Validação dos dados de precipitação pluvial do produto Merge para a Amazônia Central

Abstract

The Amazon is a vast biome, of continental dimensions, which still has areas of difficult access that added to the local peculiarities, make difficult the installation and / or expansion of networks of meteorological stations. An alternative that has been used for climatological and hydrological research is the satellites or combined products of rainfall data estimated by satellites and observed rainfall data such as the MERGE product. The MERGE product is the combination of a new technique that aims to combine the TRMM satellite data with the highest quality surface observation data on the continent of South America, however, the accuracy of the data is questionable when compared to the data collected on surface. In view of MERGE's potential contribution, it can be an extremely useful tool, the objective of this work was to evaluate the quality of the data estimated by the MERGE for the Central Amazonia, based on data observed on the surface for a period of 20 years (1998-2017). Six INMET meteorological stations were used, with a failure rate of less than 1.70%, and the application of descriptive statistics showed a strong similarity between the analyzed datasets, with Pearson's correlation being higher than 0.89 and the lowest coefficient of determination was 0.79, both in Óbidos, Belterra and Monte Alegre were the points that represented the data estimated with greater precision for the study region. Regarding the quantitative measures of performance used in the study, such as bias, coefficient of efficiency (COE), Willmott's concordance index (d), mean absolute error (MAE) and root mean square error (RMSE), the results were satisfactory, however, there was an underestimation of the product at all points analyzed. In relation to the interannual rainfall variability, it was observed an increase in the amount of precipitation in Óbidos, from one decade to another (1998-2007 and 2008-2017), while in Porto de Moz there was a decrease, although there was no trend of rainfall at any of the points analyzed at work. In the analysis of the monthly variation of precipitation was used the Norm Climatological published by INMET (1981-2010), which was well adjusted to the estimated data. Finally, the seasonal analysis showed that the region presents a heterogeneous spatialization of precipitation in relation to rainy (DJF and MAM) and dry (JJA and SON) quarters. Thus, the results showed excellent data quality estimated by the MERGE for the Central Amazonia of Brazil, when compared to the data observed and can be used as an alternative source of information on the scarcity of surface station data.