• 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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• 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.

• 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.

• 한국방재학회 논문집
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• 제9권5호
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• pp.103-113
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• 2009

본 연구에서는 관측소의 지리적 위치 및 강수특성(월별, 계절별, 연평균)을 이용하여 강원도의 강수지역을 구분하였다. 강수지역 구분은 기상관측소 66개소(기상관서: 11개소, 자동기상시스템(AWS): 55개소)의 자료를 이용하였으며, 통계적 방법 중 군집 기법인 K-means 방법을 적용하였다. 지역구분 결과, 강수지역은 5개 지역(영동지방 1개 지역 및 영서지방 4개 지역)으로 구분하였다. 계절별 평균강수량은 봄에는 강원도 전체에 유사하게 발생하였으며, 여름에는 영서지방이 높게 나타났으며, 가을과 겨울에는 영동지방이 높게 발생하였다. 연평균 강수량 및 여름철 강수량의 공간분석 결과 강원도 중 일부 지역(미시령 및 대관령일원)은 산악형 강수 특성을 나타냈으나 전반적인 현상은 아닌 것으로 판단되었다. 그러나 보다 정확한 분석을 위해서는 관측소의 고도별 분포가 미흡한 것으로 나타난 관측소의 보완 및 AWS의 자료 확충이 필요할 것으로 판단된다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제1권1호
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• pp.45-50
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• 1997

Understanding the nonlinear flow caused by orographic effects can be valuable in siting of new businesses, industries, and transportation facilities. In spite of recent work on large-amplitude waves and wave breaking, the studies of flow around large scale mountains have just begun. The generative mechanism of lee vortices in the lee of large scale mountain is investigated by Ertel's theorem. The CSU RAMS is used as a numerical model. According to the numerical results, the isentropes are depressed behind the large scale mountains. This means the vortex lines must run upward and downward along the depression surface because vortex lines adhere to isentropic surfaces. Therefore, the vertically oriented vorticity can be formed in the lee of the large scale mountain. This vorticity plays an important role for orographic precipitation, because strong vertical velocity and cloud bands are developed along isothermal deformation surface.

• 한국환경과학회지
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• 제1권1호
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• pp.45-50
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• 1992

Understanding the nonlinear flow caused by orographic effects can be valuable in siting of new businesses, industries, and transportation facilities. In spite of recent work on large-amplitude waves and wave breaking, the studies of flow around large scale mountains have just begun. The generative mechanism of lee vortices in the lee of large scale mountain Is investigated by Ertel's theorem. The CSU RAMS is used as a numerical model. According to the numerical results, the isentropes are depressed behind the large scale mountains. This means the vortex lines must run upward and downward along the depression surface because vortex lines adhere to isentropic surfaces. Therefore, the vertically oriented vorticity can be formed in the lee of the large scale mountain. This vorticity plays an important role for orographic Precipitation, because strong vertical velocity and cloud bandy are developed along isothermal deformation surface.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1171-1173
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• 2003

There are two datasets to estimate the area-mean and time-mean precipitation rate. For one, an array of surface rain gauges represents a series of rods that have to the time axis of the volume. And another data is that of a remote sensing make periodic overpasses at a fixed interval such as radar. The problem of optimally combining data from surface rain gauge data and remote sensed data is considered. In order to combining remote sensed data with Automatic Weather Station (AWS), we use optimal weighting method, which is similar to the method of [2]. They had suggested optimal weights that minimized value of the mean square error. In this paper, optimal weight is evaluated for the cases such as Changma, summer Monsoon, Typhoon and orographic rain.

• 한국환경과학회지
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• 제28권10호
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• pp.841-849
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• 2019

The purpose of this study was to evaluate the method of estimating the areal precipitation reflecting the altitude of the mountainous terrain on Jeju Island by comparing and analyzing the areal precipitation using the Thiessen polygon method and the isohyetal method in mountainous streams. In terms of constructing the Thiessen polygon network, rainfall errors occurred in 94.5% and 45.8% of the Thiessen area ratio of the Jeju and Ara stations, respectively. This resulted in large areal precipitation and errors using the isohyetal method at altitudes below 600 m in the target watershed. In contrast, there were small errors in the highlands. Rainfall errors occurred in 18.91% of the Thiessen area ratio of Eorimok, 2.41% of Witseoreum, and 2.84% of Azalea Field because of the altitudinal influence of stations located in the highlands at altitudes above 600 m. Based on the areal precipitation estimation using the Thiessen polygon method, it was considered to be partially applicable to streams on Jeju Island depending on the altitude. However, the method is not suitable for mountainous streams such as the streams on Jeju Island because errors occur with altitude. Therefore, the isohyetal method is considered to be more suitable as it considers the locations of the rainfall stations and the orographic effect and because there are no errors with altitude.

• 대기
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• 제32권2호
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• pp.135-148
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• 2022

This study investigates the influence of atmospheric river (AR) on precipitation over South Korea with a focus on regional characteristics. The 42-year-long catalog of ARs, which is obtained by applying the automatic AR detection algorithm to ERA5 reanalysis data and the insitu precipitation data recorded at 56 weather stations across the country are used to quantify their relationship. Approximately 51% of the climatological annual precipitation is associated with AR. The AR-related precipitation is most pronounced in summer by approximately 58%, while only limited fraction of precipitation (26%) is AR-related in winter. The heavy precipitation (> 30 mm day^-1) is more prone to AR activity (59%) than weak precipitation (5~30 mm day^-1; 33%) in all seasons. By grouping weather stations into the four sub-regions based on orography, it is found that the contribution of AR precipitation to the total is largest in the southern coast (57%) and smallest in the eastern coast (36%). Similar regional variations in AR precipitation fractions also occur in weak precipitation events. The regional contrast between the northern and southern stations is related to the seasonal variation of AR-frequency. In addition, the regional contrast between the western and eastern stations is partly modulated by the orographic forcing. The fractional contribution of AR to heavy precipitation exceeds 50% in all seasons, but this is true only in summer along the eastern coast. This result indicates that ARs play a critical role in heavy precipitation in South Korea, thus routine monitoring of ARs is needed for improving operational hydrometeorological forecasting.

• 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.