Precipitation Mode in the South Coast of Rio Grande do Sul Coastal Plain

Abstract

The Rio Grande do Sul Coastal Plain is a geological-geomorphological element localized on the east coast of Rio Grande do Sul. The study area belongs to the south coast of Coastal Plain, extends over 243 km, between the cities of Chui, Rio Grande and Santa Vitória do Palmar. The general purpose is identify seasonal and monthly periods of precipitation, their relation with climate variability modes El Niño Southern Oscillation (ENSO) and Southern Annular Mode (SAM), among January 2001 and October 2021. It aims to understand pluviometric behavior in the last decades. Precipitation data were extract from CPTEC/INPE - MERGE and Global Precipitation Climatology Centre. Results indicate that in the analized time, winter is the driest season, 13 records and autumn is the wetter season, seven records. Besides seasonality, months of the analised period included, from 250 months, 142 were under climatology, indicating 56,8% drougth months. Months over climatology accounted 88, revealing 35,2% humid months. Then, close to climatology, 20 months, pointed to 8%. Emphasize March, April and September as the wettest ones, six precipitation records over expected average. February, April and May as the driest ones, six precipitation records under expected average. Therefore, when analyzing and interpreting results, realize that study área is possibly indicating a drought period tendency on the analised timescale.