CONNECTION OF THE FRONTAL EXTREMITIES WHITH INTERTROPICAL CONVERGENCE ZONE AND ANALYSIS OF ASSOCIATED PHENOMENA

Abstract

The ITCZ and Frontal Extremities (FE) are the main systems producing heavy rains in the Brazilian Northeast (BNE). The Simultaneous influence of both systems causes losses in society due to floods and landslides. The study aims are as follows: identification of the FE structure connected with ITCZ; elaboration of the atmospheric circulation pattern and analysis of the associated phenomena. Frontal identification was elaborated using potential equivalent temperature advection, relative vorticity and infrared satellite images. Five events showed connection of the frontal systems with ITCZ during the study period (2008-2017). Synoptic analysis of the tropospheric structure presented differences between cases of the frontal system connected with ITCZ and cases without such connection. Both patterns of the troposphere for the frontal zone connected with ITCZ and not connected were elaborated. This connection occurs when: a) Subtropical Jet Stream (SJS) is in the southwest of Brazil; b) anticyclonic circulation at the high levels is presented in the BNE (excluding event with VCAN).  The connection does not happen when: SJS and cyclonic circulation at the high levels is in the BNE. Humid mist and heavy rain were recorded in all cases. Heavy rain (20-28/05/2017) caused 4 deaths and landslides