Observation and Simulation of Snow Particles in the Yeongdong Region of Korea

The Yeongdong region of the Korean Peninsula is vulnerable to high-impact weather events, because of its complicated geographical characteristics and East Sea effect, such that heavy snowfall episodes have frequently occurred in winter. Snow crystal play an important role in cloud and precipitation physics because it is an essential element for improvement of numerical model, and remote sensing retrieval such as radar and satellite. We have conducted an intensive measurement campaign of ‘Experiment on Snow Storms At Yeongdong (ESSAY)’ since 2013 using radiosonde soundings, several remote sensors, and a digital camera with a magnifier for taking a photograph of snowfall crystals in the region. MASC (Multi-Angle Snowflake Camera) was introduced to Korea in 2016 for the first time.

With the deployment of MASC, we had two snowfall episodes, which are Jan 27, and March 14, 2017. The 1st one with a thunder snowstorm was observed with an explosively developing Low pressure with the convective clouds reaching up to 9km. The dominant habit was riming particles, which changed into dendrite aggregates as the clouds became thin such as East-Sea effect snowflake. Interestingly the particle size distributions of riming-dominant crystals were narrow with its size decreasing, whereas those of dendrite-dominant crystals were broad with larger particles.

We also attempt to simulate two typical snowfall episodes that occurred on 23-24 February and 13-14 December 2016; one has a single-layered cloud and the other has two-layered cloud structure. This study demonstrates that the rimed particles in the first period tend to shift to aggregates of dendrites with the decrease of 850-hPa temperature. In general, the low-level clouds in the Yeongdong region are observed along with the distinctive wind shear and strong inversion in equivalent potential temperature around 2 ~ 3 km above the sea level. The simulation successfully represents the variations of the characteristics of snow particles as well as different cloud structure for both episodes. The observation and model simulations clearly suggest that snow particles primarily depend on the 850-hPa temperature.

These results will contribute to improving radar retrieval of snowfall and numerical simulations of amount and locations of snowfall in such a geographically complicated region along the coast like Yeongdong.