Modeling study of vertical structure of coastal boundary layer under sea breeze condition.

We evaluated the performance of the Weather Research and Forecasting (WRF) modelin simulating the boundary layer structure at a coastal site in Boseong, South Korea on 15 July 2018 against observations made using a radiosonde. The study site is located on the southern coast of the Korean peninsula. Although the area a few kilometers around the site is flat, it is surrounded by mountains and faces the sea to the southeast. WRF model reproduced the circulation of the land-sea breeze, but the timing of sea breeze was not well captured. Onset of sea breeze was delayed and cessation of sea breeze appeared early in the simulation. Strong westerly delayed onset of sea breeze in the morning. The simulated winds rotated in a clockwise with time in the lower boundary layer, which was consistent with observation but the simulated rotation rate of winds was faster than the observation, resulting in an earlier cessation of the sea breeze. The simulated virtual potential temperature profile were compared with observations. Large discrepancies between simulation and observation were noted at 1500 and 1800 LST. The model did not simulate thermal internal boundary layer (TIBL) at 1500 and showed early decay of PBL at 1800 LST. The causes for the discrepancies between model and observation have been discussed.