A Preliminary Assessment of the GSMaP Version 08 Products over Indonesian Maritime Continent against Gauge Data

Abstract

Abstract This study is a preliminary assessment of the latest version of the Global Satellite Measurement of Precipitation (GSMaP version 08) data which were released in December 2021, for the Indonesian Maritime Continent (IMC), using rain gauge (RG) observations from December 2021 to June 2022.Assessmentswere carried out with 586 rain gauge (RG) stations using a point-to-pixel approach through continuous statistical metrics and contingency table metrics. It was found that the coefficient correlation (CC) of GSMaP version 08 products against RG observation vary from low (CC=0.14-0.29), moderate (CC=0.33-0.45), and good correlation (CC=0.72-0.75), for the hourly, daily, and monthly scales with a tendency to overestimate, indicated by a positive RB. Even though the correlation of hourly datais still low, GSMaP can still capture diurnal patterns in the IMC, as indicated by the compatibility of the estimated peak times for the precipitation amount andfrequency. GSMaP data also managed to observe heavy rainfall, as indicated by the good probability of detection (POD) values ​​for daily data ranging from 0.71 to 0.81. Such a good POD value of daily data is followed by a relatively low false alarm ratio (FAR) (FAR<0.5). GSMaP daily data accuracy also dependson topographic conditions at IMC, especially for GSMaP real-time data. Of all GSMaP version 08 products evaluated, post-real time non-gauge calibrated (GSMaP_MVK) outperformed, followed by post-real time gauge calibrated (GSMaP_Gauge), near-real-time gauge calibrated (GSMaP_NRT_G), near-real time non-gauge callibrated (GSMaP_NRT), real time gauge callibrated (GSMaP_Now_G), and real time non-gauge callibrated (GSMaP_Now). Thus, GSMaP near real-time data has the potential for observing rainfall in IMC with faster latency.