Intercomparisons of Rainfall Estimates from TRMM and GPM Multisatellite Products over the Upper Mekong River Basin

Abstract

The aim of this study is to evaluate the accuracy of daily rainfall estimates based on the GPM level-3 final product derived from the IMERG algorithm (abbreviated as IMERG) and TRMM 3B42, version 7 (abbreviated as 3B42), in the upper Mekong River basin, a mountainous region in southwestern China. High-density rain gauges provide exceptional resources for ground validation of satellite rainfall estimates over this region. The performance of the two satellite rainfall products is evaluated during two rainy seasons (May–October) over the period 2014–15, as well as their applications in hydrological simulations. Results indicate that 1) IMERG systematically reduces the bias value in rainfall estimates at the gridbox scale and presents a greater ability to capture rainfall variability at the local domain scale compared with 3B42; 2) IMERG improves the ability to capture rain events with moderate intensities and presents higher capability in detecting occurrences of extreme rain events, but significantly overestimates the amounts of these extreme events; and 3) IMERG generally produces comparable daily streamflow simulations to 3B42 and tends to outperform 3B42 in driving hydrological simulations when calibrating model parameters using each rainfall input. This study provides an early evaluation of the IMERG rainfall product over a mountainous region. The findings indicate the potential of the IMERG product in overestimating extreme rain events, which could serve as the basis for further improvement of IMERG rainfall retrieval algorithms. The hydrological evaluations described here could shed light on the emerging application of retrospectively generated IMERG products back to the TRMM era.

Applications of TRMM- and GPM-Era Multiple-Satellite Precipitation Products for Flood Simulations at Sub-Daily Scales in a Sparsely Gauged Watershed in Myanmar

“…Our study found that IMERG-F V05 and 3B42V7 have acceptable hydrological capabilities in the Chindwin River basin, with IMERG-F being slightly better than 3B42V7. Similar findings were reported in the Ganjiang River basin [45], Beijiang River basin [24], upper Mekong River basin [36], Mishui basin [25], Yellow River source region of China [44], and Amazon basin of Peru and Ecuador [48]. Yuan et al [47] employed the first hydrological evaluation research in the Chindwin River basin and found that IMERG-F V03 performs comparatively worse than 3B42V7 in daily streamflow simulations.…”

“…techniques. However, most relevant studies [24,25,36,45,47,48,50] focused on assessing the hydrological utility of IMERG at daily or monthly time scales, while evaluations at sub-daily temporal scales have seldom been reported [44,46,49]. Furthermore, studies on the hydrological performance of all the "Early", "Late", and "Final" runs of IMERG are rare [24,25,50].…”

Ground validation of GPM IMERG and TRMM 3B42V7 rainfall products over southern Tibetan Plateau based on a high‐density rain gauge network

“…He et al . [] evaluated the accuracy of daily rainfall estimates using GPM IMERG and TRMM 3B42V7 products in Upper Mekong River basin and confirmed the outperformance of GPM IMERG over TRMM 3B42V7.…”

“…Prakash et al [2016] showed that IMERG product is superior in capturing heavy rainfall over India. He et al [2016] evaluated the accuracy of daily rainfall estimates using GPM IMERG and TRMM 3B42V7 products in Upper Mekong River basin and confirmed the outperformance of GPM IMERG over TRMM 3B42V7. Tong et al [2014b] compared five high-resolution reanalysis and satellite rainfall products, including the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis ERA-40, ERA-Interim, University of Washington data, Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation's Water Resources, and TRMM 3B42V6, with Corrected-China Meteorological Administration data set over TP.…”

Comprehensive Evaluation of Satellite‐Based Precipitation at Sub‐Daily Time Scales Over a High‐Profile Watershed with Complex Terrain

“…A number of global satellite rainfall products have been developed since the 1980s (He et al, 2016). The tropical rainfall measurement mission (TRMM), which housed the first-ever precipitation radar in space, is a collaborative effort between National Aeronautics and Space Administration (NASA) and the Japanese Aerospace Exploration Agency (JAXA) (Grecu & Bolvin, 2018).…”