Le projet INDESO (Développement de l'océanographie spatiale en Indonésie) en collaboration entre le gouvernement indonésien (Ministère des affaires maritimes et des pêches - MMAF) et la société française CLS (Collecte Localisation Satellite) promeut l'utilisation des technologies spatiales pour la surveillance des côtes et des mers indonésiennes. Cette thèse fait partie du volet sur la surveillance des récifs coralliens, mené par l'IRD (Institut de Recherche pour le Développement). L'objectif principal était de déterminer si les habitats des récifs coralliens dans l'île de Bunaken dans le nord de Sulawesi sont résilients, en utilisant i) des cartes d'habitat nouvellement conçues, ii) des données in situ et une série chronologique de 15 ans unique d'images satellites de différents capteurs très haute résolution (THR), iii) des données auxiliaires qui pourraient expliquer les changements détectés. Les résultats comprennent des cartes très détaillées de l'habitat des récifs de Bunaken (194 polygones cartographiés et un recensement de 175 habitats). L'influence de la chute du niveau de la mer sur la mortalité des coraux pendant l'événement El Niño de 2015-2016 est présentée en détail, et l'importance de ce processus est également discutée à partir de l'interprétation d'une série chronologique unique de 15 ans d'images THR. La série temporelle met en évidence des trajectoires très différentes des habitats coralliens. Nous avons conclu que le récif de Bunaken démontre une capacité de résilience et sans déphasage, mais qu'un diagnostic définitif de sa résilience reste difficile à déterminer par imagerie. Des trajectoires de l'habitat ne peuvent pas être totalement interprétées sans changer certains paradigmes de surveillance, et sans utiliser une combinaison d'observations de télédétection et de données in situ. / The INDESO (Infrastructure Development of Space Oceanography) project, in collaboration with the Indonesian Government (Ministry of Marine Affairs and Fisheries - MMAF) and the French company CLS (Collecte Localisation Satellites), promotes the use of space technologies for monitoring coastlines and Indonesian seas. This thesis is part of coral reef monitoring component, led by the IRD (Institute de Recherche pour le Développement). The main objective was to determine wether coral reef habitats on Bunaken Island in Northern Sulawesi are resilient, using (i) newly desgined habitat maps, (ii) in situ data, and a unique 15-year time series of satellite images of different very high resolution (VHR) sensors, and (iii) ancillary data that could explain the changes detected. The results include highly detailed maps of the Bunaken reefs habitat (194 polygons mapped and a census of 175 habitats). The influence of sea level fall on coral mortality during the El-Nino event of 2015 - 2016 is presented in detail, and the importance of this process is also discussed from the interpretation of a unique time series of 15 years of VHR images. The temporal series reveals very different trajectories of the coral habitats. We conclude that Bunaken reefs demonstrate an ability to resileince and without phase shift, but that a definitive diagnosis of their resilience remains difficult to determine by imagery. Habitat trajectories can not be fully interpreted without changing some monitoring paradigms and without using a combination of remote sensing and in situ data.

The objective of this study is to describe the effects of the El Niño-Southern Oscillation (ENSO) on the weather patterns in Queensland during the Australian summer monsoon. The focus is on the period from October-January when the summer monsoon is governing the weather pattern of Northern Australia. The theory part introduces the reader to the physics of the different phases of ENSO and the Australian summer monsoon. Weather station data of rainfall, minimum and maximum temperature data are investigated statistically. The presented results are an earlier onset of the monsoon season in Queensland during La Niña-events and a stronger monsoon in the sense of more or stronger active periods. Regarding El Niño's effects on the summer monsoon in Queensland no significant results were found. The results show the importance of not looking at the warm and cold phase of ENSO as opposites and agree with what Sarachik (2010) and Sturman & Tapper (1996) states. / Målet med studien är att beskriva El Niño-Southern Oscillations (ENSO) effekter på vädret i Queensland under den australiensiska sommarmonsunen. Fokus ligger på perioden oktober-januari då sommarmonsunen styr vädret över norra Australien. Teoridelen syftar till att introducera läsaren till fysiken bakom de olika faserna av ENSO och den australiensiska sommarmonsunen. Data från väderstationer i Queensland av parametrarna nederbörd, minimum och maximum temperatur undersöks statistiskt. Resultaten som presenteras indikerar en tidigare början av monsunsäsongen i Queensland under La Niña-perioder och att monsunen förstärks genom fler eller starkare aktiva perioder. I resultaten sågs ingen eller mycket svag påverkan från El Niño-perioder på monsunen i Queensland. Dessa resultat påvisar vikten av att inte se på den varma och kalla fasen av ENSO som motsatser till varandra och stämmer överens med litteratur av Sarachik (2010) och Sturman & Tapper (1996).

