摘要
本文应用常规探空资料、地面观测资料、欧洲中心细网格（0．25°×0．25°）数值预报初始场资料和NCEP／NCAR1°×1°再分析资料分析了山东一次江淮气旋降雪过程的复杂相态特征，并初步分析了成因。结论如下：（1）山东省2014年2月16-17日的雨雪天气过程，降水相态多样性和相态转化复杂性是主要特点，表现为同一时刻雨、雪和雨夹雪三种相态共存，郯城站降水相态逆转（由雨夹雪转雨再转雪），鲁东南地区降雪同时鲁西南地区降雨的“东雪西雨”现象。（2）在系统发展不强的江淮气旋降雪过程中，鲁中山区相对高海拔地区夜间强烈的辐射降温和山脉迎风坡的动力抬升作用均会造成边界层温度的降低，后期对流层低层为东北风控制时，除鲁中山区外，其迎风坡东麓或东北麓（潍坊地区）出现固态降水可能性也较大，一般情况下，地面2m温度为1～2℃，1000hPa温度为0℃左右，925hPa温度为-3℃左右，可出现固液共存降水现象。（3）相态逆转现象的发生与江淮气旋发展阶段和气温日变化两个因素紧密相关。0℃层在925hPa上下的状态是一种临界状态，可产生雨夹雪或雨，但0℃层高度下降不是由雨转雪的充分条件，还需考察冷平流发展情况。（4）当江淮气旋生成地偏东（位于长江口附近），且发展不强烈时，山东若受其影响产生降水，后期上游如有新系统发展，可能与气旋共同影响山东，造成复杂相态的江淮气旋降雪过程。
Based on the conventional sounding data, surface observation data, initial field data from ECMWF numerical model （0.25° ×0. 25°） , 1° × 1° NCEP/NCAR reanalysis data, the complex phases characteristics and primary causes of a JiangHuai-cyclone precipitation in Shandong were analyzed. Re- suits show that： （1）the rain and snow weather process happened on 16-17, February, 2014 under the background of 500 hPa zonal circulation was influenced by an eastward Jianghuai cyclone. The main fea- tures of this process were the variaty of precipitation phases and the complexity of precipitation phases transition , which means that the three phases of rain, snow and sleet coexisted; the precipitation phase reversion at Tancheng station was from sleet-rain-snow; the phenomenon of rainy west but snowy east in Shandong was contrary to the common case. （2）In the weak synoptic Jianghuai cyclone snow process, the severe radiation cooling at night at relative high altitude mountainous areas over the middle Shandong and the dynamic lifting effects of upwind slope of mountains caused the decreasing temperature of boundary layer. Therefore, when the lower troposphere was controlled by Northeasterly wind, the possibility of solid precipitation at east or northeast slopes of the mountains was larger in the later rainfall stage except the mountainous areas of middle Shandong. The coexistence of solid and fluid phase happened with 1-2℃ of air temperature 2 m above surface and about 0℃ at 1000 hPa and about -3℃ at 925 hPa usually. （3） The phenomenon of phase reversion was closely related with the development stages of Jianghuai cyclone and diurnal temperature variation. It is a critical state when 0℃ temperature layer is over 925 hPa, which can cause rain or sleet, but the drop of 0℃ temperature layer was not sufficient condition for the phase transition from snow to rain. The analysis on cold advection was also necessary. （4）The new born weather system on upstream could result in complex precipitation phase together with the Jianghuai cyclone at the later stage of cyclone precipitation, when the Jianghuai cyclone was weaker and its birthplace was nearby estuary of Changjiang river. （ 5 ） In this precipitation process, the dividing line for rain and snow areas well corresponded with the 1283gpm between 1000 hPa and 850 hPa and with the 621gpm between 1000 hPa and 925 hPa.
出处
《气象科学》
北大核心
2016年第3期411-417,共7页
Journal of the Meteorological Sciences
基金
国家自然科学基金资助项目(41175044)
中国气象局关键技术集成项目(CMAGJ2015M34)
山东省气象局重点课题(2013sdqxz02)
山东省气象局课题(2015sdqx02)共同资助
关键词
江淮气旋
复杂相态
相态转换
Jianghuai cyclone
Complex phase
Precipitation phase transition
