2007年7月9—10日江淮大暴雨的水汽图像解译研究

Interpretation of Water Vapor Image for the Rainstorm over Changjiang and Huaihe River Valley in 9-10 July 2007

为了充分发挥卫星水汽图像在区域性暴雨预报中的重要作用和发展相应的云图解译技术,采用风云2C(FY2C)卫星水汽图像与常规动力场和位涡场联合分析的方法,解译了2007年7月9—10日江淮大暴雨不同时段水汽图像的典型特征及其对应的物理涵义,探索了适用于我国区域性暴雨的云图解译技术。这一典型个例验证了卫星水汽图像与对流层中高层大气环流场和位涡场之间良好的对应关系,利用这些对应关系,总结和提炼了4个对预报江淮暴雨有指示意义的云图指标:风切变陡增引起的"干三角"结构、干冷空气大规模南下引起的大尺度"漏斗"状水汽结构、冷空气干侵入引起的斜压叶状云、新的急流核生成(气旋生)引起的白色狭长带状云线等。这些特征和指标具有明确的物理意义,对暴雨有良好的预示作用,并且较容易识别和应用。

To develop the satellite cloud image interpretation skills and adequately exert the role of satellite cloud image in the forecast for regional rainstorm, some typical features of water vapor images during dif- ferent phases of the rainstorm and their physical meaning are interpreted preliminarily, and satellite cloud image interpretation skills suitable for regional rainstorm in China are explored by analyzing FY2C water vapor images integrated with conventional dynamics fields and potential vorticity field for the rainstorm over Changjiang and Huaihe River Valley in 9 10 July 2007. The typical rainstorm event validates the good corresponding relations between satellite water vapor images and circulation and potential vorticity fields in the mid-upper troposphere. According to these relations, 4 water vapor image indicators with cer- tain forecasting meanings are summarized and abstracted： a ＂dry triangle structure＂ induced by jet break- ing and wind shear, a large-scale tundish-like shape cloud system resulting from southward intrusion of dryand cold air, a leaf-like cloud induced by dry intrusion of cold air, a white slender strip cloud line symboli- zing the generation of a new jet core, etc. These features and indicators have definite physical meanings and good indicating roles for rainstorm forecast, and are easy to be identified and applied.