Indian Ocean and via anomalous air-sea heat fluxes in the subtropics, and altering moisture advection onto SWWA. The potential impact of these Indian Ocean SSTA in driving modulations of mid-latitude precipitation across southern and western regions of Australia is assessed in atmospheric GCM simulations. The SSTA give rise to changes in the thermal properties of the atmosphere, meridional thickness gradient, subtropical jet, thermal wind, and baroclinicity over southern regions of Australia, thus modulating precipitation. In addition, links between anomalous wet conditions over East Africa and these characteristic Indian Ocean SSTA are explored during the "short rain" season in October-November. Interannual extremes m New Zealand rainfall and their modulation by modes of Southern Hemisphere climate variability, namely the Southern Annular Mode (SAM) and El Nino-Southern Oscillation (ENSO), are investigated. Late twentieth Century trends in New Zealand precipitation are examined for the period 19792006 to quantify the relative impact of recent changes in the large-scale atmospheric circulation related to the SAM and ENSO. Increasingly drier conditions over much of New Zealand can be partially explained by the SAM and ENSO. Cool season rainfall variability in southeastern Australia is investigated via a classification and characterization of the predominant types of synoptic systems occurring in the region, focusing on frontal and cutoff low systems. Two definitions of the autumn break developed for northwestern Victoria are employed to produce a synoptic climatology of the break phenomenon. Trends in characteristics of the autumn break indicate that the most recent drought in southeastern Australia is comparable in severity with the two major droughts in the twentieth Century.
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Kgatuke, Mary-Jane Morongwa. "Internal variability of the regional climate model RegCM3 over Southern Africa." Diss., Pretoria [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08132007-091356.
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Nawdiyal, Manish [Verfasser], and Eberhard [Akademischer Betreuer] Schaller. "Effect of mining on regional climate / Manish Nawdiyal ; Betreuer: Eberhard Schaller." Cottbus : BTU Cottbus - Senftenberg, 2015. http://d-nb.info/1114665258/34.
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Hoffmann, Holger [Verfasser]. "Abiotic impact of regional climate change on horticultural production / Holger Hoffmann." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2013. http://d-nb.info/1047351730/34.
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Corfee, Morlot J. "California in the greenhouse : regional climate policies and the global environment." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/16122/.
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This thesis explores how climate policy is developing at sub-national or “regional” scales of decision-making. It considers local-global connections on both the science and the politics of climate change by investigating four main research questions as they pertain to regional climate action: What triggers regional policy action on global climate change? What arguments and lines of evidence underlie the policy discourse? How do “winning” arguments gain salience? How does regional action make a difference to broader scale climate policy? The research is conducted through one in-depth case study in California. It shows that action on climate change mitigation in California is enabled in part by past action in related policy arenas of air pollution control and energy policy within a multilevel, social-practice environmental governance framework. More recently the emergences of a comprehensive policy framework is triggered by a unique policy window where a change in California’s leadership capitalised on the void of federal policy to reframe arguments for state-level action on climate change. The case study identifies two dominant policy frames leading to a third master frame or meta-narrative in the period 2004-6: i) climate change as a problem of regional environment risk; ii) mitigation policy as a “win-win” for the local economy and the environment; iii) climate change as a regional policy issue. This period represents a paradigm shift from a previous dominant framing that characterised climate change as predominantly a national rather than a state policy issue. The case study shows that today’s dominant policy frames rely upon a process of co-construction that combine insights from expert and local knowledge, thus intertwining “facts” and “ values in the policy process. “Winning arguments” or policy frames gain salience through a relatively open policy process, which permits an array of non-governmental actors -- including social movement organisations, business organisations and experts -- to operate in the outer-periphery of the policy process and generate ideas in a timely way to influence policy decisions. The research underscores the power of localising problems of global environmental change and their solutions, of taking up climate change as a regional policy issue where solutions can be tapered to reflect regional contexts and norms. It shows that there is a relatively larger scope for experimentation and social and technical innovation at regional scale, compared to broader scales of action, which can open the way for cross-scale learning and influence to emerge.
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Winter, Jonathan (Jonathan Mark). "Coupling of Integrated Biosphere Simulator to Regional Climate Model version 3." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34272.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 93-102).
