2013年4月中旬濮阳市一次极端气候事件分析

利用常规观测资料和MICAPS平台提供的相关资料,对濮阳市2013年4月18—20日的大风、强降温、中到大雪、晚霜冻、倒春寒等多种灾害性天气过程,用天气学的方法进行了综合分析.结果得出:1造成大风和强降温的高空影响系统是中路冷空气南压形成的密集的高空锋区,地面影响系统是强势庞大的冷高压.2由于东北冷涡携带的横槽不断分裂冷空气南下,使气温连续下降,致使地面气温降至0℃左右,出现了晚霜冻害,加之冷高压持续控制,使气温持续偏低,出现了倒春寒天气.3500 hPa和700 hPa的低槽、850 hPa的切变线是产生降水的影响系统,850 hPa的强锋区和地面庞大的冷高压提供了动力抬升条件.4500 hPa和700 hPa的中低空西南风急流为强降水提供了充沛的水汽供应.物理量场显示出700 hPa上强烈的辐合上升运动对降水贡献较大.5此次过程降温剧烈,850 hPa气温48 h内下降了19℃,700 hPa和850 hPa气温均降至0℃以下,使降水相态由降雨转成降雪.

An Extreme Climate Events in April of 2013 in Puyang

By using the conventional observation data and the relevant materials provided by MICAPS platform,the strong wind,cooling,snow,late frost,pollen and other severe weather process on April 18 to 20,2013 in Puyangwith the methods of science of the weather are analyzed. The result shows that as follows. 1 Effects of the strongwinds and strong cooling of air is the middle cold air south pressure forming dense high-altitude front zones in highaltitude system,the ground system is cold high strength large.2 Because the transverse groove continuous divisionof the northeast cold vortex carrying cold air southward,which make the temperature drop in a row,the surface temperaturedropped to 0℃ or so and the late frost cold,combined with the continued cold high pressure,the temperature keeplow constantly which leads to the cold spell in early spring. 3 Low trough on 500 hPa,700 hPa and 850 hPa shear lineis the precipitation system,strong frontal zone of 850 hPa and ground large cold high pressure provides the dynamiclifting condition.4 The low-level southwest jet of the 500 hPa and 700 hPa provides abundant water supply for theheavy rainfall. The physical quantity shows that the strong convergence and upward motion on 700 hPa contribute alot to the precipitation. 5 With the heavy cooling,the 850hPa temperature dropped 19 ℃ within 48 h,700 hPa and 850 hPa temperature fell to below 0℃,the precipitation phase by the rain turned into snow.