• 한국환경과학회지
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• 제7권3호
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• pp.335-348
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• 1998

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 Und speeds at Gulup-Do are analyzed and discussed with those at four inland meteorological stations. The vertical profiles of wind vector, ortho- gonality(Ω), and shear obtained from the pibal obsenrations are also presented to examine the change of wand 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 mow 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 lay- ers and non-cloud layers. The maximum Und shear Is appeared at the bel각t where the varlauon of wand direction Induced by the passage of synoptic-scale pressure system Is accompanied with the In- crease of Und 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 wand direction is showed to be at around 2km.

• 한국농림기상학회지
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• 제6권1호
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• pp.49-60
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• 2004

Northern Gyeonggi Province(NGP), consisting of 3 counties, is the northernmost region in South Korea adjacent to the de-militarized zone with North Korea. To supplement insufficient spatial coverage of official climate data and climate atlases based on those data, high-resolution digital climate models(DCM) were prepared to support weather- related activities of residents in NGP Monthly climate data from 51 synoptic stations across both North and South Korea were collected for 1981-2000. A digital elevation model(DEM) for this region with 30m cell spacing was used with the climate data for spatially interpolating daily maximum and minimum temperatures, solar irradiance, and precipitation based on relevant topoclimatological models. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Daily solar irradiances over sloping surfaces were estimated from nearby synoptic station data weighted by potential relative radiation, which is the hourly sum of relative solar intensity. Precipitation was assumed to increase with the difference between virtual terrain elevation and the DEM multiplied by an observed rate. Validations were carried out by installing an observation network specifically for making comparisons with the spatially estimated temperature pattern. Freezing risk in January was estimated for major fruit tree species based on the DCMs under the recurrence intervals of 10, 30, and 100 years, respectively. Frost risks at bud-burst and blossom of tree flowers were also estimated for the same resolution as the DCMs.

• 대기
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• 제26권2호
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• pp.321-336
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• 2016

Damages caused by torrential rain occur every year in Korea and summer time convection can cause strong thunderstorms to develop which bring dangerous weather such as torrential rain, gusts, and flash flooding. On 6 August 2013 a sudden torrential rain concentrated over the inland of Southern Korean Peninsula occurred. This was an event characterized as a mesoscale multicellular convection. The purpose of this study is to analyze the conditions of the multicellular convection and the synoptic and mesoscale nature of the system development. To this end, dynamical and thermodynamic analyses of surface and upper-level weather charts, satellite images, soundings, reanalysis data and WRF model simulations are performed. At the beginning stage there was a cool, dry air intrusion in the upper-level of the Korean Peninsula, and a warm humid air flow from the southwest in the lower-level creating atmospheric instability. This produced a single cell cumulonimbus cloud in the vicinity of Baengnyeongdo, and due to baroclinic instability, shear and cyclonic vorticity the cloud further developed into a multicellular convection. The cloud system moved southeast towards Seoul metropolitan area accompanied by lightning, heavy precipitation and strong wind gusts. In addition, atmospheric instability due to daytime insolation caused new convective cells to develop in the upstream part of the Sobaek Mountain which merged with existing multicellular convection creating a larger system. This case was unusual because the system was affected little by the upper-level jet stream which is typical in Korea. The development and propagation of the multicellular convection showed strong mesoscale characteristics and was not governed by large synoptic-scale dynamics. In particular, the system moved southeast crossing the Peninsula diagonally from northwest to southeast and did not follow the upper-level westerly pattern. The analysis result shows that the movement of the system can be determined by the vertical wind shear.

• 한국지구과학회지
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• 제24권3호
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• pp.181-189
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• 2003

이 연구는 일본 중서부 지방에서 1996년 겨울철에 발생한 뇌우의 관측 자료를 분석한 것이다. 관측기간 중 35 회의 뇌우가 발생하였으며 발생된 뇌 방전 수는 4426개였다. 관측된 뇌 방전 수를 뇌 방전 종별로 구분하여 그 발생비율을 구하였고, 뇌 방전의 종류와 기압배치와의 관계도 분석하였다. 그 결과 구름 뇌 방전의 비율은 약 78%이었으며, 양극성 낙뢰가 42.3%로 나타났다. 동계의 낙뢰활동은 미약하나 0${\sim}$5시에 가장 강하였다. 또한, 낙뢰는 북서 계절풍이 강한 경우에 활발하게 발생되고 있음을 알 수 있었다. 다중뇌와 다지점 낙뢰의 분석결과 평균 다중도는 1.4이고, 평균 다지점 낙뢰는 1.2로 나타났다.