These comments have the objective of opening discussion regarding intervention of the State in the economy, regulating prices in times of natural disasters due to the sudden increase of the demand by consumers and consequent economic exploitation by some providers. Taking the chilean case as example, the authors raise certain legislative amendments to avoid that certain providers take improper advantage of consumers in such dramatic times. / Los presentes comentarios pretenden abrir la discusión sobre si el Estado peruano debería intervenir, en tiempos de desastres naturales, en la regulación de los precios de los productos, en tanto estos suelen encarecerse ante el aumento repentino de la demanda por parte de los consumidores y el consiguiente aprovechamiento económico de algunos proveedores. Tomando como ejemplo el caso chileno, planteamos algunas modificatorias legislativas para evitar así que ciertos proveedores se aprovechen de la desesperación de los consumidores en circunstancias tan dramáticas.

The need to establish the long-term precipitation led many authors to try to understand why regulators of interannual climate variability over the Northeast of Brazil. Fluctuations in the equatorial Pacific SST acts as a modulator of climate on various time scales and are associated with the phenomenon (El Niño / Southern Oscillation). We analyzed the patterns of monthly and quarterly precipitation in Northeast Brazil (with emphasis on the eastern part of Northeast Brazil), related to the anomalies of surface temperatures of the equatorial Pacific and south Atlantic, from the SST data obtained from the Comprehensive Ocean-Atmosphere Data System and precipitation data from the universe as we know from Delaware from 1950 to 1999. The monthly precipitation by the phases of the Pacific Decadal Oscillation and rainfall were arranged both quarterly and lag. Were defined conditions of El Niño: positive anomaly; positive derivative; positive derivative if and only if the anomalies were positive and the anomaly index Interoceanic (AI). The best parameter for prediction of quarterly rainfall within the rainy season in NE, was the condition of positive derivative of the SST of the Pacific, one month before the rain (lag1) with positive correlation of 0.3 to 95% of significance, falling to 0.2 (lag2), from February to May versus April-July rainfall. The study confirmed the low levels of correlation, have been mentioned by other authors about the ENE and the SST anomalies in the equatorial Pacific. The monthly mean SST anomalies in the South Atlantic and equatorial Pacific combined showed best results when correlated with monthly precipitation over northern northeast Brazil. On the east of NE was positive correlation of 0.5, on the north of NE was 0.6, decreasing to 0.3 correlation over southern northeast at 95% significance. The two signals combined accounted for (r = 0.7) 49% of the variability in signal Comparable with isolated Pacific, which was correlated with seasonal rainfall. The increase in estimates of rainfall over east of NE occurred from the inclusion of the Atlantic SST anomalies and considered during the calculation of the average normal changes of signal detected in the Pacific Decadal Oscillation. / Fundação de Amparo a Pesquisa do Estado de Alagoas / A necessidade em prever a precipitação a longo prazo levaram muitos autores a tentar compreender os motivos reguladores da variabilidade interanual climática sobre o Nordeste do Brasil. As flutuações nas TSM do Pacífico equatorial atuam como um modulador climático em várias escalas de tempo e estão associados ao fenômeno (El Niño / Oscilação Sul). Analisamos os padrões mensais e quadrimestrais da precipitação do Nordeste do Brasil (com ênfase sobre a parte leste do Nordeste do Brasil), relacionadas às anomalias das temperaturas da superfície dos oceanos Pacífico equatorial e Atlântico sul, a partir dos dados de TSM obtidos do Compreensiv Ocean-Atmosphere Data System e dos dados de precipitação da Universidade de Delaware entre 1950 a 1999. As precipitações mensais pelas fases da Oscilação Decadal do Pacífico e as precipitações quadrimestral foram dispostas simultaneamente e em lag. Foram definidas condições de El-Niño: anomalia positiva; derivada positiva; derivada positiva se e somente se as anomalias fossem positivas e o índice anomalia Interoceânica (AI). O melhor parâmetro de prognóstico da precipitação quadrimestral, dentro da estação chuvosa do ENE, foi a condição de derivada positiva das TSM do Pacifico, um mês antes da chuva (lag1), com de correlação positiva de 0,3 a 95% de significância, caindo para 0,2 (lag2), de fevereiro-maio versus as chuvas abril-julho. Confirmaram-se os baixos índices de correlação, já foram mencionados por outros autores a respeito do ENE e as