Características e distribuição das descargas atmosféricas e dos sistemas precipitantes produtores de raios na Amazônia Oriental

Abstract

This study analyzed 10 years of spatial and temporal distribution of lightning and precipitation systems and their characteristics such as reflectivity, brightness temperature and height of the precipitation systems sampled by the Lightning Imaging Sensor (LIS), Precipitation Radar (PR) e TRMM Microwave Imager (TMI) sensors onboard of the Tropical Rainfall Measuring Mission (TRMM) satellite. This dataset is organized and stored by the research group of tropical convection of the University of Utah from December 1997 to February 2009. This work also analyzes data from outbreaks of fires detected by INPE in the period 1998 to 2008. It was selected an area bounded between 60°W to 45°W of longitudes and between 10°S to 5°N of latitudes, which was subsequently divided into nine sub-areas for more detailed information. To investigate the possible influence of burning in the number of lightning flashes, we selected eight areas, in which four present the highest number of fire outbreaks and four with the lowest ones. The precipitation systems were classified according to the method of Nesbitt et. al (2000), and obeying the new definition of the data proposed by Liu (2007). The precipitation features used in this work are named ALLPFS, which are all systems with rainfall pixels estimated by the 2A25 algorithm. These systems have the categories of PFS (present information of brightness temperature) and OTHPFS (without information of brightness temperature). Within the PFS, the systems are defined as those without ice signature (NOICE), with ice signature (WICE) and mesoscale convective systems (MCS). The most intense MCSs are defined as IMCS. The results show that the southern regions of Pará, around Belém and Marajo Island were the ones with the highest occurrence of lightning in the Amazon region, with values exceeding 20 to 35 lightning flashes/ km²/year. The NOICE systems were equally frequent in all regions. The categories WICE and MCS are those which contribute most to the production of lightning over these regions. It was also observed that the electrified systems have great contribution to the estimated amount of rainfall over central and southern parts, with percentages above 50% in the area SOUTH. The monthly variation of the lightning occurrence densities in the studied area showed that the highest occurrence of lightning was found over the city of Belem during the months from January to June, peaking in January. The highest occurrences in the southern sector of eastern Amazonia were concentrated in the months of September to December. In the analysis on the interaction between lightning and burning spot areas, it was not possible to verify a consistent correlation between lightning and fires, showing that despite the large number of fires observed on these areas, other factors influence the production of lightning flashes.