一次MCC的云图特征及成因分析

使用风云2号红外云图和TBB资料、 多要素自动气象站资料及NECP 1°×1°再分析资料, 对造成河北中部区域性暴雨的MCC云图特征、 天气尺度环境场和动力特征等进行了分析。结果表明, 构成MCC的α中尺度对流云团, 在其成熟时期, 在均匀的α中尺度砧状系统中仍有2~3个β中尺度的对流活动; MCC发生、 发展在对流层中层的短波槽、 高低空急流有利配置以及大气层结为中性或弱对流不稳定的环境条件下, 暖湿平流成为其发生、 发展的主要强迫因子; MCC形成阶段, 中层出现暖中心并且气旋性涡度增大, 辐合辐散运动随高度交替出现, 量级相当, 上升运动的层次较厚。

Satellite Cloud Image Feature of a MCC and Forming Cause Analysis

MCC satellite image features,synoptic sacle environment field and dynamic features etc of a regional torrential rain in central Hebei was analysed,using the FY-2 infrared satellite image,FY-2 satellite TBB,rainfall data of surface densified automatic stations and NECP 1°×1° reanalysis data. Resutls are as follows:2～3 meso-β scale convective clusters act on the meso-α scale anvil cloud system during the mature period of MCC;MCC happens and develops under the advantageous conditions,such as the short wave trough in the middle-level of troposthere,the appropriate allocation between low-level and high-level jet streams,and the neutral or weak convective instability environment condition. The warm wet advection is the main force factor. There is warm core in the middle-level in the forming stage of MCC,the cyclone vorticity increases and the divergence alternates with height,and the levels of ascending motion are thick.