Circulation mechanisms related to northeast Brazil rainfall anomalies

摘要: This study explores the role of upper ocean for circulation anomalies in overlying atmosphere, with focus on late boreal winter and extreme climatic events northeast Brazil. Data sources comprise rainfall records Nordeste, surface ship observations sea temperature (SST), pressure, wind fields (COADS, period 1948–1990), satellite tropical convection (HRC, 1971–1988), air analyses European Centre Medium Range Weather Forecasts (ECMWF, 1980–1991), all Atlantic sector. Interhemispheric SST gradients are most strongly associated north-south contrasts pressure meridional component, whereas inverse SST-pressure relations situ less close. Enhanced northward increase is accompanied by steeper gradient accelerated southerly which representative a displaced Intertropical Convergence Zone (ITCZ), latter turn leading to drought 850/1000 mbar layer mean similar those account gradient. During wet as compared dry years Brazil, North cooler South warmer, accordingly lower tropospheric thickness reduced north but inflated south equator, resulting increased/reduced over North/South Atlantic, well wind, stronger subsidence outer tropics northern hemisphere intensified ascending motion convective activity related southward near-equatorial belt. The evidence thus indicates ways interhemispheric exert hydrostatic control pattern, force south-north hence modulate latitude position ITCZ Nordeste rainfall.