Comparison of Polarimetric Parameters in Melting Layer and Particles Diameter Using X-band Polarimetric Radar RHI Observation

In this study, we compared the relationship between the polarimetric parameters in melting layer (ML) and the size of precipitation particles using the data obtained from the RHI observation of the X-band polarimetric radar at Niigata City in 2019 winter. The maximum value of Z[H] and Z[DR] or the minimum value of p[HV] in ML corresponded well to the mass-weighted diameter from disdrometer observation. In particular, the maximum value of Z[DR] was confirmed to be below the empirical threshold in ML for the case of small particle size. In addition, a comparison was made using indices corresponding to the mass-weighted diameter of snow particles calculated from Z[H] and K[DP] above ML, and it was found that there was more variation than in the mass-weighted diameter of raindrop on the ground. Therefore, a method to estimate the density of snowfall particles is necessary because the value of the polarimetric parameter in melting layer is considered to depend on the melting diameter