Evaluation and application of satellite precipitation products in studying the summer diurnal rainfall events in Taiwan and Luzon

High spatiotemporal resolution satellite precipitation products (herein SPPs) have great potential for investigating rainfall dynamics, including diurnal rainfall (DR). However, the relative performances of these products are regionally specific and unknown in most places. This talk presents our recent works on evaluating and applying various SPPs in studying the summer DR events in Taiwan and Luzon (an Island of Philippines nearby Taiwan). In the first part of the talk, we evaluated the four post-real-time SPPs (including TRMM-3B42 v7, IMERG-F v5, IMERG-F v6, and GSMaP v7) in studying DR events in Taiwan. Our results show that IMERG-F v6 outperforms the other SPPs more accurately (both quantitatively and qualitatively) in depicting the summer rainfall variations in Taiwan at multiple timescales (including mean status, daily, and diurnal), using more than 400 rain-gauge observations as the baseline for comparison. IMERG-F v6 also performs better than other SPPs in capturing the characteristics of DR activities. In the second part of the talk, we further evaluated the near-real-time (NRT) products of IMERG v6 (i.e., IMERG-L and IMERG-E) and GSMaP v7 (i.e., GSMaP-NRT and GSMaP-Gauge-NRT) in depicting the variation in DR in Taiwan. Two sub-components of DR variation, daily mean (Pm) and anomalies (ΔP), were evaluated, and ΔP was further separated into diurnal (S1) and semi-diurnal (S2) harmonic modes. Compared with surface observations, all NRT products underestimated Pm and ΔP; however, IMERG products are relatively better than GSMaP products in most of the examined spatial characteristics. Furthermore, temporal analysis shows that only IMERG-E depicts the phase evolution of both S1 and S2, similar to surface observations. Finally, we showed some potential use of IMERG-F v6 and TRMM-3B42 v7 in studying the long-term changes in the summer DR activities over Luzon and its adjacent seas during 2000-2019.