Memory Effect of the Southern Atlantic Subtropical Dipole

Autor(es)

Santis, Wlademir ^[1] ; Castellanos, Paola ^[2] ; Campos, Edmo ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Oceanog, Sao Paulo - Brazil

^[2] Univ Lisbon, Marine & Environm Sci Ctr, Fac Ciencias, Lisbon - Portugal

^[3] Amer Univ Sharjah, Coll Arts & Sci, Sharjah - U Arab Emirates

• Tipo de documento: Artigo Científico
• Fonte: Journal of Climate; v. 33, n. 17, p. 7679-7696, SEP 1 2020.
• Citações Web of Science: 0

Resumo

The South Atlantic subtropical dipole is the dominant mode of coupled variability in the South Atlantic, connecting sea level pressure and sea surface temperature. Previous studies have shown its great relevance to the climate conditions over South America and West Africa. We have used several numerical experiments with the Hybrid Coordinate Ocean Model to investigate the effects that an austral winter-spring dipole asserts on the South Atlantic. We explore the interaction between SST anomalies and the formation of the fossilized mixing region, which preserve temperature anomalies underneath the summer mixed layer, until they feed back to SST after the next autumn. It was found that, through this process, there is a memory effect that restores temperature anomalies from an austral winter-spring dipole back to the austral winter of the following year. The dominant mechanisms are the contribution from entrainment and surface net heat flux (NHF). Entrainment is mostly controlled by vertical temperature gradient anomalies, while surface NHF is controlled by interactions of climatological ocean heat loss and anomalies of mixed layer thickness. Our results suggest that the combined effect of entrainment and surface NHF is different in the southwest and northeast dipole regions, leading to differences in both intensity and timing of SST anomalies. Turbulent and nonlinear processes are most important to reduce entrainment in the southwest dipole region and to increase the memory effect asymmetry. (AU)

• Processo FAPESP: 17/09659-6 - Variabilidade interanual dos transportes meridionais através da rede transatlântica SAMOC (SAMBAR)
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/08572-3 - Trocas Oceânicas Inter-hemisféricas: Conexões Trópico-Extratrópico no Atlântico Sul - Análises de Observações e Resultados Numéricos
• Beneficiário: Paola Maria Castellano Ossa Fernandes
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 11/50552-4 - Impacto do Atlântico Sul na célula de circulação meridional e no clima
• Beneficiário: Edmo José Dias Campos
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 15/11366-1 - O papel do Atlântico Sul na distribuição de calor e de equilíbrio de massa na circulação global: hiato da mudança climática?
• Beneficiário: Paola Maria Castellano Ossa Fernandes
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 17/25110-4 - Estudo dos Processos Físicos Associados aos Impactos do Dipolo do Atlântico Sul no Continente Sul-Americano
• Beneficiário: Wlademir Jose de Santis Junior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado