子計畫:衛星降水資料於臺灣與鄰近地區之適用性評估與應用(I)

This is the 1st year final report of a 3-year project entitled as "Assessment and application of global satellite precipitation over Taiwan and nearby regions". Supported by this project, we have already published one SCI paper, the related results are explained as follows: The Tropical Rainfall Measuring Mission-3B42 v7 (hereafter TRMM7) has ceased in December 2019. To find out a suitable data for replacing TRMM7 in representing the rainfall characteristics over Taiwan, this study examines the performances of four different satellite precipitation products including TRMM7, IMERG-Final v5 (hereafter IMERG5), IMERG-Final v6 (hereafter IMERG6), and GSMaP-Gauge v7 (hereafter GSMaP7). More than 400 rain gauges are adopted as the reference base for evaluation. Analyses focus on the time periods that overlap in the data investigated, i.e. the summer months between 2014 and 2017, with additional comparisons between IMERG6 and TRMM7 for the summer months of 2000–2017. Our analyses show that when using local rain-gauge observations as a reference base for comparison, IMERG6 outperforms other satellite products quantitatively and qualitatively, more accurately depicting the variation in the summer precipitation of Taiwan at multiple timescales (including mean status, daily, interannual, and diurnal). IMERG6 was also found to have the best performance of the satellite products examined for depicting the contribution of summer connective afternoon rainfall (CAR) events, which is the most frequently observed weather pattern in Taiwan, to the total amount and frequency of summer precipitation. These results suggest that the use of IMERG6 instead of TRMM7 can be of benefit for obtaining accurate characteristics of the phenomenon of summer rainfall variation in Taiwan.