AVALIAÇÃO DA CONFORMIDADE DE DADOS DE PRECIPITAÇÃO DO GLOBAL PRECIPITATION MEASUREMENT COM ESTAÇÕES PLUVIOMÉTRICAS NO ESTADO DO RIO DE JANEIRO – BRASIL EM 2017

Abstract

Precipitation is an extremely important component for the understanding of the hydrological cycle and of several phenomena related to it. The understanding of this variable plays an important role for economic and social development, as well as the maintenance of human life. The use of satellites sensors to estimate rainfall events has shown to be an alternative to overcome the main limitations present in the most traditional measuring instruments such as rain gauges and radars. The Global Precipitation Measurement (GPM) is one of the most recent space missions that have this goal, launched in 2014 by the association between the NASA (National Aeronautics and Space Administration) and JAXA (Japanese Space Exploration Agency), provide rainfall data from around the globe with optimal spatial and temporal resolution. One of the products of this mission that has demonstrated good performance in precipitation estimates is the Integrated Multi-Satellite Retrievals for GPM (IMERG). This study aims to evaluate the compliance of these estimates made by IMERG with data from rainfall stations in the state of Rio de Janeiro for the year 2017 and the degree of interference of the topography in the estimates made by the satellite. Statistical metrics were used to evaluate the assertiveness and similarity of the space mission, with the presentation of these results in maps, tables and graphs. The metrics were applied in two cases, one in which were evaluated only the pixels that have pluviometric stations, and another for the use of the result of the interpolation of the precipitation measured in the stations. In both cases IMERG showed a good performance of the metrics, showing a strong positive linear correlation between the satellite and the rain gauges, in addition to relative errors predominantly below 30%. There was also a tendency in the overestimation of precipitation by IMERG. As for the topography, it was verified that there is no proportionality behaviour between the estimates and the altitude variation, but it was possible to evaluate the performance of the satellite at some altitude intervals.