Application Of Multi-source Data Fusion Algorithm In A Severe Convective Weather Process

Based on the detection data of dual doppler weather radar(changzhou station and taizhou station)combined with the conventional observation data and the ERA5 reanalysis data,this paper comprehensively analyzes the synoptic environment,the evolution characteristics of reflectivity and the 3d flow field information retrieved by dual doppler radar during a severe convective weather process occurred in Jiangsu Province on 6 July 2019.Using the above data,the experiment of multi-source meteorological data fusion algorithm is conducted to identify the surface layer wind field in the process of severe convective weather.Dual Doppler weather radar data are fused to explore the structure of hail clouds in strong convective systems.VAP(velocity azimuth processing)technology is used to retrieve the radial velocity data into vector wind field.The wind field retrieved by radial velocity and the wind fields of reanalysis data and automatic weather station data are fused by the canonical correlation analysis(CCA)method.Using the three-dimensional flow field information retrieved by the radial velocity data of dual Doppler radar and combining with the fusion reflectivity characteristics,the case model of hail cloud is obtained.Through the above analysis and exploration,the main conclusions are as follows:(1)In the process of the severe convective weather,Jiangsu Province is affected by the high-altitude cold vortex.Under the conditions of high-altitude cold troughs,high-altitude jet stream,low-level shear lines and surface convergence lines,an unstable stratification with upper dry cooling and lower warm and humid formation is formed.(2)By wind field fusion experiment,more abundant and accurate surface layer wind field information of the severe convection system is obtained,which corresponds to the characteristics of the data detected by doppler weather radar.After data fusion,the magnitude error of retrieval wind field is eliminated,the filtered wind field information is filled,and the rotation characteristics of airflow are restored.The fused wind data can capture the two main characteristics of convergence,divergence and rotation of the flow field.(3)The results of the fusion wind fields show that in the development stage of the strong convection weather system,there are cyclonic convergence flow fields on the surface layer,including ?-mesoscale cyclones and convergence lines,accompanied by anticyclonic and divergent flows.The cyclonic flow field corresponds to the position of the inflow gap in the radar echo field,and the convergence lines are located at the region of the storm front(moving direction).In the strong stage of the strong convective weather system,the surface layer flow field changes into a strong convergence and weak rotation attitude.At the same time,the disastrous weather occurs.(4)In this weather process,the hail cloud has typical radar reflectivity characteristics of strong convection monomer.There are hook echoes and inflow gaps in the lower layer.In the vertical section,there are bounded weak echo region,echo wall and overhanging echo structure.The strong echo core and the echo top are both high in height.The hail cloud has the obvious S-shaped horizontal flow field structure at the strong echo center in the middle layer.The lower layer of the hail cloud is a horizontal flow field with obvious convergence and rotation configuration.The deep zero line structure is a typical characteristic of hail formation.