Influência da temperatura da superfície do mar na ocorrência e características físicas dos sistemas convectivos no norte do Nordeste do Brasil

Abstract

This study investigated the variability of the number of occurrence and physical features of Convective Systems (CS) during the autumn season (from March to May) over the Northern Northeast Brazil (NNEB). Five different scenarios were considered based on the El Niño-Southern Oscilation (ENSO) as well as the inter-hemispheric Gradient of the Atlantic sea surface (GradATL) from 1984 to 2008. The data used in this research were from ISCCP-Tracking (CS identification) and monthly Sea Surface Temperature (SST) data for the Niño 3.4 (170°W-120°W, 5°S-5°N), North (5-20°N, 60-30°W) and South (0-20°S, 30°W-10°E) Tropical Atlantic regions from NOAA - Extended Reconstructed Sea Surface Temperature V3b (NOAA_ERSST_V3). A high variability in the occurrence of Convective Systems was observed. Relating this variability with the SST, it was noticed that CS occurrence was mainly observed when the oceanic conditions were favorable to rainfall over the NNEB (simultaneous occurrence of La Niña and southward SST gradient in the intertropical Atlantic) while CS occurrence was poorly observed in the neutral scenario (absence of El Niño and La Niña, as well as the absence of SST anomalies on the Northern and Southern Atlantic Tropical). In relation to Intertropical Convergence Zone (ITCZ), the results showed that it was more active in the favorable scenarios, El Niño/GradATL_S e La Niña/GradATL_N, i.e., when at least one ocean was favorable to the NNEB rainfall pattern. In these scenarios the physical features of CS indicated they were larger, more penetrative and had more convective activity associated, while in the unfavorable and neutral scenarios they were smaller and less convective.