Seminário do Departamento de Ciências Atmosféricas
Title: Southern African Monsoon: climatology and combined effect of global SST interannual variability modes
Presentation: Dr. Kenedy Silverio (pós-doutorando) e Dr. Tercio Ambrizzi
Abstract
Most of southern Africa (SAF), defined here as African landmass poleward of 10°S generally experiences seasonal rainfall between late September and earlier April with a peak, resembling monsoon-like regime occurring between December and February (DJF). Climatologically, during earlier monsoon (September – November; SON) heavy precipitation occurs over Western–Central Equatorial Africa and northwestern SAF, following the southward migration of Intertropical Convergence Zone (ITCZ) that favors the development of a thermal low pressure system over central Angola. In the peak monsoon (DJF), as the major heating zone migrates to the subtropics, the thermal low (known also as Angola Low) strengthens and moves southward to sit around the plateau region to the east of the Angolan and Namibian highlands, while anticyclonic system emerges over Indian subcontinent and both subtropical Highs in the Atlantic and Indian Oceans move southward. It triggers the characteristic circulation of monsoon, leading to enhanced convection and rainfall over most of SAF. However, such mean conditions can be altered by the occurrence of certain climate variability modes acting either individually or in concert. Knowing that, this talk is proposed to discusses the impact of global sea surface temperatures (SST) interannual variability modes on monsoon rainfall in SAF, emphasizing the combined effect of either El Niño Southern Oscillation (ENSO) in the tropical Pacific and South Atlantic Subtropical Dipole (SASD) in the subtropical south Atlantic Ocean or ENSO and Subtropical Indian Ocean Dipole (SIOD) in the Indian Ocean through diagnostic approaches. Implications of this knowledge for seasonal predictions and the livelihood of more than 65% of SAF population, living in rural areas and practicing agriculture are also highlighted.
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