金沙江乌东德水电站2016年1月强寒潮天气过程分析

An analysis of a strong cold wave weather process in Jinsha River Wudongde Hydropower Station dam area in January,2016

利用常规天气观测资料、地面加密自动站资料和美国(NCEP/NCAR) 1°×1°、2.5°×2.5°网格点逐6 h再分析资料,采用天气学原理和天气动力学诊断分析方法,对金沙江乌东德水电站坝区2016年1月23—25日强寒潮天气过程进行分析和总结.结果表明:中高纬横槽、南支槽、冷锋切变和地面强冷高压是坝区此次过程的主要影响系统;地面冷锋强锋区长时间维持是造成坝区持续性大风的主要原因;坝区气温骤降的主要原因是对流层低层强盛的冷平流;低层辐合、中高层辐散和较强的垂直上升运动,孟加拉湾的水汽沿着强西南气流输送,850 h Pa以上层温度在-2℃以下的垂直分布,为坝区降雪天气的产生提供了动力、水汽和凝结的温度条件.

Based on the conventional surface and upper data,intensive automatic weather station observations data,NCEP/NCAR 1°×1° and 2.5°×2.5°reanalysis data of every 6 h in terms of the synoptic principle and the dynamic diagnosis,the strong cold wave process in Jinsha River Wudongde Hydropower Station dam area has been analyzed during 23—25 January,2016.The results are as follows：the major influential systems of this process were transverse trough at middle and high latitudes,southern trough,cold front shear and strong surface cold high pressure.The strong frontal zone of surface cold front was the main reason for the persistent gale.The strong cold advection at the lower troposphere resulted in the sudden drop in temperature.The three conditions,involving the structure of lower-level convergence and upper-level divergence and strong ascending stream,the sustained water vapor of the Bay of Bengal along the strong southwest airflow and the vertical temperature distribution of the area below -2℃ above 850 hPa,comprised the main factors of dynamics,moisture and condensation for snow in Wudongde Hydropower Station dam area.