Importancia das condi??es termodinamicas nos eventos extremos de precipita??o na cidade de Belém e regi?o metropolitana

摘要

The purpose of this research was to verify the importance of thermodynamic factors on the occurrence of extreme precipitation events in the city of Belém (PA) and its metropolitan area, during the period of August 2008 to December 2009. The study of the atmosphere thermodynamics was based on the theories of Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE). To classify the extreme precipitation events the decis method was used in order to associate them to the CAPE and CINE values. It was verified that the studied region has strong convective activity during all the year, and that not always high CAPE and low CINE determine precipitation. Those situations in fact determine profound convection, but to ensure precipitation, dynamic enforcement is required. For the occurrence of extreme precipitation events during the rainy season the ITCZ is the forcing dynamic and during the dry season the squall lines contribute to them. Then when the precipitation process is exclusively CAPE dependent, a high CAPE value is required in order to generate deep convection and, consequently, precipitation. Otherwise, for dynamic contribution precipitating process a significant value of CAPE is not needed.