Impact of atmospheric soundings over tropical Atlantic on the moisture budget of Amazonia / Impacto de sondagens atmosféricas sobre o Atlântico tropical no balanço de umidade da Amazônia

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The Regional Physical-space Statistical Analysis System (RPSAS), operated by the (Brazilian) Center for Weather Forecasts and Climate Studies (CPTEC - Centro de Previsão de Tempo e Estudos Climáticos) was used in this work to evaluate the impact of assimilated geopotencial profiles from AIRS (Advanced Infrared Sounder) system on RPSAS s analyses and predictions, and on the moisture budget computed for a limited area over Amazon (between the parallels of 0° and 10° S, and meridians of 45° and 75° W) and for a period of August until October of 2004 and 2005, using its outputs. These months are inserted in a period of occurrence of one of the biggest droughts in Amazon, whose indicated cause was the existence of an inter-hemispheric gradient of sea surface temperature pattern on the Atlantic Ocean (also called "Atlantic dipole"). The study was made by using two RPSAS numerical simulations for the aforementioned period: in the first, a set of conventional and assynoptic data was used; in the second, the same package of data was used, plus the geopotencial AIRS profiles. Some comparisons using operational analyses from CPTEC and with observational data were conducted to test the RPSAS outputs. In parallel, climatological studies were done based on ERA-40 and ERA-Interim projects data, on NCEP reanalysis data, and on rainfall data sets in order to form a new approach of the 2005 drought. The results showed that the experiment with AIRS profiles generated analyses that presented the atmospheric state more properly and coherent with physical reality. The precipitation forecasts, in its turn, were overestimated. The climatology showed that the Amazon area had already presented less moisture convergence than the historical records since before July of 2004, and so did the rainfall. Furthermore, it was proved an occurrence of El Niño episode in the last semester of 2004, which was indicated as a one of the causes of the enhancement of the 2005 drought effects.

ASSUNTO(S)

assimilação de dados amazônia moisture budget balanço de umidade sondagens remotas rpsas amazon region remote soundings rpsas data assimilation

ACESSO AO ARTIGO

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