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Arid Land Geography ›› 2023, Vol. 46 ›› Issue (1): 23-35.doi: 10.12118/j.issn.1000-6060.2022.209

• Climatology and Hydrology • Previous Articles     Next Articles

Evaluation of simulation results from two cumulus parameterization schemes in RegCM4.6 in East Asia

LIU Xin1(),KANG Yanming1,XIN Yu2,CHEN Yonghang1(),ZHOU Haijiang1,QIN Han1,HE Qing2,WANG Zhimin3   

  1. 1. College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China
    2. Institute of Desert Meteorology China Meteorological Administration, Urumqi 830002, Xinjiang, China
    3. Weather Modification Office of Xinjiang Uygur Autonomous Region, Urumqi 830002, Xinjiang, China
  • Received:2022-05-10 Revised:2022-06-28 Online:2023-01-25 Published:2023-02-21

Abstract:

Previous studies have shown that the Emanuel scheme performs relatively well in simulating temperature and precipitation in East Asia. However, the user’s guide of RegCM4.6 points out that the Emanuel scheme tends to produce excessive precipitation over lands, especially in some intense individual precipitation events. In contrast, the Grell scheme tends to produce weak precipitation over tropical oceans. Therefore, the new version of the regional climate model RegCM4.6 has incorporated the Mix cumulus convective parameterization scheme, which means that the Emanuel scheme can be used over oceans and the Grell scheme over land, to compensate for the deficiencies of a single scheme. Previous validation studies have mainly focused on temperature and precipitation, and few studies have been conducted on the Mix scheme. The MODIS product from January 1st, 2016, to December 31st, 2016, was used as a reference to evaluate the simulation results of cloud fraction (CF), ice water path (IWP), and liquid water path (LWP) in East Asia from the Emanuel and Mix schemes in RegCM4.6 at various time scales. Some statistical parameters were calculated, such as the correlation coefficient (r), mean absolute error (MAE), mean bias error (MBE), and root mean square error (RMSE). The results were as follows. (1) The simulated CF were slightly overestimated in the northwest and mainly underestimated in the southeast roughly bounded by the Hu Huanyong line. The performance of the two schemes in simulating CF was the best in summer and the worst in winter. In the four seasons, the absolute values of MAE, MBE, and RMSE of the Mix scheme were generally lower than those of the Emanuel scheme. (2) The systematic deviations of IWP were negative in the whole of East Asia. Except in summer, the IWP from the two simulations and MODIS was significantly negatively correlated in the other three seasons, indicating that it was a challenge to accurately simulate physical processes related to ice particles in the cloud. (3) The LWP was underestimated by the two schemes in the Qinghai Tibet Plateau and Eastern Ocean and was overestimated in southern, central, and northern China, but the annual MBE of the Mix scheme were closer to 0. The performances of the two schemes were similar in winter. In the other three seasons, the absolute values of MAE, MBE, and RMSE of the Mix scheme were less than those of the Emanuel scheme, and the differences in MAE for the two schemes were 21-39 g·m-2. In conclusion, the Mix scheme is more suitable to simulate cloud water resources in East Asia. This study will contribute to the exploitation of cloud water resources in East Asia and provide a reference for the selection and improvement of the cumulus convection parameterization scheme in a regional climate model.

Key words: regional climate model, East Asia, cloud fraction, ice water path, liquid water path