Variabilidade da precipitação sobre a região ocidental do oeste do Sahel associada ao comportamento da frente intertropical-FIT

Abstract

The aim of this study is to increase knowledge of the climate Western Africa. Reanalysis data were used the Environment Predicition / National Center for Atmospheric Research (NCPE / NCAR), available on the website Earth Reserarch Laboratory (ESRL) to evaluate the variability of precipitation western Sahel region for the period 1948-2014. The average annual rainfall for the rainy season which occurs from July to September was 600 mm. It was found that the main mechanism responsible for the production of rainfall in the region is the Intertropical Front-FIT. It were analyzed fields the Sea Level Pressure-SLP, the Longwave Radiation-ROL and the Meridional Wind-VV to assess the latitudinal and longitudinal displacement of the subtropical high of the hemispheres, north and south to identify cloudness and convective activity and determine the location and behavior of ITF. In addition, they used the indices of the Atlantic Multidecadal Oscillation-OMA and Decadal Oscillation Pacific-ODP to identify commonalities capable of producing impacts on the climate in region. It was found that the La Niña events in any of the cold phases of the ODP were related to total rainfall above average in almost all western range including the Sahel band and below the average over the western coast. It was found that the spatial distribution of positive deviations precipitation events associated with La niñas cold phases of ODP, moved further north following the positioning of the ITF. While negative deviations from the associated rainfall La niñas warm phase in the ODP moved further south following the positioning of the FIT. Comparing the El niños 1972-73,1982-83,1987-88, and La Niñas 1954-55 1975-76 and 1988-89 it became clear that the events El niños showed a reduction in rainfall suggesting that these influence the long and severe periods of drought in the region.