Presented in this thesis is a description of the coupling of Integrated Biosphere Simulator (IBIS) to Regional Climate Model version 3 (RegCM3), and an assessment of the coupled model (RegCM3-IBIS). RegCM3 is a 3-dimensional, primitive equation limited area model used throughout the world for seasonal predictability and regional climate studies. IBIS is a dynamic global vegetation model that includes representations of land surface processes, canopy physiology, vegetation phenology, terrestrial biogeochemistry, and vegetation dynamics. A single subroutine was created that allows RegCM3 to use IBIS instead of Biosphere-Atmosphere Transfer Scheme 1 e (BATS 1 e) for surface physics calculations. In addition to coupling the two models, a revised initialization scheme was implemented for RegCM3-IBIS, including an IBIS specific prescription of vegetation and soil types, as well as a new scheme for initializing soil moisture, soil ice, and soil temperature based on simulations using the offline version of IBIS. A series of six 1-year numerical experiments were completed to assess the ability of RegCM3-IBIS to simulate the energy and water budgets, as well as surface temperature.
(cont.) The evaluation of RegCM3-IBIS was primarily based on NCEP reanalysis data, and when available, assessment with respect to NASA Surface Radiation Budget data was also included. While RegCM3-IBIS shows reasonable agreement with observations and reanalysis, a deterioration in the ability of RegCM3-IBIS to simulate, most notably, 2 m temperature and latent heat flux, is observed with respect to RegCM3 using BATS l e. However, many aspects of the RegCM3-IBIS results are encouraging, and the problems seen in the untuned version of RegCM3-IBIS are likely to be resolved given further analysis and tuning of parameters.
by Jonathan Winter.
S.M.
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Sá, Maria Elisa Seabra Azevedo Cunha e. "Regional and urban air quality modelling under a climate change scenario." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14518.
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Doutoramento em Ciências e Engenharia do AmbienteThe better understanding of the interactions between climate change and air quality is an emerging priority for research and policy. Climate change will bring changes in the climate system, which will affect the concentration and dispersion of air pollutants. The main objective of the current study is to assess the impacts of climate change on air quality in 2050 over Portugal and Porto urban area. First, an evaluation and characterization of the air quality over mainland Portugal was performed for the period between 2002 and 2012. The results show that NO2, PM10 and O3 are the critical pollutants in Portugal. Also, the influence of meteorology on O3, NO2 and PM10 levels was investigate in the national main urban areas (Porto and Lisboa) and was verified that O3 has a statistically significant relationship with temperature in most of the components. The results also indicate that emission control strategies are primary regulators for NO2 and PM10 levels. After, understanding the national air quality problems and the influence that meteorology had in the historical air quality levels, the air quality modelling system WRF-CAMx was tested and the required inputs for the simulations were prepared to fulfil the main goal of this work. For the required air quality modelling inputs, an Emission Projections under RCP scenarios (EmiPro-RCP) model was developed to assist the estimation of future emission inventories for GHG and common air pollutants. Also, the current emissions were estimated for Portugal with a higher detailed disaggregation to improve the performance of the air quality simulations. The air quality modelling system WRF/CAMx was tested and evaluated over Portugal and Porto urban area and the results point out that is an adequate tool for the analysis of air quality under climate change. For this purpose, regional simulations of air quality during historical period and future (2045-2050) were conducted with CAMx version 6.0 to evaluate the impacts of simulated future climate and anthropogenic emission projections on air quality over the study area. The climate and the emission projections were produced under the RCP8.5 scenario. The results from the simulations point out, that if the anthropogenic emissions keep the same in 2050, the concentrations of NO2, PM10 and O3 will increase in Portugal. When, besides the climate change effects, is consider the projected anthropogenic emissions the annual mean concentrations of NO2 decrease significantly in Portugal and Porto urban area, and on the contrary the annual mean PM10 concentrations increases in Portugal and decrease in Porto urban area. The O3 results are mainly caused by the reduction of ozone precursors, getting the higher reductions in urban areas and increases in the surrounding areas. All the analysis performed for both simulations for Porto urban area support that, for PM10 and O3, there will be an increase in the occurrence of extreme values, surpassing the annual legislated parameters and having more daily exceedances. This study constitutes an innovative scientific tool to help in future air quality management in order to mitigate future climate change impacts on air quality.
