PLUVIAL PRECIPITATION IN EL NIÑO, LA NIÑA AND NEUTRAL YEARS IN DIAMANTINO, MT

The aim of this work was to describe the annual, monthly and ten-day pluvial precipitation variation during El Niño Southern Oscillation and neutral years, in the city of Diamantino, MT. Data from 1968 to 2003, provided by the Instituto Nacional de Metereologia, was used. To determine the most probable annual rainfall the gamma distribution was used. To check for the data fitness to the used model, the Kolmogorov-Smirnov test was applied. In general, monthly averages have described two distinct phases for the rainfall in the region, a wet season (October to April) and a dry season (May to September). The occurrence of El Niño Southern Oscillation causes a reduction on the annual average rainfall. The rainfall distribution is altered more intensely during the La Niña phase compared to neutral years, showing the highest precipitation during the fourth to the seventh ten-days periods of the year. The El Niño years present higher precipitation during January to March. The neutral years showed the highest precipitation (1862.7mm) followed by El Niño years (1729.2mm) and La Niña years (1712.5mm).

climate; rainfall; agricultural meteorology.