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1
Spellman, Greg. „An evaluation of statistical synoptic models of rainfall in Spain“. Thesis, University of Northampton, 2003. http://nectar.northampton.ac.uk/2997/.
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This study investigates the control of atmospheric circulation patterns on rainfall incidence in Spain. The main objective of the research is to evaluate a range of statistical synoptic approaches with the aim of identifying the scheme that best models circulation to association. Spatial patterns of rainfall in Spain are first investigated using Principal Components Analysis and Cluster Analysis. Distinct precipitation affinity groups emerge that display covariant rainfall behaviour and reflect differences in latitude, the influence of topography and distance from the synoptic feature responsible for rainfall. The method allows seasonal redefinition of boundaries and the investigation of the effect of climate change. In total 24 synoptic models are investigated. The best performing models (a daily weather type model and a monthly airflow index model) use standardized data and the 500hPa contour surface. Some of the problems associated with non-stationarity are attempted by modifying models using kinematic information. Adjustments to the models (inclusion of frontal information and stochastic modelling) can improve results on a sub-regional scale. Effective models are then used to empirically downscale from General Circulation Model (GCM) scenarios obtained from the Canadian Centre for Climate Modelling and Analysis. The downscaling procedure is of limited use due to errors in GCM output but results suggest strongly increasing anticyclonicity in the Iberian area and a decrease in rainfall in many areas. There are uncertainties associated with regional scale climate change estimation using current empirical methods, nevertheless as GCM output inevitably becomes more accurate the scope for detailed regional assessment will improve
2
Jean, Michel 1959 Sept 29. „Synoptic and diagnostic analyses of CASP storm #14“. Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63998.
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Bellone, Enrica. „Nonhomogeneous hidden Markov models for downscaling synoptic atmospheric patterns to precipitation amounts /“. Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8979.
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Serra, Yolande L., und Kerrie Geil. „Historical and Projected Eastern Pacific and Intra-Americas Sea TD-Wave Activity in a Selection of IPCC AR5 Models“. AMER METEOROLOGICAL SOC, 2017. http://hdl.handle.net/10150/624034.
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The tracks of westward-propagating synoptic disturbances across the Intra-Americas Sea (IAS) and far-eastern Pacific, known as easterly waves or tropical depression (TD) waves, are an important feature of the region's climate. They are associated with heavy rainfall events, seed the majority of tropical cyclones, and contribute to the mean rainfall across the region. This study examines the ability of current climate models (CMIP5) to simulate TD-wave activity and associated environmental factors across the IAS and far-eastern Pacific as compared to reanalysis. Model projections for the future are then compared with the historical model experiment to investigate the southward shift in CMIP5 track density and the environmental factors that may contribute to it. While historical biases in TD-wave track-density patterns are well correlated with model biases in sea surface temperature and midlevel moisture, the projected southward shift of the TD track density by the end of the twenty-first century in CMIP5 models is best correlated with changes in deep wind shear and midlevel moisture. In addition, the genesis potential index is found to be a good indicator of both present and future regions of high TD-wave track density for the models in this region. This last result may be useful for understanding the more complex relationship between tropical cyclones and this index in models found in other studies.
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Malhomme, Nemo. „Statistical learning for climate models“. Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST165.
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Les modèles climatiques peinent à représenter précisément les structures de circulation atmosphérique liées aux événements extrêmes, et notamment leurs variations régionales.Cette thèse explore comment l'Allocation Latente de Dirichlet (LDA), une méthode d'apprentissage statistique issue du traitement du langage naturel, peut être utilisée pour évaluer la représentation par modèles climatiques de données telles que la pression au niveau de la mer (SLP).La LDA identifie un jeu de structures locales (ou motifs) à l'échelle synoptique, interprétables physiquement comme des cyclones et des anticyclones.La même base de motifs peut servir à décrire les données issues des modèles et des réanalyses, permettant de représenter toute carte SLP par une combinaison parcimonieuse de ces motifs.Les coefficients, ou poids, de ces combinaisons fournissent une information locale sur la configuration synoptique de la circulation.Les analyser permet de caractériser la structure de la circulation dans les réanalyses et les modèles, et ainsi d'identifier localement des biais globaux ou spécifiques aux événements extrêmes.Une erreur dynamique globale peut être définie à partir des différences de poids des données modèles avec les réanalyses.Cette méthodologie a été appliquée à quatre modèles de CMIP6.Bien que les modèles représentent correctement en général la circulation à grande échelle, leurs erreurs sont plus élevées pour les vagues de froid et de chaleur.Une source d'erreur dans tous les modèles est liée aux motifs méditerranéens.Des critères d'évaluation supplémentaires ont été proposés.L'un s'appuie sur la fréquence d'apparition des motifs dans la représentation des cartes de pression.L'autre consiste à combiner l'erreur dynamique globale avec l'erreur de température, ce qui permet de différentier entre les modèles.Ces résultats démontrent le potentiel de la LDA pour l'évaluation et la préselection des modèlesClimate models face challenges in accurately representing atmospheric circulation patterns related to extreme weather events, especially regarding regional variability.This thesis explores how Latent Dirichlet Allocation (LDA), a statistical learning method originating from natural language processing, can be adapted to evaluate the ability of climate models to represent data such as Sea-Level Pressure (SLP).LDA identifies a set of local synoptic-scale structures, physically interpretable as cyclones and anticyclones, referred to as motifs.A common basis of motifs can be used to describe reanalysis and model data so that any SLP map can be represented as a sparse combination of these motifs.The motif weights provide local information on the synoptic configuration of circulation.By analyzing the weights, we can characterize circulation patterns in both reanalysis data and models, allowing us to identify local biases, both in general data and during extreme events.A global dynamic error can be defined for each model run based on the differences between the average weights of the run and reanalysis data.This methodology was applied to four CMIP6 models.While large-scale circulation is well predicted by all models on average, higher errors are found for heatwaves and cold spells.In general, a major source of error is found to be associated with Mediterranean motifs, for all models.Additional evaluation criteria were considered: one was based on the frequency of motifs in the sparse map representation.Another one involved combining the global dynamic error with the temperature error, thus making it possible to discriminate between models.These results show the potential of LDA for model evaluation and preselection
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Du, Preez Chrisna Barbara. „A mesoscale investigation of the sea breeze in the Stellenbosch winegrowing district“. Diss., Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-02092007-093317.
