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Shallow Water Model to Simulate the Influence of Amazônia Convection on the Atlantic ITCZ Unstable

Humberto Alves Barbosa, Instituto de Ciências Atmosféricas, Universidade Federal de Alagoas, Brasil, humberto@ag.arizona.edu (Presenting)
Michelle Simões Reboita, Departamento de Ciências Atmosféricas, Universidade de São Paulo, Brasil, reboita@model.iag.usp.br

Amazônia is the second most extensive region of deep convection globally, after the West Pacific warm pool region. It is a tropical rainforest of particular interest for numerical simulations because of the influence of its convection on the Atlantic ITCZ (Atlantic Intertropical Convergence Zone) in the austral spring season. A recent modeling study has suggested that the continental heating associated with the Amazônia convention appears to be unimportant. On a day to day basis, the Atlantic ITCZ is sometimes observed angling and breaking down into a series of tropical disturbances along the equator during the March-May (MFM) as seen in animate geostationary satellite images. To assess the influence of Amazônia convection on the Atlantic ITCZ angling, we run a non-linear shallow water model to simulate barotropic aspects of Atlantic ITCZ unstable. In this model, the Atlantic ITCZ unstable was simulated by a prescribed zonally angled mass sink cross the equator. We also add into the Atlantic ITCZ angulations, the effect of particular forcing functions located at three different positions: two heating sources around Amazônia and Central Equatorial Africa and a feature terrain (elliptical idealized Andes Plateau). The model runs for 25 days to reach the steady state. Our simulations show that the Atlantic ITCZ unstable under the influence of the heating sources over the Central Equatorial Africa and Amazônia makes the trajectory of the disturbances become longer and more elongated over the Southern Hemisphere than the Northern Hemisphere. This means the Amazônia convection may contribute to the changes of the Atlantic ITCZ causing it to become unstable during austral autumn.

Science Theme:  HY (Hydrometeorology)

Session:  1C: Regional Hydrometeorology

Presentation Type:  Oral

Abstract ID: 51

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