Conexão dos sistemas frontais meridionais com a ZCIT sobre o nordeste brasileiro

Abstract

The regeneration of meridional frontal zones, has led to an increased influx of these weather systems into the Brazilian Northeast region (BNE) in 2022. The interaction of these systems with the Intertropical Convergence Zone (ITCZ) between 1000 to 850 hPa resulted in significant precipitation, causing negative economic and social impacts. This study aims to improve the quality of forecasting adverse meteorological phenomena, the formation of which is closely linked to atmospheric conditions and specific synoptic systems in the region. Satellite images from GOES-16 and METEOSAT-11 (infrared channel), provided by GIBBS - NOAA, along with ERA 5 reanalysis data (0.25° x 0.25°) from ECMWF were utilized. Meteorological fields and vertical cross-sections were visualized using OpenGrADS. A total of 27 events (from formation to dissipation) were analyzed. The most common process responsible for these intrusions into the BNE was the frontal periphery. A conceptual model, that establishes connections between these cases and their synoptic and thermodynamic characteristics, was developed. Three main types of connections were identified: Type 1 (11 cases), Type 2 (9 cases) and Type 3 (7 cases). Type 1 involves cyclogenesis and meridional regeneration of the frontal periphery towards the Equator; there was interaction between an Upper Tropospheric Cyclonic Vortex (UTCV) and the Bolivian High (BH). Type 2 is associated with a fracture in the frontal trough and cloudiness band, resulting in the formation of cloud agglomeration linked with the ITCZ; generally, interhemispheric anticyclonic vorticity was observed at high levels. Type 3 was characterized by meridional movement of the frontal band toward the ITCZ trough; throughout this process, one or more UTCVs played a significant role. Interhemispheric meridional currents were generated by UTCVs. Heavy precipitation occurred in May - August, was associated with Type 2 of connection and reached 322 mm/8 days. Notably, the most intense interactions between the Northern Hemisphere (NH) and the Southern Hemisphere (SH) predominantly occurred by Highs and Ridges. The quantity of meridional negative nuclei required to establish connections between the frontal systems and the ITCZ was around 5. In SH, this cell quantity is less than in NH, where 6-7 cells were required.