基于卫星观测的两例青藏高原低涡结构的初步分析

应用风云2C卫星云图和配有云顶亮温的MTSAT卫星红外云图,描述了两例青藏高原低涡形成、发展及消亡过程,云图清晰显示了高原低涡具有涡眼和暖心结构的特征,并利用水汽图分析揭示了缺乏水汽供应是导致这类低涡不能进一步发展并移出高原的重要原因.最后用1°×1°NCEP分析资料对高原低涡形成眼结构时的基本物理场进行了诊断计算.结果表明:低涡整体为上升气流,而涡眼区在近地层为下沉气流,上层为相对涡区较弱的上升气流;低层辐合,高层辐散.进而印证了动力学研究工作得出的高原低涡具有与热带气旋类低涡(TCLV, tropical cyclone-like vortices)类似的涡眼和暖心结构特征的结论.

Study of low vortex over Tibetan Plateau based on satellite observation

Using the FY-2C satellite images and the MTSAT infrared images the formation,development and disappearance of two cases of low vortex over the Tibetan Plateau are described.The images clearly show the characteristics of the vortex eye and warm core.The water vapor images based on the satellite are also used to reveal that the lack of water vapor supply is an important factor so that the vortex cannot develop further.By using the NCEP global 1ox1o,final-analysis data(four times per day) a diagnostic analysis is given through computing the basic physical quantity distribution.The results show that all the levels of the low vortex over the Tibetan Plateau are upward flows,the vortex eye in the surface layer is downward flows and the upper level compared to the vortex is upward flows with convergence in the low level and divergence in the upper level.It demonstrates that the conclusion from the dynamic study of the plateau vortex,i.e.the low vortex over the Tibetan Plateau has the similar structure of the tropical cyclone-like vortex(TCLV) such as vortex eye and warm core.