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Campos, Antonio Marcos Vianna. „Modelos conceituais de formação da corrente de jato no nordeste brasileiro“. Universidade Federal de Alagoas, 2010. http://repositorio.ufal.br/handle/riufal/886.
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Conselho Nacional de Desenvolvimento Científico e TecnológicoO objetivo principal deste trabalho baseou-se na elaboração e estudo das freqüências de distribuições espaciais das Correntes de Jato próximo do Nordeste Brasileiro (CJNEB) e sistemas sinóticos associados. Esta pesquisa foi realizada devido à necessidade de um maior conhecimento sobre a influência desse sistema na região e a pouca quantidade de artigos relacionados a este tipo de pesquisa. O período escolhido contou com 16 anos de análises entre os anos de 1994 e 2009. Foram utilizados os dados de reanálise do National Centers for Environmental Prediction (NCEP) no nível de 200 hPa e imagens de satélite no canal infravermelho do banco de dados do Space Science and Engineering Center (SSEC) da University of Wisconsin. A partir daí foram encontrados 1.100 casos desta corrente, representando um total de 19% dos dias analisados e 4.740 (81%) casos de ventos com velocidades entre 20 e 30 m/s. Apesar de serem registrados ventos acima de 30 m/s em todas as estações do ano, os meses que contaram com as maiores freqüências e ocorrências deste vento foram os de outono e inverno. O vento máximo registrado para esta corrente de ar em nível superior ocorreu no mês de inverno, alcançando 64 m/s (230 km/h). Em todo período foram notadas variações anuais com ciclos de 4 ou 5 anos de maiores ou menores ocorrências. Os sistemas associados à CJNEB foram os vórtices ciclônicos de altos níveis (VCAN s), cavados (CAV), alta da Bolívia (AB), ciclones do hemisfério norte (CHN) e anticiclones no atlântico sul (AAS) próximo ao equador. As distribuições espaciais encontradas das CJNEB foram referentes às direções de NW-SE, SW-NE, SE-NW, W-E, S-N e N-S. As direções de NW-SE e SW-NE foram os casos mais observadas durante todo o estudo. Foram elaborados modelos conceituais dos três tipos de CJNEB associados com seguintes sistemas sinóticos: I) AB junto com VCAN do tipo clássico perto do NEB no Atlântico e ou cavado; II) Anticiclone do Atlântico junto com VCAN no NEB tipo clássico e ou cavado; III) cavado perto do NEB junto com ciclone do hemisfério norte. Estes tipos de CJNEB tinham seguintes direções: tipo 1 de sul, sudeste e sudoeste; tipo 2 de norte e noroeste; e tipo 3 de leste e sudoeste.
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Ebisuzaki, Wesley Nobuo. „Interactions between long and synoptic-scale waves in a simple model“. Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/53524.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1987.Microfiche copy available in Archives and Science.
Bibliography: leaves 197-204.
by Wesley Nobuo Ebisuzaki.
Ph.D.
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Lukancic, Khara Diane. „SENSITIVITY OF STRONG EXTRATROPICAL CYCLONES TO LARGE-SCALE CLIMATE VARIABILITY IN THE CONTIGUOUS UNITED STATES“. OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2043.
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Extratropical cyclones are responsible for a substantial portion of midlatitude climate variability and contribute to widespread impacts. The characteristics of extratropical cyclones, such as their spatial distribution and intensity, are thought to be dependent on the large scale circulation. The relationship between cyclone characteristics and modes of large-scale climate variability has been investigated in previous studies, but interactions between modes of climate variability have largely been ignored. Since extratropical cyclone characteristics may be related to interactions between phases, quantifying these relationships is an important step in improving the climatology of extratropical cyclones. The goal of this study is to quantify relationships between modes of climate variability and characteristics of strong cyclones in the contiguous United States. Using historical sea-level pressure data, cyclone intensity, frequency, and spatial distribution are investigated using a cyclone definition that combines the requirement for low pressure (1000 hPa or lower) and positive (cyclonic) vorticity. The large scale modes of climate variability considered include El Niño Southern Oscillation (ENSO), the Pacific North American (PNA) mode, and the Arctic Oscillation (AO). The analysis is divided into three phases focusing on (1) establishing a background cyclone climatology within the study area, (2) quantifying differences in cyclone characteristics between the positive and negative phases of the individual modes of climate variability, and (3) examining the interactions between the modes of climate variability as they relate to extratropical cyclone characteristics. The results are expected to provide an improved baseline for evaluation of coupled climate models and also have the potential to improve seasonal climate predictability.
