Diurnal variability of precipitation in south region of Brazil

Abstract

Background: Brazil’s South Region Climate is heavily influenced by its geographical position, transitioning from tropical to mid-latitudes characteristics on its large latitudinal extension. That factor combined with a complex terrain and the continentality effects results on different weather and climate modes, being verified by a large thermal contrast and different pluviometric regimes throughout the year. The particularities of these climate modes still need investigation, being this study primarily objective. Methods:  It used hourly data from 95 (ninety-five) automatic meteorological stations of the South Region of Brazil, with temporal series from five to twenty years of data to calculate it’s hourly mean and investigate its comportament on the different regions of the three states. The interpolation methods IDW (inverse distance weighting) and Kriging were used to support the spatial analysis. Results: The analysis of data and the hourly map compositions indicated a well defined pattern of spatial precipitation. The lowest accumulation values are observed between midnight and 5 a.m. After dawn, the precipitation grows on the west-side of the three states, specially in between southwest of Paraná, west of Santa Catarina and northwest of Rio Grande do Sul. It reaches its maximum from midday to 3 p.m. in the west. From mid afternoon to the night, the maximum shifts from west to east, being its highest late afternoon and night, especially in between Santa Catarina and Paraná. It starts to lose strength only after midnight.