The purpose of this study is to clarify the effect of mountain-valley wind on heat island formed in urban area which is located around valley mouth. The meteorological observations were carried out over the Dalbi-valley under a clear summer pressure patterns, and some consideration were tried from the results. In order to make clear the climatological characteristics and air-mass modification process of the mountain-valley wind over the valley, the meteorological observations were done simultaneously at two points. The observational points were located at the breast and valley mouth parts, respectively. The results were as follows: First, it was found that the valley wind was observed through the daytime, and it was replaced by a mountain wind after sunset. Second, the heat budget is also investigated with observation data. The sensible heat flux over the breast of Dalbi-valley reached to about 200during daytime, which is a little more than one third of net radiation. On the other hand, the sensible heat flux represented negative values during nighttime. But the sensible heat flux over the valley mouth covered by asphalt showed plus value(about 20～30) during the nighttime.

We identified two characteristic turbulent flow cases, weakening and strengthening, which appear at the downwind side. Observations were made two times, Dec. 2-3. 1995 and Feb. 13-14. 1996 at Pusan National University site located downwind side of Kumjeong mountain. Meteorological observation system, tethersonde, was adopted to present observation. In the case of the west wind which blows perpendicular to Sanghak mountain located westward from the site, the wind speed highly increased in exponential with height. Therefore, the low level wind speed was so weak just like Taylor(1988)`s review. While the wind speed was intensified at 200-400m layer when the northwest wind blows from the continental Siberian high. We suppose it is because of the strong vertical convergence of flow between the surface inversion layer and the upper one, and also the horizontal convergence along the saddle and valley between the two mountains, Kumjeong and Sanghak-because of Bernoulli`s effect. The inversion layer existed at surface-100m and 500-600m level and the strong wind existed at about 200-400m layer.