The intensive meteorological observations including pibal balloon at Ungcheon, airsonde and 10m meteorological tower observations at Gulup-Do, where are located in the western coastal region, are taken to investigate the characteristics of the upper and lower atmospheric structure and the local circulation pattern during the period of 17 to 22 September 1996. The diurnal variations of weather elements(i.e, air temperature, humidity, pressure, and wind speed) at Gulup-Do are analyzed and discussed with those at four inland meteorological stations. The vertical profiles of wind vector, orthogonality(Ω), and shear obtained from the pibal observations are also presented to examine the change of wind structure according to the synoptic-scale pressure system`s movement. The diurnal temperature changes at Gulup-Do are more sensitive than that of inland meteorological stations in case of the inflow of southwesterlies but are not dominant due to the ocean effect under the influence of relatively cold northerlies. A well defined mixed layer is developed from the 500m to the maximum 1700m with a significant capping inversion layer on the top of it. It can be found from the vertical profiles of wind vector that the wind become generally strong at the interface heights between cloud layers and non-cloud layers. The maximum wind shear is appeared at the height where the variation of wind direction induced by the passage of synoptic-scale pressure system is accompanied with the increase of wind speed. Based on the wind orthogonality, the change of wind direction with height is more complicated in cloudy day than in clear day. In case of a fair weather, the change of wind direction is showed to be at around 2㎞