• 한국항해항만학회지
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• 제32권8호
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• pp.597-602
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• 2008

실습선 한바다호는 수면 상부의 구조물이 상대적으로 큰 선형으로 풍압력의 영향을 크게 받아 압류나 회두와 같은 현상이 비교적 크게 나타나고, 특히 접이안 또는 항내에서 저속으로 운항할 경우 이러한 외력의 영향이 현저하게 작용한다. 본 논문에서는 파도가 충분히 발달되지 않은 항내 조선을 전제로 한바다호의 풍압력과 풍압모우멘트를 산출하여 상대 풍향과 풍속에 따른 표류각과 대응 타각을 분석하였다. 또한, 실습선 한바다호의 접이안시 예인선의 소요마력 결정을 선체에 작용하는 풍압력을 기초로 산출하였고, Bow Thruster를 이용한 접이안 가능 최대 풍속을 제시하였다. 연구 결과는 풍압력이 크게 작용하는 대형선의 항내조선과 예인선 운용에 큰 도움이 될 것으로 판단된다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권2호
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• pp.91-103
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• 1999

According to numerical experiments, the Sokcho Eddy is produced at $37 5~39.0^{\circ}N$ by strong offshore winds, whereas the Ulleung Eddy is produced at $35~37^{\circ}N$ by an inflow variation of the Tsushima Current. These locations compare well with visual observations. The nonlinear 1$1/2$-layer model showed that most of the East Korea Warm Current (EKWC) driven by the Tsushima Current form the Ulleung Eddy that is larger and stronger than the Sokcho Eddy. In contrast, the nonlinear 2$1/2$-layer model showed that most of the EKWC travels further northward due to a strong subsurface current, thereby enhancing the Sokcho Eddy making it larger and stronger than the Ulleung Eddy. The Sokcho Eddy is also produced relatively offshore due to an eastward subsurface current in the frontal region. Using the 1$1/2$-layer model, when the mass of the Tsushima Current decreases, the two eddies are weakened and produce a circular shape. In the 2$1/2$-layer model the EKWC pushes the Ulleung Eddy northward after 330 days, next the Sokcho and Ulleung eddies begin to interact with each other, and then after 360 days the Ulleung Eddy finally disappears absorbed by the relatively stronger Sokcho Eddy. This behavior compares favorably with other visual observations.

• 한국환경과학회지
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• 제21권2호
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• pp.153-163
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• 2012

The seasonal variations of ozone ($O_3$) concentrations were investigated with regard to the relationship between $O_3$ and wind distributions at two different sites (Jung Ang (JA): a semi-closed topography and Seo Chang (SC): a closed topography) within a valley city (Yangsan) and their comparison between these sites (JA and SC) and two non-valley sites (Dae Jeo (DJ) and Sang Nam (SN)) located downwind from coastal cities (Busan and Ulsan). This analysis was performed using the data sets of hourly $O_3$ concentrations, meteorological factors (especially, wind speed and direction), and those on high $O_3$ days exceeding the 8-h standard (60 ppb) during 2008-2009. In summer and fall (especially in June and October), the monthly mean values of the daily maximum $O_3$ concentrations and the number of high $O_3$ days at JA (and SC) were relatively higher than those at DJ (and SN). The increase in daytime $O_3$ concentrations at JA in June was likely to be primarily impacted by the transport of $O_3$ and its precursors from the coastal emission sources in Busan along the dominant southwesterly winds (about 5 m/s) under the penetration of sea breeze condition, compared to other months and sites. Such a phenomenon at SC in October was likely to be mainly caused by the accumulation of $O_3$ and its precursors due to the relatively weak winds under the localized stagnant weather condition rather than the contribution of regional transport from the emission sources in Busan and Ulsan.

• 한국환경과학회지
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• 제5권2호
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• pp.131-140
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• 1996

Analysis of hourly variations of sulfur dioxide ($SO_2$) concentrations affected by regional climates for the period of yellow sandy dusts was carried out from March 31 through April 9, 1993. The concentration of 50, at a coastal city, Kangnung city, was much higher than that at an inland city Wonju in the west, but the hourly distrbutions of $SO_2$ concentrations show a similar tendency at both cities. Under the prevailing synoptic-scale westerly winds blowing over a high Mt. Taegualyang in the west toward Kangnung city in the eastern coastal region, the $SO_2$ at Kangnung is trapped by an easterly sea-breeze during the day and under prevailing easterly winds, it is also isolated by the high wall of Mt. Taegualyang, with its high concentration from 14 to 16 LST. Furthermore, when the westerly winds were dominent all day long the high $SO_2$ concentrations at Kangnung were produced by its intrusion from a urban city, Wonju or China in the west into a mountainous coastal city, Kangnung, to some extent, and when the air becomes rapidly cooled down at the clear daytime or the nighttime, their concentrations are also increased by a great amount of heating fuel combustion. Especilly, its maximum concentrations were shown in Wonju and Kangnung from 08 LST through 10 LST, due to the increase of auto vehicles near the beginning time of office hour and were detected again after sunset due to both increases of vehicles at the end of office hour and heating fuel combustion. During the period of Yellow Sandy Dusts which are transported from China into Korea, the $SO_2$ concentrations on rainy days at Wonju and Kangnung were much lower than the monthly mean values of $SO_2$, and their low concentrations could be caused by the scavenging process of rain.