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Leishman, Natalie. „Model Sensitivity, Performance and Evaluation Techniques for The Air Pollution Model in Southeast Queensland“. Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16148/1/Natalie_Leishman.pdf.
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One important component for successful air quality modelling is the utilisation of a reliable meteorological simulator. Evaluating the model with respect to its overall performance in predicting natural processes is no easy task. The problem is twofold, firstly there is the availability and suitability of field data with which to compare a model with and secondly there is the method of evaluation. The Air Pollution Model (TAPM), developed by the CSIRO was used to simulate the winds in Southeast Queensland (SEQ). The complex nature of the airshed makes it difficult to compare modelled data with observational data as the observational data may be influenced by local phenomena. Evaluation of the model through the use of standard statistics and monthly and seasonal statistics illustrated that overall the model predicted the annual average wind speeds and temperatures well. Through the use of synoptic clustering, more detail on model performance was gained and it was found that TAPM predicted sea breezes that occurred on high pollution days. The sensitivity of the model to the selection of input parameters such as soil type, land use, vegetation, and rain processes was also investigated.
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Leishman, Natalie. „Model Sensitivity, Performance and Evaluation Techniques for The Air Pollution Model in Southeast Queensland“. Queensland University of Technology, 2005. http://eprints.qut.edu.au/16148/.
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One important component for successful air quality modelling is the utilisation of a reliable meteorological simulator. Evaluating the model with respect to its overall performance in predicting natural processes is no easy task. The problem is twofold, firstly there is the availability and suitability of field data with which to compare a model with and secondly there is the method of evaluation. The Air Pollution Model (TAPM), developed by the CSIRO was used to simulate the winds in Southeast Queensland (SEQ). The complex nature of the airshed makes it difficult to compare modelled data with observational data as the observational data may be influenced by local phenomena. Evaluation of the model through the use of standard statistics and monthly and seasonal statistics illustrated that overall the model predicted the annual average wind speeds and temperatures well. Through the use of synoptic clustering, more detail on model performance was gained and it was found that TAPM predicted sea breezes that occurred on high pollution days. The sensitivity of the model to the selection of input parameters such as soil type, land use, vegetation, and rain processes was also investigated.
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Carpenter, McLean Kent. „West Antarctic Surface Mass Balance: Do Synoptic Scale Modes of Climate Contribute to Observed Variability?“ BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4382.
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Western Antarctica has been experiencing significant warming for at least the past fifty years. While higher Net Surface Mass Balance (SMB) over West Antarctica during this period of warming is expected, SMB reconstructions from ice cores reveal a more complex pattern during the period of warming. The mechanisms giving rise to SMB variability over the West Antarctic Ice Sheet (WAIS) are not well understood due to lack of instrumental data. The Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) are believed to contribute to WAIS SMB variability but the assumption has not been rigorously tested. SMB during years where SAM and ENSO are in extreme phases is compared to average SMB from the period 1979-2010. Additionally, atmospheric circulation anomalies are used to assess what circulation patterns accompany extreme modes of climate during the same period. The results suggest that significantly lower SMB occurs when SAM is in an extremely positive phase or ENSO is in an extremely negative phase. Additionally, atmospheric circulation anomalies show that certain circulation patterns accompany extreme modes of climate, which contribute to SMB variability over the WAIS. Ultimately, the location of low and high pressure cells is the best predictor for extreme accumulation events over the WAIS. These results are verified by assessing observed net SMB trends from a network of firn cores located from the central WAIS. Seven new firn cores are added to improve the spatial network of regional net SMB measurements. Reconstructed net SMB is calculated from new firn core records, and compared to the existing cores. The new suite of preliminary firn core records show the same significant decreasing trend that is observed in existing cores. This represents a negative region-wide SMB trend that is likely in part due to trends in SAM and ENSO.
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Wilson, Monica. „Synoptic to interannual variability in volumetric flushing in Tampa Bay, FL using observational data and a numerical model“. Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4963.
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This research provides insight into changes in volumetric flushing of the Tampa Bay estuary caused by synoptic scale wind events. The two main studies of this dissertation involve 1) using wavelet analysis to investigate the link between the El Niño-Southern Oscillation (ENSO) and the frequency and strength of volumetric flushing driven by synoptic variability and 2) using a multi-decadal model simulation to examine how extratropical/winter storms and hurricanes affect the overall flushing rates for Tampa Bay, FL.
In the first study, two analyses are performed on 55 years of observational data to investigate the effect of multiple small wind events on estuarine flushing. First I use subtidal observed water level as a proxy for mean tidal height to estimate the rate of volumetric bay outflow. Second, I use wavelet analysis on sea level and wind data to isolate the synoptic sea level and surface wind variance. For both analyses the long-term monthly climatology is removed to focus on the volumetric and wavelet variance anomalies. The overall correlation between the Oceanic Niño index and volumetric anomalies is small (r2=0.097) due to the seasonal dependence on the ENSO response. The mean monthly climatology between the synoptic wavelet variance of elevation and axial winds have similar seasonal behavior. During the winter, El Niño (La Niña) increases (decreases) the synoptic variability, but decreases (increases) it during the summer. The difference in winter El Niño/La Niña wavelet variances is about 20% of the climatological value. ENSO can swing the synoptic flushing of the bay by 0.22 bay volumes per month. These changes in circulation associated with synoptic variability have the potential to impact mixing and transport within the bay.
