Aspectos da circulação atmosférica de grande escala sobre o Norte e Nordeste do Brasil relacionados com a temperatura da superfície do mar.

Abstract

Some aspects of the large scale atmospheric general circulation, in the North and Northeast Brazil, which are related to the Sea Surface Temperature (TSM) of the Tropical Atlantic and Pacific oceans were investigated from the apparent heat source and the apparent humidity sink. Were utilized the monthly data variables temperature, specific humidity, zonal and meridional wind components and geopotential height from National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR). The used data are spaced in a grating of 2.5°x 2.5° latitude and longitude, for the standard levels from 925 to 100 hPa. Besides, the used are TSM data from a 2° x 2° latitude and longitude grid. Four episodes of ENSO and four of dipole pattern were selected. The study refers to the rainy quarter period of February to April. In the Northeast Brazil and part of Amazon, during the El Niño years, the change in the pattern of Walker cell which implies the inhibition of the convection was observed. During years of La Niña an intensification of the convection was observed. A strong precipitation variability between these events was observed. During the episodes of El Niño and positive dipole, a similar behavior of the static energy anomalies were observed. The same behavior was observed during the La Niña and negative dipole. During the warm (cold) episodes of El Niño and positive dipole (La Niña and negative dipole) the atmosphere over the areas 1 and 2 were less (more) humid. The observed above (below) mean variations in the dry static energy were more stronger during the El Niño (La Niña) years when compared to the years of positive dipole (negative dipole). Smaller (larger) areas of convergence of dry static energy in the lower levels and divergence in the upper levels during the years of El Niño (La Niña) were encountered. During the positive (negative) Dipole phases the convergence band of static energy over the Atlantic Ocean was observed more towards north (south). The Amazon region behaved as an apparent water vapor sink during the episodes of El Niño, La Niña and Dipoles positive and negative. The Northeast Brazil region behaved as an apparent water vapor source during the episodes of El Niño and positive Dipole years and as a sink during the episodes of La Niña and negative Dipole year.