anomalias da TSM do Pacífico equatorial. As anomalias da TSM médias mensais do Atlântico sul e Pacífico equatorial combinadas mostraram melhores resultados quando correlacionadas com a precipitação mensal sobre o NEB. Sobre o ENE correlação positiva de 0,5; no NNE foi de 0,6; caindo para 0,3 de correlação no SNE a 95% de significância. Os dois sinais combinados responderam por (r=0,7) 49% da variabilidade comparado ao sinal isolado do Pacífico, correlacionado com a precipitação quadrimestral. O aumento na previsão das precipitações sobre o ENE se deu a partir da inclusão das anomalias da TSM do Atlântico e por considerar durante o cálculo das médias normais as mudanças de sinal verificadas na Oscilação Decadal do Pacífico.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this study was to evaluate the effect of planting date on productivity in the cassava crop for the state of Rio Grande do Sul using the Simanihot model, when considering the influence of the ENSO phenomenon. For the evaluation of planting dates, the Simanihot model was used, using the Thornthwaite and Mather water balance model, which is coupled to Simanihot. The model was run for the last 54 years, from August 13 to December 31 every ten days, for the three cassava cultivars (Estrangeira, Fepagro RS13 and Paraguaia), 14 sites (Bagé, Bento Gonçalves, Bom Jesus, Caxias do Sul, Cruz Alta, Encruzilhada do Sul, Lagoa Vermelha, Passo Fundo, Pelotas, Porto Alegre, Santa Maria, Santana do Livramento, São Luiz Gonzaga e Torres) and to the soil mapping units that are predominant in each site. In the present study, the soil mapping units of each site were selected. he most suitable dates for the planting of cassava maniots were defined according to the average productivity curves found for local, cultivar and year characterized by the phases of the ENSO phenomenon. The results indicated that the most suitable planting period aiming at obtaining high yields, is the closest to that indicated by the Agroclimatic Zoning. It was evidenced that the ENSO phenomenon exerts a direct influence on cassava productivity in the studied areas. In years of occurrence of the El Niño phenomenon, when classified as strong, in most of the studied sites, productivity values were the highest. Years classified as El Niño with very strong intensity, the cassava crop was hampered by the high volume of rainfall and low levels of solar radiation during the planting season. On the other hand, in years of La Niña, even with below normal precipitation and solar radiation superior to the Neutral years, some places presented superior yields obtained in Neutral years. The cultivars Fepagro RS13, Estrangeira and Paraguaia expressed different productivities in the different phases of the ENSO phenomenon. / O objetivo deste estudo foi avaliar o efeito de data de plantio sobre a produtividade na cultura da mandioca para o estado do Rio Grande do Sul utilizando o modelo Simanihot, ao considerar a influência do fenômeno ENOS. Para a avaliação das datas de plantio, foi utilizado o modelo Simanihot, usando o modelo de balanço hídrico de Thornthwaite e Mather que está acoplado no Simanihot. O modelo foi rodado para os últimos 54 anos, a partir do dia 13 de agosto até 31 de dezembro a cada dez dias, para as três cultivares de mandioca (Estrangeira, Fepagro RS13 e Paraguaia), 14 locais (Bagé, Bento Gonçalves, Bom Jesus, Caxias do Sul, Cruz Alta, Encruzilhada do Sul, Lagoa Vermelha, Passo Fundo, Pelotas, Porto Alegre, Santa Maria, Santana do Livramento, São Luiz Gonzaga e Torres) e para as unidades de mapeamento de solo predominantes de cada local. As datas mais indicadas para o plantio das manivas de mandioca, foram definidas de acordo com as curvas de produtividade média encontradas para local, cultivar e ano caracterizado pelas fases do fenômeno ENOS. Os resultados apontaram que o período de plantio mais indicado visando a obtenção de altas produtividades, é o mais próximo do indicado pelo Zoneamento Agroclimático. Evidenciou-se que o fenômeno ENOS exerce influência direta sob a produtividade de mandioca nos locais estudados. Em anos de ocorrência do fenômeno El Niño, quando classificado como forte, em grande parte dos locais estudados, os valores de produtividade foram os mais altos. Anos classificados como El Niño com intensidade muito forte, a cultura da mandioca foi prejudicada pelo alto volume de precipitação pluvial e baixos índices de radiação solar durante a estação de plantio. Em contrapartida, em anos de La Niña, mesmo com precipitação abaixo da normal e radiação solar superior aos anos Neutros, alguns locais apresentaram produtividades superiores as obtidas em anos Neutros. As cultivares Fepagro RS13, Estrangeira e Paraguaia expressaram produtividades diferentes nas distintas fases do fenômeno ENOS.

