The particles with higher bulk density and bulk water fraction were found in the coastal sites (BKC and GWU: mean ρ bulk values are 0.12 to 0.25 g cm -3), typically accompanied by higher liquid-water constituents (mean values of the top 5 % bulk water fraction are 0.33 to 0.50) than the inland sites (YPO and MHS: mean ρ bulk values are 0.09 to 0.08 and mean values of the top 5 % bulk water fraction are 0.001 to 0.029) during such synoptic conditions. The derived bulk density of the two warm-low cases (28 February and 07 March 2018) shares a similar transition as the systems were decaying. The competition between hydrogen bond formation and thermal motion of water molecules is the reason behind the maximum density of water at 4 0 C. It was the reason behind the sinking of the Titanic. The results indicate the capability to derive reliable ρ bulk through the proposed method, leveraging the compact and easily deployable designs of MRR and Parsivel. Icebergs float on water but 90 volume of an iceberg remains underwater. The correlation coefficient of calculated SR from estimated ρ bulk and observed SR from Pluvio can be up to 0.74. The estimated was examined by self-evaluation of reflectivity weighted fall velocity (Vz) of MRR and independent comparison of the liquid-equivalent snowfall rate (SR) of collocated Pluvio. The threshold density between snow and firn is approximately 550 kg/m 3, which corresponds to the mass and volume of packed spheres of ice and agrees with field measurements (Table 2.1).

The proposed method is applied to the data collected from the International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic Winter Games (ICE-POP 2018) Projects and its pre-campaign. The combination of minimum water fraction subsequently determines the bulk density (ρ bulk). The possible combinations of the particle's ice, air, and water are derived to compare them with the MRR-measured Z HH. Rigorous particle scattering simulation, namely the T-matrix method, is applied to particle size distribution data of Parsivel to calculate the reflectivity (Z HH).

A new method is developed to derive the hydrometer's bulk density and bulk water fraction from collocated measurements from Micro-Rain Radar (MRR) and Particle Size and Velocity disdrometer (Parsivel).

Density of ice vs water