Estimating the Bulk Snow Density Using Collocated Parsivel and MRR Measurements: ICE-POP 2017/2018

A new method is developed to derive the bulk density of hydrometer from collocated measurements of Micro-Rain Radar (MRR) and Particle Size and Velocity disdrometer (Parsivel). Rigorous particle scattering simulation, namely T-matrix method, is applied to particle size distribution data of Parsivel to calculate the reflectivity (ZHH). The possible combinations of ice, air and water of the particle are derived by comparing with the MRR measured ZHH. The bulk density is subsequently determined by the combinations of ice, air and minimum water fraction. The observations during the International Collaborative Experiments for Pyeongchang Olympic Games Projects (ICE-POP) 2018 and its pre-campaign are applied to this new method. The estimated bulk density was examined by self-evaluation of ZHH weighted fall velocity (VZ) of MRR and independent comparison of the liquid-equivalent snow rate (SR) of collocated Pluvio. The bias values are adequately low (Vz: 0.08~0.27 m s-1, SR: 1.69~2.80 dBmm). The derived bulk density of the two warm-low cases (28 February 2018 and 07 to 08 March 2018) shares a similar transition as the systems were decaying. The particles with higher density were found in the coastal sites (BKC and GWU) which typically accompany with higher liquid-water constituents than the inland sites (MHS) during such synoptic conditions.