Evaluation of the Integrated Multi-SatellitE Retrievals for the Global Precipitation Measurement (IMERG) Product in the São Francisco Basin (Brazil)

Daniele Tôrres Rodrigues,Jean Souza Dos Reis,Helder José Farias Da Silva,Rayana Santos Araujo Palharini,Bergson Guedes Bezerra,Jório Bezerra Cabral Júnior,Pedro Rodrigues Mutti,Cláudio Moisés Santos E Silva,Weber Andrade Gonçalves

doi:10.3390/w13192714

Abstract

The São Francisco River basin is one of the largest in the Brazilian territory. This basin has enormous economic, social and cultural importance for the country. Its water is used for human and animal supply, irrigation and energy production. This basin is located in an area with different climatic characteristics (humid and semiarid) and studies related to precipitation are very important in this region. In this scenario, the objective of this investigation is to present an assessment of rainfall estimated through the Integrated Multi-SatellitE Retrievals for Global Precipitation Measurement (IMERG) product compared with rain gauges over the São Francisco river basin in Brazil. For that, a period from of 20 years and 18 surface weather stations were used to evaluate the product. Based on different evaluation techniques, the study found that the IMERG is appropriate to represent precipitation over the basin. According to the results, the performance of the IMERG product depends on the location where the rain occurs. The bias ranged from −1.67 to 0.34 mm, the RMSE ranged from 5.36 to 10.36 mm and the values of the correlation coefficients between the daily data from the IMERG and rain gauge ranged from 0.28 to 0.61. The results obtained by Student t-test, density curves and regression analysis, in general, show that the IMERG is able to satisfactorily represent rain gauge data. The exception is the eastern portion of the basin, where the product, on average, underestimates the precipitation (p-value < 0.05) and presents the worst statistical metrics.

Highlights

Precipitation is one of the most important variables in hydrometeorological studies, whose analysis encompasses applications in various activities, such as energy generation, irrigated agriculture, water resource management and monitoring areas of hydrological disaster risk, among others
North observed in the rain gauges (Figure 2a) is represented consistently by the algorithm, but Integrated Multi-SatellitE Retrievals for Global Precipitation Measurement (IMERG) underestimates precipitation in the Lower São Francisco
We present an assessment of the data from the IMERG algorithm for the São Francisco

Summary

Introduction

Precipitation is one of the most important variables in hydrometeorological studies, whose analysis encompasses applications in various activities, such as energy generation, irrigated agriculture, water resource management and monitoring areas of hydrological disaster risk, among others. The availability of reliable precipitation data, with a high spatial and temporal resolution, is essential for studies in these areas [1,2]. The precipitation database in general suffers from a high percentage of missing data. In Northeast Brazil (NEB), the percentage of failures per weather station can reach 23% in 30-year climatological series [6]. In the Amazon Basin (AMZ), the percentage of failures is highly variable, but even in the case of data previously filtered based on the standards of the World Meteorological

Methods

Results

Conclusion