Verification of availability of GSMaP rainfall data based on the comparison of observed rainfall data in Africa

Abstract

Meteorological data of sufficient quality and quantity is not readily available in developing countries given the limitations in obtaining continuous, reliable and high time resolution data. However, it is possible to estimate rainfall using Precipitation Radar sensor and other satellite-mounted sensors. The observed result and processed data are available as free rainfall data namely: “Global Satellite Mapping of Precipitation (GSMaP)”. In order to verify GSMaP data, rainfall data observed in Eastern Uganda from the period 2015 to 2016 was used. Both the accuracy of detection of the rainfall event and the rainfall amount were verified based on the comparison of hourly GSMaP products and totalized hourly, 3 hourly, 6 hourly,12 hourly and 24 hourly observed rainfall data. Although Near Real-Time dataset of GSMaP showed the highest Possibility of Detection, it showed the lowest performance in False Alarm Ratio. The measured rainfall amount and trend become closer as the interval increases from 1 hour to 24 hours in general, despite GSMaP data being underestimated compared to the observed rainfall data. The trend of accumulated rainfall data during the observation period was established and it is observed that the onset of the rainy season can be identified from GSMaP data.