Publication Date:
2023-06-16
Description:
The Tibetan Plateau (TP) is called the “Third Pole”, which contains the largest amount of snow and glaciers outside the polar regions. As an important and variable feature of the land surface, snow coverage on the TP has great impacts on regional climates. However, the commonly used ERA5 reanalysis in dynamic downscaling largely overestimates the snow depth for the TP. To improve the representation of snow cover in ERA5, a new ERA5 driven downscaling dataset (High Asia Refined analysis version 2, HAR v2) was generated by the Weather Research and Forecasting (WRF) model with the bias-corrected snow depth. This study aims to identify and better understand the impacts of bias-corrected initial snow conditions on dynamical downscaling simulations, by comparing the HAR v2 with a 5-year ERA5 forced WRF simulation without bias correction of initial snow depth (referred to as WRF_ERA5). Results show that the bias correction significantly improves the simulation of air temperature at 2 m (T2), with regional mean cold bias reduced by 0.2-2.4°C, but no significant improvement in precipitation simulation is found. Further comparative analysis reveals that higher snow depth in WRF_ERA5 leads to T2, mean daily precipitation, summer extreme precipitation, and contributions of convective precipitation to summer mean daily precipitation decrease by 0-4°C, 0-60%, 0-40%, and 0-10%, respectively, in most areas of the TP. Overall, this study confirms the importance of snow cover for the TP climate.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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