P4.21 Meridional Propagation of the Convection in South America (1999

P4.21

Meridional Propagation of the Convection in South America

Luiz A. T. Machado, CTA/IAE/ACA, Sao Jose dos Campos, Brazil; and J. P. Duvel, H. Laurent, and J. R. Siqueira

Using ISCCP data from 1987 to 1990 we have studied the interdiurnal fluctuation of the

convective activity over South America. The first principal component, mainly during

Austral Spring, shows a meridional propagation of the convective activity from the

southeast Brazil to the northwest of South America. This cloud cover fluctuation, with a

typical period of 3 to 6 days, is the main interdiurnal oscillation in the Amazon region and

seems to be associated with the cold front penetration in South America continent.

This cold surges from middle latitudes to the tropics is been investigated taking intoaccount

a larger series of data to analyze its interannual variations and their relationships with the

cold front penetrations in South America.<