Evaluation of IMERG Precipitation Products in the Southeast Costal Urban Region of China

Abstract

The intensification of extreme precipitation has aggravated urban flood disasters, which makes timely and reliable precipitation information urgently needed. As the high-quality and widely used satellite precipitation products, Integrated Multi-satellitE Retrievals for GPM (IMERG), have not been well investigated in coastal urban agglomerations where damages from precipitation-related disasters are more severe. With precipitation measurements from local high-density gauge stations, this study evaluates three IMERG runs (IMERG ER, IMERG LR, and IMERG FR) in the southeast coastal urban region of China. The evaluation shows that the three IMERG products severely overestimate weak precipitation and underestimate heavy precipitation. Among the three runs, the post-corrected IMERG FR does not show a substantial improvement compared to the near-real-time IMERG ER and IMERG LR. The performance of IMERG varies depending on the precipitation pattern and intensity, with the best estimation ability occurring in the coastal urban region in summer and in the northern forests in winter. Due to the year-round urban effect on precipitation variability, IMERG cannot detect precipitation events well in the central high-density urban areas, and has its best detection ability on cultivated lands in summer and forests in winter. Within the urban agglomeration, IMERG shows a poorer performance in areas with higher urbanization levels. Thus, the IMERG products for coastal urban areas need considerable improvements, such as regionalized segmental corrections based on precipitation intensity and the adjustment of short-duration estimates by daily or sub-daily precipitation measurements.

Bias Correction of IMERG Data in the Mountainous Areas of Sumatra Based on A Single Gauge Observation

“…However, previous research shows that the IMERG data at Kototabang can still capture the probability density function (PDF) of rainfall well [21]. In addition, the tendency of IMERG to underestimate high-intensity rainfall may also be the reason for the decrease in CSI values at such high rainfall intensities [61][62][63]. Although all corrected and original IMERG data show the same detection trend, each method shows different POD, FAR and CSI values for each threshold (Figure 8).…”

Evaluation and Applicability Analysis of GPM Satellite Precipitation over Mainland China

“…Such evaluation studies can provide important knowledge for the subsequent development of next-generation satellite precipitation products for better hydrometeorological applications. GPM IMERG products have been widely evaluated by various researchers with different evaluation indicators and statistical methods [19][20][21][22]. However, previous studies are mostly reported for different geographical regions.…”