针对2016年2月21-23日和2017年2月21-22日川西高原东部连续强降雪过程进行分析,利用NCEP再分析资料、常规高空、地面、云图资料对环流背景场和物理量场分析研究,结果表明:降雪前期500 h Pa为高原槽或西风槽配合有高空锋区影响,700 h Pa在甘肃南部有切变南下,地面上为冷高压扩散到高原,后期为南北槽叠加形式。中低层水汽源地都在孟加拉湾,前期水汽通量强,比湿大,后期水汽通量弱,比湿小,但低层受偏东水汽通量与地形抬升关系,结合500 h Pa的弱水汽辐合使降雪持续。降雪时都出现了较强的垂直上升运动,这与地形抬升有一定关系,其上升高度与降雪强度之间存在关系。降雪前期湿位涡MPV1中高层都为正值,低层为负值区,到后期低层转为弱的正值区,而MPV2则正好相反;云图上3次降雪在01-02时开始,都有云团合并加强,黑体亮温梯度明显增加时出现降雪,且小时降雪量较大。
文章使用葵花9号卫星资料与常规观测资料,利用环流形势分析、物理量场分析与云图分析对2023年8月上中旬四川地区两次降水过程进行分析。结果表明:1) 两次过程按主要影响系统可分为西南涡与东海台风型、南亚高压型。2) 高时空分辨率的葵花卫星云图可清晰分别对流云边界与轮廓,更容易判断对流发展的阶段、强度变化与移动方向。3) 对流云从初生到产生强降水的发展特征主要可分为单独对流云过程与有对流云融合过程两类,两类最主要的区别就是对流云融合过程比单独对流云过程多了加速发展过程,在亮温不变或波动上升阶段后有一明显的再加速下降过程。4) 最低红外亮温低于210 K且观测到红外亮温快速下降、红外与水汽亮温同步降低至212 K以下、红外与水汽亮温差降低至2 K以下,使用这三个特征来预测强降水产生时间,可提高预测的准确性。The Himawari-9 satellite data and conventional observation data were used to analyze the two heavy precipitation processes in Sichuan in August 2023, using circulation situation analysis, physical quantity field analysis and cloud image analysis. The results show that 1) the two processes can be categorized into the Southwest China vortex and East China Sea typhoon type, the South Asian high type, the South China Sea typhoon type, and the Western Pacific Subtropical High type according to the main influencing systems. 2) The high temporal and spatial resolution of the Himawari satellite cloud image can clearly separate the boundary and outline of the convective cloud, which makes it easier to judge the stage of convective development, intensity change and moving direction. 3) The development characteristics of convective clouds from the initial generation to the production of heavy precipitation can be divided into two categories: the process of convective clouds alone and the process of convective cloud fusion. The main difference between the
