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1
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.
2
Mabuchi, Kazuo. "A numerical study of climates and atmospheric CO2 concentrations using a regional climate model with a Biosphere-Atmosphere Interaction Model (BAIM)." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149573.
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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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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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Tesfaye, Melaku. "Atmospheric aerosol distributions and their climatic effects over South Africa using remote sensing observations and regional climate model." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/79190.
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Atmospheric aerosols are small solid and liquid particles suspended in the Earth's atmosphere which originate from
anthropogenic and natural activities. Unlike greenhouse gases, aerosol particles are relatively short-lived in the
atmosphere and exhibit multidimensional heterogeneity with respect to their composition, size, sources, mixing state
and the spatio-temporal distributions. The concentration and climatic influences of atmospheric aerosols are much
higher closer to their source regions. Therefore, to have a better understanding of the role of aerosols, their
distribution and climatic impacts must be understood and quantified on a regional scale rather than on a
global‐average basis. There are multiple sources of aerosols/precursor gases in South Africa (SA) which build a
complex mixture of atmospheric particulates. This contribution presents a detailed study of aerosol climatology over
SA as well as examines the direct radiative and semi-direct climatic effects of individual/total aerosol particles based
on their sources. The climatological study has shown that, in terms of aerosol load spatial variation, SA can be
classified into three parts: the upper, central, and lower part; which corresponds to high, medium and low aerosol
loads. The seasonal variation of aerosol optical signatures shows that the prevailing sources of aerosols are different
in each part of SA. The lower part is dominated by particles that are induced from the air mass transport from the
surrounding marine environment and other SA/neighbouring regions. The central and upper parts of SA are primarily
loaded by windblown mineral dust particles and aerosols that result from anthropogenic/biomass burning activities.
Following the aerosol climatological study, using the 12 year (1997 - 2008) runs of the Regional Climate Model
(RegCM4), the mass distribution, radiative influences and semi-direct climatic effects of wind-eroded desert dust
particles, different species of aerosols that are induced from anthropogenic and biomass burning activities over SA
are examined. Investigating the influence of aerosols, based on their sources, is essential to improve the scientific
understanding about the two-way interaction and feedback among various species of aerosols, radiation and different
climatic variables. This is also important to distinguish the climatic signals of anthropogenic aerosols from that of
natural aerosols as well as to devise climate change mitigation strategies. Before employing RegCM4 for these
purposes, the model’s performance in reproducing the major observational features of aerosol optical fields over SA
was evaluated. Among various semi-direct climatic influences of aerosols, this study examined their effects on:
surface temperature, surface sensible heat flux, net atmospheric radiative heating rate, hydrological variables (in
terms of cloud cover and cloud liquid water path), boundary layer, surface pressure and surface wind fields. The
study also assessed the dependency of aerosols’ semi-direct effects on seasonal variation of meteorological
parameters as well as its reliance on atmospheric aerosol distributions and properties. Overall, the semi-direct effect
assessments delivered not only an important contribution towards the understanding of the interaction and feedback
between different types of aerosols-radiation-climate (at a regional level), but also offered insightful information
about the mutual interrelationships among different climatic feedbacks. Among different aerosol species in SA, this
study critically underscores that the wind-eroded desert dust particles have a dominant climatic signal in SA.
Therefore, wind-eroded desert dust particles are of high importance and need to be incorporated in climate change
studies over South Africa. Additionally, the dominance of dust particle climatic signals perhaps requires some
attention from governmental or non-governmental environmental organizations which are working in and around
South Africa: at least in terms of making some strategic plans on how to reduce the dust production and dispersion.Thesis (PhD)--University of Pretoria, 2013.
Geaography, Geoinformatics And Meterology
PhD
Unrestricted
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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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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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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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Zhang, Yan. "Influence of biomass burning aerosol on land-atmosphere interactions over Amazonia." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-07122005-120105/.
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Darmaraki, Sofia. "Canicules océaniques en Méditerranée : détection, variabilité passée et évolution future." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30072.
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L'objectif principal de ce travail de thèse est d'étudier la variabilité passée et l'évolution future des épisodes de températures océaniques anormalement chaudes en Méditerranée. Ces évènements, appelés canicules océaniques ou Marine Heatwaves en anglais (MHW), sont connues pour exercer une pression considérable sur les écosystèmes marins et les pêcheries associées un peu partout dans le monde. Nous proposons une nouvelle méthode de détection automatique des MHWs d'été basée sur le 99ème centile de la température quotidienne de la surface de la mer (TSM) en climat présent et tenant compte de la diversité géographique de la zone. La probabilité d'occurrence des MHWs et leurs caractéristiques spatio-temporelles sont ensuite étudiées. D'autres indicateurs intégrés tels que la durée, l'intensité, l'extension spatiale maximale ou la sévérité permettent de compléter la description des MHWs. Au cours de cette thèse et en fonction des applications, la méthode de détection est appliquée à différents types de données : observations in-situ aux bouées, produit satellitaire et différents modèles haute résolution et couplés haute fréquence du système climatique régional (RCSMs pour Regional Climate System Model en anglais) y compris le nouveau modèle CNRM-RCSM6 et l'ensemble Med-CORDEX multi-modèle (5) et multi-scénarios (3). L'algorithme de détection est d'abord testé sur la MHW de 2003 afin de montrer qu'il est peu sensible aux différents paramètres de réglage. L'évaluation des simulations rétrospectives et historiques montrent que les RCSMs sont capables dans l'ensemble de bien reproduire l'occurrence et les caractéristiques des MHWs observées par satellite. Nous étudions ensuite la variabilité passée des MHWs de surface (1982-2017) ainsi que leurs facteurs explicatifs en utilisant le modèle CNRM-RCSM6. Nous examinons, leurs caractéristiques entre 20-55 m de profondeur, là où la plupart des mortalités de masse liées au stress thermique des écosystèmes méditerranéens ont été observées dans le passé. L'analyse indique une augmentation de la durée et de l'intensité des évènements de surface au fil du temps, tandis que les MHWs de 2003, 2012 et 2015 sont détectées comme les évènements les plus sévères de la période. Par ailleurs, pour la canicule 2003 des différences importantes dans la contribution des échanges air-mer et de la diffusion vertical de chaleur sont mis en évidence pour les différents sous-bassins méditerranéens. Nous montrons également que la tension de vent joue un rôle clé sur l'intensité des anomalies de température en surface ainsi que leur propagation verticale. Enfin, nous utilisons l'ensemble Med-CORDEX de RCSMs pour évaluer l'évolution future des MHWs dans la région sur la période 1976-2100. Nos résultats suggèrent des évènements plus longs et plus sévères au fur et à mesure que le réchauffement climatique s'intensifie. D'ici à 2100 et dans le cadre du scénario le plus pessimiste (RCP8.5), les simulations projettent au moins une MHW de longue durée chaque année, jusqu'à 3 mois plus longue, environ 4 fois plus intense et 40 fois plus sévère que les évènements actuels. On s'attend à ce qu'elles se produisent entre juin et octobre, affectant au plus fort de leur extension l'ensemble du bassin. Cette évolution s'explique principalement par une augmentation de la TSM moyenne, mais l'augmentation de la variabilité quotidienne de la TSM joue également un rôle notable. Jusqu'au milieu du 21ème siècle, les caractéristiques des MHWs augmentent indépendamment du choix du scénario d'émission, dont l'influence devient plus évidente à la fin de la période. Enfin, l'analyse individuelle des modèles révèle différentes familles de réponses au changement