In the second study, volumetric changes from large scale weather events are investigated using a numerical circulation model simulation (1975-2006) to find the cumulative impact of flushing on the bay by extreme events. The strong wind speeds, duration of high winds and wind direction during these events all affect the amount of water flushed in and out of the estuary. Normalized volume anomalies are largest when wind components blow up/down the estuary in the NE/SW direction. Wind induced normalized flushing rates for all 10 extratropical/winter storms range from 12% to 40% and from 14% to 40% for all 10 hurricanes. All storms discussed in this study caused winds greater than 15 m s-1 (~30 knots). The direction of the winds had an impact on the flushing rates during these extreme events. Storm9 (February 1998) and Hurricane Gabrielle (September 2001) experienced the smallest total volume changes (14% and 13%). Both storms experienced weak axial and co-axial winds causing volume changes to be small. The Storm of the Century (March 1993) and Hurricane Frances (September 2004) saw the largest total volume changes of 40%. They both had strong winds blowing in the NE direction. Hurricane Frances had two wind peaks and lingered in the area for approximately 48 hours, so both strength and duration of winds played a large role in the total volume change. Total inflow and outflow rates per year show that there is year to year variability of flushing in Tampa Bay.
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Splawinski, Sophie. „An assessment of freezing rain processes in the Saint- Lawrence River Valley: synoptic-dynamic analysis and operational model verification“. Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121459.
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Freezing rain (FZRA), a hazardous meteorological phenomenon, poses a significant threat to the general public and can severely damage societal infrastructure. The phenomenon is well known throughout the St-Lawrence River Valley (SLRV), which is known to have one of the highest frequencies of FZRA in the world owing to its orography and spatial orientation. Our focus is to provide meteorologists with the means to better predict both the onset and duration of FZRA at Montreal (CYUL), Quebec City (CYQB), and Massena (KMSS) in a two-stage process: by introducing a new 2-dimensional elliptic regression statistical forecast model and to assess synoptic and mesoscale conditions associated with past events. Analysis of a 27-year period, from 1979 through 2005, was conducted with a total of 99, 102, and 70 FZRA events at CYQB, CYUL, and KMSS, respectively. Our statistical analysis provides meteorologists with the POZR (probability of freezing rain): the ability to input model forecasted temperatures at two pressure levels and determine the probability of the onset of FZRA based on a 30-year climatology of northeasterly related precipitation. Synoptic-dynamic analysis of past events acknowledges the need for a high-resolution forecast model to adequately resolve mesoscale processes crucial to FZRA maintenance. Tests performed using a verification dataset (2006-2011 ZR event data) show the accuracy and feasibility of the model, which could be implemented by forecasting offices. Furthermore, synoptic-dynamic assessment of events within the verification dataset and forecast model comparison provide insight into missed forecasts, great forecasts and false alarms. Utilizing these methods could provide meteorologists with the opportunity to produce more highly accurate forecasts of both the onset and duration of freezing rain events.La pluie verglaçante (PV) est une forme de précipitation qui pose un danger non seulement pour le secteur publique mais également pour le secteur aérien. Ce phénomène est particulièrement connu dans la vallée du fleuve St. Laurent (VFSL). L'orientation de la vallée ainsi que l'orographie explique ce nombre accru d'évènement. Le but vise est donc de fournir aux météorologues les outils nécessaires pour améliorer les prévisions de durée et de location de PV pour les villes de Montréal (CYUL), Québec (CYQB), et Massena (KMSS). Afin d'y parvenir, deux étapes sont requises : la première, introduire un nouveau modèle statistique de prévision et la deuxième, évaluer les conditions synoptiques et meso-échelle des évènements au cours des 27 dernières années. Pendant cette période, 99, 102, et 70 évènements de PV se sont produit à CYQB, CYUL, et KMSS, respectivement. Notre analyse statistique fourni aux météorologues une probabilité d'occurrence de PV (POZR). L'analyse est un moyen d'introduire les prévisions de température à deux différents niveaux et déterminer la probabilité de PV en utilisant un modèle baser sur les données provenant d'une climatologie de précipitations et de vents dans la VFSL. Les analyses synoptiques et dynamiques des évènements passés nous ont montré la nécessité d'incorporer un modèle de prévisions à haute résolution dans la vallée; nécessaire pour résoudre adéquatement l'orographie. Ceci est impératif pour la réussite de prévisions de PV. Ensuite, en utilisant un ensemble de données de vérification, on effectues des analyses de faisabilité et de précision du modèle, ce qui peut être utilise dans un bureau de prévisions. Finalement, une comparaison d'évènements de POZR variées démontre les forces et faiblesses dans les modèles de prévisions actuels. Ces derniers, couplés avec un nouveau modèle de prévision de PV, fourni au météorologues une opportunité de produire des prévisions de PV plus précises dans la VFSL.
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Anderson, John W. „An analysis of a dust storm impacting Operation Iraqi Freedom, 25-27 March 2003“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FAnderson.pdf.
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Salehjee, Saima Qasim. „Making scientists : developing a model of science identity“. Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14670.
