• 한국수자원학회논문집
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• 제48권5호
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• pp.393-407
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• 2015

본 연구에서는 충주댐 유역을 대상으로 레이더 자료를 이용하여 호우의 산지효과 특성을 분석하였다. 먼저 적절한 무강우 기간과 절단값을 결정하여 독립호우사상을 선정하였다. 이러한 독립호우사상으로부터 산지효과의 발현 여부를 판단할 주요호우사상을 선정하였다. 또 레이더 자료를 이용하여 전체 기간과 호우중심 기간의 평균반사도를 산정하고, 산지 부근의 반사도와 평균반사도를 비교하여 반사도의 변화를 분석하였다. 아울러 본 연구에서는 호우의 특성인자를 선정하고 로지스틱 회귀분석을 수행하여 충주댐 유역 호우의 산지효과 발현 조건을 확인하였다. 그 결과를 정리하면 다음과 같다. 먼저 산악 지역을 통과하는 호우의 이동선상에서의 반사도 변화를 검토한 결과 호우의 시작 지점에 비하여 산악 지역에서의 반사도가 증가한 것으로 확인되었다. 둘째, 산지효과 발현 조건을 탐색하기 위해 로지스틱 회귀분석을 수행한 결과 충주댐 유역에서는 임계값이 호우의 이동속도 4km/hr, 접근각도 $90^{\circ}{\pm}5^{\circ}$, 강우강도 4mm/hr인 경우에 산지효과의 발현 여부 적중률이 가장 높은 것으로 확인되었다.

• 대기
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• 제18권4호
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• pp.367-386
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• 2008

The Weather Research and Forecasting (WRF) model was designed to identify the role of the Taebaek Mountains in the occurrence of heavy snowfall in Yeongdong area with a strong northeast wind on January 20-21, 2008. To this end, in addition to the control simulation with the realistic distribution of the Taebaek Mountains, a sensitivity experiment that removed the orography over the Taebaek Mountains was performed. The control simulation results showed that the resulting wind field and precipitation distribution were similar to what were observed. Results from the sensitivity experiment clearly demonstrates the presence of orographic lifting on the windward slope of the mountains. It is concluded that the altitude of the Taebaek Mountains is the main controlling factor in determining the distribution and amount of precipitation in the Yeongdong area for the case of heavy snowfall in January 2008.

• 한국수자원학회논문집
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• 제42권6호
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• pp.465-480
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• 2009

본 연구에서는 다중회귀분석을 이용하여 산악효과를 야기하는 지형인자와 강수와의 관계를 파악하였다. 섬 전체가 산악지형인 제주도의 연평균강수량과 지수홍수법으로 산출한 확률강우량을 강수자료로 사용하여 산악효과를 야기하는 지형인자로 선정한 고도, 위 경도와 회귀모형을 구성하였다. 회귀분석 결과 연평균강수량과 고도와의 선형관계가 확률강우량에서도 동일하게 나타났으며, 고도이외에 위도, 경도를 각각 추가인자로 고려할 경우 강우량과 더욱 강한 상관성을 보였다. 또한, 고도와 위도, 경도를 모두 고려한 회귀모형을 이용한 지형공간분석 결과 제주도의 실제 강수특성과 마찬가지로 남동부로 편중된 강수형태를 보여 모형의 적합성을 증명하였다. 그러나 지속시간 및 재현기간과 무관하게 높은 고도에서 회귀식의 유효성이 감소하므로, 높은 고도에서의 추가적인 산악효과인자의 강수량에 대한 영향이 존재될 것으로 판단되므로 추후 연구가 필요하다.

