Spatiotemporal Trends of Extreme Precipitation in Caraguatatuba (SE Brazil) from CHIRPS Data (1981–2024) Using GEE and Climate Indices

Abstract. Climate change has intensified the variability and frequency of extreme events, particularly affecting vulnerable coastal urban areas. In Caraguatatuba, located on the north coast of S˜ao Paulo, the impacts are exacerbated by social inequalities and inadequate infrastructure. However, detailed analyses of climate indices in the region are still scarce. This study analyzes precipitation patterns in Caraguatatuba, calculating climate indices to identify trends and support risk mitigation. CHIRPS daily precipitation data at 0.05° spatial resolution were processed using Google Earth Engine and R to compute the ETCCDI indices PRCPTOT, CDD, CWD, R95p, R99p, Rx1day, and Rx5day. Statistical tests were applied to detect significant trends. The results indicate an increase in consecutive dry periods (CDD, p=0.0065) and at the intensity of daily extreme rainfall (Rx1day, p=0.0044) in the southwestern area, while other indices did not show significant trends. These findings highlight the city’s increasing climate vulnerability and the urgent need for adaptation strategies. By offering a replicable framework based on open-access remote sensing and cloud platforms, this study supports policy development to enhance urban resilience and monitoring climate-related disasters in coastal cities.