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This study is an analysis of a three-phase study with twelve professional scientists and non-scientists (Phase One), one-hundred and twenty-three science and non-science university students (Phase Two) and thirty secondary school girls (Phase Three), to illustrate their ‘science lives’. I have used identity theories and transformational learning theory (TLT) to illustrate transformation or movement of learners towards, or away from, science. The understanding of these models and theories have led me to design a theoretical model of science identity (Sci-ID) that represents the global forces (GF) experienced by learners, the social agencies and agents (SA) that embody those forces, the transformational learning (TL) experiences (events, triggers and interventions) that shape personal meaning, and the inclinations and individual internal agency (IIA) that impact upon individuals’ subject and career choices. I have adopted semi-structured ‘narrative’ styled interviews, a descriptive questionnaire and science ‘intervention evaluation’ approaches from the three cohorts. The data generated has been analysed in several ways, including the use of synoptic analysis to construct individual stories about the participants, in third-person voice, from their responses. These stories and the broader, aggregated, thematic, outcomes have been used to examine the Sci-ID model. These outcomes stress three main themes related to the study (or not) of science, that include (i) progressive transformational learning and smooth transformation, (ii) progressive transformational learning and wavering transformation and (iii) reconstructive transformational learning and wavering transformation. These themes indicates that people in life accept and reject certain TL experiences that either ‘go with their IIA’ or ‘go against it’. The majority find their way, choose and select TL experiences exhibiting small or medium movement towards or away from science. However, very few people exhibit large movement accompanied by regressive TL experiences. This study also reveals the existence of two very broad kinds of people (i) people who demonstrate stable pro-science or anti science and (ii) ‘fluid’ people who populate the centre-ground between pro-science and anti-science people. The fluid group caught my attention because their IIA shows greater ambivalence and the impact of GF, SA, incorporating events, triggers and interventions appear to have more impact than on those with a more stable science identity. Therefore, through six science education-based interventions I was able to work with – and influence - more ‘fluid’ kinds of secondary school girls. I used a number of mini-transformative experiences that led them to gain appreciation of science-based education and possible future science careers.
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Dean, John Robert. „Improving Summer Drought Prediction in the Apalachicola-Chattahoochee- Flint River Basin with Empirical Downscaling“. Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/geosciences_theses/12.
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The Georgia General Assembly, like many states, has enacted pre-defined, comprehensive, drought-mitigation apparatus, but they need rainfall outlooks. Global circulation models (GCMs) provide rainfall outlooks, but they are too spatially course for jurisdictional impact assessment. To wed these efforts, spatially averaged, time-smoothed, daily precipitation observations from the National Weather Service cooperative network are fitted to eight points of 700 mbar atmospheric data from the NCEP/NCAR Reanalysis Project for climate downscaling and drought prediction in the Apalachicola-Chattahoochee-Flint (ACF) river basin. The domain is regionalized with a factor analysis to create specialized models. All models complied well with mathematical assumptions, though the residuals were somewhat skewed and flattened. All models had an R-squared > 0.2. The models revealed map points to the south to be especially influential. A leave-one-out cross-validation showed the models to be unbiased with a percent error of < 20%. Atmospheric parameters are estimated for 2008–2011 with GCMs and empirical extrapolations. The transfer function was invoked on both these data sets for drought predictions. All models and data indicate drought especially for 2010 and especially in the south.
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Burgin, Laura Elizabeth. „The impacts of weather and climate change on the spread of bluetongue into the United Kingdom“. Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3208.
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A large epizootic of the vector-borne disease bluetongue occurred in northern Europe from 2006-2009, costing the economies of the infected countries several hundreds of millions of euros. During this time, the United Kingdom (UK) was exposed to the risk of bluetongue by windborne incursions of infected Culicoides biting midges from the northern coast of mainland Europe. The first outbreaks which occurred in the UK in 2007 were attributed to this cause. Although bluetongue virus (BTV) no longer appears to be circulating in northern Europe, it is widely suggested that it and other midge-borne diseases may emerge again in the future, particularly under a changing climate. Spread of BTV is strongly influenced by the weather and climate however limited use has been made of meteorologically based models to generate predictions of its spread to the UK. The extent to which windborne BTV spread can be modelled at timescales from days to decades ahead, to inform tactical and strategic decisions taken to limit its transmission, is therefore examined here. An early warning system has been developed to predict possible incursion events on a daily timescale, based on an atmospheric dispersion model adapted to incorporate flight characteristics of the Culicoides vectors. The system’s warning of the first UK outbreak in September 2007 was found to be greatly beneficial to the UK livestock industry. The dispersion model is also shown to be a useful post-outbreak epidemiological analysis tool. A novel approach has been developed to predict BTV spread into the UK on climate-change timescales as dispersion modelling is not practical over extended periods of time. Using a combination of principal component and cluster analyses the synoptic scale atmospheric circulations which control when local weather conditions are suitable for midge incursions were determined. Changes in the frequency and timing of these large scale circulations over the period 2000 to 2050 were then examined using an ensemble of regional climate model simulations. The results suggest areas of UK under the influence of easterly winds may face a slight increase in risk and the length of the season where temperatures are suitable for BTV replication is likely to increase by around 20 days by 2050. However a high level of uncertainty is associated with these predictions so a flexible decision making approach should be adopted to accommodate better information as it becomes available in the future.
