Avaliação horária da precipitação na cidade de Maceió via dados observados Chirps Terraclimate

Abstract

Rainfall is one of the most important meteorological variables in the daily lives of urban populations. The city of Maceió, capital of Alagoas – East of Northeast Brazil (ENEB) has 50 neighborhoods and a population of approximately one million people. Because it has few studies on urban rainfall, the objective of the study is to evaluate urban rainfall in the city of Maceió via observational data and precipitation products. Precipitation products (CHIRPS - Climate Hazards Group InfraRed Precipitation with Station and TerraClimate) were used together with data from automatic meteorological stations (AMS) from CEMADEN between 2016 to 2022 and conventional meteorological stations (CMS) from INMET between 1981 to 2021 statistical indicators (R², r, EPE and RMSE) were used to validate the precipitation products. Maps of hourly rainfall frequencies via the Spline spatial interpolation method were made using QGIS software version 3.28. The correlations were satisfactory in the seasonal scale, in the TerraClimate product (R2 = 0.56, R2 = 0.53 and R² = 0.62) being superior to the CHIRPS product (R² = 0.49 R² = 0.29 and R² =0 ,60) respectively in the rainy season, dry season and transition season. On the annual scale, TerraClimate and CHIRPS products obtained Pearson's coefficient r = 0.85 and r = 0.79 in due order. Highlighting the higher values obtained for EPE and RMSE in CHIRPS compared to the TerraClimate product. This is due to different spatial resolution between products and data sampling techniques. The occurrence of hourly rains in Maceió, distributed in the high and low parts are different. In the upper part of the city, the highest hourly rainfall records are due to the mesoscale and synoptic systems, with the preferred times between 04:00 and 07:00 am in the homogeneous groups. In the lower part of the city, less rainfall was recorded despite the proximity of the coastal and lagoon environments. The environmental degradation observed through the NDVI points to the loss of vegetation in the last two decades, being associated with the greater urbanization process, which interferes with the dynamics of rainfall in Maceió.