• 대기
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• 제26권3호
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• pp.401-412
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• 2016

A 3D sonic anemometer has been installed at Yongpyong alpine slope since Oct. 23th 2014 to observe the slope winds and to analyze turbulent characteristics with the change in surface cover (grass and snow) and the synoptic wind strength. Eddy covariance method has been applied to calculate the turbulent quantity after coordinate transformation of a planar-fit rotation. We have carefully selected 3 good episodes in the winter season (23 October 2014 to 28 February 2015) for each category (9 days in total), such as grass and snow covers in case of weak synoptic wind condition, and grass cover of strong synoptic wind. The diurnal variations of the slope winds were well developed like the upslope wind in the daytime and downslope wind in the nighttime for both surface covers (grass and snow) in the weak synoptic forcing, when accordingly both heat and momentum fluxes significantly increased in the daytime and decreased in the nighttime. Meanwhile, diurnal variation of heat flux was not present on the snow cover probably in associated with significant fraction of sunlight reflection due to high albedo especially during the daytime in comparison to those on the grass cover. In the strong synoptic regime, the most dominant feature at Yongpyong, only the southeasterly downslope winds were steadily generated irrespective of day and night with significant increases in momentum flux and turbulent kinetic energy as well, which could suggest that local circulations are suppressed by the synoptic scale forcing. In spite of only one season analysis applied to the limited domain, this kind of an observation-based study will provide the basis for understanding of the local wind circulation in the complex mountain domain such as Gangwon in Korea.

• 수산해양기술연구
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• 제28권4호
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• pp.398-411
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• 1992

The characteristics of local climate in the vicinity of Duckyang Bay have been investigated with the analysis of the surface observation data of Gohug District and the aerological data of Kwangju. In principal features of local climate, the annual range in temperature appeared identical with the mean value(24~$25^{\circ}C$) of the south coastal area, and evaporation from April to September was likely less than precipitation. The average speed of surface wind in Summer seemed higher than in other seasons on account of wea breeze. Relative humidity was 74%, annual average. In the mean cloud cover Summer(6.4) showed greater deal of amount than Winter(4.2). Duration of sunshine was the longest in May(268.4hrs), while the shortest in February(188.4hrs). The amount of the precipitable water was the greatest in July, whereas the least in January, and in Summer the greatest, in Autumn the second greatest, and in Spring the third greatest, and in Winter the least in consideration of seasonal orders. The Summer deviation was most remarkable around all sides. The direction of vector wind appeared the most changeable on the earth surface. At an altitude of 300mb all the winds blew west around all months. Moreover, water vapor transport was measured to be the greatest in Summer; while the least in Winter. So was the deviation of water vapor transport. And lastly frequency of occurrence of days in which a little cloud appeared(less than 5/10) was high except for Summer, when northerly winds blew; while frequency of occurrence of day plenty of clouds floated was outstandingly high at the time of strong southerly winds.

• Journal of Ecology and Environment
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• 제38권2호
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• pp.175-183
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• 2015

Extremely strong winds and heavy rainfall caused canopy gaps in a mixed Abies holophylla broadleaf forest and a Quercus mongolica-dominated forest in Odaesan National Park, Korea in October 2006. The impact of the combination of strong winds and torrential rain on the development of forest gaps and canopy structures were investigated. The mean size of newly created gaps were $205m^2$ in the mixed forest and $86m^2$ in the Quercus forest, and were created by 2.8 and 1.4 gapmaker trees, respectively. Among the 73 trees lost in the mixed forest, 59% succumbed because of direct wind damage while 41% were struck by neighboring trees that fell into them. Most of these trees downed by wind were uprooted (74%), while the trees downed by neighboring tree falls snapped (78%). 21 trees in the Quercus forest died from direct wind damage, and 57% of them were uprooted. Although the relative density of Abies nephrolepis and A. holophylla represented only 0.2% and 6.4%, respectively, of all species in the intact mixed forest, they accounted for 27% and 15%, respectively, of all trees affected by wind on that site. In fact, 85% of the total A. nephrolepis and 91% of the total A. holophylla in the mixed forest fell directly due to strong wind. By contrast, only one Abies species, A. nephrolepis, was found in the Quercusdominated forest, and it accounted for 7.3% of the species composition. These findings suggest that A. nephrolepis and A. holophylla are particularly susceptible to high winds because of their great heights and shallow root systems.

