Comprehensive Evaluation of Satellite‐Based Precipitation at Sub‐Daily Time Scales Over a High‐Profile Watershed with Complex Terrain

Abstract

In this study, a preliminary quantitative evaluation of global precipitation measurement (GPM) mission precipitation products at sub-daily time scales was performed in a typical and small watershed with complex terrain in southwestern China. The world heritage Jiuzhaigou Valley, which has been affected by many rainfall-triggered debris-flow disasters after the Ms 7.0 earthquake on 8 August 2017, was selected as the study area. The "early", "late" and "final" half-hourly GPM precipitations and hourly observations by four rainfall stations were used, and various indicators (general statistical indices, classification indicators, and a joint probability distribution function) were adopted as metrics to evaluate the GPM rainfall. Results indicated that the early and late hourly products showed a medium degree of correlation with ground observations, while the final hourly product showed better performances and may be used for research-level applications in the study area. GPM products could approximately reproduce the diurnal cycles of observed precipitation whereas the relationship between peak rainfall and duration spell was in good agreement with ground observations. The 1-hour final product was unable to significantly reduce the rate of missing report for rain although it was calibrated by global monthly data. An event-based evaluation showed that the GPM performed well for the cumulative rainfall. The assessment results support the development of early-warning models for rainfall-triggered geological disasters, provide useful implications on the improvement of rainfall retrieval algorithm in complex mountainous areas, and may be used as reference for scientific studies in poorly sampled regions with similar geographical conditions as the Jiuzhaigou Valley.

Quantitative Analysis of the Effects of an Earthquake on Rainfall Thresholds for Triggering Debris-Flow Events

“…We use the gridded rainfall dataset to check the reliability of the new GPM data for future application in debris-flow monitoring and warning. Correlation coefficients of 0.67, 0.53, and 0.56 are obtained for Jiuzhaigou, Wenchuan, and Lushan areas, respectively, (Figure 6), which indicates that the reliability needs to be further improved, as also confirmed by Liu et al (2019). Though any satellite-based method will cause inevitable uncertainties (Carr et al, 2015), a combination with the methods used in this study could be an important supplement for debrisflow warning in ungauged areas with earthquakes.…”

Vertical structures of abrupt heavy rainfall events over southwest China with complex topography detected by dual‐frequency precipitation radar of global precipitation measurement satellite

“…Liu et al . (2019) indicated that the changes in total precipitation for the subregions of China were closely related to the occurrence and development of precipitation vertical structures. Figure 6 presents integrated nonliquid water path (IWP in mm), integrated liquid water path (LWP in mm), total water path (TWP in mm, TWP = IWP + LWP) and ratio of liquid water path (RLWP, that is, LWP/TWP) for AHREs caused by stratiform and convective rainfalls over different terrains.…”

“…The region of southwest China, located in the east of the Tibetan Plateau (TP) and characterized by complex topography, is prone to frequent AHREs in warm season (Zheng et al ., 2016; Liu et al ., 2019). Many studies focus on climatological aspects of AHREs, such as occurrence frequency, intensity, diurnal variations, synoptic conditions and meso‐α‐scale environmental conditions (Wang and Zhou, 2005; Xiao and Chen, 2010; Zhang et al ., 2019; Gao and Li, 2020; Li et al ., 2020; Chen et al ., 2020a; 2021).…”

An observational view of rainfall characteristics and evaluation of ERA5 diurnal cycle in the Yarlung Tsangbo Grand Canyon, China

“…Effectiveness and accuracy of precipitation measurement play a critical role in disaster mitigation in the area. Furthermore, most gridded precipitation datasets from climate model outputs, and reanalysis products, are not ideally suited for investigating precipitation‐triggered geological hazards in this region because they tend to overestimate the amount of heavy precipitation over the TP and complex topography (Liu et al ., 2019; Gu et al ., 2020). Detailed investigation of the precipitation characteristics around the YGC could provide the fundamental information required for understanding the region's atmospheric processes, which in turn are critical to understanding its cryospheric and hydrological processes.…”