climatique. Ces différences s'expliquent plus probablement par le choix du modèle global forçant, plutôt que par les biais individuels des modèles régionauxThe Mediterranean Sea is considered a "Hot Spot" region for future climate change and depending on the greenhouse emission scenario, the annual mean basin sea surface temperature (SST) is expected to increase from +1.5 °°C to +3 °°C at the end of the 21st century relative to present-day. This significant SST rise is likely to intensify episodes of extreme warm ocean temperatures in the basin, named as Marine heatwaves (MHWs), that are known to exert substantial pressure on marine ecosystems and related fisheries around the world. In this context, the main aim of this PhD work is to study the past variability and future evolution of MHWs in the Mediterranean Sea. We propose a detection method for long lasting and large-scale summer MHWs, using a local, climatological 99th percentile threshold, based on present-climate daily SST. MHW probability of occurrence and characteristics in terms of spatial variability and temporal evolution are then investigated, using additional integrated indicators (e.g. duration, intensity, spatial extension, severity) to describe past and future events. Within the PhD and depending on the applications, the detection method is applied to various datasets : In-situ observation at buoys, high-resolution satellite product, various high- resolution and fully-coupled Regional Climate System Models including the recently developed CNRM-RCSM6 and the multi-model (5), multi-scenario (3) Med-CORDEX ensemble. The detection method is first tested on the 2003 MHW in order to assess its sensitivity to various tuning parameters. We conclude that its characterization is partly sensitive to the algorithm setting. Hindcast and historical mode simulations show that models are able to capture well observed MHW characteristics. We then assess past surface MHW variability (1982-2017) and their underlying driving mechanisms using the CNRM-RCSM6 model. We examine their characteristics from surface to 55m depth, where most thermal stress-related mass mortalities of Mediterranean ecosystems have been observed in the past. The analysis indicates an increase in duration and intensity of surface events with time, while MHWs of 2003, 2012 and 2015 are identified as the most severe events of the period. In particular, an anomalous increase in shortwave radiation and a lower-than-normal vertical diffusion and latent heat loss appeared to be responsible for the development of the MHW 2003, with wind playing a key role in the intensity of temperature anomalies at the sea surface. Differences on the dominant forcing, however, are sometimes evident in the different subbasin.We finally use the Med-CORDEX RCSM ensemble to assess the future MHW evolution in the basin over 1976-2100. Our results suggest longer and more severe events with higher global-warming rates. By 2100 and under RCP8.5, simulations project at least one long- lasting MHW every year, up to 3 months longer, about 4 times more intense and 42 times more severe than present-day events. Their occurrence is expected between June-October affecting at peak the entire basin. Their evolution is found to mainly occur due to an increase in the mean SST but an increase in daily SST variability plays also a noticeable role. Up to mid-21st century MHW characteristics rise independently of the choice of the emission scenario, whose influence becomes more evident by the end of the period
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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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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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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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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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Zabel, Florian. "Land-atmosphere coupling between a land surface hydrological model and a regional climate model." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-151446.
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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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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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Polanski, Stefan. "Simulation der indischen Monsunzirkulation mit dem Regionalen Klimamodell HIRHAM." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5250/.
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In dieser Arbeit wird das regionale Klimamodell HIRHAM mit einer horizontalen Auflösung von 50 km und 19 vertikalen Schichten erstmals auf den asiatischen Kontinent angewendet, um die indische Monsunzirkulation unter rezenten und paläoklimatischen Bedingungen zu simulieren. Das Integrationsgebiet des Modells erstreckt sich von etwa 0ºN - 50ºN und 42ºE - 110ºE und bedeckt dabei sowohl die hohe Topographie des Himalajas und Tibet Plateaus als auch den nördlichen Indischen Ozean. Das Ziel besteht in der Beschreibung der regionalen Kopplung zwischen der Monsunzirkulation und den orographischen sowie diabatischen Antriebsmechanismen.
Eine 44-jährige Modellsimulation von 1958-2001, die am seitlichen und unteren Rand von ECMWF Reanalysen (ERA40) angetrieben wird, bildet die Grundlage für die Validierung der Modellergebnisse mit Beobachtungen auf der Basis von Stations- und Gitterdatensätzen. Der Fokus liegt dabei auf der atmosphärischen Zirkulation, der Temperatur und dem Niederschlag im Sommer- und Wintermonsun, wobei die Qualität des Modells sowohl in Bezug zur langfristigen und dekadischen Klimatologie als auch zur interannuellen Variabilität evaluiert wird. Im Zusammenhang mit einer realistischen Reproduktion der Modelltopographie kann für die Muster der Zirkulation und Temperatur eine gute Übereinstimmung zwischen Modell und Daten nachgewiesen werden. Der simulierte Niederschlag zeigt eine bessere Übereinstimmung mit einem hoch aufgelösten Gitterdatensatz über der Landoberfläche Zentralindiens und in den Hochgebirgsregionen, der den Vorteil des Regionalmodells gegenüber der antreibenden Reanalyse hervorhebt.
In verschiedenen Fall- und Sensitivitätsstudien werden die wesentlichen Antriebsfaktoren des indischen Monsuns (Meeresoberflächentemperaturen, Stärke des winterlichen Sibirischen Hochs und Anomalien der Bodenfeuchte) untersucht. Die Ergebnisse machen deutlich, dass die Simulation dieser Mechanismen auch mit einem Regionalmodell sehr schwierig ist, da die Komplexität des Monsunsystems hochgradig nichtlinear ist und die vor allem subgridskalig wirkenden Prozesse im Modell noch nicht ausreichend parametrisiert und verstanden sind.
Ein paläoklimatisches Experiment für eine 44-jährige Zeitscheibe im mittleren Holozän (etwa 6000 Jahre vor heute), die am Rand von einer globalen ECHAM5 Simulation angetrieben wird, zeigt markante Veränderungen in der Intensität des Monsuns durch die unterschiedliche solare Einstrahlung, die wiederum Einflüsse auf die SST, die Zirkulation und damit auf die Niederschlagsmuster hat.In this study the regional climate model HIRHAM with a horizontal resolution of 50 km and 19 vertical levels is applied over the Asian continent to simulate the Indian monsoon circulation under present-day and past conditions. The integration domain extends from 0ºN - 50ºN and 42ºE - 110ºE and covers the high topography of Himalayas and Tibetan Plateau as well as the northern Indian Ocean. The main objective is the description of the regional coupling between monsoon circulation and orographic as well as thermal driving mechanisms of monsoon. A 44-years long simulation from 1958-2001, driven at the lateral and lower boundaries by European reanalysis (ERA40), is the basis for the validation of model results with observations based on station and gridded data sets. The focus is on the the long-term and decadal summer and winter monsoon climatology and its variability concerning atmospheric circulation, temperature and precipitation. The results successfully reproduce the observations due to a realistic simulation of topographic features. The simulated precipitation shows a better agreement with a high-resolution gridded data set over the central land areas of India and in the higher elevated Tibetan and Himalayan regions than ERA40. In different case and sensitivity studies the main driving mechanisms of the Indian monsoon (Sea Surface Temperatures, strength of the Siberian High in winter and soil moisture anomalies) are investigated. The results show, that the simulation of these mechanisms with a regional climate model is also difficult related to the complex non linear monsoon system and the small-scale processes, which are not just sufficiently parameterized and understood in the model. A paleoclimatic experiment for a 44-years long time slice in mid-holocene (6000 years before present), which is driven by a global ECHAM5 simulation, shows significant changes in the monsoon intensity due to the different solar forcing, which influences the SST, the circulation and the precipitation.
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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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Sangelantoni, Lorenzo. "From regional to local climate scenario: toward an integrated strategy for climate impacts reduction." Doctoral thesis, Università Politecnica delle Marche, 2016. http://hdl.handle.net/11566/243106.
