Droughts in Homogeneous Areas of South America and Associated Processes during the Months of Austral Spring and Summer  

作　　者：Mariah Sousa GOMES Iracema Fonseca de Albuquerque CAVALCANTI Gabriela V.MULLER 

机构地区：[1]General Coordination of Earth Science(CGCT),National Institute for Space Research(INPE),Avenida dos Astronautas,1758,CEP:12227-010,Sao Josédos Campos,SP,Brasil [2]National Scientific and Technical Research Council(CONICET),Argentina [3]Center for Climate Variability and Climate Change Studies(CEVARCAM),Faculty of Engineering and Water Sciences(FICH).National University of Litoral(UNL),Ciudad Universitaria,Ruta Nacional,168-km 472.4-[S3000ADQ]-Santa Fe,Argentina

出　　处：《Advances in Atmospheric Sciences》2024年第12期2337-2353,共17页大气科学进展（英文版）

基　　金：Support Foundation(FAPESP)/Belmont Forum-CLIMAX-2015-50687-8;Coordination for the Improvement of Higher Education Personnel(CAPES)-88887145932/2017-01;CAPES-project88882.330673/2019-01;the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)project306393/2018-2 and GVM thanks the National Agency for Scientific and Technological Promotion(ANPCyT)projects PICT-2019-2019-03982 and PICT-2019-2019-00481;National University of the Litoral(UNL)project CAI+D-2020-50620190100082LI;National Council for Scientific and Technical Research(CONICET)project PIP 11220200102257CO.

摘　　要：Droughts that occurred in selected areas located in homogeneous regions of South America during the austral springs(SON)and summers(DJF)from 1982 to 2019 are identified using the Standard Precipitation Index(SPI).Four areas were analyzed for droughts in SON,and three areas were analyzed for droughts in DJF.The areas in the Amazon suffered from the majority of their droughts during El Niño years,while most of the droughts in the areas of southern Brazil,Uruguay,and North Argentina occurred during La Niña years.In southeastern and central-western parts of Brazil,droughts occurred during both phases of El Nino-Southern Oscillation(ENSO)and also during neutral years.Thus,other processes besides ENSO are likely related to the observed droughts.The droughts were investigated for each area and month,and composites of atmospheric and oceanic variables during both seasons were analyzed for the selected cases.Regional and large-scale field composites were examined to identify the main processes associated with dry conditions in the different areas.Regional features were related to the influence of high pressure over southern and southeastern areas and the divergence of moisture flux in all areas.Meridional circulations contributed to subsidence over the dry regions.The large-scale influential features include SST anomalies,wavetrains over the South Pacific Ocean with centers of action over South America that produced subsidence in the study areas,and convection anomalies in the Maritime continent and surrounding areas.Therefore,the droughts were associated with a combination of regional and large-scale features that produced subsidence over the analyzed regions.

关 键 词：DROUGHTS South America regional features large-scale features 

分 类 号：P426.616[天文地球—大气科学及气象学]