Helicity Calculation Of WPR Data And Its Application In Serve Convective Weather

Both observation studies and numerical modeling point to the fact that the wind directions veer with height is critical factor in developmenting severe storms.Helicity is the physical parameter that describes the rotation and motion of airflow in the wind field, and it can also reflect the temperature advection in the atmosphere under some conditions. So the changes of helicity are a good indicator concerning analysing and prediction of severe convective weather.The development of storms depends on vertical movement of atmosphere. The thesis presents the method of calculating helicity using WPR data. And two diagnostic analysis in the thesis on helicity of serve convective weather result in the following conclusions:1. Helicity computed by WPR data has better time resolution, with its variations almost consistent with that of rainfall; and changes in helicity is commonly ahead of the changes of rainfall by 1 hour.2. There is no distinctive linear relationship between helicity value and rainfall amount.3. Helicity is a good indicator for variations of wind field with changes in height.4. WPR data as the wind data for computing helicity is feasible and ismore suitable for nowcasting work compared with other wind data. It can effectively observe the whole process when forming storms, and is an important predictor for nowcasting workhand.