• 대기
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• 제19권4호
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• pp.345-370
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• 2009

Numerical experiments using the Weather Research and Forecasting (WRF) model were done to identify the role of the mountain ranges in the northern part of the Peninsula (referred as "the northern mountain complex"), in the occurrence of two heavy snowfall events over the Yeongdong region on 7-8 December 2002 and 20-21 January 2008. To this end, control simulations with the topography of the northern mountain complex and other simulations without the topography of the mountain complex were performed. It was revealed that the amount of snowfall over the Yeongdong region from the control simulation much more exceeded that of the simulation without the topography of the mountain complex. This increase of the snowfall amount over the Yeongdong region can be explained as follows: As the upstream flow approached the northern mountain complex, it deflected around the northern mountain complex due to the blocking effect of the mountains with a low Froude number less than ~0.16. This lead to the strengthening of northeasterly over the East Sea and over the Yeongdong region. The strong northeasterly is accompanied with much more snowfall over the Yeongdong region by intensifying air-mass modification over the sea and the orographic effect of the Taeback mountains. Thus, it was concluded that the topography of the northern mountain complex is one of the main factors in determining the distribution and amount of precipitation in the Yeongdong region when there is an expansion of the Siberian High toward the East Sea.

• 한국환경과학회지
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• 제25권5호
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• pp.705-713
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• 2016

This study investigates the concentration sudden rise in fine particle according to resuspended dust from paved roads after sudden heavy rain in Busan on August 25, 2015. The localized torrential rainfall in Busan area occurred as tropical airmass flow from the south and polar airmass flow from north merged. Orographic effect of Mt. Geumjeong enforced rainfall and it amounted to maximum 80 mm/hr at Dongrae and Geumjeong region in Busan. This heavy rain induced flood and landslide in Busan and the nearby areas. The sudden heavy rain moved soil and gravel from mountainous region, which deposited on paved roads and near roadside. These matters on road suspended by an automobile transit, and increased fine particle concentration of air. In addition outdoor fine particle of high concentration flowed in indoor by shoes, cloths and air circulation.

• 통합자연과학논문집
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• 제7권3호
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• pp.214-218
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• 2014

The main objective of this study is to analyse the influence factors of snowfall enhancement by glaciogenic seeding in a mountainous area. Twenty-five seeding experiments have been conducted during the period of February to April 2010. To use two rates seeding experiments (SR1: $1.04g\;min^{-1}$, SR2: $2.08g\;min^{-1}$) have been tested to get an appropriate ratio for snowfall enhancement at Daegwallyeong area. The conditions of seeding are able as followings: surface temperature <$0^{\circ}C$, wind speed <5 m/s, wind direction between 0 and $130^{\circ}$. The experiment results indicated that in the case of SR1 was more effective than SR2. The number of small ice particles below 1.0 mm was increased during seeding period measured by PARSIVEL disdrometer near generator. Most of snowfall enhancement by seeding was observed the inflow of the easterly wind blew in toward Gangwon regions from the East Sea and the supersaturated supercooled liquid water due to orographic effect.

• 대기
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• 제22권1호
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• pp.57-71
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• 2012

Influences of orographic and ocean effect, which depend on the detailed geographic characteristics, upon winter time (December-February) precipitation in the Yeongdong region are investigated. Most of precipitation events in the Yeongdong region during the wintertime are associated with moist northeasterly (coming from the northeast direction) winds and also the spatial distribution of precipitation shows a great difference between Mountain area (Daegwallyeong) and Coastal area (Gangneung). The linear correlation coefficient between the meteorological variables obtained from NCEP/NCAR Reanalysis Data and precipitation amount for each precipitation type is calculated. Mountain type precipitation is dominated by northeasterly wind speed of the low level (1000 hPa and 925 hPa) and characterized with more precipitation in mountain area than coastal area. However, Coastal type precipitation is affected by temperature difference between ocean and atmosphere, and characterized with more precipitation in coastal area than mountain area. The results are summarized as follows; In the case of mountain type precipitation, the correlation coefficient between wind speed at 1000 hPa (925 hPa) and precipitation amount at Daegwallyeong is 0.60 (0.61). The correlation is statistical significant at 1% level. In the case of coastal type precipitation, the correlation coefficient of temperature difference between ocean and 925 hPa (850 hPa) over the East sea area and precipitation amount at Gangneung is 0.33 (0.34). As for the mountain type precipitation, a detailed analysis was conducted in order to verify the relationship between precipitation amount at Daegwallyeong and low level wind speed data from wind profiler in Gangneung and Buoy in the East Sea. The results also show the similar behavior. This result indicates that mountain type precipitation in the Yeongdong region is closely related with easterly wind speed. Thus, the statistical analysis of the few selected meteorological variables can be a good indicator to estimate the precipitation totals in the Yeongdong region in winter time.

