The Doppler Radar Data Characteristic Analysis On North Eastern Cold Vortex

In this paper, the characteristic analysis on the special structure of north-eastern cold vortex based on Doppler radar data and some research about single Doppler radar detecting large scale cyclonic circulation have been finished. Meanwhile, some images of Doppler radial velocity have been provided for some wind profile images.The obvious character of Doppler radial velocity was found when Doppler radar detected the large-scale rotation circulation—northeastern cold vortex. The distributions of the max and min radial velocity centers as well as the zero line on Doppler radar image are very similar to the medium or small-scale cyclone and typhoon. These characters of Doppler radial velocity are associated with the cyclonic circulation distribution and the Doppler velocity. When at the same level, the wind speed of cyclonic circulation is proportion to the distance of "r"from the center to the cyclonic circle till the strongest wind region. Then the wind speed will be inverse proportion to the distance of "r"from the strongest wind region away and the wind speed of the cyclonic center is small or zero. The distribution of cyclonic circle velocity meets a part of rankine model. One of cyclonic circles (the cyclonic circles in the strongest wind region) come into the radar valid area and it is tangent with the scan radius of radar .the Doppler velocity will emerge plus and minus velocity centers. We define this cyclonic circle as the max velocity circle;the radius is "R", and the velocity as rotation speed. The Rankine model has been used in numeric model in order to prove that character. A series of numeric model results have identified that Doppler radar can detect parts of northeasterncold vortex. The northeastern cold vortex is so large that Doppler radar can only detect a part of it.Doppler radar and the numeric model image determined the center position of northeastern cold vortex. The two centers of velocity can be read from the velocity image. The intersection that two perpendicular of two radius crossing the two centers of velocity is the center of the north eastern cold vortex, or the intersection crossing perpendicular of one radius and the extended zero line, then the moving pathway and the relation between the moving pathway and precipitation will be determined.The spatial and temporal character of cold and warm advection distribution and the divergence and convergence was analyzed according to Doppler radar data, then the vary phase of the northeastern cold vortex will be identified.The information of north-eastern cold vortex including the moving pathway, the Variety of intensity, the velocity of rotation, the radius and the azimuth can be gotten by detecting this weather system continually and this research will be useful for the service and research in the future. Meanwhile, The method that uses Doppler radar data to analyze three processes of cold vortex is innovative and valuable for forecasters.