Conexões entre a circulação do hemisfério norte e os vórtices ciclônicos da alta troposfera na região Nordeste do Brasil: um estudo de caso.

Abstract

This work investigates the connections between the circulation of the northern hemisphere and the cyclonic vortices of the upper troposphere of Northeast Brazil. A case study is done for the period from 15 to 25 November 1986. Weather satellite images, daily rainfall totals and data at grid points of the National Meteorological Center (NMC) are used. The cyclone caused above-normal precipitation in several northeastern states. Its development was not typical. The vortex forms at the level of 500 hPa on the 18th of November over the south of the Northeast of Brazil and adjacent ocean areas while a trough is seen in the same area at the level of 200 hPa. THE penetration of an austral frontal system at low latitudes helps the formation of the vortex in the troposphere medium. A second frontal frontal system favors the amplification of the trough in 200 hPa and the consequent detachment of the cyclone three days after. Bolivia's anticyclone is present at the level of 200 hPa one day after the cyclone forms at 500 hPa. The formation of the anticyclone is the result of the coupling between a counterclockwise vortex located over the eastern equatorial Pacific and the ridge associated with the first southern frontal system. Amplification of a mid-latitude trough located in North America do Sul plays a fundamental role in this process.