Study on Characteristics of Snow Particle with the Different Meteorological Conditions in the Mountainous Region (Yeongdong) of Korea

The mountainous region (Yeongdong) of Korea has sometimes meteorological disasters such as breakdown accidents due to heavy weight of accumulated snow, and traffic accidents due to slippery road condition in winter. Determining the occurrence and phase of precipitation is a major challenge in winter weather forecasting over the complex terrain. Snow particles as a basic element of solid precipitation play an important role in cloud and precipitation physics. However, there have been very few studies on cold clouds and snow particles in the mountainous region. Therefore, this study investigates the characteristics of snow particles and snowfall with the different meteorological conditions based on the combined integration of numerical modeling and upper-air observations. We used the temporally high-resolution dataset of rawinsonde soundings and snow particle photographs for snowfall episode of two-layered cloud structure that occurred on 29-30 January, 2016. We found out that rimed particles tend to turn into dendrite-like particles as 850-hPa temperature decreases with time. Rawinsonde soundings showed well-defined low-level clouds around 2 ~ 3 km along with distinctive wind directional shear and strong inversion in equivalent potential temperature above the cloud layer. Sensitivity experiments were also carried out to investigate the effects of various meteorological factors on snow particle characteristics using a high resolution cloud resolving model, namely Cloud Resolving Storm Simulator (CReSS). First, temperature (TEMP) experiment based on the real test showed a significant difference in precipitation type such as increase (3.5 times) in graupel in the first period and increase (6.5 times) in snow in the second period, compared with the control (CTRL) experiment. The result of snow particle characteristics did not change with removing upper cloud layer. After all, snow particle characteristics appear to primarily depend upon temperature.