This paper examines scallop (Argopecten purpuratus) booms experienced in the Pisco-Paracas Region of southern Peru, triggered by the 1982-1983 and the 1997-1998 mega-El Niño Southern Oscillation (ENSO) events.The quiet fishing ports have been transformed by these booms, which have attracted outside stakeholders transforming the local society. Government institutions in their role as resource managers and environmental stewards have attempted to control access to a region that until recently contained the only marine protected area of Peru.This situation has led to rapid growth in the scallop industry, the overexploitation and depletion of the shellfish, creating a sustainability crisis. Furthermore, this paper examines contradictions and relationships across local, regional, national, and international scales. / Este trabajo examina los ciclos de expansión (boom) de la explotación de la concha de abanico (Argopecten purpuratus) observados en la región Pisco-Paracas del sur del Perú, resultantes de los fenómenos El Niño de 1982-1983 y 1997-1998.Los apacibles puertos de pesca han sido transformados por estos booms productivos que han atraído actores externos y han generado un impacto en la sociedad local. Las instituciones gubernamentales, en su papel de administradores de recursos y protectores del medio ambiente, han tratado de controlar el acceso a una región que hasta hace poco contenía la única área marina protegida del Perú.Esta situación ha producido un rápido crecimiento de la industria de la concha de abanico, su sobreexplotación y el agotamiento de dicho recurso, y ha producido una crisis de sostenibilidad. Asimismo, este trabajo examina las contradicciones y las relaciones entre las escalas local, regional, nacional e internacional.

O objetivo deste estudo foi verificar as influências dos fenômenos El Niño/La Niña (EN/LN) no rendimento regional de trigo cultivado no Paraná entre 1976 e 2002. Os dados de produtividade foram obtidos junto à SEAB e os meteorológicos junto ao IAPAR, e agrupados em 6 regiões produtoras (norte, noroeste, oeste, sudoeste, sul e centro-oeste). A tendência tecnológica da série de cada região foi eliminada para facilitar a associação entre a ocorrência dos eventos EN/LN e os desvios na produtividade regional. O balanço hídrico climatológico seqüencial de Thornthwaite-Mather (CAD = 100 mm) na escala decendial permitiu detectar a situação da umidade do solo regional durante o período de cultivo em cada ano com desvio significativo de produtividade. Verificou-se queda do rendimento em anos de El Niño nas regiões centro-oeste e oeste, e tendência a acréscimo ao rendimento em anos de La Niña na região sul. Para as regiões norte, noroeste e sudoeste não foi encontrado efeito significativo desses fenômenos sobre o rendimento regional. / The aim of this study was to verify the influences of El Niño/La Niña (EN/LN) in the regional yield of wheat in Paraná from 1976 to 2002. The yield and meteorological data were grouped in 6 regions, i.e., north, northwest, west, south, southwest, and central west. The technological trend of the yield series was eliminated to allow associations between the occurrence of the events EN/LN and the deviation of regional yield. Sequential climatological Thornthwaite-Mather water balance (SWC = 100 mm) on a 10-days time scale was used to detect the regional soil moisture conditions during the growth period in each year with large yield deviation. There was yield decrease in years of EN in the center-west and west regions, and tendency of yield increase in LN years in the south region. In the north, northwest, and southwest regions there was no significant effect of the EN/LN on the regional wheat yield.

Made available in DSpace on 2014-08-20T14:25:47Z (GMT). No. of bitstreams: 1 dissertacao_mari_firpo.pdf: 1272617 bytes, checksum: f59407ea3e3a879715dca6636c682cbe (MD5) Previous issue date: 2008-02-15 / In this paper the results of Cold and heat waves and their relationships with to El Niño and La Niña events in 13 meteorological stations in Rio Grande do Sul along the years of 1967 up to 2005 are presented. Daily frost and maximum and minimum air temperature data were used. The anomalies were obtained subtracting the average year (climatological normal to the data set) of each year which was analyzed. Cold waves were considered the period of five or more days of consecutive negative minimum temperature and hot waves for the same time but in positive anomalies and maximum temperature. It was also used a quantil technique to split in quartile segments the highest anomalies values and the anomalies interval values of each wave in order to classify them according to its intensity and termic amplitude respectively. Only the waves of five days were classified. Analyzing the waves average behavior it was observed that the cold ones happen more in the winter and that there is an homogeneity related to its distribution in the state. On the other hand, the heat waves happen also in the colder months, but their distribution is heterogeneous, happening more in the meteorological stations located more in the northern part of the state. The relationships between frosts and waves it was noticed that there is a positive correlation between the frosts average number and the cold waves and negatives average number to the heat ones, statistically significant at 1% level in the months of June and July, but not in August. The relationships between cold and heat waves and the ENSO events show that, in general, the occurrence of La Niña increases the number of cold waves and decreases the heat waves in Rio Grande do Sul, while the El Niño increases the heat waves and decreases the cold waves. It was also analyzed the frost relationships with ENSO events and it was noted that in the months of June and July there is a higher occurrence of frosts during La Niñas. However, in August this occurrence is higher during El Niños / Neste trabalho são apresentados os resultados do estudo feito sobre a ocorrência de ondas de frio e calor e suas relações com El Niño e La Niña, em 13 estações meteorológicas do Rio Grande do Sul para o período entre os anos de 1967 a 2005. As anomalias foram obtidas subtraindo-se o ano médio (normal climatológica para a série de dados) de cada ano em questão. Foram consideradas ondas de frio, os períodos de cinco ou mais dias consecutivos de anomalias negativas de temperatura mínima e ondas de calor, o mesmo período de anomalias positivas de temperatura máxima. Foi utilizada a técnica dos quantis para dividir, em ordens quartílicas, os maiores valores de anomalias e os valores de intervalo de anomalias de cada onda, a fim de classificá-las quanto a intensidade e a amplitude térmica, respectivamente. Apenas as ondas de 5 dias foram classificadas. Analisando o comportamento médio das ondas, observou-se que as de frio ocorrem mais no inverno e que há uma homogeneidade quanto à sua distribuição no Estado. Já as ondas de calor também ocorrem mais nos meses mais frios, mas sua distribuição é heterogênea, ocorrendo em maior quantidade nas estações meteorológicas localizadas mais ao norte do Estado. Notou-se que há uma correlação positiva entre o número médio de geadas e o número médio de ondas de frio e negativa quanto as ondas de calor, significativas a 1% para os meses de junho e julho, mas não para o mês de agosto. As relações entre ondas de frio e calor e os eventos ENSO mostraram que, em geral, a ocorrência de La Niña faz aumentar o número de ondas de frio e diminuir o número de ondas de calor no Rio Grande do Sul, enquanto a ocorrência de El Niño faz aumentar o número de ondas de calor e diminuir as ondas de frio. Quanto às geadas, também foi analisada sua relação com os eventos ENSO e constatou-se que nos meses de junho e julho, há uma maior ocorrência de geadas nos meses de La Niña, porém, no mês de agosto, essa ocorrência é maior nos meses de El Niño