• 대한지리학회지
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• 제52권1호
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• pp.1-13
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• 2017

이 연구에서는 서울의 1941~1970년과 1971~2000년의 평균 일최저기온의 차이와 이의 조화파 합성에서 11월 중순의 기온 상승기(온난기)와 11월 하순의 기온 정체기(한랭기)를 설정하고, 온난기와 한랭기의 평균기온의 경년변화와 이에 영향을 미치는 종관장의 특성을 조사하였다. 온난기에는 시베리아 고기압, 주변 해면기압과 925hPa 면의 바람장 등에 기온 상승에 상응하는 경년변화가 나타나지 않는다. 온난기 기온이 높은 시기(1972~1979)에는 우리나라 북부를 중심으로 고기압 편차와 고기압성 회전 편차가 나타나 겨울철 계절풍이 약화되어 기온이 상승하는 온난기가 나타나는 것으로 판단된다. 한랭기에는 시베리아 고기압은 약화되고 있으나 홋카이도 동쪽 저기압이 강화되고 우리나라 부근의 서풍이 강화되어 우리나라의 기온 상승이 억제되거나 하강하는 것으로 나타났다.

• 대기
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• 제16권3호
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• pp.225-234
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• 2006

Convective systems propagate eastward with a persistent pattern in the longitude-time space. The characteristic structure and fluctuation of convective system is helpful in determining its predictability. In this study, convective index (CI) was defined as a difference between GOES-9 window and water vapor channel brightness temperatures following Mosher (2001). Then the temporal-spatial scales and variational characteristics of the summer convective systems in the East Asia were analyzed. It is found that the average moving speed of the convective system is about 14 m/s which is much faster than the low pressure system in the summer. Their average duration is about 12 hours and the average length of the cloud streak is about 750km. These characteristics are consistent with results from other studies. Although the convective systems are forced by the synoptic system and are mostly developed in the eastern edge of the Tibetan Plateau, they have a persistent pattern, i.e., appearance of the maximum intensity of convective systems, as they approach the Korean Peninsula. The consistency of the convective systems, i.e., the eastward propagation, suggests that there exists an intrinsic predictability.

• 한국농림기상학회지
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• 제21권4호
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• pp.366-372
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• 2019

북한 지역은 남한에 비해 기상관측 지점이 매우 적기 때문에 남한에서 강수 추정에 주로 이용되는 PRISM 모형을 그대로 적용하여 강수분포를 추정하기는 어렵다. 이처럼 자료가 불충분한 지역의 강수분포를 추정하기 위하여, 저해상도 PRISM 모형 구동 결과에 강수-지형 관계에 근거한 보정 값을 적용해 강수 분포를 추정할 수 있는 하이브리드 방식이 개발되어 사용되고 있다. 본 연구에서는 기존 북한지역의 고해상도 강수 분포도 추정 방식을 개선된 방법에 따라 1981-2010년 평년 기간의 적산 강수량 분포도를 제작하고자 하였다. 우선, 남한지역의 270m 해상도 DEM과 종관관측지점의 고도값으로부터 IDW한 가상지형간의 편차(고도편차)를 계산하였다. PRISM 모형을 이용하여 종관관측지점의 강수량을 기반으로 2,430m의 저해상도 가상강수 분포도를 제작한 후, 종관 및 방재 기상 관측지점의 강수자료를 이용해 270m의 고해상도 강수분포도를 제작하여 둘 간의 편차(강수편차)를 계산하였다. 남한지역의 고도편차와 강수편차를 이용하여 4방위 경사향에 따른 월별 강수-지형 관계 회귀식을 도출하였고, 최종적으로 북한지역의 27개 기상 관측지점으로부터 PRISM 모형을 구동하여 만든 2,430m의 저해상도 강수분포도에 강수-지형간 회귀식을 반영하여 해상도가 향상된 강수분포도를 산출하였다. 새롭게 제작된 북한지역의 강수분포는 기존 강수분포도와 비교했을 때 지형의 영향이 더욱 잘 반영된 효과를 확인할 수 있었다. 강수분포도에 따르면, 연평균 적산강수량은 1,159mm이며, 표준편차는 253mm로 추정되었다.