A interação entre as alterações climáticas e a qualidade do ar é neste momento um assunto emergente em termos de implementação de políticas e de investigação. As alterações climáticas causarão mudanças no clima, o que irá afetar a concentração e dispersão dos poluentes atmosféricos. Assim, o principal objetivo deste trabalho é avaliar os impactos das alterações climáticas na qualidade do ar em 2050 em Portugal e na área urbana do Porto. Numa primeira fase, realizou-se uma caracterização da qualidade do ar em Portugal para o período de 2002 a 2012, na qual se identificou que os poluentes NO2, PM10 e O3 são os mais críticos em termos de qualidade do ar. Adicionalmente, foi analisada a influência da meteorologia na qualidade do ar para esses três poluentes nas duas maiores áreas urbanas nacionais (Porto e Lisboa), sendo que o O3 é estatisticamente dependente da temperatura na maioria das suas componentes. Após o entendimento dos problemas de qualidade do ar nacionais e da influência da meteorologia nos mesmos, o sistema de modelos WRF-CAMx foi testado e todos os seus dados de entrada foram preparados. As emissões nacionais atuais foram estimadas com maior detalhe de desagregação para melhorar as simulações de qualidade do ar; o modelo de emissões, EmiPro-RCP, foi desenvolvido para estimar as emissões de 2050 tendo em conta os cenários de emissão RCPs. O sistema de modelos WRF-CAMx foi testado e avaliado para Portugal e para a área urbana do Porto, verificando-se que é uma ferramenta adequada para realizar as simulações de qualidade do ar em cenário climático. Realizaram-se simulações regionais com o modelo CAMx versão 6.0, para dois períodos: histórico e futuro (2045-2050), de forma a simular os impactos do clima futuro e das futuras emissões antropogénicas na qualidade do ar para a região de estudo. O cenário climático, bem como as emissões, foram projetadas tendo como base o cenário RCP8.5. Os resultados provenientes das simulações demonstram que, se as emissões antropogénicas se mantiverem constantes em 2050, as concentrações de NO2, PM10 e O3 irão aumentar em Portugal. Quando, aos efeitos das alterações climáticas se juntaram as futuras emissões antropogénicas, verifica-se que as concentrações médias anuais de NO2 irão diminuir e as concentrações médias anuais de PM10 aumentam em Portugal e diminuem na área urbana do Porto. Os resultados de O3 estão relacionados com as variações de concentração dos seus precursores, verificando-se as maiores reduções nas áreas urbanas e os aumentos nas áreas suburbanas. Toda a análise realizada aos dados das simulações para a área urbana do Porto indica que, no caso de PM10 e O3, irá existir um aumento de ocorrência de valores extremos de concentração, ultrapassando os valores legislados de cada poluente. Este estudo constitui uma ferramenta científica inovadora que pode ser relevante para uma futura e cuidada gestão da qualidade do ar, de forma a mitigar os impactes das alterações climáticas na qualidade do ar.
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Bannister, Daniel. "Föhn winds on South Georgia and their impact on regional climate." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/56865/.
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South Georgia is a small and mountainous island, located in the remote Southern Ocean. The island’s subantarctic climate is controlled by its location and steep orography; with 19 peaks over 2000m and situated within a belt of strong westerly winds South Georgia acts as an effective barrier to the winds that impinge upon it. Since the 1920s, average summer temperatures have risen by ~1oC on South Georgia. Coupled with this has been an increase in the rate of glacial retreat throughout the last century, with glaciers on the northeast leeside of the island retreating at a faster rate than those on the southwest side. These asymmetrical changes are thought to be linked with the strengthening of the westerlies. If the strength of the westerlies is sufficient, downslope winds can develop on the leeside of the island causing significant temperature increases as the descending air warms adiabatically; this is known as the föhn effect. Therefore, the aim of this thesis is to investigate whether the observed asymmetric pattern of regional warming and glacier retreat are caused by the föhn warming process. To explore the link between the föhn effect and its impact on the regional climate of South Georgia, a 10 year climatology (2003 – 2012) of föhn events is created. Using automatic weather station observations to identify abrupt changes in temperature, humidity and wind speed, it is found that föhn events are frequently observed (874 events are identified in total) with one event occurring every four days. Following this, sensitivity simulations with the Weather Research and Forecasting model for four föhn cases studies are presented, with the aim of deducing the optimal model setup for South Georgia. The model analysis is largely supported by observations, and föhn flow is well captured at high (< 3.3km) horizontal resolution. With the model optimised for South Georgia, a 21 month model run (at 0.9km resolution) produces the first ever detailed regional climatology of South Georgia. The results from this simulation illustrate the asymmetrical impact of föhn on the island’s climate. During September 2011 – August 2012, modelled föhn events produced +2oC air temperature anomalies and up to 3m water equivalent ablation at the termini of South Georgia’s north-eastern glaciers. This supports the view that föhn is partly responsible for the asymmetrical retreat of glaciers, via enhanced leeside surface warming and melting. These results support the original hypothesis that an enhancement of the föhn warming process could have implications on future asymmetrical warming and melt.
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Yang, Zhao, Francina Dominguez, Xubin Zeng, Huancui Hu, Hoshin Gupta, and Ben Yang. "Impact of Irrigation over the California Central Valley on Regional Climate." AMER METEOROLOGICAL SOC, 2017. http://hdl.handle.net/10150/625202.
