Abstract:Two cold air events that happened in Qiongzhou Channel were modeled by mesoscale dynamic model WRF and diagnostic model CALMET, and the research focuses on the near surface wind. Horizontal grid spaces of four nests in WRF model are 27 km, 9 km, 3 km and 1 km respectively. The fourth nest with 1 km grid space of CALMET and the fifth nest in WRF is set as model initial field for down grid space to 200 m, so as to get the final field which is able to fulfill the resolution required. Wind speed and direction of CALMET 200 m, WRF 1 km and WRF 200 m are contrasted with the observed winds at 21 observing stations (including 6 anemometer towers) distributed in the two sides of the Qiongzhou Channel. The main conclusions are as follows: (1) CALMET 200 m speed RMSE is much less than the two other experiments with time going, but there is not any notable difference in wind direction RMSE. In the height of 60-80 m, RMSE can not show any difference in wind direction, either. (2) At 10 m height, CALMET 200 m wind is diagnosed to be the best with the average error varing from 4 m·s-1 to 0 m·s-1. The average errors of the other two experiments are about 2 m·s-1 bigger than CALMET 200 m. The distribution of errors is more concentrated in direction. In 60-80 m height, the three experiments have almost the same results. But the result of WRF 200 m wind speed shows worse than the results of the other two experiments, while not differences in wind direction are found in the three experiments. (3) Smaller wind speed and direction average errors of WRF/CALMET system in non cold air condition show that the system can perform better when the atmospheric stratification is relatively stable.