Evaluation of Performance of Polar WRF Model in Simulating Precipitation over Qinghai-Tibet Plateau

Abstract

: Considering the complex topographic forcing and large cryosphere concentration, the present study utilized the polar-optimized WRF model (Polar WRF) to conduct downscaling simulations over the Qinghai-Tibet Plateau (TP) and its surrounding regions. Multi-group experiments with the 10 km horizontal resolution are used to evaluate the modeling of precipitation. Firstly, on the basis of the model ground surface properties upgrade and the optimized Noah-MP, the “better-performing” configuration suite for modeling precipitation is comprehensively examined. Various model parameters such as nudging options, five cumulus parameterization schemes, two planetary boundary layer schemes, and six microphysics schemes are investigated to further refine the Polar WRF configuration. Moreover, the precipitation simulation for a full calendar year is compared with multiple reanalyses and observations. The simulations demonstrate that the Polar WRF model successfully captures the general features of precipitation over this region and is sensitive to model parameters. Based on the results, it is recommended to use grid nudging with q intensity coefficient of 0.0002, the multi-scale kain-fritsch cumulus parameterization, the Yonsei University boundary layer scheme, and the Morrison 2-mom microphysics with reduced default droplet concentration value of 100 cm –3 . Overall, the model performance is better than the ERA-interim and TRMM 3b42. It is comparable to, and in some cases slightly better than, the CRA-Land, especially in the prediction for the western part of the plateau where in situ observations are limited, and the cryosphere-atmosphere interaction is more pronounced.