• 한국환경과학회지
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• 제23권10호
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• pp.1673-1691
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• 2014

Although most natural disaster related studies conducted in Korea recently have been related to typhoons or severe rainstorms, the occurrence frequency of disasters due to windstorms or rainstorms is also high. To reduce the strong wind damage caused by strong windstorms due to climate change, basic studies of strong winds are necessary. Therefore, in this study, the types and representative cases of windstorms that were observed to have been higher than 14 m/s, which is the criterion for strong-wind warnings from the Korea Meteorological Administration, were selected from among those windstorm cases that occurred on the Korean Peninsula for 10 years to conduct a statistical analysis of them and determine their synoptic meteorological characteristics. The cases of windstorms occurring on the Korean Peninsula were divided into six weather patterns according to the locations of the anticyclones/cyclones. Among these types, the SH type, which occurs when Siberian Highs expand into the Korean Peninsula, showed the highest occurrence frequency, accounting for at least the majority of the entire occurrence frequency of windstorms together with that of the EC type, which occurs when cyclones develop on the East Sea, and there was no clear yearly trend of the occurrence frequencies of windstorms. The monthly occurrence frequencies of windstorms were formed mainly by typhoons in the summer and the Siberian Highs in the winter, and the months with the highest windstorm occurrence frequencies were December and January, in which mainly the SH and EC type windstorms occurred. March showed the next highest occurrence frequency with10 times, and SH windstorms occurred the most frequently in March, followed by the CC, SC, and EC types of windstorms, in order of precedence. Therefore, attention to these types of windstorms is required. Countermeasures against storm and flood damage in Korea targeting the summer should be re-reviewed together with pre-disaster prevention plans, because cases of storm and flood damage due to windstorms occur more frequently than those due to typhoons, and they occur throughout the year.

• Wind and Structures
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• 제31권5호
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• pp.459-472
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• 2020

This study focused on the non-synoptic, tornado-like wind-induced effects on flexible horizontal structures that are extremely sensitive to winds. More specifically, the nonuniform, intensive vertical wind-velocity and transient natures of tornado events and their effects on the global behavior of a long-span bridge were investigated. In addition to the static part in the modeling of tornado-like wind-induced loads, the motion-induced effects were modeled using the semi-empirical model with a two-dimensional (2-D) indicial response function. Both nonlinear wind-induced static analysis and linear aeroelastic analysis in the time domain were conducted based on a 3-D finite-element model to investigate the bridge performance under the most unfavorable tornado pattern considering wind-structure interactions. The results from the present study highlighted the important effects due to abovementioned tornado natures (i.e., nonuniform, intensive vertical wind-velocity and transient features) on the long-span bridge, and hence may facilitate more appropriate wind design of flexible horizontal structures in the tornado-prone areas.

• 한국지구과학회지
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• 제26권7호
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• pp.732-743
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• 2005

본 연구에서는 2003년 기상청에서 분류한 강수유발 기압유형을 근거로 1973년부터 2002년까지 30년간 전국 61소의 시간별 강수자료를 사용하여 우리나라 강수의 특성을 살펴보았다. 시간강수자료를 이용하여 강수의 시작과 종료를 정의하여 지속시간과 집중호우까지의 도달시간을 조사하였고 집중호우 발생 확률을 분석하였다. 지난 30년 동안 한반도의 강수현상을 조사한 결과 연평균 약 179회의 강수가 발생하였으며, 강수지속시간과 강수량은 각각 2.9시간과 7.1 mm로 나타났다. 저기압형에 의한 강수가 전체의 약 $59\%$를 차지했고, 여름에는 장마형, 가을에는 전선형과 태풍형, 겨울에는 지세형의 강수가 나타나는 계절적 특징을 보여주었다. 태풍과 장마 등 열대기류와 관련된 강수유형들은 10 mm 이상의 강수량을 보인 반면에, 국지적인 규모로 나타나는 유형들은 5 mm 미만의 약한 강수량을 보였다. 전체 강수현상 중 집중호우로 이어진 경우는 $1.24\%$로 호우 기준까지 약 12.9 시간이 소요되었다. 집중호우를 자주 유발하는 유형은 장마형과 저기압형으로 나타났으나, 발생 확률은 태풍직접형, 태풍변질형, 열대류수렴형이 높았다. 지역별로는 남해안 지역은 태풍직접형과 태풍변질형, 영동지역은 태풍직접형, 경기 및 강원북부는 태풍변질형, 열대류수렴형과 장마형이, 그리고 충청지역은 태풍변질형과 열대류수렴형에 의한 집중호우의 가능성이 큰 것으로 분석되었다. 기상청에서 분류하였던 강수의 유형은 다소 주관적인 면을 가지고 있으나 한반도 강수의 특성을 파악하는 데 별 무리가 없었다. 특히 새롭게 분류를 시도한 열대류수렴형은 여름철에 많은 강수를 유발하는 기압계로 주목할 필요가 있다고 본다.