Data Quality Analysis of 3836 C-Band Dual-linear Polarimetric Weather Radar and Its Observation of a Rainfall Process

The technical status of upgraded 3836 C-band Dual-linear Polarimetric Weather Radar (3836 radar) in Beijing Meteorological Bureau in 2004 is studied. Based on the large area stratus rainfall observation over Beijing on November 19, 2004, the 3836 radar's measurement quality and its detection ability are presented. According to the characteristics of the scattering and orientations of the precipitation particles with different phases in the space within the melting-layer (so-called bright band), a model is established, in which the bright band can be identified by applying the fuzzy logic method to three polarimetric radar observation variables and the height. The radar measurements are used to assess the outputs from the model and discuss the variation features of different phased hydrometeors within the melting-layer.The results show that: ① the phase distribution structure of hydrometeors of the storm revealed by the 3836 radar data, except the LDR non-analysed data, is reasonable and similar to those from foreign polarimetric radars. ② The result from the established model based on the 3836 radar measurements is reasonable and able to reflect the feature of melting-layer. ③ Upon the polarimetric radar measurements, the melting-layer is characterized by a drop in ρ_hv (0) associated with Z and Z_DR peaks, the cause is that the ice particles descend below 0 ℃ height, melt into large rain drops, and the break into more rain droplets, resulting in the variation rule that the Z_H and Z_DR increase first then decrease while ρ_hv (0) is just on the contrary in this layer. In additional, the maximum Z is observed at a higher altitude than that of the maximum Z_DR and minimum of ρ_hv (0). It indicates that the maximum eccentricity of melted hydrometeors occurs at a lower level in the atmosphere than that with the maximum size, assuming the largest particles are located near the reflectivity maximum.It is a preliminary study on examining the potential ability of polarimetric weather radar upgraded from ChIna New generation RADar (CINRAD) in detecting microphysical structure of rainfall storm, which may provide more useful help and reference to the further development of polarimetric radar in China.