Variabilidade da precipitação em tempo e espaço associada à Zona de Convergência Intertropical

Abstract

This study aims to present an atmospheric analysis of spatial and temporal variability of the Intertropical Convergence Zone (ITCZ) in Belem, Jakarta and Nairobi, which are located on the continents of South America, Asia and Africa, respectively. For this, daily precipitation and observed long wave radiation data for the period 1999 to 2008 were used, and mathematical and statistical techniques, such as the arithmetic mean and the Morlet wavelet transform were applied. In general, the results indicate that spatially, the month rainfall varies considerably, since that the three studied cities are located far apart in different continents in the tropical zone. This occurs mainly during the months from January to May, period of greatest activity of the ITCZ in the southern hemisphere. The atmospheric variations observed from the phase wavelet scalograms indicate that the interdecadal scales, annual, interannual and intraseasonal scales are rainfall modulators. Such scales can be represented by the ocean-atmosphere phenomenon mechanisms of El Niño Southern Oscillation and intraseasonal oscillation of Madden and Julian. The contribution of these phenomena to the rainfall distribution over these regions is evident during the study period, and Nairobi, in spite of being located at latitude similar to that of Belem, shows low evidence of the annual cycle and high at interdecadal scale. In the case of Belem and Jakarta oscillations at multiscale rainfall concentrated in the mechanisms scales that modulate the rain associated with the annual cycle and intraseasonal cycle during the period.