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Situata al centro del Mediterraneo, uno degli “hot-spot” del cambiamento climatico, l’Italia è considerata una delle aree più suscettibili al cambiamento climatico globale. L’unicità della posizione geografica e l’elevata eterogeneità climatica rendono difficoltoso elaborare uno scenario climatico univoco per i differenti pattern climatici. In questo contesto, disporre di informazioni climatiche da scala regionale a locale diventa di strategica importanza. La ricerca si basa su questa essenziale transizione, definendo due scenari climatici per il 21° secolo a differente scala spaziale. Uno scenario a scala regionale, riferito alla penisola italiana e uno a scala locale che considera stazioni della regione Marche. Gli scenari climatici si basano su simulazioni numeriche di modelli climatici a differente risoluzione. Le simulazioni sono state post-processate con una tecnica di correzione statistica quantile mapping (QM). Entrambi gli scenari indicano un forte incremento delle temperature in tutte le stagioni specialmente in estate. Le piogge sono attese diminuire in estate e moderatamente aumentare nel nord-Italia d’inverno. Per le Marche, l’ultima generazione di modelli climatici è concorde nell’indicare un considerevole incremento delle temperature e diminuzione delle precipitazione durante l’estate. Le piogge autunnali e invernali sono però attese in incremento. Seppur applicato con diverse configurazioni, l’effetto del QM sul segnale climatico è del tutto simile nei due esperimenti. La ricerca vuole apportare nuovi elementi al dibattito scientifico relativo all’effetto di questa tecnica, sul segnale climatico. Ci si interroga sull’eventuale revisione degli attuali scenari climatici basati su simulazioni non soggette a correzione e quindi influenzate da intrinseco errore. La ricerca fornisce infine dei data set di simulazioni climatiche validate e statisticamente corrette direttamente utilizzabili per la riduzione del rischio climatico e dei suoi impatti.Lying at the center of Mediterranean basin, one of the most sensitive area to anthropogenic climate change, Italy is expected to be particularly susceptible to global climate change. Unique geographical position and heterogeneous climatic features make difficult defining a comprehensive climate scenario. In such context, establishing regional to local climate information is of strategical importance for all-level society. Doctoral research is based on this conceptual and methodological transition. Two climate scenarios, one at regional and one at local scale are defined. The regional climate scenario considers an area roughly covering Italy, and a local scenario focuses over Marche region stations. Climate scenarios rely on two different-resolution climate model ensemble simulations. Numerical simulations were post-processed according to the quantile mapping (QM) bias correction technique. Original and bias-corrected climate simulations were employed to define 21st century climate change signal (CCS) over principal climate variables. Both scenarios agreed on identifying a severe increase of temperature in all the seasons, especially in summer. Precipitation are projected strongly decrease in summer and increase in winter only over north-Italy. Concerning Marche region stations, newest generation of climate models agree on the severe temperature increase and precipitation reduction in summer but an equivalent increase of autumn-winter precipitation was found. Albeit adopting different configurations, QM coherently affected original CCS in both experiments. Research offers elements to scientific debate on the effect of a common post-processing practice on the CCS. Should we reconsider climate scenarios only relying on original climate model projections? Moreover, following climate services principles, outputs of this research provide comprehensive climate information directly usable by professionals involved in climate risk and impacts research.
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Butke, Jason Thomas. "An evaluation of a point snow model and a mesoscale model for regional climate simulations." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 154 p, 2007. http://proquest.umi.com/pqdweb?did=1251900251&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Bachner, Susanne. "Daily precipitation characteristics simulated by a regional climate model, including their sensitivity to model physics." Sankt Augustin : Asgard-Verlag, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=9783537878632.
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Cassano, John J., Alice DuVivier, Andrew Roberts, Mimi Hughes, Mark Seefeldt, Michael Brunke, Anthony Craig, et al. "Development of the Regional Arctic System Model (RASM): Near-Surface Atmospheric Climate Sensitivity." AMER METEOROLOGICAL SOC, 2017. http://hdl.handle.net/10150/625161.
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The near-surface climate, including the atmosphere, ocean, sea ice, and land state and fluxes, in the initial version of the Regional Arctic System Model (RASM) are presented. The sensitivity of the RASM near-surface climate to changes in atmosphere, ocean, and sea ice parameters and physics is evaluated in four simulations. The near-surface atmospheric circulation is well simulated in all four RASM simulations but biases in surface temperature are caused by biases in downward surface radiative fluxes. Errors in radiative fluxes are due to biases in simulated clouds with different versions of RASM simulating either too much or too little cloud radiative impact over open ocean regions and all versions simulating too little cloud radiative impact over land areas. Cold surface temperature biases in the central Arctic in winter are likely due to too few or too radiatively thin clouds. The precipitation simulated by RASM is sensitive to changes in evaporation that were linked to sea surface temperature biases. Future work will explore changes in model microphysics aimed at minimizing the cloud and radiation biases identified in this work.
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Fosser, Giorgia [Verfasser]. "Precipitation statistics from regional climate model at resolutions relevant for soil erosion / Giorgia Fosser." Karlsruhe : KIT Scientific Publishing, 2014. http://www.ksp.kit.edu.
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Shawki, Dilshad. "South Asian precipitation response to regional sulphur dioxide emissions in a global climate model." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/51093.
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Aerosols have an inhomogeneous distribution across the globe because of their short lifetimes in the atmosphere. They impose a localised radiative forcing close to their emission source that is effective at driving circulation changes and influencing the hydrological cycle. One such type of circulation that has recently been suggested to be affected by aerosols is the South Asian summer monsoon, which provides 80% of annual rainfall to over a billion people during the summer months. I used the UK Met Office HadGEM3 coupled global climate model to investigate, for the first time, the centennial-scale South Asian precipitation responses to removing regional anthropogenic sulphur dioxide emissions. This study is unique since these experiments have never been attempted on a scale that is multi-regional, centennial and in a fully coupled ocean-atmosphere model setup. Despite the imposed localised heating in my experiments resulting from emissions removals over the United States, Europe, East Asia, South Asia or the northern mid-latitudes as a whole, the large-scale spatial pattern and magnitude of the precipitation response over South Asia was similar for all experiments. This was due to the ocean responding to the atmosphere enabling the full response to be realised and the ocean dynamics driving a structurally similar global climate response. The sum of the responses from the experiments where the emissions are removed from the United States, Europe and East Asia resemble the response seen in the experiment where emissions are removed in the entire northern mid-latitude band, suggesting that the response is roughly linear, with East Asia being the largest contributor to the response. East Asia’s proximity to South Asia meant that it was more effective at influencing the land-sea thermal contrast, pressure gradients, and therefore the local monsoon circulation itself. On the other hand, local emissions removals, i.e. over South Asia itself, led to decreases in precipitation over central and northern India, a result not seen in any other experiment. Moreover, the response of the circulation was still found to be the main driver of the response in this case, despite changes to the clouds making them thinner and less reflective. In the future, further work is warranted to allow for comparisons with other coupled ocean-atmosphere models performing similar multi-regional experiments, to enhance confidence in our results and to further our understanding of the processes involved. Similar experiments can also be performed to explore the role of other short-lived pollutants, such as tropospheric ozone. The insight provided could prove invaluable for informing emissions reduction policies and for understanding the implications for short-term regional climate prediction.
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Tang, Chao. "Model estimations of possible climate changes of surface solar radiation at regional scales over Southern Africa and the South West Indian Ocean." Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0055/document.
