Extreme Intertropical Convergence Zone shifts over Southern Maritime Continent

Autor(es)

Vasques Freitas, Ana Carolina ; Aimola, Luis ; Ambrizzi, Tercio ; de Oliveira, Cristiano Prestrelo

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Science Letters; v. 18, n. 1, p. 2-10, JAN 2017.
• Citações Web of Science: 1

Resumo

This study investigated the Intertropical Convergence Zone (ITCZ) extreme shifts in the Southern Maritime Continent (SMC) region in austral spring during the period 1979-2015. The results have shown that the ITCZ Southern Boundary (SB) presents great correlations with a meridional Sea Surface Temperature (SST) gradient and Indian Ocean Dipole (IOD) events. However, besides these local forcing, the extreme ITCZ shifts are also influenced by El Nino-Southern Oscillation (ENSO) events and an associated zonal SST gradient. The extreme shifts are due mainly to the combination of changes in Walker Circulation (WC) in the Pacific and Indian Ocean (IO) and local SST anomalies. Therefore, during ITCZ southward extreme shifts, the WC is stronger leading to the strengthening of the northwest equatorial winds in the IO, which pumps moist air and boosts the diabatic heating in the SMC due to the local positive SST anomalies present in this region. Otherwise, during northward extreme shifts, the WC is weaker, not allowing the performance of the northwest equatorial winds in the IO, which associated with the local negative SST anomalies, leads to drier conditions in the SMC region. Another interesting result found here is that a strong meridional or zonal index not necessarily implies a larger shift. The combination of very strong ENSO and IOD events can lead to greater ITCZ SB shifts. Besides, the ITCZ SB shifts can act as a bridge linking IOD and ENSO. (AU)

• Processo FAPESP: 08/58101-9 - Impact of the Southwestern Atlantic Ocean on South American climate for the 20th and 21st centuries
• Beneficiário: Tercio Ambrizzi
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 15/50324-2 - Untangling the drivers of ocean variability in the Southwest Atlantic
• Beneficiário: Tercio Ambrizzi
• Modalidade de apoio: Auxílio à Pesquisa - Regular