Análise de Índices de Precipitação na Amazônia Ocidental (Analysis of Precipitation Indices in the Western Amazon)

Este trabalho tem como objetivo verificar as correlacoes de indices de deteccao de mudancas climaticas dependentes da precipitacao pluvial, na Amazonia Ocidental e analisar suas relacoes com a Oscilacao Decenal do Pacifico (PDO), Oscilacao Multidecenal do Atlântico (AMO) e anomalias de Temperatura da Superficie do Mar (TSM) nas regioes do Pacifico Nino 1+2, Nino 3, Nino 3+4, Nino 4, e nas regioes do Atlântico, Indice do Atlântico Norte Tropical (TNAI) e Indice do Atlântico Sul Tropical (TSAI). Utilizou-se uma serie de indices de precipitacao de 36 pontos de grades, no periodo de 1970 a 2001, provenientes de reanalise do projeto ERA-40 do European Center for Medium-Range Weather Forecasts (ECMWF), e de anomalias de TSM e oscilacoes climaticas, PDO e AMO, disponiveis no site do NCEP (National Centers for Environmental Prediction). Realizou-se a correlacao (coeficiente de correlacao de Pearson) entre as anomalias de TSM e a media aritmetica anual dos 36 pontos de grade de cada indice. Observou-se que as regioes do El Nino apresentaram uma fraca influencia sobre a precipitacao total da regiao estudada. O Indice simples de intensidade diaria (SDII) apresenta forte correlacao com o TSAI, mostrando que este indice e bem afetado pela variabilidade da TSM do Atlântico Sul. Portanto. Compreende-se que os indices de extremos climaticos da Amazonia Ocidental sao influenciados pelas oscilacoes interdecenais. A B S T R A C T This work aims to study the relationship of detection rates of climate change dependent on rainfall in Western Amazon and analyze their relations with the Pacific Decadal Oscillation (PDO), Multidecadal Atlantic Oscillation (AMO) and surface temperature anomalies Sea (SST) in the Pacific regions Nino 1 +2, Nino 3, Nino 3 +4, Nino 4, and regions of the Atlantic, Tropical North Atlantic Index (TNAI) Index and the Tropical South Atlantic (TSAI). We used a series of rainfalls of 36 grid points in the period 1970-2001, from reanalysis project ERA-40 from the European Centre for Medium-Range Weather Forecasts (ECMWF), and SST anomalies and fluctuations climate, PDO and AMO, available on the website of the NCEP (National Centers for Environmental Prediction). We conducted correlation (Pearson correlation coefficient) between the SST anomalies and the annual arithmetic mean of 36 grid points of each index. We observed that the regions of the El Nino showed a weak influence on the total precipitation of the studied region. The simple daily intensity index (SDII) has a strong correlation with TSAI, showing that this ratio is much affected by the variability of the South Atlantic SST So. It is understood that the indices of climate extremes in western Amazonia are influenced by fluctuations interdecadais. Keywords: Climate variability, climate change, climate indices.