Application Of The Data Of Lightning On Thunderstorm Multi-scale Analysis And Lightning Nowcasting

Insight into the atmospheric energy structure on dynamics, thermal and humidity, exploring Cloud-to-Ground (CG) flash evolution and its coupling with other meteorological elements and improving lightning nowcasting methods are all of great significance for studies on mechanism of meso-and micro-scale disastrous weather and lightning nowcasting. The analysis of convective weather on7th July,2009was made with the data of lightning detection, Doppler radar data, FY series satellites and routine meteorological data, as well as further studies on building up the CG flash nowcasting platform based on cross-correlation algorithm. Evaluation tests and discussion on extrapolation parameters was made through10thunderstorms occurred in2011, Nanjing. It was revealed that:1. Multi-scale analysis on thunderstorm:(1) Based on the energy structural forecasting method, the plot of wind and potential temperature show important signs before the occurrence of convection. Negative flash ratio of thunderstorm is higher. But for positive flash, strength reinforcement and scaled-up occurred after convective system reached the mature stage.(2) The negative CG flashes mainly occur in the front of region with echo intensity between40dBZ and45dBZ whose echo top is higher than11km, which can provide theoretical basis on lightning nowcasting. The negative CG flashes are of good instructive sense to forecast the future trend of intense echo zone. Correlation between distribution of CG flashes and strong wind shear as well as heavy rain has been confirmed.2. Lightning nowcasting:(1) Evaluation tests shows that the CG flash nowcasting platform based on cross-correlation algorithm can be effective to achieve0～1h forecast. Accuracy during mature stage is higher than any other stages. From a macro perspective, extrapolation effect is better when CG flashes have a wide range and compact structure. From the microscopic point of view, as the equivalent flash frequency increases, more effective extrapolation and forecast will achieve.(2) The CG flash nowcasting platform has the function of setting adjustable parameters including the target module, search area and equivalent CG flash frequency threshold. With strengthen of thunderstorm and extension of forecasting period, set value of the target module’s length is to be increased. Only reasonable search regional settings can ensure the accuracy and reliability of forecasting results. Through the threshold setting of equivalent CG flash frequency, data quality control and speed improvement can be achieved as well as lightning early warning combined with local features.