Diurnal cycle of precipitation in Brazil

Abstract

Abstract The diurnal cycle is an important mode of climatic variability associated with different aspects of micro, meso and large scale meteorological phenomena. Thus, we performed a study of the space-time variability of the diurnal cycle based on the longest time series (13-years) of precipitation with hourly sampling and covering all regions of Brazil. The dataset was collected during the period from 1st January 2008 to 31th December 2020. We used data from 411 rain gauges installed in automatic weather stations. In order to evaluate regional aspects, we conducted a cluster analysis with different configurations (4, 5 and 6 groups). We identified a considerable heterogeneity in the hour of maximum precipitation in Brazil and three main types of diurnal cycle were observed: i) maximum precipitation at mid- to late afternoon associated with strong local convection activity; ii) diurnal cycle with intense precipitation during nighttime at the Amazon basin, the coast of Northeast Brazil and the Southern region; iii) semidiurnal cycles with low precipitation rate at the Northeast Brazil. Seasonality promotes changes in the spatial distribution of types of diurnal cycles, while interannual variability influences on the intensity of maximum precipitation, mainly at the Amazon basin and Southern region.