Abstract
This paper evaluated the latest version 6.0 Global Satellite Mapping of Precipitation (GSMaP) and version 6.0 Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) products during 2018 Typhoon Mangkhut in China. The reference data is the rain gauge datasets from Gauge-Calibrated Climate Prediction Centre (CPC) Morphing Technique (CMORPHGC). The products for comparison include the GSMaP near-real-time, Microwave-IR merged, and gauge-calibrated (GSMaP_NRT, GSMaP_MVK, and GSMaP_Gauge) and the IMERG Early, Final, and Final gauge-calibrated (IMERG_ERUncal, IMERG_FRUncal, and IMERG_FRCal) products. The results show that (1) both GSMaP_Gauge and IMERG_FRCal considerably reduced the bias of their satellite-only products. GSMaP_Gauge outperforms IMERG_FRCal with higher Correlation Coefficient (CC) values of about 0.85, 0.78, and 0.50; lower Fractional Standard Error (FSE) values of about 18.00, 18.85, and 29.30; and Root-Mean-Squared Error (RMSE) values of about 12.12, 33.35, and 32.99 mm in the rainfall centers over mainland China, southern China, and eastern China, respectively. (2) GSMaP products perform better than IMERG products, with higher Probability of Detection (POD) and Critical Success Index (CSI) and lower False Alarm Ratio (FAR) in detecting rainfall occurrence, especially for high rainfall rates. (3) For area-mean rainfall, IMERG performs worse than GSMaP in the rainfall centers over mainland China and southern China but shows better performance in the rainfall center over eastern China. GSMaP_Gauge and IMERG_FRCal perform well in the three regions with a high CC (0.79 vs. 0.94, 0.81 vs. 0.96, and 0.95 vs. 0.97) and a low RMSE (0.04 vs. 0.06, 0.40 vs. 0.59, and 0.19 vs. 0.34 mm). These useful findings will help algorithm developers and data users to better understand the performance of GSMaP and IMERG products during typhoon precipitation events.
Highlights
Both the Global Satellite Mapping of Precipitation (GSMaP) and Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) products can generally capture the spatial distribution of 72-h accumulated precipitation (Figure 2b–g), and the satellite-only precipitation products are not significantly different from their bias-adjusted products
The satellite-only products slightly underestimated the precipitation in the rainfall center over southern China but showed overestimation in the rainfall center over eastern China
The most impressive feature of GSMaP products is that the rainfall intensity closely resembles that higher precipitation intensity than that of IMERG in the rainfall center over southern China
Summary
The new generation of satellite precipitation products of IMERG make use of the merits of PERSIANN-CSS, CMOPRH, and TRMM Multi-satellite Precipitation Analysis (TMPA) [18]. Both IMERG and GSMaP are multi-satellite rainfall products with a combination of infrared (IR) algorithms and passive microwave (PMW) algorithms. This merged PMW–IR information enhances the respective advantages of separate PMW or IR satellite-based rainfall estimates.
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