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Irrigation, while being an important anthropogenic factor affecting the local to regional water cycle, is not typically represented in regional climate models. An irrigation scheme is incorporated into the Noah land surface scheme of the Weather Research and Forecasting (WRF) Model that has a calibrated convective parameterization and a tracer package is used to tag and track water vapor. To assess the impact of irrigation over the California Central Valley (CCV) on the regional climate of the U.S. Southwest, simulations are run (for three dry and three wet years) both with and without the irrigation scheme. Incorporation of the irrigation scheme resulted in simulated surface air temperature and humidity that were closer to observations, decreased depth of the planetary boundary layer over the CCV, and increased convective available potential energy. The result was an overall increase in precipitation over the Sierra Nevada range and the Colorado River basin during the summer. Water vapor rising from the irrigated region mainly moved northeastward and contributed to precipitation in Nevada and Idaho. Specifically, the results indicate increased precipitation on the windward side of the Sierra Nevada and over the Colorado River basin. The former is possibly linked to a sea-breeze-type circulation near the CCV, while the latter is likely associated with a wave pattern related to latent heat release over the moisture transport belt.
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Meissner, Cathérine. "High-resolution sensitivity studies with the regional climate model COSMO-CLM." Karlsruhe Univ.-Verl. Karlsruhe, 2008. http://d-nb.info/992844436/04.
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Lange, Stefan. "On the evaluation of regional climate model simulations over South America." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17342.
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Diese Dissertation beschäftigt sich mit regionaler Klimamodellierung über Südamerika, der Analyse von Modellsensitivitäten bezüglich Wolkenparametrisierungen und der Entwicklung neuer Methoden zur Modellevaluierung mithilfe von Klimanetzwerken. Im ersten Teil untersuchen wir Simulationen mit dem COnsortium for Small scale MOdeling model in CLimate Mode (COSMO-CLM) und stellen die erste umfassende Evaluierung dieses dynamischen regionalen Klimamodells über Südamerika vor. Dabei untersuchen wir insbesondere die Abhängigkeit simulierter tropischer Niederschläge von Parametrisierungen subgitterskaliger cumuliformer und stratiformer Wolken und finden starke Sensitivitäten bezüglich beider Wolkenparametrisierungen über Land. Durch einen simultanen Austausch der entsprechenden Schemata gelingt uns eine beträchtliche Reduzierung von Fehlern in klimatologischen Niederschlags- und Strahlungsmitteln, die das COSMO-CLM über tropischen Regionen für lange Zeit charakterisierten. Im zweiten Teil führen wir neue Metriken für die Evaluierung von Klimamodellen bezüglich räumlicher Kovariabilitäten ein. Im Kern bestehen diese Metriken aus Unähnlichkeitsmaßen für den Vergleich von simulierten mit beobachteten Klimanetzwerken. Wir entwickeln lokale und globale Unähnlichkeitsmaße zum Zwecke der Darstellung lokaler Unähnlichkeiten in Form von Fehlerkarten sowie der Rangordnung von Modellen durch Zusammenfassung lokaler zu globalen Unähnlichkeiten. Die neuen Maße werden dann für eine vergleichende Evaluierung regionaler Klimasimulationen mit COSMO-CLM und dem Statistical Analogue Resampling Scheme über Südamerika verwendet. Dabei vergleichen wir die sich ergebenden Modellrangfolgen mit solchen basierend auf mittleren quadratischen Abweichungen klimatologischer Mittelwerte und Varianzen und untersuchen die Abhängigkeit dieser Rangfolgen von der betrachteten Jahreszeit, Variable, dem verwendeten Referenzdatensatz und Klimanetzwerktyp.This dissertation is about regional climate modeling over South America, the analysis of model sensitivities to cloud parameterizations, and the development of novel model evaluation techniques based on climate networks. In the first part we examine simulations with the COnsortium for Small scale MOdeling weather prediction model in CLimate Mode (COSMO-CLM) and provide the first thorough evaluation of this dynamical regional climate model over South America. We focus our analysis on the sensitivity of simulated tropical precipitation to the parameterizations of subgrid-scale cumuliform and stratiform clouds. It is shown that COSMO-CLM is strongly sensitive to both cloud parameterizations over tropical land. Using nondefault cumulus and stratus parameterization schemes we are able to considerably reduce long-standing precipitation and radiation biases that have plagued COSMO-CLM across tropical domains. In the second part we introduce new performance metrics for climate model evaluation with respect to spatial covariabilities. In essence, these metrics consist of dissimilarity measures for climate networks constructed from simulations and observations. We develop both local and global dissimilarity measures to facilitate the depiction of local dissimilarities in the form of bias maps as well as the aggregation of those local to global dissimilarities for the purposes of climate model intercomparison and ranking. The new measures are then applied for a comparative evaluation of regional climate simulations with COSMO-CLM and the STatistical Analogue Resampling Scheme (STARS) over South America. We compare model rankings obtained with our new performance metrics to those obtained with conventional root-mean-square errors of climatological mean values and variances, and analyze how these rankings depend on season, variable, reference data set, and climate network type.
