Jin-Yim Jeong

A Case Study on the Impact of Ground-based Glaciogenic Seeding on Winter Orographic Clouds at Daegwallyeong

The purpose of this study was to investigate the impact of ground-based glaciogenic seeding on orographic clouds in the Daegwallyeong area on 13 March, 2013. The experiments was conducted by releasing silver iodide (AgI) under following conditions: surface temperature below , wind direction between 45 and , and wind speed less than . Two seeding rates, (SR1) and (SR2), were tested to obtain an appropriate AgI ratio for snowfall enhancement in the Daegwallyeong area. Numerical simulations were carried out by using the WRF (Weather Research and Forecast) model with AgI point-source module which predicted dispersion fields of AgI particles. The results indicated that the target orographic clouds contained adequate amount of supercooled liquid water and that the dispersion of AgI particles tended to move along the prevailing wind direction. To validate the seeding effects, the observation data from FM-120 and MPS as well as PARSIVEL disdrometer were analyzed. In this case study, glaciogenic seeding significantly increased the concentration of small ice particles below 1 mm in diameter. The observation results suggest that SR1 seeding be reasonable to use the ground-based seeding in the Daegwallyeong area.

Microphysical properties of low-level clouds and fogs in a mountain area of South Korea

Measurements of microphysical properties in low-level clouds and fogs were carried out at Daegwallyeong in the northeastern mountainous region of South Korea. The microphysical characteristics are presented through analyzing the number concentration, mean diameter, liquid water contents and size distribution of cloud particles sampled with the groundbased Forward Scattering Spectrometer Probe (FSSP). The aim of this study is to analyze the influence of the proposed cloud condensation nuclei (CCN) type on the size and the number of cloud droplets. Observational cases are classified 5 sectors according to backward air mass trajectories from the NOAA/ARL HYSPLIT model. Clean maritime cloud is characterized by sector 1 trajectories and clean continental cloud is by sector 2. Contaminated maritime cloud is by sector 3 and contaminated continental cloud is by sector 4. Sector 5 trajectories are undefined air masses. On average, the droplet number concentrations in marine clouds were lower than for continental c...

Case Study of Ground-Based Glaciogenic Seeding of Clouds over the Pyeongchang Region

Ground-based glaciogenic seeding experiments were conducted at the Daegwallyeong Cloud Physics Observation Site (CPOS) from 2012 to 2015 for the target area Yongpyeong, which lies 9 km away. The preseeding (NOSEED) and seeding (SEED) periods were defined based on the simulation results of AgI concentration (>10 L−1) in the Weather Research and Forecast (WRF) model with the modified Morrison scheme in microphysics. It was difficult to determine whether snow enhancement via seeding occurred over the entire target area due to uncertainties associated with limitations such as observations and numerical model based on only two points (seeding and target sites). However, in three of four cases, the vertical reflectivity from micro rain radar, total concentration, and average size of snow particles observed at PARSIVEL and precipitation increased in the seeding effect time. In two of four cases, the simulated increased precipitation during the seeding effect time was also observed. In one case that did not show changes after seeding, it is analyzed that a sufficient cloud depth was not supplied to the seeding region due to the blocking effect of the Taebaek Mountains.