Preliminary Discussion On Automatic Identification Of Frontal Line From Radar Echo Features

The Doppler weather radar is an effective instrument to monitor and forecastdisastrous weather, which can get accurate information of wind field and identify thetypical wind field of severe convection, thus can discern and predicts disastrousweather caused by wind. By use of the data from Doppler radar, the automation ofidentifying cold front is discussed.In chapter one, the development of weather radar at home and abroad, thepurposes of this research and structures of this research are given.The macro-scale structure of the cold front and its character of the windstructure on the radial velocity map are discussed in chapter two. In order to testifythe method of identifying frontal line automatically, Matlab is used to simulate thecold front moving from the northwest to the radar and right over the radar. Then the3-D structure of frontal surface is constructed and the shape of frontal line on PPI isanalyzed. After that, the space distribution of cold and warm advection is revealedthough the actual example.Then in chapter three, after searching the zero-velocity points and minimumvelocity of negative-velocity area, referring to combined shear algorithm ofWSR-88D, the frontal line is identified by the threshold of combined shear andreflectivity.Subsequently, in the way of DLL (dynamic link library) we finished the moduleof the frontal line identification using Visual C++, which can be put to use in theRPG of the Doppler radar in chapter four.In chapter five, using the project to identify a storm which happened in Hunanprovince on May 13 2002, we compared the results and found that this module hadgood ability to identify the front system from the radar in this storm.Finally, in chapter six we made a discussion of the limits and the ability of thismodule for further research of detecting cold front accurately.