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Andersson, Malin, and Erica Erikson. "The Ability of Regional Climate Models to Simulate Weather Conditions on Nordenskiöldbreen, Svalbard." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354430.
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In this project, we analyse the ability of two regional climate models to simulate meteorological conditions on Nordenskiöldbreen, a glacier in Svalbard. To do so, regional climate model output is compared with in situ measurements from an automatic weather station. Detailed information about the weather conditions on Nordenskiöldbreen is important for simulating the glacial mass balance in a changing climate. The parameters analysed were the following: temperature, air pressure, relative humidity, precipitation, cloud cover, wind speed and wind direction. The weather station did not measure all parameters, cloud cover was instead estimated through the incoming longwave radiation and temperature, while precipitation was calculated from snow depth. The results show that the models represent certain parameters better than others. Temperature, air pressure and wind speed and direction are found to be simulated with high precision. Poorest agreement is found for precipitation, which appears to be both difficult to simulate and observe. Relative humidity and cloud cover show average agreement with the station. The conclusion of the project is that the estimation of some of the parameters is satisfactory, while others are lacking. None of the models can be determined to have performed significantly better than the other.I det här projektet analyserades två regionala klimatmodellers förmåga att simulera meteorologiska förhållanden på Nordenskiöldbreen, en glaciär på Svalbard. Detta gjordes genom jämförelser av data från regionala klimatmodeller mot lokala mätningar från en automatisk väderstation. Detaljerad information om väderförhållandena på Nordenskiöldbreen är viktigt för att kunna simulera glaciärens massbalans i ett föränderligt klimat. Parametrarna som jämfördes var temperatur, lufttryck, relativ luftfuktighet, nederbörd, molntäcke samt vindhastighet och vindriktning. Stationen mätte inte alla parametrar, molntäcket uppskattades istället genom inkommande långvågig strålning och temperatur, medan nederbörd beräknades via snödjup. Resultatet visar att modellerna representerar vissa parametrar bättre än andra. Temperatur, lufttryck, vindhastighet och vindriktning simuleras med hög precision. Parametern med lägst samband är nederbörd, somverkar vara svår både att simulera och observera. Relativ luftfuktighet och molntäcke har ett medelmåttigt samband till stationen. Slutsatsen av projektet är att modellernas uppskattning av några parametrar är tillräckligt bra, medan andra är bristfälliga. Ingen av modellerna kan bedömas ha presterat signifikant bättre än den andra.
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Meyer, Jonathan D. D. "Modeling and Projection of the North American Monsoon Using a High-Resolution Regional Climate Model." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5802.
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This dissertation aims to better understand how various climate modeling approaches affect the fidelity of the North American Monsoon (NAM), as well as the sensitivity of the future state of the NAM under a global warming scenario. Here, we improved over current fully-coupled general circulation models (GCM), which struggle to fully resolve the controlling dynamics responsible for the development and maintenance of the NAM. To accomplish this, we dynamically downscaled a GCM with a regional climate model (RCM). The advantage here being a higher model resolution that improves the representation of processes on scales beyond that which GCMs can resolve. However, as all RCM applications are subject to the transference of biases inherent to the parent GCM, this study developed and evaluated a process to reduce these biases. Pertaining to both precipitation and the various controlling dynamics of the NAM, we found simulations driven by these bias-corrected forcing conditions performed moderately better across a 32-year historical climatology than simulations driven by the original GCM data.
Current GCM consensus suggests future tropospheric warming associated with increased radiative forcing as greenhouse gas concentrations increase will suppress the NAM convective environment through greater atmospheric stability. This mechanism yields later onset dates and a generally drier season, but a slight increase to the intensity during July-August. After comparing downscaled simulations forced with original and corrected forcing conditions, we argue that the role of unresolved GCM surface features such as changes to the Gulf of California evaporation lead to a more convective environment. Even when downscaling the original GCM data with known biases, the inclusion of these surface features altered and in some cases reversed GCM trends throughout the southwest United States. This reversal towards a wetter NAM is further magnified in future bias-corrected simulations, which suggest (1) fewer average number of dry days by the end of the 21st century (2) onset occurring up to two to three weeks earlier than the historical average, and (3) more extreme daily precipitation values. However, consistent across each GCM and RCM model is the increase in inter-annual variability, suggesting greater susceptibility to drought conditions in the future.