Les effets du changement climatique sur les îles du Pacifique constituent un enjeu majeur pour les populations insulaires. En particulier, les précipitations constituent un des paramètres sensibles car elles conditionnent la ressource en eau. Le but de cette thèse est mettre d'apporter les premiers éléments de réponse relatifs à l'évolution des précipitations au cours du 21ème siècle sur Tahiti. Dans un premier temps, les précipitations à Tahiti ont été caractérisées à partir des mesures issues du réseau d'observation de Météo France. La saison des pluies, de novembre à avril, constitue la saison d'intérêt, car c'est à cette période de l'année que les cumuls de pluie sont les plus élevés. En effet, la zone de convergence du Pacifique sud (SPCZ), siège de la convection profonde, est la principale source de précipitations à Tahiti en été austral (Décembre-Janvier-Février). A l'échelle interannuelle et interdécennale, les phénomènes El Niño Southern Oscillation (ENSO) et Interdecadal Pacific Oscillation (IPO) induisent des migrations nord/sud et est/ouest de cette zone de convergence qui l'éloignent ou l'approchent de Tahiti. L'IPO, implique un déplacement de la SPCZ vers le nord-est en phase positive, ce qui induit des cumuls plus élevés observés à Tahiti. Elle est déplacée vers le sud-ouest en phase négative de l'IPO, d'où une diminution des pluies à Tahiti. L'étude montre qu'en IPO positif, l'occurrence d'événements El Niño intenses est favorisée. Pour ces cas de figure, la SPCZ migre brutalement vers le nord-est et adopte une orientation zonale au-dessous de l'équateur. Cette configuration l'éloigne de Tahiti et perturbe le flux d'alizés de sud-est, il en résulte alors des pluies orographiques très abondantes sur les côtes sud-est de l'île. Suite à cet état des lieux des précipitations observées, une méthodologie originale, en l'absence de toute autre expérience internationale sur la région, a été mise en œuvre pour obtenir un modèle capable de distinguer l'île et capturer au mieux les effets orographiques. Deux descentes d'échelle successives ont été nécessaires pour passer du modèle couplé global CNRM-CM, à 150 km de résolution, au modèle à aire limitée ALADIN-Climat, de résolution 12 km, centré sur Tahiti. Les sorties du modèle régional obtenues ont été confrontées aux observations sur la partie historique. Un lien a été établi entre les précipitations observées et modélisées sur la période passée. Ce lien est construit entre stations d'observations et points de grille du modèle exhibant un comportement similaire relatif aux phases de l'ENSO. Il a été supposé encore pertinent au 21ième siècle pour déduire les précipitations futures les plus réalistes à Tahiti, à partir des précipitations simulées par le modèle à 12 km, suivant deux scénarios du GIEC (RCP4.5 et RCP8.5). La structure spatiale du réchauffement climatique de type El niño conforte la pertinence du lien établi. Les résultats obtenus concernent les côtes sud de Tahiti. Les précipitations vont augmenter progressivement tout au long du 21ème siècle, en réponse au réchauffement global. A Papara, il est tombé en moyenne sur la période 1961-2011 pendant l'été austral 695 mm de pluie. Il tombera en moyenne sur la période 2070-2100, 825 mm selon le scénario RCP4.5, 814 mm selon le scénario RCP8.5, soit une augmentation d'un peu moins de 20 %. Ajoutés à cet accroissement à long terme, les événements El Niño induiront un excédent de précipitations. Mais cet effet sera réduit en fin de période dans le RCP8.5. A l'inverse, les événements La Niña s'accompagneront toujours d'un déficit de précipitations mais sans arriver à contrecarrer l’accroissement à long terme. / The effects of climate change on Pacific islands is a major concern for the local populations. The rainfall parameter, specifically, appears as one of the sensitive parameters, as it determines water resources. The goal of this thesis is to bring a first insight into the 21st century evolution of precipitation in Tahiti.The first step was to characterize rainfall in Tahiti using data records from the observation network of Meteo France. The “rainfall season”, lasting from November to April, is the season of interest, as rainfall amounts are the highest at this time of the year. Indeed, the South Pacific Convergence Zone (SPCZ), host of deep convection, remains the principal source of rainfall in Tahiti in austral summer (December-January-February). On interannual and interdecadal timescales, the El niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO) imply north/south and east/west migrations of the SPCZ, drawing it away, or closer to Tahiti. The positive phase of the IPO involves a north-eastward displacement of the SPCZ, which causes higher rainfall amounts in Tahiti. The SPCZ is displaced towards the south- west during negative IPO phase, leading to a decrease of rainfall in Tahiti. The study reveals that the IPO positive phase favor the occurrence of intense El niño events. In those