• 환경영향평가
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• 제11권2호
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• pp.79-91
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• 2002

Four dimensional data assimilation (FDDA) technique was considered for 3 dimensional wind field in coastal area and a set of 3 numerical experiments including control experiments has been tested for the case of the synoptic weather pattern of the weak northerly geostrophic wind with the cloud amount of less than 5/10 in autumn. A three dimensional land and sea breeze model with the sea surface temperature (SST) of 290K was performed without nudging the observed wind field and surface temperature of AWS (Automatic Weather System) for the control experiment. The results of the control experiment showed that the horizontal temperature gradient across the coastline was weakly simulated so that the strength of the sea breeze in the model was much weaker than that of observed one. The experiment with only observed horizontal wind field showed that both the pattern of local change of wind direction and the times of starting and ending of the land-sea breeze were fairly well simulated. However, the horizontal wind speed and vertical motion in the convergence zone were weakly simulated. The experiment with nudgings of both the surface temperature and wind speed showed that both the pattern of local change of wind direction and the times of starting and ending of the land-sea breeze were fairly well simulated even though the ending time of the sea breeze was delayed due to oversimulated temperature gradient along the shoreline.

• 대한원격탐사학회지
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• 제34권6_3호
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• pp.1383-1398
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• 2018

해상풍은 복잡한 해양 현상을 이해하는 데 가장 기초 요소 중 하나이다. 1990년대 초부터 산란계를 활용하여 전세계 바람장 자료를 생산해왔지만, 낮은 해상도로 인해 해양 연구에 제한적으로 사용되었다. Synthetic Aperture Radar(SAR)는 이러한 한계점을 보완하여 고해상도의 바람장 자료 생산이 가능하다. KOMPSAT-5는 한반도 최초의 X-band SAR 탑재 인공위성으로 고해상도 해상풍 산출이 가능하다. 본 연구는 KOMPSAT-5 후방산란계수 자료를 활용하여 산출한 해상풍의 검증 결과를 최초로 제시하였다. 18장의 KOMPSAT-5 ES 모드 자료를 수집하여 해양 부이와의 일치점 데이터베이스를 생산하였다. 정확한 해상풍 산출을 위해 육지 화소, 스페클 잡음, 선박 화소를 제거하는 전처리 과정을 거쳤고, 해양 부이 실측 자료에 Liu-Katsaros-Businger (LKB) 모델을 통해 10-m 중성 바람으로 변환하여 기준 자료로 활용하였다. XMOD2를 활용하여 산출한 해상풍은 후방산란계수 산출식에 따라 $2.41-2.74m\;s^{-1}$의 평균 제곱근 오차를 보였다. 분석 결과 KOMPSAT-5 후방산란계수 자료를 활용하여 해상풍을 산출하는 경우, 대기 중력파, 파랑, 내부파를 포함한 해양 기상 환경과 레인지 모호성(range ambiguity), 입사각의 이산적 불연속적 분포를 포함한 영상 품질에 의한 잠재적 오차 요인이 존재함을 규명하였다.

• 한국지구과학회:학술대회논문집
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• 한국지구과학회 2010년도 춘계학술발표회 논문집
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• pp.134-134
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• 2010

Sea ices at the Tatarskiy Straitin the East/Japan Sea appear from November to April. Cold and fresh water, melted from the sea ices, may contain nutrients which are indispensable to spring bloom of phytoplankton and may provide a preferable condition to the spring bloom through changes in vertical structure of water column and stratification. Relation between the spring bloom along the Primorye coast and sea ices in the Tatarskiy Strait were investigated using multi-satellite multi-sensor data; ten-year SeaWiFS chlorophyll-a concentration data and PAR data, sea surface temperatures from NOAA/AVHRR, sea ice concentration and near-surface wind speed data from DMSP/SSMI, near-surface wind vectors from QuikSCAT, and others. We provided evidences of southwestward flowing cold water masses from sea ice and its relation of chlorophyll-a concentration. This study showed that year-to-year variations of chlorophyll-a concentration in spring were positively correlated with those of sea ice concentrations at the Tatarskiy Strait.