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INDEJE, MATAYO. "PREDICTION AND NUMERICAL SIMULATION OF THE REGIONAL CLIMATE OF EQUATORIAL EASTERN AFRICA." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000810-143914.
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INDEJE, MATAYO. Prediction and Numerical Simulation of the Regional Climate of Equatorial Eastern Africa. (Under the direction of Dr. Fredrick H. M. Semazzi.). The objective in this investigation was to provide a better understanding of the mechanisms and physical processes responsible for climate variability over the equatorial eastern Africa, and explore potential for short-term climate prediction. Both statistical and numerical methods have been employed in this research. Application of cluster analysis yields 8 and 9 homogeneous climatic zones respectively for the variability of the annual and seasonal rainfall. Regions that are prone to drought or floods during the different phases of El Niño-Southern Oscillation (ENSO) are delineated. Positive rainfall anomalies occur in much of the region during March-May (MAM) and October-December (OND) of the ENSO(0) years and negative anomalies dominate during the following ENSO(+1) years. These rainfall patterns are useful for short-term climate monitoring over the region. The relationship between the Quasi-Biennial Oscillation (QBO) in the lower stratospheric zonal winds and the long-rains of MAM is more significant in lagged than in simultaneous, with the most distinct relationships occurring over the western parts of the region. The QBO-index explains about 36% of the seasonal rainfall variance. There is a 60/63 percent likelihood for the occurrence of above/below normal rainfall during the westerly/easterly phase of the QBO-index. The NCAR Regional Climate Model (RegCM2) simulations have demonstrated the added value of the nesting approach in improving regional climate simulations. The model reproduces the observed characteristics of the Turkana low-level jet. The study has shown the importance of orographic forcing, the large-scale background monsoon flow and depth of the channel in the development and maintenance of the jet. Thermal and frictional forcing play equivalent roles as that of the large-scale winds in the formation of the jet. The identified regions of strong winds associated with the jet are important to the safety in the aviation industry and are also potential for alternative renewable energy resources in the form of wind energy. Large-scale orography is the most important factor. Divergence and anticyclonic vorticity partly explains the observed split in the jet cores. The dynamics of the flow in the channel and the dry conditions observed over the wider part of the valley is in partly explained by the Bernoulli theorem as applied to barotropic steady and non-viscous flows. Air-sea interaction phenomenon over the Indian Ocean, and the latitudinal location and intensity of the large-scale Walker and Hadley circulations are the main physical mechanisms responsible for the climate variability over the region during the wet and dry years. Abundant rainfall is associated with the presence of a midtropospheric cyclonic wind shear across the equator, and a negative vertical wind shear. Likewise, dry conditions are associated with the presence a strong westerly/southerly wind anomaly that occurs throughout the troposphere. Short-term climate prediction models developed in this study are capable of skillfully reproducing the space-time evolutions and distribution of the seasonal rainfall over the region, and specifically the observed floods that occurred during the 1997 ENSO year. Preliminary application of the RegCM2 in the prognostic mode successfully produces a 3-months projection of the extreme seasonal anomalies associated with the 1997 ENSO event. These models can be exploited further in operational short-term climate prediction over equatorial eastern Africa.
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Boyd, Jamie Lorna. "Global and regional assessment of Neogene climate and palaeoceanography using dinoflagellate cysts." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16324/.
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The Neogene Period (23.03–2.59 Ma) has been referred to as ‘the making of the Modern world’, which eventually, via a relatively consistent cooling trend, culminated in the present day climate conditions on Earth. Researching the Neogene provides important information for understanding how modern patterns of atmospheric and oceanic circulation developed, and how sensitive they are to environmental change. Climate and environmental parameter proxies are used to investigate past changes, and dinoflagellate cysts have great potential as their distribution can be limited by temperature, salinity, nutrient availability and sea ice cover. This project aims to use dinoflagellate cysts to study the evolution of the oceans over the Neogene and to further develop the potential of the climate proxy. This is achieved by collating all of the previously published literature on Neogene dinoflagellate cysts into a database and analysing the data on global and regional scales. This study allows for the first global synthesis, using dinoflagellate cysts, of changes that took place during the Neogene. It was found that, on a global scale, the distribution of Neogene dinoflagellate cysts was strongly controlled by temperature and can be correlated to the previously established cooling trend of the Neogene. However, short term climate changes superimposed on the overall cooling trend of the Neogene, cannot be observed. Changes to marine gateways have been shown to affect the composition of dinoflagellate cyst assemblages regionally, and caused allopatric speciation. New primary data from Cyprus demonstrates an increase in diversity in the Pliocene, which differs to the regional diversity. This reveals the importance of the difference between local and regional signals, and why it is important to understand, and to thoroughly explore, the datasets used in a global compilation.
