Simulation And Prediction Of East Asian Winter Monsoon By Regional Climate Model CWRF

Based on the results of CWRF(Climate Extension of Weather Research and Forecasting model)regional climate model for long-term climate simulation and return test,this paper selects a variety of main meteorological data to simulate and predict the East Asian winter climate state,East Asian Winter Monsoon and East Asian winter climate charact ERA-Istics under different types of ENSO background.The time range of simulation and prediction evaluation is 1979-2016 and 1991-2020 respectively.The main conclusions are as follows:(1)CWRF model can simulate the average circulation intensity and distribution charact ERA-Istics in East Asia in winter.The simulation intensity of winter wind is consistent with the observation results,and the frequency and region of northerly wind are simulated well.The simulated ground temperature and rainfall are consistent with the observation field of China station.The simulation and observation results show that the precondition of precipitation in South China is the two important water vapor transport branches in the bay of Bengal and the West Pacific.They converge in South China,which bring abundant and stable water vapor for the continuous precipitation in South China.(2)The heat balance analysis shows that the heat difference between East Asia and the sea is obvious.In most parts of East Asia,there are negative value regions of<Q1>that is,atmosph ERA-Ic heat sink,while in the sea near Japan,the heat source is the heat source,with the center value of 300 W/m~2,which is the strongest atmosph ERA-Ic heat source area in East Asia winter monsoon.There is a significant high value center of<Q2>in the south of the Yangtze River,which makes the region generally have more precipitation in winter.(3)The model not only simulates the intensity difference of winter wind system under two ENSO warm cold events from the aspects of East Asia trough,Sib ERA-Ian cold high pressure and 850 hPa abnormal wind field,but also simulates the Philippine air cyclones/anticyclone circulation and other low-level systems closely related to them,it better reflects the difference in the spatial distribution charact ERA-Istics of winter temperature and precipitation in China under the two types of ENSO warm and cold events,indicating that the regional climate model has certain simulation skills for the winter climate in China under the two types of ENSO events,and it is researched through the circulation field.The main reason is that the local SST anomaly affects the Walker circulation,changing the release of convective latent heat,and then forming an abnormal anticyclone/cyclone circulation system in the Philippines,which has a corresponding impact on local and China's temperature and precipitation.(4)The CWRF regional climate model can better optimize the prediction results of BCC?CSM1.1m on the average winter circulation in East Asia,and shows a high degree of correlation with the ERA5 comparison data,especially in the increase in inter-annual variability.It proves that it has high prediction skills and excellent downscaling ability for various weather elements in winter.(5)The CWRF model also shows excellent downscaling ability in the evaluation of temperature and precipitation prediction,which reduces the temperature deviation in South China to a certain extent.In terms of inter-annual variability,the temperature forecasts in Northeast China,Yunnan and coastal areas have been significantly improved.The time correlation has reached more than 0.6,while the BCC?CSM1.1m is basically a negative correlation.Increasing the resolution can significantly improve the spatial correlation of precipitation,and the spatial correlation coefficient is more than 0.5 higher than the prediction result of BCC?CSM1.1m,and optimizes the temporal correlation of the interannual variation of the Yunnan local,southeast and eastern coastal areas of China's precipitation prediction.