Relação da anomalia semanal de temperatura da superfície do mar com a chuva no Ceará

Abstract

The annual precipitation cycle in Ceará reveals two distinct phases: five months with high precipitation, followed by months with low volume. The Intertropical Convergence Zone (ITCZ), observed near the 2° South latitude in March and April, is the main driver of rainfall in the region. Among the factors influencing the positioning of the ITCZ, the interhemispheric gradient of sea surface temperature (SST) in the Tropical Atlantic (TA) stands out as one of the most significant. Considering the correlation between rainfall volume in Ceará and SST in the TA, this study explores the linkage between SST anomalies and precipitation on a weekly scale. For this research, correlation analyses and composites were conducted using precipitation data from Ceará provided by the Ceará Foundation for Meteorology and Water Resources (FUNCEME) and SST data from the National Oceanic and Atmospheric Administration (NOAA). The weekly climatologies revealed that the highest precipitation indices in Ceará, on average, occur in week 13 (March) of the year. Additionally, SST in the Southern Tropical Atlantic reaches its maximum values around week 14 (southern autumn) and minimum values in week 34 (southern spring), while SST in the Northern Tropical Atlantic peaks around week 42 (northern autumn) and hits its minimum values in week 8 (northern spring), findings consistent with prior studies. The interhemispheric gradient demonstrated a significant correlation with weekly precipitation, particularly between weeks 11 and 18. During years of substantial rainfall between weeks 11 and 18, the TA SST values showed a notable negative gradient. In years of low rainfall, a positive gradient was observed. These results support the influence of TA conditions on precipitation variations in the state of Ceará.