Remote Sensing Precipitation Nowcasting Based On Radar And Geostationary Meteorological Satellite

The study of precipitation nowcasting is very important for reducing the economic losses caused by meteorological disasters in China.At the same time,it also plays an important role in guiding the arrangement of large national activities.It is an important basis for improving the accuracy of nowcasting to study rainfall nowcasting predictability based on radar and satellite data.Based on 4 field precipitation data and 4926 data of China's geostationary meteorological satellite FY-2F,the influence of remote sensing data type,precipitation system,precipitation intensity and season on the predictability of precipitation nowcasting is systematically studied.The following conclusions are obtained:(1)The type of radar prediction data affects the accuracy of prediction.It is found that the basic reflectivity data of radar is used for the rainfall nowcasting,and then the predicted results are retrieved to precipitation,and the accuracy is higher than that of the first inversion.By comparing and analyzing the three search radius parameters,it is found that the search radius is set to L1 type(Lead Time*2+6)better,the POD index is 1 hour 70.95%,2 hours is 67.47%,and the error is also low.(2)The precipitation system obviously affects the predictability of radar remote sensing precipitation.It is found that the predictability difference of each precipitation system is not significant through the precipitation system forecast experiments of the accumulated cloud,hail cloud,stratiform cloud and mixed precipitation on the ground radar echo image.Overall,the stratiform cloud precipitation system is stable and predictability is slightly better than others.The POD index is 82.95% for 1 hour and 82.21% for 2 hours.(3)The influence of precipitation of different intensities on radar rainfall nowcasting is quite different.On the whole,the greater the precipitation intensity is,the higher the hit rate is.The lowest hit rate of light rain forecast is 1 hour,18.82%,2 hours 6.53%,and the error is bigger.The hit rate of rainstorm is higher,1 hour are 89.97%,2 hours are 79.31%,but the forecast error of rainstorm is also bigger.(4)Taking the FY-2F data as an example,the predictability of the precipitation nowcasting of the geostationary meteorological satellite in different precipitation systems,different rainfall intensity and different months in the rainy season is studied.The average 1 hour precipitation forecast BIAS,Corr,RMSE,POD,FAR and CSI were respectively-0.08,0.66,0.75 mm/h,0.55,0.28,0.46,and 2 hours precipitation forecast of BIAS,Corr,RMSE,POD,1.074,0.42,0.46,0.31.It is found that the prediction accuracy of different precipitation systems is quite different,for example,the detection probability POD of rain clouds and cumulus clouds for 2 hours is 0.73 and 0.58 respectively.In the same precipitation system,the development process or the elimination process has no obvious influence on the prediction results.As far as precipitation intensity is concerned,the prediction accuracy of rainstorm and heavy rain is better than that of small rain and medium rain,and the accuracy of 0.5 hour is equivalent to 1 hour and 2 hours of heavy rain.The forecast accuracy of different rainy months is slightly different.Generally speaking,the forecast effect in July is relatively good,but slightly worse in May and September.