Verification and Evaluation of Wind Field Accuracy of Shanghai X-Band Phased Array Weather Radar Network

High spatiotemporal resolution three-dimensional wind field data is needed for short-term severe convective weather forecasting. Currently, Shanghai has built five X-band phased array weather radars, forming an array weather radar network (AWR) and conducting network observation.The AWR can provide real-time wind field data, including single radar radial velocity, dual radar retrieved wind field, three radar synthesis wind field, and retrieved wind field based on three-dimensional variational data assimilation (3DVAR). However, the error of wind field data still require quantitative comparative analysis, and the accuracy of wind field is a key factor affecting short-term severe convective weather forecasting. It is necessary to accumulate a large amount of long-term observation and experimental data to verify the accuracy of wind field, in order to determine whether the retrieved wind field of the AWR can truly approximate the actual atmospheric dynamic conditions.
In order to verify the accuracy of the 3D wind field data of the Shanghai AWR, this article selects a total of 25 precipitation processes in Shanghai from May 1 to September 30, 2021, including stable precipitation, convective precipitation, and typhoon precipitation. The wind measurement data obtained from the L band balloon sounding in Shanghai is used as the true value. The wind field data obtained from the sounding at different longitude, latitude and altitude are compared with the 3D wind field data of the AWR after spatial accurate matching, and the L band wind-profiler data is also used to compare. The results are as follows: (1) Comparing the wind data measured by sounding with the AWR retrieved wind field, it was found that there is a relatively high correlation between them. The U-wind correlation coefficient is 0.98, the V-wind correlation coefficient is 0.87, the wind direction correlation coefficient is 0.9, and the wind speed correlation is 0.89. The overall deviation of phased array radar compared to sounding is about 1.4m/s. The AWR retrieved wind field data is limited by the position and height of the radar reflectivity, as well as the number of radar coverage that can be observed simultaneously. (2) The comparison results of the L band wind-profiler wind data and AWR retrieved wind show that in the process of stable precipitation, the wind field retrieved by the AWR is more consistent with the results of wind-profiler wind products; In the process of convective precipitation, due to The unevenness of the environmental wind field in convective precipitation can reduce the accuracy of wind measurement, and therefore it is not enough to explain the rationality of the AWR retrieved wind field.
Key words: array weather radar (AWR); retrieved wind field; sounding; verification and evaluation