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Walther, Connie Verfasser], Christian [Akademischer Betreuer] Bernhofer, Martin [Akademischer Betreuer] Horwath und Johannes [Akademischer Betreuer] [Quaas. „Atmospheric Circulation in Antarctica : Analysis of Synoptic Structures via Measurement and Regional Climate Model / Connie Walther. Betreuer: Christian Bernhofer. Gutachter: Martin Horwath ; Johannes Quaas“. Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/109539536X/34.
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Cuviello, Matthew P. Konrad Charles Edward. „A model for refining precipitation-type forecasts for winter weather in the Piedmont region of North Carolina on the basis of partial thickness and synoptic weather patterns“. Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,932.
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Thesis (M.A.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Dec. 18, 2007). "... in partial fulfillment of the requirements for the degree of Masters in the Department of Geography (Climatology)." Discipline: Geography; Department/School: Geography.
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Bari, Driss. „Etude du brouillard en zone côtière par modélisation des processus physiques de la couche limite atmosphérique : cas du Grand Casablanca (Maroc)“. Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30316/document.
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Le brouillard est un phénomène météorologique très difficile à prévoir, même à très courte échéance, en raison de sa grande variabilité spatiale et temporelle qui est due à des interactions complexes entre divers processus physiques. Dans cette thèse, les caractéristiques météorologiques locales et les processus synoptiques favorables aux brouillards sur la région du Grand Casablanca (Maroc) sont examinés à l'aide des observations horaires aux deux stations météorologiques permanentes de cette région côtière. Un algorithme de classification objectif est développé et utilisé pour classer les événements en des types de brouillard les plus rencontrés. Cette étude climatologique a mis en évidence que le brouillard a le plus souvent un caractère localisé et que le type d'advection-rayonnement est le plus fréquent sur la région, suivi des types d'affaissement de stratus et de rayonnement. Quand le brouillard intéresse simultanément les deux stations, la probabilité d'observer deux types différents est assez élevée. Les processus advectifs liés à la circulation de brise de mer au cours de l'après-midi, suivis de ceux radiatifs en début de nuit jouent un rôle important dans la formation du brouillard sur la région. Des simulations numériques à l'aide du modèle Méso-NH sont réalisées. Ces simulations ont confirmé que les processus physiques impliqués dans le cycle de vie du brouillard peuvent être différents selon la nature géographique de la surface. Elles ont aussi mis en évidence que la prévision numérique du brouillard en zone côtière est sensible à la température de la surface de la mer, à la topographie locale, et à l'occupation du sol. De plus, la prévision du brouillard côtier dépend fortement de la capacité du modèle à reproduire correctement la circulation de brise au cours de l'après-midi et les processus radiatifs en début de nuit. Les simulations systématiques des cas de brouillard de l'hiver 2013-2014 a montré la capacité du modèle Méso- NH à reproduire l'occurrence du brouillard avec néanmoins un taux relativement élevé de fausses alarmes, en particulier à la station côtièreThe prediction of fog remains a challenge due to its time and space variability and to the complex interaction between the numerous physical processes influencing its life cycle. During the first stage of this thesis, the local meteorological and synoptic characteristics of fog occurrence over the Grand Casablanca region (Morocco) are investigated. To achieve this, hourly surface meteorological observations, at two synoptic stations of this coastal region, are used. An objective fog-type classification has been developed in this work and used to discriminate the fog events into the well known types. This fog climatology points out that the fog is often localized and that it is predominantly of advection-radiation type, followed by fog resulting from cloud base lowering and radiation fog. Besides, two different fog types can occur when fog simultaneously concerns the two stations. The advective processes associated with sea breeze circulation during the daylight, followed by the radiative processes often leads to fog formation over this coastal region. Numerical simulations are performed later using the meso-scale non-hydrostatic model Meso-NH. These simulations confirm that the physical processes, governing the life cycle of fog, can be different according to the physiographic features of the area. Moreover, the numerical prediction of coastal fog over heterogeneous area is very sensitive to sea surface temperature, land local topography and land cover. It also depends on the model's ability to reproduce the sea breeze circulation during the daylight followed by the radiative processes early in the night. The systematic numerical simulations of the fog events that occurred during the winter 2013-2014 indicate the Meso-NH's ability to well capture the fog occurrence with a relatively high false alarm rate, particularly over the coastal station
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Treguier, Anne-Marie. „Effets des vents fluctuants et de la topographie sur la turbulence océanique à moyenne échelle“. Brest, 1987. http://www.theses.fr/1987BRES2003.