• Ocean and Polar Research
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• 제35권3호
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• pp.193-203
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• 2013

A GPS-drifter was newly designed to observe the sea surface skin current and to estimate the direct wind effect on the sea surface. After conducting a test to establish and verify the accuracy of the GPS itself in the laboratory, in-situ experimental campaigns at Saemangeum in Gunsan city and Haeundae in Busan city, Korea, were carried out to ascertain the drifter track and to estimate the velocity data set on Oct. 3, 15, 23, 27 and Nov. 25, 2011. The current meters, RCM9 and ADCP, were moored together to remove the background current field, and the wind data were obtained from several marine stations such as towers and buoys in these areas. The drifter-observed velocity show good agreement with the flow obtained by the HF radar in the Saemangeum area. The direction of the wind-driven current extracted from the drifter-observed velocity was completely deflected to the right, however the degree of the angle was different according to the drift types. The average speed of the wind-driven current matched with 2.19~2.81% of the wind speed and the deflection angle was about $8.0{\sim}10.9^{\circ}$ without adjustment for the land-sea effect, and about 2.19~2.84% and $4.1{\sim}6.0^{\circ}$ with the adjustment for the land-sea effect.

• Ocean and Polar Research
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• 제25권spc3호
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• pp.361-371
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• 2003

The effect of bottom friction on the steady wind-driven circulation in the Yellow Sea and the East China Sea (YSECS) has been studied using a two-dimensional numerical model with and without tidal forcing. Upwind flow experiment in YSECS has also been carried out with a schematic time variation in the wind field. The surface water setup and circulation pattern due to steady wind forcing are found to be very sensitive to the bottom friction. When the effects of tidal currents are neglected, the overall current velocities are overestimated and eddies of various sizes appear, upwind flow is formed within the deep trough of the Yellow Sea, forming a part of the topographic gyre on the side of Korea. When tidal forcing is taken into account, the wind-induced surface elevations are smoothed out due to the strong tide-induced bottom friction, which is aligned almost normal to the wind stresses; weak upwind flow is farmed in the deep trough of the Yellow Sea, west and south of Jeju. Calculation with wind forcing only through a parameterized linear bottom friction produces almost same results from the calculation with $M_2$ tidal forcing and wind forcing using a quadratic bottom friction, supporting Hunter (1975)'s linearization of bottom friction which includes the effect of tidal current, can be applied to the simulation of wind-driven circulation in YSECS. The results show that steady wind forcing is not a dominant factor to the winter-time upwind flow in YSECS. Upwind flow experiment which considers the relaxation of pressure gradient (Huesh et al. 1986) shows that 1) a downwind flow is dominant over the whole YSECS when the northerly wind reaches a maximum speed; 2) a trend of upwind flow near the trough is found during relaxation when the wind abates; 3) a northward flow dominates over the YSECS after the wind stops. The results also show that the upwind flow in the trough of Yellow Sea is forced by a wind-induced longitudinal surface elevation gradient.

• Journal of Ecology and Environment
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• 제47권2호
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• pp.49-62
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• 2023

Background: Over the past three decades, gradual eustatic sea-level rise has been considered a primary exogenous factor in the increased frequency of flooding and biological changes in several salt marshes. Under this paradigm, the potential importance of short-term events, such as ocean storminess, in coastal hydrology and ecology is underrepresented in the literature. In this study, a simulation was developed to evaluate the influence of wind waves driven by atmospheric oscillations on sedimentary and vegetation dynamics at the Skallingen salt marsh in southwestern Denmark. The model was built based on long-term data of mean sea level, sediment accretion, and plant species composition collected at the Skallingen salt marsh from 1933-2006. In the model, the submergence frequency (number yr^-1) was estimated as a combined function of wind-driven high water level (HWL) events (> 80 cm Danish Ordnance Datum) affected by the North Atlantic Oscillation (NAO) and changes in surface elevation (cm yr^-1). Vegetation dynamics were represented as transitions between successional stages controlled by flooding effects. Two types of simulations were performed: (1) baseline modeling, which assumed no effect of wind-driven sea-level change, and (2) experimental modeling, which considered both normal tidal activity and wind-driven sea-level change. Results: Experimental modeling successfully represented the patterns of vegetation change observed in the field. It realistically simulated a retarded or retrogressive successional state dominated by early- to mid-successional species, despite a continuous increase in surface elevation at Skallingen. This situation is believed to be caused by an increase in extreme HWL events that cannot occur without meteorological ocean storms. In contrast, baseline modeling showed progressive succession towards the predominance of late-successional species, which was not the then-current state in the marsh. Conclusions: These findings support the hypothesis that variations in the NAO index toward its positive phase have increased storminess and wind tides on the North Sea surface (especially since the 1980s). This led to an increased frequency and duration of submergence and delayed ecological succession. Researchers should therefore employ a multitemporal perspective, recognizing the importance of short-term sea-level changes nested within long-term gradual trends.

