Open AccessThe South American Water Balance: The Influence of Low-Level Jets
Author(s) -
Maria Jussara Rodrigues do Nascimento,
Dirceu Luís Herdies,
Diego Oliveira de Souza
Publication year - 2016
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/jcli-d-15-0065.1
Subject(s) - water balance , environmental science , evapotranspiration , precipitation , climatology , amazon rainforest , sink (geography) , moisture , atmospheric sciences , hydrology (agriculture) , geology , meteorology , geography , ecology , geotechnical engineering , cartography , biology
To study the climatology of the water balance over South America and analyze the influence of low-level jets (LLJs), a climate study of the water balance and its main components was performed, specifically in the Amazon and La Plata basin (LPB) region, from 1979 to 2008. The results showed that on average for the analysis period, the Amazon basin and LPB performed as a sink of moisture (ET < P) and as a moisture convergence for the regions, which accounted for approximately 62% and 43% of the precipitation, respectively. During the study period, 884 days with an occurrence of LLJs were observed, occurring most frequently during the winter and around 0000 and 0600 UTC. When considering the water balance for the days with LLJs, it was observed that the Amazon acts as a source of moisture, especially in the dry season, and that the LPB behaves as a sink during all months. The influence of the LLJ as a modulator for precipitation on the LPB is clear, as the precipitation is 32% higher during the LLJ events compared with days without LLJs. This main pattern shows that the moisture convergence trough of the LLJs is crucial for the water balance on the LPB, whereas evapotranspiration is a more important variable of the water balance on the Amazon basin with or without the LLJs.