EFFECT OF OROGRAPHY ON RAINS THROUGH THE ANALYSIS OF CLIMATE INDEXES IN THE WESTERN PLATEAU REGION OF PAULISTA

Abstract

The present research analyzed the effect of relief on the variability and extremes of rainfall in the central portion of the state of São Paulo, using 31 surface rainfall gauges. For this, it applied the methods of filling gaps (Regional Weighting), rainfall classification (Rain Anomaly Indexes) and precipitation indexes (Rclimdex). Through the methods used, it was verified that the pluviometric variability showed in the admitted parameters of normality with about 17% of the years, in the wet parameters about 18% of the years and in the dry parameters about 15% of the years of the historical series of 1979 -2017. In addition, it was found that among the thirty-eight years of the historical series, the year 1983 was the wettest and the year 2014 the driest. As these were two distinct representative years (wet and dry) of rainfall, it was noted through the rainfall indexes, they showed the strength of the orographic effect in the intensification of rainfall in volume and number of extreme days in the higher regions located in the southern portion of the study area. Therefore, due to the altitude that manifests itself associated with a sharp altimetric difference that establishes a high slope, which the central region of the state of São Paulo has, its morphological characteristics play an important role with the process of intensification of the rains, mainly in the years rainy.

Keywords:
Precipitation; Rainfall anomaly index; Extreme years; RClimdex; Relief