• 신재생에너지
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• 제1권1호
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• pp.44-53
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• 2005

To understand general status of the national wind environment and to distinguish potential areas to be developed as a largescale wind farm, a synoptic wind map of the Korean Peninsula is established by processing remote sensing data of the satellite, NASA QuikSCAT which Is deployed for the SeaWinds Project since 1999. According to the validation results obtained by comparing with the measurement data of marine buoys of KMA(Korea Meteorological Administration), the cross-correlation factor Is greatly Improved up to 0.87 by blending the sea-surface dat3 of QuikSCAT with NCEP/NCAR CDAS data. It is found from the established synoptic wind map that the wind speed in winter is prominent temporally and the South Sea shows high energy density up to the wind class 6 spatially. The reason is deduced that the northwest winds through the yellow Sea and the northeast winds through the East Sea derived by the low-pressure developed in Japan are accelerated passing through the Korea Channel and formed high wind energy region in the South Sea; the same trends are confirmed by the statistical analysis of meteorological observation data of KMA.

• 한국해양학회지
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• 제23권3호
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• pp.97-109
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• 1988

한국 동해의 wind stress와 wind-stress curl의 값을 수산진흥원 정선관측 바람자료를 근거로 하여 계산하였다. 바람에 의한 해수 이용을 염두에 두고 주로 지속적이고 강한 바람을 취해서 구한 월평균 wind stress 값들은 동해 전체에서 구한 기존의 값들과 거의 같았으나 wind-stress curl의 경우는 그 값이 훨씬 크게 나타났다. 이는 동해가 국지적으로 지형적인 영향을 받은 것으로 판단된다. 한편 바람에 의한 상층수의 이동으로 울릉도 부근에는 계절에 관계없이 난수괴(warm core)가 존재 하나 그 위치는 고정되어 있지 않다.

• 한국환경과학회지
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• 제24권9호
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• pp.1199-1210
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• 2015

There were 35 typhoons affecting Korean Peninsula from 1999 to 2009(The average annual number of typhoon is 3.18). Among these typhoons, the number of typhoon passing through the Yellow sea, the Southern sea and the East sea were 14, 6 and 15 respectively. Wind speed on the height of 10 m can be finally estimated using the surface roughness after we calculate wind speed on the height of 300 m from the data on the surface of 700 hPa. From the wind speeds on the height of 10 m, we can understand the regional distributions of strong wind speed are very different according to the typhoon tracks. Wind speed range showing the highest frequency is 10~20 m/s(45.69%), below 10 m/s(30.72%) and 20~30 m/s(17.31%) in high order. From the analysis of the wind speed on the hight of 80 m, we can know the number of occurrence of wind speed between 50 and 60 m/s that can affect wind power generation are 104(0.57%) and those of between 60 and 70 m/s that can be considered as extreme wind speed are even 8(0.04%).

• 한국환경과학회지
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• 제31권7호
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• pp.617-635
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• 2022

The effect of coupled data assimilation (DA) on the meteorological prediction in the west coastal region of Korea was evaluated using a coupled atmosphere-ocean model (e.g., COAWST) in the spring (March 17-26) of 2019. We performed two sets of simulation experiments: (1) with the coupled DA (i.e., COAWST_DA) and (2) without the coupled DA (i.e., COAWST_BASE). Overall, compared with the COAWST_BASE simulation, the COAWST_DA simulation showed good agreement in the spatial and temporal variations of meteorological variables (sea surface temperature, air temperature, wind speed, and relative humidity) with those of the observations. In particular, the effect of the coupled DA on wind speed was greatly improved. This might be primarily due to the prediction improvement of the sea surface temperature resulting from the coupled DA in the study area. In addition, the improvement of meteorological prediction in COAWST_DA simulation was also confirmed by the comparative analysis between SST and other meteorological variables (sea surface wind speed and pressure variation).