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Les variations du rayonnement solaire en surface (SSR) peuvent avoir un impact significatif sur divers aspects du système climatique, et notamment sur le développement socio-économique d’un pays. Pour identifier les impacts possibles du changement climatique sur le rayonnement solaire en surface à l'échelle régionale (~ 50 km) en Afrique australe jusqu'à la fin du 21ème siècle, on a analysé les données mensuelles produites dans le cadre du projet CORDEX-Afrique sur la période 1979-2099. Ces données sont issues des sorties de 5 modèles régionaux de climat (RCM) forcés par 10 modèles globaux de climat (GCM) CMIP5, pour deux scénarios d’émissions, RCP4.5 et RCP8.5, en Afrique australe (SA) et sur une partie du SWIO (0-40°S ; 0- 60°E). Pour contribuer au projet futur proposé qui vise à approfondir l'étude des changements de SSR à l'échelle locale (~ 1 km de résolution horizontale) à l'île de la Réunion et à l'île Maurice, situées dans le Sud-ouest de l'océan Indien (SWIO), près du bord d’Est du domaine CORDEX-Afrique, des simulations climatiques ont été réalisées sur trois fenêtres temporelles de 10 ans : a) le passé 1996-2005 ; et b) le futur 2046-2055 et 2090-2099, en utilisant la version 4 du RCM RegCM (RegCM4), forcé par : 1) les réanalyses climatiques ERA-Interim (ERAINT) du centre européen pour les prévisions météorologiques à moyen terme (ECMWF) pour simuler un passé récent seulement ; et 2) deux GCMs (HadGEM2-ES et GFDL-ESM2M) de l’exercice CMIP5 de simulations du climat passé et futur pour le scénario d’émissions RCP8.5 à l’échelle régionale de 50km en Afrique australe et dans le sud-ouest de l’océan Indien (0-40°S ; 0- 100°E). L’analyse de l’impact du changement climatique sur le SSR sur la base de ces simulations reste cependant limitée, à cause de leur couverture temporelle (3 périodes de 10 ans) et du nombre de modèles (2 GCMs, 1 RCM) et de scénarios (1 RCP) utilisés. Il ressort de l’analyse des simulations de l’ensemble CORDEX-Afrique que : 1) sur la période passée récente, les GCMs forceurs surestiment généralement SSR d'environ 1 W/m2 en été austral (DJF : Décembre-Janvier-Février), et de 7,5 W/m2 en hiver austral (JJA : Juin-Juillet-Août), tandis que les RCMs, forcés par ces GCMs, sous-estiment SSR d'environ -32 W/m2 et de -14 W/m2 en été et en hiver, respectivement. 2) Les projections multi-modèles de changement de SSR simulées par les RCMs et leurs GCMs forceurs sont assez cohérentes. Les GCMs prévoient, en moyenne multi-modèles, une augmentation statistiquement significative de SSR d'environ 8 W/m2 en 2099 selon le scénario RCP4.5 et de 12 W/m2 en 2099 selon le scénario RCP8.5 sur le Centre de l’Afrique australe (SA-C), et une diminution de SSR, avec un degré de confiance élevé, d'environ -5 W/m2 en 2099 selon le scénario RCP4.5 et de -10 W/m2 en 2099 selon le scénario RCP8.5, pendant la saison DJF, en Afrique équatoriale (EA-E). Dans ces deux régions, les RCMs produisent, en moyenne multi-modèles, des tendances similaires (avec un degré de confiance élevé) à celles des GCMs, mais sur des zones d’extension spatiale plus faible que celle des GCMs. Cependant, pour la saison JJA, une augmentation de SSR, d'amplitude similaire dans les simulations GCMs et RCMs (~5 W/m2 en 2099 selon le scénario RCP4.5 et 10 W/m2 selon le scénario RCP8.5), est attendue dans la région EA-E. 3). Une diminution significative de la nébulosité (environ -6% en 2099) est attendue sur le continent sud-africain pour les GCMs comme pour les RCMs. 4) Le scénario RCP8.5 produit des changements d’amplitude supérieure de 2.5W/m2 pour les GCMs forceurs et de 5W/m2 pour les RCMs en 2099 à celle pour le scénario RCP4.5. 5). Comme pour les sorties du modèle RegCM4, les structures des biais ou des changements de SSR issu des RCMs du programme CORDEX-Afrique sont globalement corrélées avec celles de couverture nuageuse totale des RCMs. L’analyse des sorties du modèle RegCM4 indique que :Changes in Surface Solar Radiation (SSR) have the potential to significantly impact diverse aspects of the climate system, and notably the socio-economic development of any nation. To identify the possible impacts of climate change on SSR at regional scales (~50 km) over Southern Africa and the South West Indian Ocean (SA-SWIO; 0-40°S ; 0- 100°E) up to the end of the 21st century, a slice downscaling experiment consisting of simulations covering three temporal windows: a) the present 1996-2005; b) the future 2046-2055 and 2090-2099 conducted with the Regional Climate Model (RCM) RegCM version 4, driven by the European Center for Medium-range Weather Forecasting (ECMWF) ERA-Interim reanalysis (ERAINT, only present) and 2 Global Climate Model (GCMs: HadGEM2-ES and GFDL-ESM2M) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under RCP8.5 scenario, are performed and evaluated. Since the slice simulation is of limited temporal coverage, number of regional and driven global models and climate change forcings, mainly because of the limit of available computational resources, the study towards a comprehensive knowledge of SSR changes in context of climate change is thus extended: an ensemble consisting of outputs from 20 regional climate downscaling realisations based on 5 RCMs that participated in the Coordinated Regional Downscaling Experiment (CORDEX) program (CORDEX-Africa) along with their 10 driving GCMs from CMIP5 covering southern Africa (0-40°S; 0- 100°E) during the period of 1990-2099 is analyzed under RCP4.5 and RCP8.5 up to 2099.The slice experiment indicates that 1) RegCM4 simulates present-day seasonal climatology, (surface air temperature, precipitation and SSR) quite well, but has a negative total cloud cover bias (about -20% in absolute percentage) when forced by the ERAINT and the two GCMs. 2) Internal variability of RegCM4-simulated annual means SSR (about 0.2 W/m2) is of one order smaller than the model bias compared with reference data. 3) RegCM4 simulates SSR changes in opposite signs when driven by the different GCMs under RCP8.5 scenario. 4) Electricity potential calculated using first-order estimation based on the RegCM simulations indicates a change less then 2% to 2099 with respect on present level.It is also found from the ensemble study that: 1) GCMs ensemble generally overestimates SSR by about 1 W/m2 in austral summer (December, January, and February, short as DJF) and 7.5 W/m2 in austral winter (June, July and August, short as JJA), while RCMs ensemble mean shows underestimations of SSR by about -32 W/m2 and -14 W/m2 in summer and winter seasons respectively when driven by GCMs. 2) Multi-model mean projections of SSR change patterns simulated by the GCMs and their embedded RCMs are fairly consistent. 3) GCMs project, in their multi-model means, a statistically significant increase of SSR of about 8 W/m2 in RCP4.5 and 12 W/m2 in RCP8.5 by 2099 over Centre Southern Africa (SA-C) and a highly confident decreasing SSR over Eastern Equatorial Africa (EA-E) of about -5 W/m2 in RCP4.5 and -10 W/m2 in RCP8.5 during the DJF season. RCMs simulate SSR change with statistical confidence over SA-C and EA-E area as well with a little spatial extension compared to GCMs. However, in the JJA season, an increase of SSR is found over EA-E of about 5 W/m2 by 2099 under RCP4.5 and 10 W/m2 under RCP8.5, of similar amplitudes in both the GCMs and RCMs simulations. 4) Significant cloudiness decrease (about -6 % to 2099) is found over continent of SA for GCMs and also shown in RCMs. 5) Larger SSR changes are found in the RCP8.5 scenario than in the RCP4.5 scenario in 2099, with about 2.5 W/m2 enhanced changes in GCMs and about 5 W/m2 in RCMs. 6) Either the biases or the changes pattern of SSR are overall correlated with the patterns of total cloud cover from RCMs in CORDEX-Africa program (for RegCM4 as well). The slice experiment indicates that
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Wi, Sungwook. "Impact of Climate Change on Hydroclimatic Variables." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/265344.
