How do GPM and TRMM precipitation products perform in alpine regions? A case study in northwestern China's Qilian Mountains

Satellite technologies provide valuable areal precipitation datasets in alpine mountains. However, coarse resolution still limits the use of satellite precipitation datasets in hydrological and meteorological research. We evaluated different time scales and precipitation magnitudes of Tropical Rainfall Measurement Mission 3B43 V7(TRMM) and Global Precipitation Measurement(GPM) products for alpine regions using ground precipitation datasets from January 2015 to June 2019 obtained from 25 national meteorological stations and 11 sets of T-200B weighing precipitation gauges in the Qilian Mountains. The results indicated that GPM outperformed TRMM at all temporal scales at an elevation <3500 m with a higher probability of detection(POD), false alarm ratio(FAR), and frequency bias index(FBI) and performed best at 3000 m; TRMM performed better than GPM at an elevation >3500 m, with the best performance at 4000 m. GPM and TRMM had the best estimation accuracy in areas with monthly precipitation of 30 mm and 40 mm, respectively. Both TRMM and GPM products underestimated mid to large daily precipitation and overestimated light daily precipitation averaging <2 mm/d. This research not only emphasizes the superiority of GPM/TRMM in different regions but also indicates the limitations of precipitation algorithms.