The impacts of biomass burning smoke on local rainfall and the structure of the atmospheric boundary layer have been actively studied in recent years. However, whether the large-scale biomass burning in the later dry season over Amazonia Region could influence the dry-to-wet transition season have not been examined. Previous observations have shown that the substantial increase of rainfall from dry to wet season over Amazonia are actually caused by small changes of the atmospheric thermodynamic structure relative to those over other monsoon regions. Consequently, the onset date of wet season can vary greatly as influenced by external or internal anomalous forcings. Thus, it is possible that the transition of the atmospheric thermodynamic structure and circulation from dry to wet season is also sensitive to the impacts of biomass burning smoke. To test this hypothesis, we have forced RegCM3 model with direct radiative forcing of smoke inferred from MODIS for the transition season (August to November). The comparison with control run helps us to examine the direct and semi-direct influences of smoke on the transition from dry to wet season. Our preliminary results show that the direct and semi-direct forcings of smoke could significantly influence the rainfall and related atmospheric and land surface conditions during the transition. However, these changes are sensitive to the prescribed vertical distribution of the aerosols.

Lodgepole pine (Pinus contorta Douglas ex Louden) is the most widespread pine in North America and the single most abundant tree species in British Columbia (BC). Its vast distribution, diversity and economic value make it an important species for timber harvest and subsequent reforestation. Climate change raises serious concerns over the adaptability and effective management of BC’s future forests. The majority of lodgepole pine seedlings requested for replanting are produced from seed obtained from wild stands, but the relationship between climate variation and the seed production of natural populations has yet to be assessed. The purpose of this study is to determine if variation in P. contorta seed yield is related to the climate of BC. Historical cone collection data were obtained from archived records of 1948 seedlots in 22 different natural stand seed planning zones (SPZs) of BC. Collections were made between 1963 and 2013 and seed yield (kg fresh seed/hL cone) was determined for each seedlot. First, natural variation in seed production of lodgepole pine was examined in 18 different SPZs. The Nass Skeena Transition (NST) represents a unique intersection between continental and maritime ecosystems and was found to have a significantly higher mean seed yield compared to all other zones, with the exception of Hudson Hope (HH). However, variance in seed yield for NST was found to be an order of magnitude higher than that of other SPZs, indicating that seed production in this region is exceptionally variable. These findings provide a valuable geographic baseline for the reproductive fitness of lodgepole pine, suggesting that climate adaptation and mitigation strategies for some areas of the province may need to be region-specific. In addition, the relationship between climate variation and the seed production of P. contorta in BC was evaluated. The climate of each region was described using dynamically-downscaled Global Circulation Model (GCM) and reanalysis climate output from the Canadian Regional Climate Model (CRCM). Annual, winter, and summer means were explored for each of the climate variables of interest: total precipitation (mm) and surface air temperature (°C). Temporal correlations between the mean annual seed yield anomaly and the anomaly of both climate variables were significant under a variety of climate schemes in a number of SPZs. Significant overall trends in climate variables were also captured using GCM-driven CRCM output. While these two analyses independently highlighted significant relationships between seed yield and climate, their joint implications were unclear. Shifts in the CRCM boundary conditions revealed that the results lacked robustness during the historical period, inhibiting the investigation of future projections. Ambiguous age ranges for each cone collection and temporal restrictions of the seed collection data may be partially responsible for these inconclusive results. Results from the first half of this thesis suggest that, with few exceptions, seed production is relatively stable across SPZs spanning a wide range of climate regimes. Thus, the investigation of the relationship between reproductive fitness and climate may be complicated by the extraordinary adaptability of lodgepole pine and the high genetic variation in natural populations. / Graduate

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.