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The conventional approach to the frequency analysis of extreme rainfall is complicated by non-stationarity resulting from climate change. In this study significant trends in extreme rainfall are detected using statistical trend tests (Mann-Kendall test and t-test) for all over the Korean Peninsula. The violation of the stationarity for 1 hour annual maximum series is detected for large part of the area especially for southwestern and northeastern regions. For stations showing non-stationarity, the non-stationary generalized extreme value (GEV) distribution model with a location parameter in the form of linear function of time makes significant improvement in modeling rainfall extremes when compared to the stationary GEV model. The Bartlett-Lewis rainfall model is used to generate annual maximum series for the purpose of generating the Intensity-Duration-Frequency (IDF) curve. Using 100 sets of 50 year synthetic annual maxima, it is found that the observed annual rainfall maximum series are reasonably represented by the model. The observed data is perturbed by change factors to incorporate the climate change scenario from the WRF (Weather Research and Forecasting) regional climate model into IDF estimates. The IDF curves for the future period 2040-2079 show highest estimates for all return periods and rainfall durations. The future IDF estimates show significant difference from the IDF estimates of the historical period (1968-2000). Overall, IDF curves show an increasing tendency over time. A historical and future climate simulation is evaluated over the Colorado River Basin using a 111-year simulation (1969-2079) of the WRF climate change scenario. We find the future projections show statistically significant increases in temperature with larger increases in the northern part of the basin. There are statistically insignificant increases in precipitation, while snowfall shows a statistically significant decrease throughout the period in all but the highest elevations and latitudes. The strongest decrease in snowfall is seen at high elevations in the southern part of the basin and low elevations in the northern part of the basin.
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Bergman, Ottar. "A Regional Analysis of Changing Climate Conditions and Glacier Mass Balance in Svalbard." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-383930.
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The Arctic archipelago of Svalbard has experienced among the greatest increases in temperature on Earth in the last few decades. The changing climatic conditions have a large impact on the glacier mass balance. This study makes use of a highresolution model dataset with data on climatic and glacier conditions on Svalbard from 1957 to 2018. The model dataset is used to analyse the spatiotemporal variability in glacier mass balance across Svalbard and linking those changes to long-term trends in meteorological conditions. The study is focused on the spatial gradients in trends between two regions in Svalbard, the coldest part of the archipelago, Nordaustlandet and the milder southern part of the main island Spitsbergen. The north eastern (NE) region is found to have a greater increase in annual air temperature over the simulation period with 5.5 °C compared to 3.5 °C for the south western (SW) region. The increase in annual summer temperatures is much smaller with a total increase of 1 °C for the NW and 1.5 °C for the SW. Both regions show a small, but significant, increase of precipitation. Relative humidity and cloud cover in the NE are increasing slightly over the time period, probably due to retreating sea ice cover. Glacier melt and runoff are increasing in both regions, which is contributing to significant negative trends in the mass balance. The increase in melt and run off is stronger in the SW than in the NE. There’s a strong correlation between summer air temperature and glacier mass balance, melt and runoff. Refreezing in the NE is decreasing much faster than in the SW. Refreezing is strongly correlated with annual air temperatures in the NE and not in the SW, probably due to lower temperatures in the NE region.
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Zhang, Yan. "The radiative effect of aerosols from biomass burning on the transition from dry to wet season over the amazon as tested by a regional climate model." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26510.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009.Committee Chair: Fu, Rong; Committee Member: Dickinson, Robert E.; Committee Member: Nenes, Athanasios; Committee Member: Webster,Peter J.; Committee Member: Yu, Hongbin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Paxian, Andreas [Verfasser], and Heiko [Akademischer Betreuer] Paeth. "Future changes in climate means and extremes in the Mediterranean region deduced from a regional climate model / Andreas Paxian. Betreuer: Heiko Paeth." Würzburg : Universitätsbibliothek der Universität Würzburg, 2013. http://d-nb.info/103683655X/34.
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Wovrosh, Alex J. "The Role of Regional Sea Surface Temperatures on the Amundsen-Bellingshausen Seas Low as Depicted by Atmospheric Model Intercomparison Project Simulations." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1406817246.
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Zabel, Florian [Verfasser], and Wolfram [Akademischer Betreuer] Mauser. "Land-atmosphere coupling between a land surface hydrological model and a regional climate model / Florian Zabel. Betreuer: Wolfram Mauser." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1029662487/34.
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Meißner, Cathérine [Verfasser], and C. [Akademischer Betreuer] Kottmeier. "High-resolution sensitivity studies with the regional climate model COSMO-CLM / Cathérine Meißner ; Betreuer: C. Kottmeier." Karlsruhe : KIT Scientific Publishing, 2008. http://d-nb.info/1185225358/34.
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Gutjahr, Oliver [Verfasser], and Günther [Akademischer Betreuer] Heinemann. "Climate simulations with the regional climate model COSMO-CLM for the Saar-Lor-Lux region and Rhineland-Palatinate / Oliver Gutjahr ; Betreuer: Günther Heinemann." Trier : Universität Trier, 2014. http://d-nb.info/1197806822/34.
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Kulaiappan, Palanisamy Hindumathi. "Le niveau de la mer actuel : variations globales et régionales." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30166/document.