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Gueneau, Arthur. "Crop water stress under climate change uncertainty : global policy and regional risk." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78495.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 113-121).
Fourty percent of all crops grown in the world today are grown using irrigation, and shifting precipitation patterns due to climate change are viewed as a major threat to food security. This thesis examines, in the framework of the MIT Integrated Global System Model, the potential impacts of climate change on crop water stress and the risk implications for policy makers due to underlying uncertainty in climate models. This thesis presents the Community Land Model - Agriculture module (CLM-AG) that models crop growth and water stress. It is a global generic crop model built in the framework of the Community Land Model and was evaluated for maize, cotton and spring wheat. A full climate model, the IGSM-CAM, was first used to force CLM-AG and show the regional disparity of the response to climate change. Some areas like the Midwest or Equatorial Africa benefit from the higher precipitations associated to climate change while others like Europe or Southern Africa see the irrigation need for crops increase. The effect of a mitigation policy appeared contrasted, as water-stress for some areas (including Europe and Africa) is increased if greenhouse gases emissions are limited while for other areas (Central Asia, United States) it is reduced. A second analysis was carried in Central Zambia using uncertainty ensembles. The ensembles demonstrate the notable extent of the uncertainty stemming from different climate sensitivities and different regional patterns in climate models. Crops are impacted differently but a consistent result is that climate mitigation policies reduce uncertainty in crop water stress, making it easier to plan for any anticipated future climate change.
by Arthur Gueneau.
S.M.in Technology and Policy
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Marien, Lennart Christopher [Verfasser]. "Towards well-balancing the regional hydrostatic climate model REMO / Lennart Christopher Marien." Hamburg : Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky, 2019. http://d-nb.info/1229625690/34.
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Thrasher, Bridget L. "Regional climate modeling studies of western North America under early Eocene conditions /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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Mendola, Meredith Lynne. "Regional-climate and Local-microbial Controls on Ecosystem Processes During Grassland Restoration." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1338.
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Root productivity likely has consequences for the composition, activity, and recovery of soil microbial populations and the belowground processes mediated by these organisms. In tallgrass prairie, ecotypic variation potentially exists in response to a strong precipitation gradient across the Great Plains. Thus, ecotypic variation within a species may differentially affect belowground net primary productivity (BNPP), the associated soil microbial community, and may scale up to affect ecosystem processes. The goals of this study were to elucidate: (1) whether ecotype, environment, or an ecotype by environment interaction regulate BNPP of a dominant species (Andropogon gerardii) collected from and reciprocally planted in common gardens across a precipitation gradient, and (2) whether variation in BNPP scales to affect microbial biomass and ecosystem processes. I quantified root biomass, BNPP (using root ingrowth bags), soil microbial biomass, and nutrient mineralization rates in root-ingrowth cores below six population sources of A. gerardii (2 Illinois, 2 eastern Kansas, and 2 central Kansas) established in southern Illinois, eastern Kansas, and central Kansas. An ecotype effect was found on above and belowground net primary productivity, but these findings did not translate to soil response variables. Microbial populations themselves may affect the productivity and composition of prairie species. In a second study, soil ecological knowledge (SEK) was tested by applying a native prairie soil slurry amendment to restoration plots to determine efficacy of this method as a restoration practice. The goals of this two year study were to elucidate: (1) whether a slurry amendment of prairie soil would increase above and belowground productivity and belowground ecosystem processes in a prairie restoration, and (2) to evaluate whether differences in plant diversity will scale to affect belowground productivity and ecosystem processes. I quantified aboveground net primary productivity (ANPP) and species composition, as well as root biomass, belowground net primary productivity (BNPP), soil microbial biomass, and nutrient mineralization rates in root-ingrowth cores installed in treated and control plots. A treatment effect was noted on root biomass and total PLFA biomass; however, there was no treatment effect on cover, ANPP, or soil microbial processes. Though the soil microbial community did represent native prairie soil, there was poor establishment of prairie plant species. These factors may be due to the limited time available for data collection and the lack of precipitation in the second growing season. Longer studies may be necessary to fully examine the effects of soil slurry amendments as restoration tools.
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Ekhtiari, Nikoo. "Interactions between water-bodies and atmosphere at regional to global scales." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20565.
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Ziel dieser Dissertation ist es, mithilfe zweier Herangehensweisen, das Verständnis der Zusammenhänge verschiedener physikalischer Prozesse des Klimasystems zu verbessern.
