Climate projections of air temperature and precipitation in sao paulo using the regcm4 regional model

Abstract

This study aims to evaluate changes in the average values of precipitation and temperature over the state of São Paulo (Brazil) and in three indexes of climatic extremes (consecutive dry days-CDD, rainy extremes-R95p, and heatwave duration-HWD) between the present period and the end of the 21st century, based on a regional climate model. Three simulations/projections of the Regional Climate Model (RegCM4) were used for the present (1995-2014) and future (2080-2100) climate, and the analysis was divided into summer (DJF) and winter (JJA). The simulations consider the most pessimistic scenario for the concentration of greenhouse gases in the atmosphere of the IPCC (RCP8.5). Observed data from the Climate Prediction Center (CPC) are used to analyze the dexterity of simulations in the present climate for precipitation and air temperature. In the summer, the simulations overestimate the rainfall on the coast, while they represent it closer to the observed in the winter. For air temperature, there are underestimates on the south coast for both seasons. In the interior of the state, the simulated temperatures in summer are close to what was observed, whereas in the winter there is an overestimation of this variable. Regarding the climatic indices, there is little change in the CDD for the summer, and an increase for the winter, mainly in the interior of the state, while R95p shows a sign opposite to the CDD. HWD shows a decrease in DJF in the interior and an increase in the coastal region for JJA. The interior of São Paulo is identified as the region most susceptible to consecutive dry and extreme rainy days, while heatwaves show a more relevant sign of an increase in the south and east of the state during the winter.