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Le niveau de la mer est une des variables climatiques essentielles dont la variabilité résulte de nombreuses interactions complexes entre toutes les composantes du système climatique sur une large gamme d'échelles spatiales et temporelles. Au cours du XXème siècle, les mesures marégraphiques ont permis d'estimer la hausse du niveau de la mer global entre 1,6 mm/an et 1,8 mm/an. Depuis 1993, les observations faites par les satellites altimétriques indiquent une hausse du niveau de la mer plus rapide de 3,3 mm/an. Grâce à leur couverture quasi-globale, elles révèlent aussi une forte variabilité du niveau de la mer à l'échelle régionale, parfois plusieurs fois supérieure à la moyenne globale du niveau de la mer. Compte tenu de l'impact très négatif de l'augmentation du niveau de la mer pour la société, sa surveillance, la compréhension de ses causes ainsi que sa prévision sont désormais considérées comme des priorités scientifiques et sociétales majeures. Dans cette thèse, nous validons d'abord les variations du niveau de la mer mesurées par la nouvelle mission d'altimétrie satellitaire, SARAL-AltiKa, en comparant les mesures avec celles de Jason- 2 et des marégraphes. Un autre volet de cette première partie de thèse a consisté à estimer les parts respectives des facteurs responsables des variations du niveau de la mer depuis 2003 en utilisant des observations issues de l'altimétrie satellitaire (missions altimétrique Jason-1, Jason-2 et Envisat), de la mission GRACE, et des profils de température et salinité de l'océan par les flotteurs Argo. Une attention particulière est portée à la contribution de l'océan profond non 'vue' par Argo. Nous montrons que les incertitudes dues aux approches du traitement des données et aux erreurs systématiques des différents systèmes d'observation nous empêchent encore d'obtenir des résultats précis sur cette contribution. Dans la deuxième partie de la thèse, en utilisant les données de reconstruction du niveau de la mer dans le passé, nous étudions la variabilité régionale du niveau de la mer et estimons sa hausse totale (composante régionale plus moyenne globale) de 1950 à 2009 dans trois régions vulnérables: l'océan Indien, la mer de Chine méridionale et la mer des Caraïbes. Pour les sites où l'on dispose de mesures du mouvement de la croûte terrestre par GPS, nous évaluons la hausse locale du niveau de la mer relatif (hausse du niveau de la mer totale plus mouvement de la croûte locale) depuis 1950. En comparant les résultats de ces trois régions avec une étude précédente sur le Pacifique tropical, nous constatons que le Pacifique tropical présente la plus forte amplitude des variations du niveau de la mer sur la période d'étude. Dans la dernière partie de la thèse, nous nous concentrons par conséquent sur le Pacifique tropical. Nous analysons les rôles respectifs de la dynamique océanique, des modes de variabilité interne du climat et du forçage anthropique sur les structures de la variabilité régionale du niveau de la mer du Pacifique tropical depuis 1993. Nous montrons qu'une partie importante de la variabilité régionale du niveau de la mer du Pacifique tropical peut être expliquée par le mouvement vertical de la thermocline en réponse à l'action du vent. En tentant de séparer le signal correspondant au mode de variabilité interne du climat de celui de la hausse régionale du niveau de la mer dans le Pacifique tropical, nous montrons également que le signal résiduel restant (c'est-à-dire le signal total moins le signal de variabilité interne) ne correspond probablement pas à l'empreinte externe du forçage anthropiqueSea level is an integrated climate parameter that involves interactions of all components of the climate system (oceans, ice sheets, glaciers, atmosphere, and land water reservoirs) on a wide range of spatial and temporal scales. Over the 20th century, tide gauge records indicate a rise in global sea level between 1.6mm/yr and 1.8 mm/yr. Since 1993, sea level variations have been measured precisely by satellite altimetry. They indicate a faster sea level rise of 3.3 mm/yr over 1993-2015. Owing to their global coverage, they also reveal a strong regional sea level variability that sometimes is several times greater than the global mean sea level rise. Considering the highly negative impact of sea level rise for society, monitoring sea level change and understanding its causes are henceforth high priorities. In this thesis, we first validate the sea level variations measured by the new satellite altimetry mission, SARAL-AltiKa by comparing the measurements with Jason-2 and tide gauge records. We then attempt to close the global mean sea level budget since 2003 and estimate the deep ocean contribution by making use of observational data from satellite altimetry, Argo profiles and GRACE mission. We show that uncertainties due to data processing approaches and systematic errors of different observing systems still prevent us from obtaining accurate results. In the second part of the thesis, by making use of past sea level reconstruction, we study the patterns of the regional sea level variability and estimate climate related (global mean plus regional component) sea level change over 1950-2009 at three vulnerable regions: Indian Ocean, South China and Caribbean Sea. For the sites where vertical crustal motion monitoring is available, we compute the total relative sea level (i.e. total sea level rise plus the local vertical crustal motion) since 1950. On comparing the results from these three regions with already existing results in tropical Pacific, we find that tropical Pacific displays the highest magnitude of sea level variations. In the last part of the thesis, we therefore focus on the tropical Pacific and analyze the respective roles of ocean dynamic processes, internal climate modes and external anthropogenic forcing on tropical Pacific sea level spatial trend patterns since 1993. Building up on the relationship between thermocline and sea level in the tropical region, we show that most of the observed sea level spatial trend pattern in the tropical Pacific can be explained by the wind driven vertical thermocline movement. By performing detection and attribution study on sea level spatial trend patterns in the tropical Pacific and attempting to eliminate signal corresponding to the main internal climate mode, we further show that the remaining residual sea level trend pattern does not correspond to externally forced anthropogenic sea level signal. In addition, we also suggest that satellite altimetry measurement may not still be accurate enough to detect the anthropogenic signal in the 20 year tropical Pacific sea level trends
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Yalew, Amsalu W., Georg Hirte, Hermann Lotze-Campen, and Stefan Tscharaktschiew. "Economic Effects of Climate Change in Developing Countries: Economy-wide and Regional Analysis for Ethiopia." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-227554.
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Quantifying the economic effects of climate change is a crucial step for planning adaptation in developing countries. This study assesses the economy-wide and regional effects of climate change induced productivity and labor supply shocks in agriculture in Ethiopia. The study shows, in worst case scenario, the effects on national GDP may add up to -8% with uneven regional effects ranging from -10% in agrarian regions (e.g. Amhara) to +2.5% in urbanized regions (e.g. Addis Ababa). Cost-free exogenous structural change scenarios in labor markets and transaction costs may offset about 20-30% of the ripple effects of climate change. Therefore, the ongoing structural transformation in the country may underpin the resilience of the economy to climate change. Nevertheless, given the role of agriculture in the current economic structure of the country and the potency of biophysical impacts of climate change, adaptation in the sector is indispensable. Otherwise, climate change may hamper economic progress of the country, and make rural livelihood unpredictable.
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Huang, Yan. "Assessments of the Direct and Indirect Effects of Anthropogenic Aerosols on Regional Precipitation over East Asia Using a Coupled Regional Climate-Chemistry-Aerosol Model." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6870.
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An aerosol module is developed and coupled to a regional climate model to investigate the direct and indirect effect of anthropogenic aerosols (sulfate and carbonaceous aerosols) on climate with a focus on precipitation over East Asia. This fully coupled regional climate-chemistry-aerosol model is capable of understanding the interactions between the aerosol perturbation and climate change. The simulated aerosol spatial and seasonal distributions are generally consistent with the observations. The magnitude of the simulated total aerosol concentration and optical depth is about 2/3 of the observed value, suggesting the estimated climatic effects in this work are reasonable and conservative.
With the implementation of various aerosol effect, i.e., direct, semi-direct, 1st and 2nd indirect effect, the aerosols?impacts on climate are assessed over the region. The direct, semi-direct and 1st indirect effects generate a negative surface solar forcing, leading to a surface cooling, and the semi-direct effect also heats the atmosphere by BC absorption. This, in turn, increases the atmospheric stability and tends to inhibit the precipitation. The precipitation reduction is largest in the fall and winter, up to -10% with the inclusion of both direct and 1st indirect effects. The 2nd indirect effect using BH94 scheme produces a comparable magnitude in long-wave heating as the solar cooling, leading to the nighttime temperature warming of 0.5K, and a reduction in the diurnal temperature range. The precipitation reduction from the 2nd indirect effect strongly depends on the auto-conversion scheme, with about -30% in the fall and winter, and -15% in the spring and summer using BH94 scheme, while less than -5% using TC80 scheme. By allowing the feedbacks between aerosols and climate, the coupled model generally decreases the discrepancies between the model-simulated and observed precipitation and aerosols over the region. The EOF analysis of the climatological precipitation from last century over East Asia shows a decreasing mode in the EOF leading modes in the fall and winter, and is generally geographically consistent with the distribution of the model simulated precipitation reduction from anthropogenic aerosols.
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Tisell, Camilla. "An investigation of the surface fluxes and other parameters inthe regional climate model RCA1 during ice conditions." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303758.
