Evaluation of GPM IMERG Products for Extreme Precipitation over Indonesia

Abstract

Accurate information on extreme rain is essential for vulnerability analysis and early warning systems of hydrometeorological disasters. One newly launched satellite that can provide information about extreme precipitation is the Global Precipitation Measurement (GPM), which produces half-hour grid data through the Integrated Multi-Satellite Retrieval for GPM (IMERG) system. This work evaluates the performance of IMERG data to measure extreme precipitation indices over Indonesia. Three types of GPM IMERG data: IMERG-Early, IMERG-Late, and IMERG-Final, were validated by rain gauge data in Indonesia for extreme rain indices from 2016 to 2019. Overestimated values for extreme precipitation indices were dominated by low-intensity precipitation such as PRCPTOT, R1mm, and CDD indices. On the contrary, underestimated values of extreme precipitation indices dominated by high-intensity precipitation such as R90p, R95p, R50mm, and RX1day indices. Moreover, the different types of IMERG data showed a similar pattern with slightly different values for identifying extreme precipitation indices. Thus, a more comprehensive study is needed to improve GPM IMERG in observing the extreme precipitation over Indonesia.