Impact of the Land-Sea Temperature Contrast on the Snowfall Structure over the Western Coastal Region of the Korean Peninsula

Abstract

In this study, the structure of the typical snowfall which is caused by air-mass modification and is confined over the western coastal region of the Korean Peninsula is investigated using the Weather Research and Forecasting model. In the case of the western coastal snowfall, there are many cases wherein the clouds are confined offshore and do not penetrate inland. Therefore, to clarify the structures related to the snowfall penetration, four experiments are performed with different land-surface air temperature. In the control experiment, the horizontal temperature contrast is observed to establish a density barrier over the coastal region, which induces the upward motion that develops snowfall. However, the density barrier blocks the horizontal inland wind flow, which confines the snowfall over the offshore region. To examine the role of the density barrier, three additional experiments are performed with different 2- m air temperature over land. Intensified horizontal temperature contrast is found to induce a strong density barrier and upward motions over the upstream region of the density barrier, which enhances local snowfall. Additionally, the strong density barrier acts as a blocking wall, which interrupts the inland penetration of the snowfall. When the temperature contrast is weakened, the snowfall intensity is reduced but the snowfall is able to penetrate further inland, meaning that the horizontal land/sea temperature contrast is an important factor for the forecasting of the snowfall over the western coastal region of the Korean Peninsula.