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In this study data from the regional climate model RCA1 is compared to measured data to investigate how good the model is during ice conditions and mainly how well the turbulent surface fluxes are described by the model. Comparisons of the sensible heat flux and the momentum flux as well as mean parameters are included. The measured data used are from the Bothnian Bay measured during the BASIS field experiment in February to March 1998. RCA1 (Rossby Centre regional Atmospheric model) is a regional climate model for Northern Europe based on HIRLAM and forced by ERA-40 data. Two different grid points of the RCA1 44 km grid have been chosen with geographical coordinates as close as possible to the two measuring sites. The first site is a small peninsula south of the town Umeå at the east coast of Sweden and the second one is the ship R/V Aranda anchored in the sea ice outside the Finnish west coast. The model presents generally too large negative (downward) sensible heat fluxes and too large momentum fluxes over ice. The largest difference between modelled and measured sensible heat fluxes are seen after warm front passages due to melting conditions. There are some uncertainties in the comparison of modelled fluxes and measured fluxes at Umeå due to a complex and varying ice cover around this measuring site. The vertical structure in the atmosphere has also been studied and modelled temperature, wind and humidity profiles were compared to radiosondes at the Umeå site. Two periods with on-ice flow and off-ice flow was analysed and one of the main differences was that for the on-ice situation an internal boundary layer was built up over the ice. Modelled profiles are generally smoother then measured profiles and inversions and other small-scale phenomena like low-level jets are almost never described correctly by the model but there are tendencies of the phenomena to occur.Sammanfattning av ”En undersökning i hur bra den regionala klimatmodellen RCA1 beskriver olika parametrar över is, i huvudsak de turbulenta flödena”. I denna undersökning har den regionala klimatmodellen RCA1 jämförts med mätdata för att se hur bra modellen är över is och framförallt hur bra den beskriver de turbulenta flödena över is. RCA1 är en regional klimatmodell för norra Europa baserad på HIRLAM och som drivs av ERA-40 data. Modelldata har jämförts med mätdata från två platser i Bottenviken, en liten halvö utanför Umeå på den svenska östkusten och forskningsfartyget Aranda som var fastankrad i havsisen utanför Finlands västkust. Mätningarna gjordes under BASIS fältexperiment i februari till mars 1998. Modellen ger generellt för stora negativa (nedåtriktade) sensibla värmeflöden över is och likaså för stora impulsflöden över is. Den största skillnaden mellan modellvärden och mätningar förekom efter det att varmfronter passerat och detta beror delvis på smältförhållanden. I jämförelsen av de turbulenta flödena beräknade av RCA och de uppmäta turbulenta flödena från Umeå finns det vissa osäkerheter pga. den komplicerade issituationen runt denna mätplats med mycket varierande isförhållanden. Den vertikala strukturen i atmosfären har också undersökts och temperatur, vind och fuktighetsprofiler har jämförts. Två perioder varav en där det blåste från havet mot isen (on-ice) och en där det blåste från isen mot havet (off-ice) valdes ut och en av skillnaderna var att det bildades ett internt gränsskikt över isen i on-ice perioden. Modellen har en tendens att släta ut profilerna och småskaliga fenomen som inversionsskikt, inversionshöjder och low-level jets är nästan aldrig korrekt beskrivna i modellen men det finns tendenser till inversioner och vindmaximum.
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Kothe, Steffen [Verfasser], Bodo [Akademischer Betreuer] Ahrens, and Heiko [Akademischer Betreuer] Paeth. "The radiation budget in a regional climate model / Steffen Kothe. Gutachter: Bodo Ahrens ; Heiko Paeth. Betreuer: Bodo Ahrens." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2012. http://d-nb.info/1044772549/34.
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Vial, Jessica. "Climate model simulations of winter northern hemisphere atmospheric blocking : statistical assessment, dynamical perspective, regional impacts and future change." Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/38862/.
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Li, Peng. "Temporal and Spatial Variability of Surface Solar Radiation over the South-West Indian Ocean and Reunion Island : Regional Climate Modeling." Thesis, La Réunion, 2015. http://www.theses.fr/2015LARE0021/document.
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Ce travail documente la variabilité spatiale et temporelle du rayonnement solaire à la surface sur le sud-ouest de l'océan Indien (SOOI) et l'île de La Réunion à l'aide de deux modèles régionaux de climat (MRC) : les modèles RegCM et WRF. La première partie de ce travail est dédiée à l'analyse de la variabilité temporelle du rayonnement solaire à l'aide du modèle RegCM sur le SOOI avec une résolution spatiale modérée (50km). S'agissant du premier travail sur la modélisation régionale du climat pour l'étude du rayonnement solaire dans le SOOI, une première série de tests pour illustrer les performances du modèle et sa sensibilité au choix des paramétrisations physiques (transfert radiatif, convection), à la taille du modèle, et à la résolution spatiale, est effectuée. Le schéma radiatif par défaut, le schéma CCM, et le schéma convectif mixte : Grell sur les terres et Emanuel sur les océans, donnent les résultats les plus satisfaisants pour la région, comparés aux autres options disponibles. La variabilité climatique interannuelle, intrasaisonnière et jour-à-jour est ensuite examinée sur la base des indices climatiques. Dans un premier temps, plusieurs paramètres (vent horizontal, température, humidité relative) issus des réanalyses ERA-Interim et utilisés comme paramètres d'entrée pour le modèle RegCM, sont analysés en lien avec ceux correspondant fournis en sortie du modèle, pour vérifier l'aptitude du modèle à maintenir les signaux ENSO (El-Nino Southern Oscillation), IOD (Indian Ocean Dipole), MJO (Madden-Julian Oscillation) et les Talwegs Tropicaux-Tempérés (TTT). Dans un second temps, le rayonnement solaire à la surface simulé par le modèle RegCM est mis en lien avec ces différents modes de variabilité. La seconde partie du travail est consacrée à l'analyse de la variabilité spatiale du rayonnement solaire à la surface à La Réunion à l'aide du modèle WRF à très haute résolution spatiale (750m) pour différentes échelles de temps : interannuelle, intrasaisonnière, jour-à-jour. Une classification est appliquée sur les sorties de rayonnement produites par WRF, et le lien avec la circulation atmosphérique de grande échelle est analysé dans chacune des classes. Les résultats de la modélisation sont validés à l'aide des données d'observations du réseau Météo France et des produits satellite CM SAF. Les résultats indiquent que les MRC ont la capacité de représenter la variabilité temporelle et spatiale du rayonnement solaire à La RéunionThis work documents the temporal and spatial variability of surface solar radiation (SSR) over the southwest Indian Ocean (SWIO) and Reunion Island using two complementary Regional Climate Models (RCMs): RegCM4 and WRF. The first part of the work is dedicated to the analysis of the temporal variability of SSR based on RegCM4 over the SWIO at a moderate spatial resolution (50km). Because RegCM4 is the first RCM that focuses on the solar radiation research over the SWIO region, a first series of test experiments with this model to illustrate the model performance and its sensitivity to the choice of the physical parameterizations (radiation, convection), the domain size, and the spatial resolution, are performed. The default CCM radiative and the mixed convective scheme: Grell scheme over land and Emanuel scheme over ocean, give better performance over the SWIO compared to the other available options. The interannual, intraseasonal and synoptic climate variability is then examined through the climate indices and several ERA-Interim parameters (U, V, T and RH) are firstly analyzed along with the corresponding RegCM4 output data to check whether the RegCM4 model forced by ERA-Interim reanalyses is able to maintain the El-Nino Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), the Madden-Julian Oscillation (MJO) and the Tropical Temperate Trough (TTT) signals. Secondly, simulated SSR in association with the different modes of variability is examined. In the second part, SSR spatial variability over Reunion Island is analyzed based on WRF simulations at very fine resolution (750m) for seasonal, intraseasonal, and daily time scales. Clustering classification is applied to WRF simulated SSR over Reunion and the effect from the atmospheric circulation is checked together. Météo France observations and CM SAF are used to validate the results of the model. The results indicate that regional climate models have the ability to present the temporal and spatial variability of SSR over Reunion
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Marke, Thomas. "Development and Application of a Model Interface to couple Land Surface Models with Regional Climate Models for Climate Change Risk Assessment in the Upper Danube Watershed." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-91622.
