The atmospheric and oceanic ifluences on the 2019/2020 South America drought

GOMES, MARIAH SOUZA; CAVALCANTI, IRACEMA FONSECA DE ALBUQUERQUE; MÜLLER, GABRIELA

Congreso; 102nd Annual Meeting of the American Meteorological Society; 2022

American Meteorological Society

Several atmospheric and oceanic features during 2019/2020 affected South America,resulting in a severe drought that caused many impacts on several sectors, asagriculture, water resources, and environment. In a regional scale, there was areduction of humidity 􀀁ux over the continent, and in a large scale, the occurrence ofdifferent processes could have contributed to the dry conditions. There was apersistent pattern of west-east convection anomalies in the tropical Paci􀀂c, and areduction of kinetic energy in the atmosphere over the South Paci􀀂c that could berelated to the steady conditions observed over South America and southeast SouthAtlantic from September 2019 to March 2020. The extreme positive phase of theIndian Ocean Dipole during 2019 austral spring was another event that could haveinfluenced temperature and precipitation in South America. The SuddenStratospheric Warming that occurred in September 2019 induced the negative phaseof the Southern Annular Mode in December, which generated subsidence over thesubtropics and affected the precipitation over South America. In addition, fromSeptember 2019 to March 2020, the heating observed in the stratospherepropagated to the troposphere over South America. During the whole period, therewere positive SST anomalies in all oceans, mainly in the North Atlantic Ocean,which could have contributed also to subsidence over South America through ameridional circulation. At the end of the studied period, the development of La Niñaextended the situation of reduced precipitation in South Brazil.