Meteorological context of the onset and end of the rainy season in Central Amazonia during the 2014–15 Go-Amazon Experiment

Other literature type English OPEN
Marengo, Jose A. ; Fisch, Gilberto F. ; Alves, Lincoln M. ; Sousa, Natanael V. ; Fu, Rong ; Zhuang, Yizhou (2017)

The onset and demise of the rainy season in Amazonia are assessed in this study using meteorological data from the Go Amazon experiment, with focus is on the 2014–15 rainy season. In addition, global reanalyses are also used to identify changes in circulation leading to the establishment of the rainy season in the region. Our results show that the onset occurred in January 2015, 2–3 pentads later than normal, and the rainy season during austral summer of 2015 exhibited several periods with consecutive dry days in both Manacapuru and Manaus, which are not common for the wet season, and thus determining below normal precipitation. The onset of the rainy season has been strongly associated with changes in large-scale weather conditions in the region due to the effect of the MJO. Regional thermodynamic indices (CAPE, CIN) and the height of the PBL did not present a significant difference between the onset and demise of wet season 2015. This suggests that local changes such the regional thermodynamic characteristics may have not influenced the onset of the rainy season. Variability of the large-scale circulation was responsible for regional convection and rainfall changes in Amazonia during the austral summer of 2014–15.
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