Numerical study of sea fogs off the west coast of the Korean Peninsula using a Single Column Model coupled with WRF

Sea fog is a weather phenomenon that usually occurs below a marine boundary layer. Over the past several decades, efforts have been made to understand clearly the physical mechanisms of formation, evolution and dissipation of sea fogs using numerical modeling. Recently, 3D numerical simulations with a very high horizontal and vertical resolution have been carried out using mesoscale models to identify the influences of the turbulent mixing within PBL, radiative cooling at the fog top, even aerosols, on the formation of sea fogs. However, expensive computation cost is a big concern for these 3D model simulations with high resolution. Alternatively approach is to use a 1D model, i.e., single column model. However, a typical 1D model does not resolve the horizontal advection and pressure gradient force and therefore it is limited to radiation fog studies. More recent approach is to couple a 1D model with a 3D model to compensate for the limitation of a 1D model. In this study, WRFV3.1.1 is used as a 3D model and Cloud Layers Unified By Binormals (CLUBB) is employed as a 1D model. For the 3D simulation, three nested domains of 18 km, 6 km, 2 km are used along with 64 layers in the vertical. Horizontal advections of heat and moisture, geostrophic winds and vertical motion produced every hour from WRFV3.1.1 are provided as an external forcing into the 1D model, CLUBB. CLUBB is designed for studying stable boundary layer as well as convective boundary layer and also supports sophisticated double moment microphysics (e.g., Khairoutdinov and Kogan scheme, and Morrison scheme). Several sea fog events observed in the eastern part of the Yellow Sea near the west coast of Korea are simulated and the effects of radiative cooling and turbulence are examined and a sensitivity tests of microphysics are done using CLUBB. Detailed results will be presented in the conference.