Avaliação da precipitação pluvial em Angola e os sistemas meteorológicos atuantes

Abstract

The influence of tropical convection is an important factor for the occurrence of rainfall in Africa. One of the most important mechanisms for the occurrence of extreme precipitation in Africa is the Intertropical Convergence Zone (ZCIT), in which most of the rain occurs in the southern summer. The main objective of this study was to evaluate the rainfall regime in Angola and the dynamics meteorological systems and see how they are associated with variations in the pattern of raiThe methodology used to carry out this study started with the validation of the CPC rainfall, then the description of the cluster analysis method, the climatology of the rainfall over the study region and finally analysis of the dynamic and thermodynamic patterns on the synoptic scale with NCEP reanalysis data, which influence the spatial distribution of rainfall over the region of Angola.The results of the statistical measures in the validation of the rainfall data CPC estimated in function of the observed rainfall showed that, in general, the values were below the averages, thus showing that the CPC data did not have a good representation in relation to the rainfall of the seasons from INAMET. In the cluster analysis it was found that 4 groups (from 3 to 6) had 2 periods: dry (autumn-winter) and rainy (spring-summer) well defined, with accumulation of precipitation throughout the year. the northern part with rain peaks in the months of April and November (with a monthly average of 131.59 mm / month and 136.42 mm / month, respectively), the central-southeastern region and the eastern region with a peak of rain in the summer, mainly in the month January (with a monthly average of 116.54 mm / month and 216.94 mm / month), respectively and the southwest region known as a desert zone with maximum peak rainfall in April (with a monthly average of 41.62 mm / month).the results of the twelve months analyzed showed that rainfall starts with the arrival of spring (September, October and November) and spreads to almost all regions with the arrival of summer (December, January and February), showing that the rain in all the analyzed seasons has very marked annual cycles, with the rain concentrated in the summer months (December, January and February), which is the period of greatest convection, being the rainiest months from September to February. of dynamic and thermodynamic patterns on the synoptic scale, showed that moisture transport and increased convection over the regions of Angola, is favored by the convergence of winds and mass displacement at low levels, being associated with the position of the ZCIT during the spring seasons it’s summer.