Aspectos dinâmicos e termodinâmicos de vórtices ciclônicos de altos níveis com convecção em seu interior.

Abstract

Extreme precipitation events cause significant socioeconomic and environmental impacts. In the Northeast Region of Brazil (NEB), Upper-Level Cyclonic Vortices (ULCVs) are meteorological systems that operate between 200–300 hPa, characterized by a cold core and a closed cyclonic circulation. These systems are often associated with unstable weather conditions, such as increased cloudiness, heavy rainfall, and strong winds, particularly in their periphery. The study of ULCVs is essential to understand the dynamic and thermodynamic processes that influence weather and climate, especially in the NEB region. Understanding the structure and evolution of ULCVs is crucial for improving the prediction of extreme events, such as heavy rainfall, and for reducing associated socioeconomic and environmental impacts. The objective was to analyze the dynamics and thermodynamics using the vorticity tendency equation, the apparent heat source (Q1), and the apparent moisture sink (-Q2). Using ERA5 reanalysis data for temperature fields and satellite imagery, it was possible to identify the presence of ULCVs within the area bounded by latitudes 10°N to 30°S and longitudes 65°W to 15°W, and to distinguish between ULCVs with and without internal convection. Among the cases identified, two events were selected: the case of 16 January 2011 and the case of 29 January 2016. In the first case, precipitation resulting from convective activity affected part of the eastern region of Bahia State. In the second case, precipitation impacted the states of Alagoas, Pernambuco, and part of Paraíba. The ERA5 dataset revealed relative vorticity and Q1 and -Q2 fields, showing patterns that contributed to the formation of convection. The analysis of Q1 indicated a heat source located between the cores of the ULCVs. For the case of 16 January, heating occurred between 500 and 200 hPa, while for the case of 29 January, heating was observed between 600 and 300 hPa. These heating patterns are associated with the release of latent heat during condensation, reinforcing the development and activity of deep convection. The results from the relative vorticity field demonstrate an intrusion of positive vorticity, associated with anticyclonic motion, which propagates vertically until reaching the core of the Upper-Level Cyclonic Vortex (ULCV), favoring the development of convection within it.