Application Study Of Radar Data And Lightning Location System Data In Lightning Forecasting

Lightning is a disastrous weather phenomenon which accompanied by a strong convective process. Lightning have a strong destruction because it has a strong current, the high temperature, the violent shock wave and a strong electromagnetic radiation. The data obtained by Doppler radar, lightning location system, radiosonde and NCEP1°×1°final analyses were analyzed to study the temporal and spatial variations of lightning and lightning distribution, the lightning warning indicator and the lightning potential indicator. It is mainly concerned with four aspects as it follows:(1) The characteristics of the temporal and spatial variation of the thunderstorm activities in Shandong are analyzed with EOF methods. The data from2007to2010obtained by lightning location system.The results are as follows:the consistency of thunderstorm activities in all area in Shandong, and a reverse is known by comparing the thunderstorm activities in the peninsula region to south area and in other areas. The data from June to August obtained by lightning location system were analyzed to study the spatial variations of lightning, it is found that the lightning distribution is connected with heavy precipitation, but the main precipitation region is not consistent with lightning density increasing.(2) The data from2007to2010obtained by lightning location system, within100km of the Qihe radar station were analyzed to study the temporal variations of lightning. The results of this study are:The lightning flashes mostly occur in a period from June to August, and the lightning activities have no a single trend and have different peak and trough time.(3) The data obtained by Doppler radar, radiosonde and lightning location system from41convective cells, which occurred in the periods of July-August2009and June2010, within200km of the Qihe radar station were analyzed to study the lightning warning indicator. The characteristics of radar parameters ahead of lightning occurrence were studied by means of statistical method. The best predictor of the onset of cloud-to-ground (CG) lightning was found to be a40-dBz reflectivity level detected at an altitude with an environmental temperature of-10℃, with an average leading time of21min. The percent of doom (POD), false alarm rate (FAR) and critical success index (CSI) are96%,14%and83%, respectively. Echo tops reaching or exceeding10km and vertically integrated liquid water content (VIL) exceeding8.5kg·m-2were necessary conditions prior to or at the time of the first CG lightning occurrence. When the three parameters (radar reflectivity, echo top height and VIL) were analyzed synthetically, it is found that the best predictor of the onset of CG lightning was a25-dBzreflectivity at an altitude with an environmental temperature of-20℃, which could effectively reduce the FAR and improve the CSI.(4) The0-6th thunderstorm potential of within100km of the Qihe radar station from June to August can be forecasted by means of analyzing the data obtained by NCEP1°×1°final analyses, and with the method of backward selection and stepwise regression analysis (α=0.05).