An observational view of rainfall characteristics and evaluation of rainfall products in the Yarlung Tsangbo Grand Canyon, China
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China (x.chen@itpcas.ac.cn)
The Yarlung Tsangbo Grand Canyon (YGC), one of the world’s deepest canyons, is located within the East Himalayas, which are remote and poorly instrumented. A rain‐gauge network was established around the YGC region. More than three years data collected from the network, disclose that the spatial pattern of rainfall distribution. There are two regions (500 m and 2500 m AMSL) with high precipitation in the YGC. Diurnal cycles showed some variations among sites, but a clear floor was visible around afternoon and peak values exhibited in the early morning. The monthly precipitation in the YGC region shows two peaks in April and July. Vertical convection and vapor transport are important for extreme rainfall in this region.
GPM IMERG evaluation demonstrates that the data reasonably captured the observed seasonal and diurnal variations in the precipitation but with much weaker seasonal and diurnal variations compared with the gauge data. The GPM IMERG overestimated and underestimated the light and heavy precipitation, respectively, leading to a significant underestimation of the rainfall frequency and intensity at both the daily and monthly scales. Some possible mechanism for the underestimation was investigated to help scientists to improve the satellite precipitation product.
Our observations indicate that ERA5 cannot reproduce the diurnal patterns of precipitation in the YGC region. ERA5 showed a wet bias when estimating light cumulus rainfall and a dry bias when estimating heavier (convective) precipitation. The erroneous diurnal variation of ERA5 precipitation (false afternoon rainfall) was due to the CAPE (Convectively Available Potential Energy)-based convective precipitation scheme. The higher ERA5 precipitation than observation was due to the large-scale rainfall scheme in the Integrated Forecasting System (IFS) of ERA5.
These analysis have help us understanding the impacts of YGC valley on the water vapor transport and extreme rainfall outbreak mechanism.
How to cite: Chen, X.: An observational view of rainfall characteristics and evaluation of rainfall products in the Yarlung Tsangbo Grand Canyon, China, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2196, https://doi.org/10.5194/egusphere-egu23-2196, 2023.