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Les fluctuations du vent sont un des mecanismes pouvant generer la variabilite oceanique d'echelle moyenne, observee notamment dans l'atlantiuqe nord-est. La reponse de l'ocean est calculee par un modele numerique spectral, qui resout les equations quasi-geostrophiques dans le cas non lineaire et stratifie. Dans une premiere partie, nous decrivons la turbulence d'echelle moyenne generee par les fluctuations du vent dans un ocean a fond plat. L'energie de la reponse se partage entre un regime lineaire constitue d'ondes de rossby barotropes a grande echelle, et un regime non lineaire. Nous etudions la sensibilite de la reponse a tous les parametres physiques (echelle et energie du vent, frottement, rotation de la terre,stratification). Nos resulats montrent que le parametre cle est le rapport de la plus grande echelle forcee au rayon de rossby. Dans une seconde partie, nous etudions lm'influence d'une topographie aleatoire de faible hauteur sur la dynamique des tourbillons forces par le vent. La generation de courants moyens correles a la topographie est mise en evidence, ainsi qu'une diminution importante des echelles spatiales au fond. Enfin, nous montrons que la presence de topographie induit une intensification au fond dans le cas de la turbulence libre, et par contre une plus grande intensification en surface dans le cas de la turbulence forcee. La reponse de notre modele, surtout en presence de topographie, presente des caracteristiques proches de la variabilite observee dans l'atlantique nord-est, ce qui confirme l'importance des fluctuations du vent pour la generation de cette variabilite
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Žák, Michal. „Synoptic Interpretation of Numerical Prognostic Models Outputs“. Doctoral thesis, 2006. http://www.nusl.cz/ntk/nusl-267504.
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Kavulich, Michael J. Jr. „Local Dynamics of Synoptic Waves in the Martian Atmosphere“. Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10149.
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The sources and sinks of energy for transient waves in the Martian atmosphere are investigated, applying diagnostic techniques developed for the analysis of terrestrial baroclinic waves to output from a Mars General Circulation Model. These diagnostic techniques include the vertically averaged eddy kinetic energy and regression analysis.
The results suggest that the primary source of the kinetic energy of the waves is baroclinic energy conversion in localized regions. It is also shown that there exist preferred regions of baroclinic energy conversion. In addition, it is shown that downstream baroclinic development plays an important role in the evolution of the waves and in the baroclinic energy conversion process. This is the first time that evidence for downstream baroclinic development has been found for an atmosphere other than the terrestrial one.
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Sobie, Stephen Randall. „Climate model downscaling of Vancouver Island precipitation using a synoptic typing approach“. Thesis, 2010. http://hdl.handle.net/1828/3083.
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A statistical downscaling technique is employed to link atmospheric circulation produced by climate models at the large-scale to precipitation recorded at individual weather stations on Vancouver Island. Relationships between the different spatial scales are established with synoptic typing, coupled with non-homogeneous Markov models to simulate precipitation intensity and occurrence in historical and future periods. Types are generated through a clustering algorithm which processes daily precipitation observations recorded by Environment Canada weather stations spanning 1971 to 2000. Large-scale atmospheric circulation data is taken from an ensemble of climate model projections made under the IPCC AR4 SRES A2 scenario through the end of the 21st century. Atmospheric predictors used to influence the Markov model are derived from two versions of the data: Averages of model grid cells selected by correlation maps of circulation and precipitation data; a new approach involving Common Empirical Orthogonal Functions (EOFs) calculated from model output over the Northeast Pacific Ocean. Circulation-based predictors capture the role of sea level pressure (SLP), and winds in influencing coastal precipitation over Vancouver Island.
The magnitude and spatial distribution of the projected differences are dependent on the predictors used. Projections for 2081 to 2100 made using common EOFs result in most stations reporting no statistically significant change compared to the baseline period (1971 to 2000) in both seasons. Projections using averaged grid cells find winter season (Nov-Feb) precipitation anomalies produce values that are modestly positive, with typical gains of 6.5% in average precipitation, typical increases of 7.5% rising up to 15% in extreme precipitation, and little spatial dependence. In contrast, average and extreme summer precipitation intensity (Jun-Sep) declines negligibly at most island weather stations with the exception of those on the southern and western sections, which experience reductions of up to 20% relative to the latter thirty years of the twentieth century. Precipitation occurrence decreases slightly in both seasons at all stations with declines in the total days with measurable precipitation ranging from 2% to 8% with reductions also seen in the length of extended periods of precipitation in both seasons.
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Walther, Connie. „Atmospheric Circulation in Antarctica: Analysis of Synoptic Structures via Measurement and Regional Climate Model“. Doctoral thesis, 2015. https://tud.qucosa.de/id/qucosa%3A29285.
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Validation of the Regional Climate Model HIRHAM with measurements, especially from radiosondes and GPS-signal-retrieval. Analysis of synoptical structures in Antarctica and comparison of the precipitation in different phases of the Antarctic Oscillation.
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Hsieh, Ying-Hsun, und 謝瑩薰. „Using potential vorticity of two layer model to explore the characteristics of winter midlatitude synoptic-scale system“. Thesis, 2006. http://ndltd.ncl.edu.tw/handle/3uz7k9.
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碩士國立中央大學
大氣物理研究所
94
The potential vorticity (PV) on each isentropic surface and potential temperature at the lower boundary play important roles in dynamic process of midlatitude synoptic-scale systems. But single isobaric surface or isentropic surface can not represent both PV and potential temperature at the same time. We need understand the dynamic process by combining variant isobaric or isentropic surfaces when exploring the synoptic-scale system. In this paper, we use 310K isentropic surface as the interface to simplify the atmosphere into a two layer system. The main purpose is to explore whether the layered potential vorticity (LPV) can represent the characteristic and dynamic process of midlatitude synoptic-scale system more clearly and concisely than isentropic potential vorticity (IPV). This study is divided into two parts. The first part is, by comparing LPV of lower troposphere with satellite image, 1000 hPa geopotential height, and TRMM rainfall data, during January 2001, to examine whether LPV can show appropriately the characteristics of intensity, position, growth, movement and precipitation of midlatitude synoptic-scale system. The results clearly shows lower troposphere is consistent with satellite image, 1000 hPa geopotential height, and precipitation. The maximum of PV is well-matched with the extratropical cyclone center, low pressure trough, front and rain belt. Similarly, low PV has salient relation with high pressure ridge. The second part is by computing local meridional PV gradients of upper and lower troposphere to get stability, then comparing the pressure of weather systems in stable and unstable status to explore the connection between the local baroclinic instability and the growth of synoptic-scale system. From Monte Carlo test, local baroclinic instability has highly relationship with the intensity of synoptic-scale system. In other words, the system intensity in unstable status is stronger then stable status. In summary, this study indeed shows LPV can represent the characteristics and dynamic process of midlatitude synoptic-scale system more clearly and concisely than IPV. Besides, we also discover that LPV consistent with perturbation in tropical area pretty well. Thus, LPV is a very good tool in studying the dynamic process of system.
