The role of the South Indian and Pacific oceans in South American monsoon variability

Autor(es)

Drumond, A. R. de M. ^[1] ; Ambrizzi, T. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Oceanog, Dept Phys Oceanog, BR-05508120 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Dept Atmospher Sci, Inst Astron Geophys & Atmospher Sci, BR-05508120 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: THEORETICAL AND APPLIED CLIMATOLOGY; v. 94, n. 3-4, p. 125-137, NOV 2008.
• Citações Web of Science: 12

Resumo

This work has investigated the impact of three different low-frequency sea surface temperature (SST) variability modes located in the Indian and the Pacific Oceans on the interannual variability of the South American Monsoon System (SAMS) using observed and numerical data. Rotated Empirical Orthogonal Function (REOF) analysis and numerical simulations with a General Circulation Model (GCM) were used. One of the three SST variability modes is located close to southeastern Africa. According to the composites, warmer waters over this region are associated with enhanced austral summer precipitation over the sub-tropics. The GCM is able to reproduce this anomalous precipitation pattern, simulating a wave train emanating from the Indian Ocean towards South America (SA). A second SST variability mode was located in the western Pacific Ocean. REOF analysis indicates that warmer waters are associated with drought conditions over the South Atlantic Convergence Zone (SACZ) and enhanced precipitation over the sub-tropics. The GCM indicates that the warmer waters over Indonesia generate drought conditions over tropical SA through a Pacific South America-like (PSA) wave pattern emanating from the western Pacific. Finally, the third SST variability mode is located over the southwestern South Pacific. The composites indicate that warmer waters are associated with enhanced precipitation over the SACZ and drought conditions over the sub-tropics. There is a PSA-like wave train emanating from Indonesia towards SA, and another crossing the Southern Hemisphere in the extra-tropics, probably associated with transient activity. The GCM is able to reproduce the anomalous precipitation pattern, although it is weaker than observed. The PSA-like pattern is simulated, but the model fails in reproducing the extra-tropical wave activity. (AU)

• Processo FAPESP: 01/13816-1 - Componente brasileiro do experimento de campo do jato de baixos níveis a leste dos Andes: interações em meso e grande entre as bacias Amazônica e do Prata
• Beneficiário: Jose Antonio Marengo Orsini
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 06/53917-5 - A influencia do anetus sobre a migracao meridional da zona de convergencia intertropical do atlantico.
• Beneficiário: Anita Rodrigues de Moraes Drumond
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 01/06842-6 - Estudo da influência do Oceano Atlântico subtropical no clima da América do Sul
• Beneficiário: Anita Rodrigues de Moraes Drumond
• Modalidade de apoio: Bolsas no Brasil - Doutorado