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Marke, Thomas. "Development and application of a model interface to couple land surface models with regional climate models for climate change rusk assessment in the upper danube watershed." kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/9162/.
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Emelie, Wennerdahl. "Change in Thunderstorm Activity in a Projected Warmer Future Climate: a Study over Europe." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-337148.
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In the last 100 years, a rise in the global mean temperature has been noted, and projections show even higher temperatures in the future. The temperature rise can lead to changes in the weather patterns and therefore the thunderstorm activity in a future warmer climate has been investigated in this study. The future projections were made with an ensemble of 8 General Circulation Models downscaled with the regional climate model RCA4, developed at SMHI. Temperature and humidity data at four different levels in the atmosphere has been used to compute three different stability indices. Stability indices indicate potential for deep convection in the atmosphere, from which thunderstorms are developed. It was found that the projections show an increase in thunderstorm potential in a warmer future climate. In Sweden, the projections show an increase with about 15 more days with risk of thunderstorms at the end of the 21st century for the RCP4.5 scenario, corresponding to an increase of 40% in the south, and an even larger increase in the north. For the RCP 8.5 scenario, the projected change in days with risk of thunderstorms corresponds to an increase about 20 days, or about 60% more thunderstorm days in south of Sweden. In other parts of Europe, the increase is expected to be even larger, mainly in the mountain regions. It was also found that the thunderstorm season is projected to be extended in the future, with more days with risk of thunder in May and September. The increase in number of days with risk of thunderstorms is a result of the greater amount of water vapour that the atmosphere is able to hold in a warmer climate. Even if thunderstorms are projected to increase, other factors counteract, such as a decrease in the vertical temperature gradient and a decrease in the difference between moisture in the upper and the middle atmosphere. Yet, taken together the days with risk of thunderstorms are projected to become more frequent.Under de senaste hundra åren har medeltemperaturen på jorden ökat med cirka 1°C, vilket har medfört förändringar i klimatet. Temperaturen kommer att fortsätta stiga på grund av den redan förhöjda halten växthusgaser i atmosfären, och om växthusgaser fortsätter släppas ut kan det förväntas bli ännu varmare. I och med att temperaturen fortsätter stiga är det mycket som pekar på att vädret i allmänhet kommer förändras, som till exempel förändrat mönster i åskoväder. I denna studie har risken för åska i ett framtida klimat studerats. Åska och konvektion bildas framförallt på grund av tre komponenter: instabilitet i atmosfären, fuktigheten i luften och en mekanism som får luften att lyftas från marken. En instabil luftmassa fås framförallt en varm sommardag när solen värmer marken, vilket medför att luften vid marken blir betydligt varmare än luften ovanför. Den andra faktorn är beroende av fuktigheten i luften, om luften är tillräckligt fuktig finns risk att större åskmoln kan bildas. De första två faktorerna kan beskrivas med vad som kallas stabilitetsindex. I denna studie beräknades risken för djup konvektion med hjälp utav stabilitetsindex. Temperatur-och fuktighetsdata från den regionala klimatmodellen RCA4, framställd på SMHI, användes för att beräkna dessa stabilitetsindex. Studien visar på att dagar med risk för åska förväntas öka i slutet av detta seklet med omkring 10-15 dagar per år över Sverige, med ännu fler dagar med risk för åska i södra Europa. En förhöjd åskrisk kan även förväntas vid bergskedjor så som svenska fjällen och Alperna. Den främsta anledningen till att åska förväntas bli vanligare är till följd av att temperaturstigningen möjliggör högre halt vattenånga i atmosfären, och därmed kommer fuktigheten i luften att öka. En längre åsksäsong har även noteras, med tidigare start i maj, och även förlängd i september.
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Shao, Yongning. "A simulation of the effects of Gulf of Mexico sea surface temperature anomalies using the Canadian Regional Climate Model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29784.pdf.
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Shao, Yongning. "A simulation of the effects of Gulf of Mexico sea surface temperature anomalies using the Canadian Regional Climate Model /." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27408.
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The Canadian Regional Climate Model (CRCM) has been used to investigate the effects of Gulf of Mexico sea surface temperature (SST) anomalies on the regional climate. Three sets of experiments have been performed, each consisting of a control run and with two different imposed Gulf SST anomalies. The first is a uniform increase or decrease of the SST by 5K over the entire Gulf. The second and third experiments use 5K SST anomalies of smaller extent, characteristic of warm core rings shed off the Loop Current in the Gulf. The experiments are carried out for either 15 or 30 days, and statistics are computed after discarding the first 5 days of the integration.The response of the SST anomalies are qualitatively similar in the three cases, except the response to the anomaly over the entire Gulf is stronger due to the much larger extent of the anomaly. For a positive SST anomaly, precipitation and moisture over the Gulf and southeastern U.S. both increase. The 1000mb temperature field shows a clear warming over the Gulf and adjacent areas, delineating the imposed SST anomaly. A low level cyclonic circulation forms over the Gulf and southeastern U.S. region, while an anticyclonic circulation develops at the upper levels. The negative SST anomaly experiments show a qualitatively similar response, except it is of opposite sign with a smaller magnitude.
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McCormack, Trudy. "An evaluation of the Canadian Regional Climate Model simulation of the 1999 to 2004 drought over the Canadian Prairies." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66806.
Full textAbstract:
The information from the Canadian Regional Climate Model (CRCM) can be applied to improve prediction of Prairie drought in order to reduce its devastating environmental, societal, and economical effects. One can, for example, use the CRCM to investigate the importance of certain feedbacks in maintaining the drought. A necessary step before using the CRCM for such purposes is to establish how well the model reproduces observed features of the drought. In this study, satellite and surface station data from the recent and severe Canadian Prairie drought of 1999-2004 are used to compare with the model output. The absolute data fields examined include precipitation, cloud properties, and top-of-atmosphere albedo. Cloud amount-Standardized Precipitation Index (SPI) correlations, and top-of-atmosphere albedo-SPI correlations are also compared. Overall, the CRCM performs well in the areas examined and gives confidence in its usefulness as a tool to understanding Prairie drought.Les informations du modèle régional canadien du climat (MRCC) peuvent être utilisées pour améliorer la prédiction de la sécheresse dans la Prairie afin de réduire ses effets environnementaux, sociétaux et économiques dévastateurs. Il est possible, par exemple, d'utiliser le MRCC pour déterminer l'importance de certains effets de rétroaction sur la maintenance de la sécheresse. Une étape préliminaire nécessaire a l'usage du MRCC a de telles fins est déterminer l'efficaté avec laquelle la modèle reproduit les caractéristiques observées de la sécheresse Dans cette étude, des données satellites et de stations au sol de la sécheresse récente et sévère la Prairie Canadienne de 1999-2004 sont utilisées et comparées aux données de sortie du modèle. Les champs de données étudies incluent la précipitation, les propriétés des nuages et l'albédo du sommet de l'atmosphère. La corrélation entre la quantité de nuage et l'indice standardisé de précipitation (ISP) et la corrélation entre l'albedo du sommet de l'atmosphère et l'ISP sont aussi comparées. Globalement, le MRCC obtient de bon résultats dans les domaines étudies et donne confiance en son utilité comme outil dans la compréhension de la sécheresse de la Prairie.