An overview of precipitation climatology in Brazil: space-time variability of frequency and intensity associated with atmospheric systems

Abstract

ABSTRACT The climatic characteristics of Brazil present marked spatial and temporal precipitation contrasts, which are reviewed according to four main indices: PRCPTOT – total precipitation; Rmm – number of days with precipitation; Rx1day – maximum 1-day precipitation; and SDII – simple precipitation intensity index. The study used data for 12 hydrographic basins from 1975 to 2005. The seasonal distribution of these precipitation indices in Brazil is summarized concerning the main atmospheric systems acting in South America. The austral summer and autumn present the maximum PRCPTOT, Rmm, and Rx1day, related to the South American Monsoon System and Intertropical Convergence Zone. However, in the winter, the extreme northern and eastern coast also present high Rx1day. Maximum values of SDII occur during the four seasons in southwestern Brazil, related to mesoscale convective complexes. Precipitation anomalies are also affected by the sea surface temperature of the Tropical Southern Atlantic and Equatorial Pacific Oceans.