Im ersten Teil verwende ich Klimanetzwerke zu die gemeinsame Abhängigkeit von Meeresoberflächentemperaturen (SSTs) und Niederschlägen in Hinsicht auf globale charakteristiken und räumlichen Muster untersuchen. In diesem Kontext ist die El Niño Southern Oscillation (ENSO) das wichtigste Phänomen, welches großskalig SSTs und Niederschläge beeinflusst. Durch meine Analyse decke ich kurz und weitreichende Verbindungen auf und zeige deren Abhängigkeit von der jeweiligen ENSO-Phase (El Nino, La Nina, neutrale Phase). Darüber hinaus werden durch die Kombination einer diskreten Wavelet-Transformation mit dem Konzept der gekoppelten Klimanetzwerkanalyse die skalenspezifischen Verbindungen aufgelöst, die bei der ursprünglichen Auflösung der Daten oft übersehen werden.
Im zweiten Teil der Arbeit verwende ich Simulationen des COnsortium for Small scale MOdeling (COSMO) Climate Limited-area Modell (CCLM) und untersuche die Auswirkungen des Sobradinho-Stausees.
In dieser Arbeit benutzen ich das Flake Modell, um das vertikale Temperaturprofil des Sees zu bestimmen. Durch die Einbettung des Flake Modells in das CCLM konnte ich den Sobradinho-Stausee untersuchen. Dabei simuliere ich zwei verschiedene Szenarien. Die Simulationsergebnisse verifiziere ich mithilfe meteorologischer Daten von Oberflächen- und Satellitenmessungen. Die Ergebnisse zeigen, dass der See sowohl die bodennahe Temperatur als auch Wind- und Luftfeuchtigkeitsmuster der Umgebung beeinflusst. Zudem wird die Luftfeuchtigkeit durch den See erhöht und bewirkt Seewinde. Die Effekte des Sees auf die Luftfeuchtigkeit und temperaturen beschränken sich nicht nur auf die Nähe des Sees, sondern auch auf relativ weit entfernte Gebiete.This dissertation aims at improving our understanding of the mechanisms of interactions between physical processes within the climate system via two different approaches. In the first part, I have utilized climate networks to understand the mutual interdependence between sea surface temperatures (SST) and precipitation (PCP) in terms of global characteristics and spatial patterns. In this context, the globally most relevant phenomenon is the El Niño Southern Oscillation (ENSO), which strongly affects large-scale SST variability as well as PCP patterns all around the globe. My analysis uncovers both local and remote statistical connections and demonstrates their dependence on the current ENSO phase (El Niño, La Niña or neutral phase). Furthermore by combining time-scale decomposition by means of a discrete wavelet transform with the concept of coupled climate network analysis unravel the scale-specific connections that are often overlooked at the original resolution of the data. In the second part of this thesis, I have focused on simulations with the COnsortium for Small scale MOdeling (COSMO) Climate Limited-area Model (CCLM) and investigate the effects of Lake Sobradinho, a large reservoir in Northeastern Brazil, on the local near-surface atmospheric and boundary layer conditions. In this thesis, the FLake model (Freshwater Lake model) is applied for obtaining the lake’s vertical temperature profile. I have simulated two alternative scenarios. The performance of the simulation is compared with data from surface meteorological stations as well as satellite data. The obtained results demonstrate that the lake affects the near-surface air temperature of the surrounding area as well as its humidity and wind patterns. Moreover, the humidity is significantly increased as a result of the lake’s presence and causes a lake breeze. The observed effects on humidity and air temperature also extend over areas relatively far away from the lake.
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Florack, Alyssa. "Local Governments Taking on Climate Change: Situating City Actions in the Global Climate Regime:." Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:108629.
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Thesis advisor: David DeeseGiven the current political environment in the US, there is great doubt about the future of American policy on climate change. Still, the optimistic future of American climate policy relies on the new group of leaders that have emerged from municipal government. Although local government is traditionally ignored in favor of the publicity of international negotiations between countries, cities have established a role at the forefront of climate policy over the past ten years. These local governments serve half of the world’s population and often are extremely vulnerable to the impacts of climate change, making their contributions more important than ever. Although they face a unique set of difficulties, cities are able to take a range of actions impossible at higher levels of government, reaching communities in unprecedented ways and innovating new policies. This project aims to analyze how local governments fit into the global political regime on climate change, testing the theoretical framework of multilevel governance against reallife examples in Boston and New York City. Further, this paper finds that cities compensate for their relatively small size and limited jurisdiction through a unique set of actions and collaborative relationships, enabling these local actors to become international leaders on this complex global issue
Thesis (BA) — Boston College, 2017
Submitted to: Boston College. College of Arts and Sciences
Discipline:
Discipline: Departmental Honors
Discipline: Environmental Studies