Author(s): Narongrit Luangdilok; Watin Thanathanpon; Ticha Lolupiman; Kachapond Chettanawanit; Piyamarn Sisomphon; Sathit Chantip; Apimook Mooktaree; Theerapol Charoensuk

Linked Author(s): Narongrit Luangdilok

Keywords: Rainfall; IMERG; GPM; Thailand

Abstract: With high spatial resolution and longer records, the Integrated Multi-satellitE Retrievals for GPM (IMERG) products can be potentially integrated into operational monitoring and forecasting systems. This study aimed to investigate the IMERG rainfall products by comparing them against rain gauge observations in Thailand. The precipitation data (2001 to 2020) from IMERG-Early-Run and rain gauges were transformed into 3-hourly and daily accumulated rainfall for evaluation, divided into spatial distribution and quantitative consistency analysis. The results show that the spatial distribution of daily rainfall data from the IMERG-Early-Run matched with rain gauge data well, with 0.94,0. 34, and 0.63 for POD, FAR, and CSI, respectively. In the 3-hourly time scale, the verification statistics are slightly lower, with 0.76 of POD, 0.52 of FAR, and 0.41 of CSI. In terms of quantitative accuracy, the precipitation data from IMERG was higher than from the rain gauges for light rain events. Conversely, the IMERG provided underestimated rainfall for medium, heavy, and very heavy rainfall events. The RMSE varied seasonally in the range of 1.3-4.7 mm and 4.2-14.6 mm for 3-hourly and daily time scales; the highest value (the lowest value) can be found in the rainy season (the dry season). In conclusion, this study highlighted the potential use of IMERG Early Run as a trustworthy source of spatial precipitation estimates in various regions of Thailand.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0791-cd

Year: 2023