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Eerkes-Medrano, Laura. „Slush-ice berms on the west coast of Alaska: development of a conceptual model of formation based on input from and work with local observers in Shaktoolik, Gambell and Shishmaref, Alaska“. Thesis, 2017. http://hdl.handle.net/1828/7744.
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Bering Sea storms regularly bring adverse environmental conditions, including large waves and storm surges of up to 4 m, to the west coast of Alaska. These conditions can cause flooding, erosion and other damage that affects marine subsistence activities and infrastructure in the low-lying coastal communities. Storm impacts also include interactions with sea ice in various states: large floes, shore-fast ice, the acceleration of sea-ice formation in frazil or slush state, and the formation of slush-ice berms. Slush-ice berms are accumulations of slush ice that develop under the right wind, water level, water and air temperature, and snow conditions. During a strong wind event, large amounts of slush may be formed and pushed onto the shore, where the slush can accumulate, solidify and protect communities from flooding and erosion. Slush ice berms can also be problematic, restricting access to the coast and presenting other hazards. Residents of Shishmaref and Shaktoolik, communities on the west coast of Alaska, observed the formation of slush-ice berms during storms that occurred in 2007, 2009 and 2011. These formations are important to the communities, and it would be useful to develop the capacity to predict their occurrence. However, scientific work has not been conducted on this phenomenon, with the result that a physical conceptual model describing the formation of slush-ice berms does not exist. In recognition of this need, a project thesis was designed, and had as its main objective to identify and document the environmental and synoptic weather conditions that lead to these types of events, and to develop a descriptive physical conceptual model of slush-ice berm formation. A key to this work was the engagement of traditional knowledge holders and local observers to gather data and information about slush ice and slush-ice berm formation, along with the specific dates when these events took place. This dissertation is organized around three major elements: development of a conceptual model of slush-ice berm formation; presenting the traditional knowledge gathered that led to the development of this model; and documenting the methods and tools used to engage traditional knowledge holders and local observers in this process. In this dissertation, the knowledge from traditional knowledge holders on slush ice formation is presented in the context of feeding into a physical scientific process – specifically, developing a descriptive physical conceptual model of slush-ice berm formation. It is expected that this type of research will contribute to slush-ice berm forecasting which would aid communities’ safety by improving assessment of environmental risk.Graduate
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Soderi, Mirco. „Semantic models for the modeling and management of big data in a smart city environment“. Doctoral thesis, 2021. http://hdl.handle.net/2158/1232245.
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The overall purpose of this research has been the building or the improve-
ment of semantic models for the representation of data related to smart cities
and smart industries, in such a way that it could also be possible to build
context-rich, user-oriented, ecient and eective applications based on such
data. In some more detail, one of the key purposes has been the modelling of
structural and the functioning aspects of the urban mobility and the produc-
tion of instances exploiting the Open Street Map, that once integrated with
trac sensors data, it has lead to the building and displaying of real-time
trac reconstructions at a city level. One second key purpose has been the
modelling of the Internet of Things, that allows today to seamlessy and e-
ciently identify sensing devices that are deployed in a given area or along a
given path and that are of a given type, and also inspect real-time data that
they produce, through a user-oriented Web application, namely the Service
Map. A pragmatic approach to the modelling has been followed, always tak-
ing into consideration the best practices of semantic modelling on one side
for that a clean, comprehensive and understandable model could result, and
the reality of the data at our hands and of the applicative requirements on
the other side. As said, the identication of architectures and methods that
could grant eciency and scalability in data access has also been a primary
purpose of this research that has led to the denition and implementation
of a federation of Service Maps, namely the Super Service Map. The archi-
tecture is fully distributed: each Super Service Map has a local list of the
actual Service Maps with relevant metadata, it exposes the same interface
as actual Service Maps, it forwards requests and builds merged responses,
also implementing security and caching mechanisms. As said, the identica-
tion of technologies, tools, methods, for presenting the data in a user-friendly
manner is also has been a relevant part of this research, and it has led among
the other to the denition and implementation of a client-server architecture
and a Web interface in the Snap4City platform for the building, manage-
ment, and displaying of synoptic templates and instances thanks to which
users can securely display and iteract with dierent types of data. In end,
some eort has been made for the automatic classication of RDF datasets
as for their structures and purposes, based on the computation of metrics
through SPARQL queries and on the application of dimensionality reduc-
tion and clustering techniques. A Web portal is available where directories,
datasets, metrics, and computations can be inspected even at real-time.