The Characteristic Of Mesoscale Convective System And Mesoscale Convective Vortex In Summer Over East China

Mesoscale convective system (MCSs) and mesoscale convective vortex (MCVs) often cause severe weather events and heavy rain. So they are one of mesoscale of severe weather systems. However, there is quite a lack of working on census of MCS and MCV at East China in summer. So, it is necessary to do research on the characteristic of MCS and MCV. In this article, a method which combines MCV detection of Davis et al.(2002) with self-identification of MCS from infrared imagery is developed. With this method, MCSs and MCVs in east china are identified from the historic data and their characteristics are analyzed. As this is done, the further researches will focus on the environment of MCS and the vertical structure of MCV. The results are shown as followed:(1) In the figure of the average height on center of vortex, it is clear that the proportion of 850hPa is largest, compared with that the leading ratio is 500hPa in USA. This phenomenon is possibly caused by the differences of terrain between East China and USA. What's more, there is no corresponding relationship between the average height on center of vortex and the sale & shape of MCS.(2) The outcome of the distribution of thickness implies that the thickness of MCV in East China is quite thin. Most of these thicknesses are about 100hPa. The number of thickness lager than 500hPa is rather small except the MCV produced by MαECS. Above all, the MCV in East China is a shallow system at low level.(3) By judging the position of MCS and MCV, it is helpful to understand that MCV in east China is averagely situated at the north part of MCS, including the northwest and northeast part. The proportion of other locations is low. Besides, the compact of the scale and shape on relative locations is rather low.(4) In east part of China, the region of precipitation in M a CCS is well consist with the profile of-52°temperature on top of cloud. And the extreme value of precipitation is located in the region of-52°temperature. The M a ECS and MβECS are strengthened by combining two convective clouds in their lifecycle stages. So, there will be a heavy rain. Above all, there is a relationship between the characteristics of precipitation and the scale & shape of MCSs.(5) The research on environment of MCS suggested that the typical character of region of production is including the relative humidity of 95% at 850hPa and the weak vertical wind shear. The pattern of low and high level, the interaction between jet at low and high level and the divergence of low and high level are important to decide the scale and shape of MCS.(6) The research on vertical structure of MCV implies that no matter what kind of MCS is, the vertical structure of temperature and vorticity at the center of MCV is the same as other kinds. The vertical structure of temperature shows there is a cold corn at low-mid levels and a warm corn at high levels. The vertical structure of vorticity shows there is a convergence at low-mid levels and a divergence at high levels. These vertical characteristics mean there will be an upward motion in MCVs, and the cold moist air will be lead to high levels. So releasing latent heat is helpful to make precipitation. The rainfall is the reason why the surface is cold. All this will be a circle for maintaining and strengthening the MCV.