실제 대기경계층 내에 놓인 언덕 지형 주위 유동은 단순 모델을 적용한 풍동 실험이나 수치해석 결과와 는 큰 차이가 발생한다. 승학산은 풍향각에 따른 협곡, 매우 가파른 언덕 및 급격한 언덕을 지나는 유동의 후류 특성 등에 대한 여러 가지 지형적 특징을 지니고 있다. 이와 같은 유동 특성을 분석하기 위해 50m 높이의 기상 타워를 설치하여 30m, 40m, 50m 에서의 풍속 및 풍향을 각각 10분 평균으로 측정하였다. 경계층 풍속 분포 측정 결과, 급격한 언덕을 가진 풍향각에서는 큰 구배를 가지는 풍속 분포가 측정되었다. 특정 풍향각에 대하여 난류강도 분포가 협곡과 가파른 언덕에서 큰 값을 관찰할 수 있었으며, 프로파일 법으로 계산된 표면조도 역시 지형적인 특성으로 인한 경계층 풍속 분포를 효과적으로 나타내었다. 반면 시간적으로 분류된 대기안정성이 유동에 끼치는 영향은 복잡한 지형적 특성으로 인해 열유동 현상이 크게 나타나지 않는 것을 확인할 수 있었다.

자연지형에 의한 기류 변화를 CFD 모델과 풍동실험을 통하여 비교 연구하였다. 해안에 인접한 남부 산악지 형을 대상으로 풍동실험과 몇 종류의 CFD 모델 시뮬레이션을 수행하였다. 사용한 CFD 모델은 2 가지로, 하나는 LES 난류모델을 사용하는 가상경계기법을 활용한 유한체적법(Finite Volume Method, FVM) 코드와또하나는 4 가지 RANS 난류모델이 선택사양으로 제공되는 상업용 CFD 모델이다. 지형에 의해 풍속이 증가되는 지점과 감소되는 지점에서 수 직풍속분포를 직접 비교하고 상관도를 구하였다. CFD 모델과 풍동실험과의 상관도(R)는 0.890~0.965로 매우 높게 나 타났으며, CFD 모델중 VBM LES CFD 모델은상관도 0.965로나타나풍동실험을가장잘모사하는것으로분석되었다.

Climate data were obtained over an eight-year period (July 2013 to June 2021) using an automatic weather observation system (AWS) installed at the foot of Mt. Geumo in Chilgok, Gyeongbuk. Using climate data, the statistical and meteorological characteristics of the local circulation between the Nakdong River and Mt. Geumo were analyzed. This study is based on automatic weather observation system data for Dongyeong, along with comparative climate data from the Korea Meteorological Administration (Chilgok) and the Gumi meteorological observatory. Over the eight- years, mountain and valley winds have occurred 48 times a year on average, with the highest occurring in May and the weakest winds in June and December. When mountain winds occurred, the temperature in the nearby lowland region more strongly decreased than when valley winds blew. However, the potential to use mountain winds to improve urban thermal environments is limited because mountain winds occur infrequently in summer when a drop in nighttime temperature is required.

The mean wind speed and turbulence intensity profiles in the atmospheric boundary layer were extracted from a LIDAR remote sensing campaign in order to apply for CFD validation. After considering the semi-steady state field data requirements to be used for CFD validation, a neutral atmosphere campaign period, in which the main wind direction and the power-law exponent of the wind profile were constantly maintained, was chosen. The campaign site at the Pohang Accelerator Laboratory, surrounded by 40~50m high hills, with an apartment district spread beyond the hills, is to be classified as a semi-complex terrain. Nevertheless, wind speed profiles measured up to 100m above the ground fitted well into a theoretical-experimental logarithmic-law equation. The LIDAR remote-sensing data of the sub-layer of the atmospheric boundary layer has been proven to be superior to the data obtained by conventional extrapolation of the wind profile with 2 or 3 anemometer measurements.

A system coupled the prognostic WRF mesoscale model and CALMET diagnostic model has been employed for predicting high-resolution wind field over complex coastal area. WRF has three nested grids down to 1km during two days from 24 August 2007 to 26 August 2007. CALMET simulation is performed using both initial meteorological field from WRF coarsest results and surface boundary condition that is Shuttle Radar Topography Mission (SRTM) 90m topography and Environmental Geographic Information System (EGIS) 30m landuse during same periods above. Four Automatic Weather System (AWS) and a Sonic Detection And Ranging (SODAR) are used to verify modeled wind fields. Horizontal wind fields in CM_100m is not only more complex but better simulated than WRF_1km results at Backwoon and Geumho in which there are shown stagnation, blocking effects and orographically driven winds. Being increased in horizontal grid spacing, CM_100m is well matched with vertically wind profile compared SODAR. This also mentions the importance of high-resolution surface boundary conditions when horizontal grid spacing is increased to produce detailed wind fields over complex terrain features.

As prevailing synoptic scale westerly wind blowing over high steep Mt. Taegulyang in the west of Kangnung coastal city toward the Sea of Japan became downslope wind and easterly upslope wind combined with both valley wind and sea breeze(valley-sea breeze) also blew from the sea toward the top of the mountain, two different kinds of wind regimes confronted each other in the mid of eastern slope of the mountain and further downward motion of downlsope wind along the eastern slope of the mountain should be prohibited by the upslope wind. Then, the upslope wind away from the eastern slope of the mountain went up to 1700m height over the ground, becoming an easterly return flow in the upper level of the sea. Two kinds of circulations were detected with a small one in the coastal sea and a large one from the coast toward the open sea. Convective boundary layer was developed with a thickness of about 1km over the ground in the upwind side of the mountain in the west, while a thickness of thermal internal boundary layer(TIBL) from the coast along the eastern slope of the mountain was only confined to less than 200m. After sunset, under no prohibition of upslope wind, westerly downslope wind blew from the top of the mountain toward the coastal basin and the downslope wind should be intensified by both mountain wind and land breeze(mountain-land breeze) induced by nighttime radiative cooling of the ground surfaces, resulting in the formation of downslope wind storm. The wind storm caused the development of internal gravity waves with hydraulic jump motion bounding up toward the upper level of the sea in the coastal plain and relatively moderate wind on the sea.

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 ㎞, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind field should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.