• 한국환경과학회지
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• 제15권12호
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• pp.1141-1154
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• 2006

Orographic effect is one of the important factors to induce Local circulations and to make atmospheric turbulence, so it is necessary to use the exact topographic data for prediction of local circulations. In order to clarify the sensitivity of the spatial resolution of topography data, numerical simulations using several topography data with different spatial resolution are carried out under stable and unstable synoptic conditions. The results are as follows: 1) Influence of topographic data resolution on local circulation tends to be stronger at simulation with fine grid than that with coarse grid. 2) The hight of mountains in numerical model become mote reasonable with high resolution topographic data, so the orographic effect is also emphasized and clarified when the topographic data resolution is higher. 2) The higher the topographic resolution is, the stronger the mountain effect is. When used topographic data resolution become fine, topography in numerical model becomes closer to real topography. 3) The topographic effect tends to be stronger when atmospheric stability is strong stable. 4) Although spatial resolution of topographic data is not fundamental factor for dramatic improvement of weather prediction accuracy, some influence on small scale circulation can be recognized, especially in fluid dynamic simulation.

• 한국환경과학회지
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• 제12권12호
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• pp.1245-1254
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• 2003

A numerical simulation for 11 February 1996 has been done to grasp main mechanisms of the occurrence of strong downslope winds near Gangnung area. The simulation performed by using ARPS (Advanced Regional Prediction System) showed that enhanced surface winds were not related with a reflection of vertically propagating gravity waves. Froude numbers were about 1.0, 0.4 and 0.6 for the atmosphere above Daekwanryoung and above a place located 220km upstream, and above another place located 230km downstream from the Taebak mountains, respectively. This suggested that as a subcritical flow ascended the upslope side of the Taebak mountains, Froude numbers would tend to increase according to the increase in wind speed, and near the crest the flow would become supercritical and continue to accelerate as it went down the downslope side until it was adapted back to the ambient subcritical conditions in a turbulent hydraulic jump. Simulated Froude numbers corroborated the hydraulic jump nature of the strong downslope wind. In addition, the inversion was found near the mountain top height upstream of the mountains, and it was favorable for the occurrence of strong downslope winds.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.244-252
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• 2021

Wind plays an important role in cases of unexpected radioactive pollutant dispersion, deciding distribution and concentration of the leaked substance. The accurate prediction of wind has been challenging in numerical weather prediction models, especially near the surface because of the complex interaction between turbulent flow and topographic effect. In this study, we investigated the characteristics of atmospheric dispersion of radioactive material (i.e. ¹³⁷Cs) according to the simulated boundary layer around the HANARO research nuclear reactor in Korea using the Weather Research and Forecasting (WRF)-Mesoscale Model Interface (MMIF)-California Puff (CALPUFF) model system. We examined the impacts of orographic drag on wind field, stability calculation methods, and planetary boundary layer parameterizations on the dispersion of radioactive material under a radioactive leaking scenario. We found that inclusion of the orographic drag effect in the WRF model improved the wind prediction most significantly over the complex terrain area, leading the model system to estimate the radioactive concentration near the reactor more conservatively. We also emphasized the importance of the stability calculation method and employing the skillful boundary layer parameterization to ensure more accurate low atmospheric conditions, in order to simulate more feasible spatial distribution of the radioactive dispersion in leaking scenarios.