The influence of topography on wind over the Sea of Japan

Wind is the critical factor in determining regional weather patterns and climate. Also, winds over the ocean directly effect the exchange of heat, moisture and gases between the atmosphere and the ocean surface. In this paper, the wind distribution over the Sea of Japan is analyzed by using wind data observed by the NASA Scatterometer (NSCAT). A synoptic view of the wind fields over the Sea of Japan is provided in January 1997. Remarkable evidence of a land topography effect is shown as a convergence of the surface wind field during cold-air outbreaks. The Changbai mountains are located in North Korea upstream of the outbreak winds, and the wind field was deformed by them over the western part of the Sea of Japan. Strong northwesterly winds (westerly winds) of about 16 to 20 m/s were observed off Vladivostok (the Korea Peninsula). They converge while blowing over the sea. A wind shadow, in which the wind speed is less than 8 m/s, is seen downwind of the mountains and extends more than 200 km. Numerical experiments using a three-dimensional local circulation model were performed to investigate the formation mechanisms of the outbreak-wind deformation. The results shows that the land topography is essential to form the convergence of the surface winds observed by NSCAT.