Investigation of Fog Structure Affected By Gravity Waves in the Mountainous Region of Pyeongchang, Korea, the Place for the 2018 Winter Olympics and Paralympics

Usually fog is known to be a passive phenomenon since cooling and moistening of air parcels near the surface has been its primary formation mechanism. This means that fog formation depends on environmental conditions. However, some studies suggest that fog becomes very active and dynamic, in that fog top radiative cooling due to fog droplets leads to destabilization, once fog is formed. The destabilization can produce a strong shear in the inversion layer and promote Kelvin-Helmholtz instability. In several studies, quasi-periodic oscillations of temperature, visibility, wind and water vapor, which have periods of 6-40 minutes, are observed to be related to both gravity waves and Kelvin-Helmholtz instability within the fog layer. Furthermore, a numerical study suggests that Kelvin-Helmholtz instability near the top of the fog layer may also affect fog microphysics. However, microphysical and dynamical processes of fog are not well-known and have non-linear relationships among processes that are related to fog formation. For these reasons, improving the accuracy of the fog forecasting/nowcasting system is challenging. We have an opportunity to enhance our understanding on fog processes over complex terrain during the ICE-POP (the International Collaborative Experiments for Pyeongchang 2018 Winter Olympics and Paralympics) campaign. For this purpose, we attempt to investigate Kelvin-Helmholtz instability within the fog layer and the fog microphysics affected by gravity waves using data from a Fog Monitor (FM-120) and meteorological instruments installed near the ground at the mountainous terrain of Pyeongchang, Korea during the ICE-POP campaign. More details will be presented at the conference.