La vitiviniculture est un secteur économique et culturel important en Bourgogne. L’actuel changement climatique soulève diverses questions notamment sur son impact sur les cultures. Dans cette thèse, l’idée est d’élaborer une méthodologie afin de répondre à la problématique : quels seront les impacts possibles des changements de températures sur la phénologie du Pinot noir en Bourgogne à l’horizon 2031-2048 ?L’évolution des températures en Bourgogne depuis 1961 est caractérisée par un saut positif de température à la fin des années 1980 suivi par une période où la température augmente d’environ 1,5°C.L’un des intérêts de cette thèse réside dans l’élaboration, en suivant une stratégie élaborée durant la thèse, d’une base de données spatialisée réalisée sur la période 1989-2009 afin d’estimer la capacité du modèle WRF à reproduire le climat bourguignon en désagrégeant des données climatiques de large échelle. Le modèle reproduit de façon satisfaisante le cycle saisonnier et la variabilité spatiale climatique globale aux biais près (froid sur les Tx et chauds sur les Tn).Pour régionaliser le changement climatique, WRF a été utilisé pour désagréger des données issues du scénario SRES/A2 sur les périodes 1970-1987 et 2031-2048. Après avoir été évalués et intercomparés trois modèles phénologiques utilisant les données de températures moyennes pour simuler les dates d’occurrence des stages phénologiques du Pinot noir, ont été appliqués sur ces désagrégations.L’impact de l’augmentation des températures à l’horizon 2031-2048 (SRES/A2), estimée à 1,35°C en moyenne, se caractérise par une précocité de la floraison d’au moins 7 jours et une précocité de la véraison d’au moins 15 jours. La durée interstade est également diminuée de l’ordre de 5 jours. / The viticulture is an important economic and cultural sector in Burgundy. The current climate change raises a number of issues including its impact on crops. In this thesis, the idea is to develop a methodology to address the problem: what are the potential impacts of changes in temperature on the phenology of Pinot noir in Burgundy for years 2031-2048?The evolution of temperatures in Burgundy since 1961 is characterized by a positive temperature shift at the end of the 1980s followed by a period where the temperature increases of about 1.5 ° C.One of the interests of this thesis is to develop, following a strategy developed during the thesis, a spatial database conducted over the period 1989-2009 to estimate the ability of the WRF model to reproduce the climate Burgundy by disaggregating large scale data. The model reproduces satisfactorily the seasonal and spatial variability in global climate despite bias (cold on the Tx and hot on the Tn).To regionalize the climate change, WRF was used to disaggregate data from the scenario SRES/A2 on the periods 1970-1987 and 2031-2048. After being evaluated and inter-compared three phenological models, using average temperatures data to simulate the dates of occurrence of phenological stages of Pinot Noir, have been applied to these decompositions.The impact of warming temperatures on the horizon 2031-2048 (SRES/A2), estimated at 1.35 ° C on average, is characterized by an earlier flowering and veraison of about 7 and 15 days respectively. The interstadial duration is also reduced of about 5 days.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-05-08T16:23:16Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_rodrigo_da_silva_pereira.pdf: 1723922 bytes, checksum: 18533319b08c17041a8e5681e41087ff (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-05-09T10:54:02Z (GMT) No. of bitstreams: 2 dissertacao_rodrigo_da_silva_pereira.pdf: 1723922 bytes, checksum: 18533319b08c17041a8e5681e41087ff (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-09T10:54:02Z (GMT). No. of bitstreams: 2 dissertacao_rodrigo_da_silva_pereira.pdf: 1723922 bytes, checksum: 18533319b08c17041a8e5681e41087ff (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Esta dissertação tem como propósito geral a análise do clima presente e o comportamento futuro dos eventos extremos de precipitação local de curta duração com potencial para causar alagamento nas principais cidades do Rio Grande do Sul abrangendo diferentes regiões do Estado: Porto Alegre, Caxias do Sul, Santa Maria e Pelotas. Baseado no histórico de alagamentos de cada cidade e nos dados diários de precipitação obtidos das estações meteorológicas do INMET (Instituto Nacional de Meteorologia) obteve-se o limiar que identificou a taxa de precipitação que representa um evento com potencial para causar alagamento na cidade, sendo os eventos divididos em caso de atenção (percentil 25) ou de alerta (percentil 75) nas 48h precedentes à ocorrência do alagamento. Os resultados revelaram um crescimento sutil dos casos, tanto atenção quanto alerta, nos últimos 53 anos. A cidade de Porto Alegre foi a que apresentou os menores limiares para condição de alagamento, o que era esperado devido sua maior urbanização. Ao avaliar o comportamento sazonal dos casos constatou-se que no clima presente (1961-2013), o trimestre julho-agosto-setembro foi a época do ano mais propícia a casos de alagamentos. Posteriormente, os casos foram correlacionados com três índices climáticos que medem as anomalias de TSM (Temperatura da Superfície do Mar) do Atlântico Sul e do Pacífico, no intuito de avaliar se suas ocorrências estão associadas a fenômenos climáticos de grande escala. As correlações encontradas variaram de fracas a moderadas, mas com alto nível de confiança estatística para o IME (Índice Multivariado do ENOS). O uso de modelagem climática regional (modelo ETA-HadCM3) denotou que num cenário futuro (A1B de acordo com o Painel Intergovernamental sobre Mudanças Climáticas) para o período de 2021-2070 haverá no geral, um pequeno acréscimo no número de casos de atenção para todas as cidades, quando comparado aos valores observados no clima presente (1961-2013). Em Pelotas, haverá uma mudança na climatologia dos eventos com deslocamento da estação com maior número de casos do trimestre JAS (clima presente) para o OND (cenário futuro). / This work has as general purpose the analysis of present climate and future behavior of short duration extreme local rainfall events with potential for causing flooding in major cities in Rio Grande do Sul State covering different regions: Porto Alegre, Caxias do Sul, Santa Maria and Pelotas. Based on history of floods of each city and on the rainfall data obtained from meteorological stations of INMET (National Institute of Meteorology), the thresholds that have identified which precipitation rate is an event with the potential to cause flooding in the city were obtained, being such events divided in case of attention (25th percentile) or case of alert (75th percentile) in 48 hours before the occurrence of flooding. The results showed a subtle increase of cases, both as alert and attention in the last 53 years. The city of Porto Alegre was presented the least thresholds for flooding condition, which was expected due to its increased urbanization. In assessing the seasonal behavior of the cases it was found that in this climate, the July-August-September was the time of year most facilitates cases of flooding. Later, cases were correlated with three climate indices that measure the SST (Sea Surface Temperature) anomalies in order to assess whether their occurrences are associate to large-scale climatic phenomena. It was found weak to moderate correlations, but with a high level of statistical confidence for the EMI (ENSO Multivariate Index). The use of regional climate model (ETA-HadCM3) denotes that in a future scenario (A1B following International Panel on Climate Change) for the period 2021-2070 will be in general an increase number of cases of attention for all cities, when compared to those observed in the present climate (1961-2013). In Pelotas there will be a climatological change due to a displacement of the season with more cases: from JAS quarter (present) to OND quarter (future scenario).

