Estudo de casos de chuvas intensas no planalto costeiro da Bahia.

Abstract

In this work three cases of intense precipitation events observed on the coastal elevated plain of Bahia State are investigated focusing on the analysis of the rainfall variability and the characterization of the meteorological systems involved. Hourly and daily pluviometric total obtained by means of automatic weather stations, meteorological satellite images and reanalysis data were usd. The first case, observed on the night of the 14th and dawn of the 15th October 2006, was associated with deep convection organized on the mesoscale (cloud clusters) that developed in the area of a trough on the easterly flow over Bahia State. The maximum hourly precipitation was high in Teixeira de Freitas (47.5 mm) and Eunápolis (31.0 mm), and of lower intensity in Ilhéus (16.5 mm). In the second case, registered on the night of the 10th and dawn of the 11th November 2006, the formation of the South Atlantic Convergence Zone favored the development of cloud clusters which provided the hourly maximum of 18.25 mm in Teixeira de Freitas and 32.75 mm in Eunápolis. The third case occurred on 11th April 2007, associated with an austral frontal system displacement toward lower latitudes, favored by trough amplification in the middle and upper troposphere. The hourly maximum rainfall was 21.5 mm in Eunápolis and 23.5 mm in Ilhéus. The three cases were associated with wind field convergence (divergence) in the low (high) troposphere, ascending motion in the entire atmospheric column, and high moisture content in the low and middle troposphere, in the area of the coastal elevated plains of Bahia State.