cases, the SPCZ is critically displaced to the north-east and lies zonally just south of the equator. Accordingly, the SPCZ is drawn away from Tahiti and alters the south-east flow of trade winds. As a result, substantial orographic precipitation affect the south-east coasts of Tahiti.Following the assessment of observed precipitation for the period 1961-2011, an original method has been set up to obtain a model able to resolve the island and capture the orographic effects at best. Two successive downscaling steps have been necessary to get the limited area model ALADIN-Climat over Tahiti (at the resolution of 12 km), starting from the global coupled model CNRM-CM with a resolution of 150 km. The regional model outputs have been compared to the observed records over the historical period. A linkage between observed and modeled precipitation has been defined. This linkage has been built between meteorological stations and model grid cells exhibiting similar behaviour regarding the phases of ENSO. It has been assumed that this linkage is still relevant in the 21st century. In this way, future precipitation in Tahiti, as realistic as possible, are deduced from modeled precipitation (at 12 km of resolution), following two IPCC scenarios (RCP4.5 and RCP8.5). The El niño-like spatial structure of global warming further confirms the relevance of the linkage built previously. The results obtained concern the southern coasts of Tahiti. Rainfall would gradually increase along the 21st century, as a consequence of global warming. In Papara, the austral summer mean rainfall height is 695 mm over the period 1961-2011. The mean value, for the period 2070-2100, would be 825 mm for the scenario RCP4.5 and 814 mm for the scenario RCP8.5, let say an increase of a little less than 20%. Superimposed to this long-range raise, El niño events would induce an excess of rainfall. This effect would be reduced at the end of the 21st century in RCP8.5. Conversely, La niña events would always involve a decline of rainfall, but would not succeed in counteracting the long-range increase.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the present work we studied the vertical profile of the Global Ocean temperature in years of occurrence El Nino-Southern Oscillation events, to better understand the functioning of this phenomenon. For its realization were used three sets of ocean reanalysis: ORAS4 produced by European Centre for Medium-range Weather Forecasts, the GODAS produced by National Centers for Environmental Prediction and SODA produced by Carton and Giese, 2008. The three sets of reanalysis showed the same potential temperature pattern in all layers of depth. The Ocean Temperature Index Equatorial Pacific is very well El Nino-Southern Oscillation events, as detected all El Niños and La Niñas occurred in the period of 52 years. Finally, it is concluded that the proposed new index can be used to determine (characterization) of El Nino-Southern Oscillation events with the same precision as the Oceanic Niño Index, and with superior accuracy for predicting El Nino-Southern Oscillation events as it detects these events several months in advance of the Oceanic Niño Index. Therefore, we can add one more tool to help us predict and better understand the El Nino-Southern Oscillation events. / No presente trabalho foi estudado o perfil vertical da temperatura do Oceano Global, em anos de ocorrência de eventos de El Niño Oscilação Sul, para compreender melhor o funcionamento deste fenômeno. Para a sua realização foram utilizados três conjuntos de reanálises oceânicas: ORAS4 produzida pelo European Centre for Medium-range Weather Forecasts, o GODAS foi desenvolvido pelo National Centers for Environmental Prediction e SODA desenvolvido por Carton e Giese, 2008. Os três conjuntos de reanálises apresentaram o mesmo padrão de temperatura potencial em todas as camadas de profundidade. O Índice de Temperatura Oceânica do Pacífico Equatorial representa muito bem os eventos de El Niño-Oscilação Sul, uma vez que detectou todos os EL Niños e La Niñas ocorridos no período de 52 anos. Por fim, conclui-se que o novo índice proposto pode ser utilizado para determinação (caracterização) de eventos de El Niño-Oscilação Sul com a mesma precisão que o Índice de Niño Oceânico, e com superior precisão para a previsão de eventos de El Niño-Oscilação Sul, uma vez que detecta estes eventos com alguns meses de antecedência em relação ao Índice de Niño Oceânico. Assim podemos acrescentar mais uma ferramenta que nos ajudará a prever e entender melhor os eventos de El Niño-Oscilação Sul.