Made available in DSpace on 2014-08-20T14:25:52Z (GMT). No. of bitstreams: 1 dissertacao_gilson_carlos_da_silva.pdf: 6390842 bytes, checksum: 4ee553c938a05c41b76eeb4831643835 (MD5) Previous issue date: 2011-08-31 / The time-variation feature of extreme precipitation events (those can result in flooding) on east and north regions of the Santa Catarina State, one of the Brazilian regions most attained by damages owning to heavy rain episodes, is analyzed in this study. For this, it were selected some cities whose history of flooding based on many sources, as the Defesa Civil Estadual was employed to built a threshold to identify the precipitation events that can cause flooding. The observed precipitation data, from 1951 to 2010, from ANA (Agência Nacional de Águas) was used to the analysis of daily rainfall occurred until fifteen days before the flooding and for the counting of this type of event. The methodology employed to detect these events was based on mean thresholds following the rainfall observed on the selected cities. The counting of the occurrences generated the time-variation over such period, indicating positive and also some negative, although not significant tendencies on this region, and a significative linear correlation with global scale climate phenomena in some of the cities. It is also observed the seasonal behavior for the present time and for a future climate scenario, ranging from 2070 to 2100, which aim is to give information to a better planning of the cities, through the regional climate model HadRM3P, from Hadley Centre (UK), simulated and provided by CCST (Centro de Ciências do Sistema Terrestre) do INPE (Instituto Nacional de Pesquisas Espaciais), considering the A2 scenario (more pessimist) following IPCC (Intergovernmental Panel on Climate Change). In comparison against present climate, the estimated projection by climatic model shows an increasing of the frequency of these extreme precipitation events in all selected cities, for all seasons mainly in autumn. / Este estudo analisa o aspecto temporal dos eventos extremos de precipitação com potencial para causar inundação na região Leste e Norte do Estado de Santa Catarina, uma das regiões brasileiras que mais sofrem transtornos devido à chuva intensa. Foram selecionadas algumas cidades cujo histórico de inundação construído através de várias fontes, como a Defesa Civil Estadual foi usado para a confecção de um limiar para identificar tais eventos. Foram utilizados dados de precipitação da ANA (Agência Nacional de Águas) no período de 1951 a 2010, para análise da chuva diária ocorrida até quinze dias antes das inundações e para a quantificação dos eventos extremos de precipitação com potencial para provocar inundação. A metodologia empregada para detecção desses eventos foi a de limiares médios, baseada na análise pontual da precipitação nas cidades atingidas. A quantificação do número de eventos gerou a variação temporal no período, em que pode-se analisar as ocorrências de tendência positiva e também alguma negativa, embora não significativa na região, além de correlação linear significativa, em algumas cidades, com fenômenos climáticos de escala global. É examinado também o aspecto climatológico sazonal do presente e de um cenário climático para o final do século (2070-2100), cujo objetivo é fornecer informações para um melhor planejamento das cidades, usando dados do modelo climático regional HadRM3P, do Hadley Centre (UK), simulados e fornecidos pelo Centro de Ciências do Sistema Terrestre do Instituto Nacional de Pesquisas Espaciais (CCST/INPE), considerando o cenário A2 (mais pessimista) do IPCC (Painel Intergovernamental sobre Mudanças Climáticas). Na comparação com o clima presente, a projeção simulada pelo modelo climático indicou aumento da frequência de ocorrência dos eventos em todas as cidades, para todas as estações do ano, principalmente para o outono.

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.

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 ...

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 Réunion. / This 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.

Screen level temperature is measured at 2 meters above the ground. It is one of the most used atmospheric characteristics in various applications in meteorology and other fields related to weather prediction. Essential is not only the knowledge of its current state, but also its prediction. It is forecasted by numerical weather prediction (NWP) models from the atmospheric current state. Its long-term characteristics can be obtained from the integration of climate models. This text discusses fundamental parametriza- tions, mostly related to temperature forecast, used in the NWP model ALADIN and the regional climate model RegCM. Physical processes which influence temperature are studied using ALADIN in several cases which include the presence of low cloudiness, gravity waves and inappropriate thermic coefficient. A detailed description of the most relevant parametrization schemes is given and the results are studied in a form of indi- vidual feedback loops. Most dominant processes are also found. However, the level of 2 meters above the ground is not the model level, so temperature at 2 meters is obtained by interpolation from the surface temperature and the lowest model level temperature. Using RegCM, two differently complex interpolation schemes are compared to each other. 1