| In this paper,observations of the operational dual-polarization radars that recently deployed in China are first used to find factors affecting the measurement accuracy and the corresponding quality control methods.Then,a optimized hydrometeor classification algorithm and its verification method are proposed to highlight the main advantages of polarimetric radars.The networking technology of polarimetric observations is also studied,and the radar networking test with different regions and different wavelengths are carried out.Finally,the application of dual-polarization radars in severe convective storms is studied.Based on the polarimetric radar observations in Southern China,the polarimetric observational characteristics combined with phased-array radar observations,hydrometeor classification results and 3D wind fields products of a squall line in May 11,2014 and a supercell in May 9,2016 are presented.The main contents and conclusions include:(1)Three major aspects that affect the data quality of polarimetric radars are introduced,such as the disturbance of non-meteorological echoes,the limitation of microwave propagation and scattering,and the restriction of radar hardware.It is found that ZDR is the most sensitive polarimetric variable,while ?hv and ?Dp are relatively more reliable.The corresponding characteristics can be used to eliminate clutters in the quality control procedure,and a quality verification method and a quality quantification method are also proposed.(2)The microphysical processes in different hydrometeors lead to the differences in the polarimetric characteristics and their sensitivity.Through fuzzy logic operation,melting layer identification and empirical threshold examination,10 kinds of hydrometeors are classified by 6 kinds of input variables.For polarimetric radars with different locations and wavelengths,the optimized parameters are obtained by a statistical method,and the reliability of this procedure is verified by the comparison with sounding and ground observations.(3)In different network schemes,the S band radar network in Southern China provides a relatively stable and fine result despite the poor spatial-consistency in the melting layer.The fusion network of X-and S-band radars in Nanjing area shows the advantage of X band radar in blind compensation,although its resolution is reduced.By contrast,the X band radar network in Beijing area provides observations and products with high temporal and spatial resolution,but it depends on high-level quality control method.(4)The S-band polarimetric radar in Zhuhai has effectively monitored the squall line in May 11,2014.The classification results of rain-hail mixture region are located in the front of the bow echo,corresponding to the mid-altitude radial convergence zone,and the ground also find hail shooting records.In the microphysical analysis,the coalescence growth of a large number of graupel and supercooled water droplets occurs above the melting layer,some of the generating hail fall to the ground.During the evolution of this squall line,the area of the rain-hail mixture region is related to the strengthening or weakening of convective storms,which has a value for operational application.(5)From the collaborative observations of a supercell occurred in May 9,2016,the S-band polarimetric radar in Guangzhou clearly find that the hook echo generated in the lower level during the mature stage,supercooled water droplets appear on the top of the bounded weak echo region,and large hail grow wthin the echo overhang.The introduction of hydrometeor classification algorithm can intuitively show the information from polarimetric variables.With the help of high-resolution observations from phased-array radar,it is found that the relationship between inflow and outflow is the key factor for the formation and dissipation of the hook echo.The rain-hail mixture area provided by the hydrometeor classification product is closely connect with the supercell lifecycle,and its quantitative analysis can be better used in the nowcasting. |
PDF Full Text Request