• 대기
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• 제30권3호
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• pp.293-309
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• 2020

There are lots of indices that define the intensity of East Asian summer monsoon (EASM) in climate systems. This paper assesses the prediction skill for EASM indices in a Global Seasonal Forecasting System (GloSea5) that is currently operating at KMA. Total 5 different types of EASM indices (WNPMI, EAMI, WYI, GUOI, and SAHI) are selected to investigate how well GloSea5 reproduces them using hindcasts with 12 ensemble members with 1~3 lead months. Each index from GloSea5 is compared to that from ERA-Interim. Hindcast results for the period 1991~2010 show the highest prediction skill for WNPMI which is defined as the difference between the zonal winds at 850 hPa over East China Sea and South China Sea. WYI, defined as the difference between the zonal winds of upper and lower level over the Indian Ocean far from East Asia, is comparatively well captured by GloSea5. Though the prediction skill for EAMI which is defined by using meridional winds over areas of East Asia and Korea directly affected by EASM is comparatively low, it seems that EAMI is useful for predicting the variability of precipitation by EASM over East Asia. The regressed atmospheric fields with EASM index and the correlation with precipitation also show that GloSea5 best predicts the synoptic environment of East Asia for WNPMI among 5 EASM indices. Note that the result in this study is limited to interpret only for GloSea5 since the prediction skill for EASM index depends greatly on climate forecast model systems.

• 한국해양학회지:바다
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• 제24권3호
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• pp.439-447
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• 2019

지금까지의 연구 결과를 토대로 하여 대마난류의 순환역학에 관한 몇 가지 쟁점들을 정리해 보고 향 후 해결할 문제점들을 짚어보는 기회로 삼고자 하였다. 주요 관심 사항은 대마난류의 형성, 그 수송량의 계절변동 및 동해 내부에서의 분지 현상이다. 대마난류는 북태평양 아열대순환의 일부로서 북태평양 전지구적 바람장에 의해 형성된다. 그러나 마찰, 만의 지형, 장벽효과 등에 따라 그 수송량은 민감하게 변한다. 수송량의 계절변동에 대해서는 여러 학자들에 의해 많은 요인들이 제시되어 왔으나 아한대 바람장이 이와 가장 밀접히 연관되어 있는 것으로 밝혀졌다. 그러나 향후, 아한대 바람장 뿐만 아니라 아열대 바람장까지를 포함한 북태평양 전체 바람장과의 관계를 보여줄 수 있는 연구가 필요해 보인다. 대마난류의 두 분지인 동한난류와 일본연안류의 형성 기작으로서 그동안 서안강화 현상과 해저지형 효과가 가장 유력하게 제시되어 왔다. 그러나 서안강화는 동한난류의 계절변동을 설명할 수 없다는 문제점을 갖고 있음으로 이를 대체할 다른 기작에 대한 연구가 필요하다고 사료된다.

• 한국기후변화학회지
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• 제9권3호
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• pp.209-221
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• 2018

The characteristics of heat wave events in Seoul are analyzed using weather station data from Korea Meteorological Administration (KMA) and European Centre for Medium-Range Weather Forecast (ECMWF) ERA-Interim reanalysis data from 1979 to 2016. Heat waves are defined as events in the upper 10th percentile of the daily maximum temperatures. The associated synoptic weather patterns are then classified into six clusters through Self-Organizing Map (SOM) analysis for sea-level pressure anomalies in East Asia. Cluster 1 shows an anti-cyclonic circulation and weak troughs in southeast and west of Korea, respectively. This synoptic pattern leads to southeasterly winds that advect warm and moist air to the Korean Peninsula. Both clusters 2 and 3 are associated with southerly winds formed by an anti-cyclonic circulation over the east of Korea and cyclonic circulation over the west of Korea. Cluster 4 shows a stagnant weather pattern with weak winds and strong insolation. Clusters 5 and 6 are associated with F?hn wind resulting from an anti-cyclonic circulation in the north of the Korean Peninsula. In terms of long-term variations, event frequencies of clusters 4 and 5 show increasing and decreasing trends, respectively. However, other clusters do not show any long-term trends, indicating that the mechanisms that drive heat wave events in Seoul have remained constant over the last four decades.