Fonte de umidade para a convecção em vórtices ciclônicos de altos níveis: estudos de caso.

Abstract

In the seasonal scale part of the spatial and temporal variability of the rains on the Northeast of Brazil it is due to upper tropospheric cyclonic vortex (VCAN). The VCAN is a cyclonic circulation system that occurs frequently in southern summer and is defined as a low pressure system in the synoptic scale, formed initially in the high troposphere which in some situations can extend to the lowest levels of the atmosphere and whose closed cyclonic circulation has the cooler center than the periphery (Kousky and Gan 1981, Gan 1982). Although in the literature it is possible to find several studies that explore both from the synoptic point of view and from the dynamic aspects of the VCAN some aspects related to this system need more detailed, for instance the relationship between VCAN and rainfall in several areas of the Northeast of Brazil. This work intends to analyze the characteristics of the transport of moisture to the region of operation of two cases of VCAN the first occurred between January 19 and 24 of 2004 and the second between January 1 and 15 of 2014 the choice of cases took into account the distinct nature of the effects caused by the phenomenon's performance the former brought high precipitation values associated the second one was more active in precipitation inhibition for the NEB region. For the work were generated geopotential and wind images of 1000 up to 150hPa from the ERA-Interim reanalysis data belonging to the European Center for Medium-Range Weather Forecasts also from these data were generated fields of divergence and transport of moisture integrated vertically in its zonal and southern componentes. Precipitation data were obtained through the Global Precipitation Climatology Project and precipitation data estimated by Tropical Rainfall Measuring Mission together with the use of GOES 12 and GOES-13 + METEOSAT 10 satellite imagery of the enhanced infrared channel belonging to the Divisão de Satélites Ambientais do Instituto Nacional de Pesquisas Espaciais and also data of surface meteorological station of the Agência Executiva de Gestão da Água do estado da Paraíba. After analyzing the data it was possible to note that the areas where precipitation occurred during the VCAN episode are also the areas where there is a sign of moisture transport convergence In addition, it is verified that the humidity that feeds the VCAN originates from the humidity that penetrates South America and that in common situations would converge in the North region of the country (more precisely in the Amazon) it takes a detour towards the area of performance of the VCAN.