Comparative Evaluation of the GPM IMERG Early, Late, and Final Hourly Precipitation Products Using the CMPA Data over Sichuan Basin of China

Shunxian Tang,Hao Wang,Jianxin He,Xingang Fan,Shuangyu Yao,Rui Li

doi:10.3390/w12020554

Abstract

The Global Precipitation Measurement (GPM) mission has generated global precipitation products of improved accuracy and coverage that are promising for advanced hydrological and meteorological studies. This study evaluates three Integrated Multi-satellitE Retrievals for GPM (IMERG) Hourly products, including the Early-, Late-, and Final-run products (IMERG-HE, IMERG-HL, and IMERG-HF, respectively), over Sichuan Basin of China. This highly complex terrain of the steep mountainous region offers further scrutiny on the quality and applicability of the data. The China Meteorological Precipitation Analysis (CMPA) data from January 2016 to December 2018 are used as the reference for the evaluation. Results show that: (1) At grid scale, IMERG-HL and IMERG-HF outperform IMERG-HE in terms of correlation coefficient (CC) and root-mean-square error (RMSE), but IMERG-HL has smaller relative bias (RB) than that of the IMERG-HF (by 21.16%). IMERG-HF presents the highest probability of detection (POD = 0.52) and critical success index (CSI = 0.32), except for high false alarm ratio (FAR) for light precipitation. (2) At regional scale, IMERG-HF outperforms IMERG-HE and IMERG-HL in annual evaluation in all the metrics except for the serious overestimation as shown in RB (20.18%, 3.84%, and 4.97%, respectively). Its accumulative precipitation deviation mainly comes from moderate precipitation events (1–10 mm/h), while better detection capability is seen in light precipitation (<1 mm/h). Seasonally, IMERG-HF performs the best in winter, while IMERG-HL performs the best in the other seasons. (3) IMERG-HF captures the peak precipitation more accurately in all seasons. In reproducing the diurnal cycle, IMERG-HF performs better in winter, while IMERG-HL performs better in summer and autumn, and IMERG-HE in spring. However, all three products overestimate the early morning precipitation (01:00–08:00 local standard time) of the diurnal cycle in spring, summer, and autumn.

Highlights

Precipitation plays a critical role in the global hydrological cycle and energy exchange of the atmosphere [1,2,3,4]
Its accumulative precipitation deviation mainly comes from moderate precipitation events (1–10 mm/h), while better detection capability is seen in light precipitation (
For the precipitation from 0.1 to 0.3 mm/h, the frequency values of the China Meteorological Precipitation Analysis (CMPA) data and the three Integrated Multi-satellitE Retrievals for GPM (IMERG) products are 3.38%, 2.48%, 3.01%, and 3.62%, respectively. These results indicate that the IMERG-HF product slightly exaggerate the detection ability of light precipitation

Summary

Introduction

Precipitation plays a critical role in the global hydrological cycle and energy exchange of the atmosphere [1,2,3,4]. The ground-based Doppler weather radars can provide real-time, accurate, and refined internal structure of precipitation [20], while its actual detection performance is often affected by factors such as the beam blockage, the electromagnetic wave attenuation, and other measurement errors [21,22,23]. Some of these influencing factors can be resolved by using networked radars, but it is unsuitable for application in the mountainous and oceanic regions [24,25,26]. Spaceborne remote sensors may be the most reliable and stable way to measure the global precipitation due to their extensive spatial coverage and continuous monitoring [3,13,27]

Methods

Results

Conclusion