• 한국해양공학회지
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• 제35권4호
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• pp.273-286
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• 2021

In recent years, as human casualties and property damage caused by hazardous waves have increased in the East Sea, precise wave prediction skills have become necessary. In this study, the Simulating WAves Nearshore (SWAN) third-generation numerical wave model was calibrated and optimized to enhance the accuracy of winter storm wave prediction in the East Sea. We used Source Term 6 (ST6) and physical observations from a large-scale experiment conducted in Australia and compared its results to Komen's formula, a default in SWAN. As input wind data, we used Korean Meteorological Agency's (KMA's) operational meteorological model called Regional Data Assimilation and Prediction System (RDAPS), the European Centre for Medium Range Weather Forecasts' newest 5th generation re-analysis data (ERA5), and Japanese Meteorological Agency's (JMA's) meso-scale forecasting data. We analyzed the accuracy of each model's results by comparing them to observation data. For quantitative analysis and assessment, the observed wave data for 6 locations from KMA and Korea Hydrographic and Oceanographic Agency (KHOA) were used, and statistical analysis was conducted to assess model accuracy. As a result, ST6 models had a smaller root mean square error and higher correlation coefficient than the default model in significant wave height prediction. However, for peak wave period simulation, the results were incoherent among each model and location. In simulations with different wind data, the simulation using ERA5 for input wind datashowed the most accurate results overall but underestimated the wave height in predicting high wave events compared to the simulation using RDAPS and JMA meso-scale model. In addition, it showed that the spatial resolution of wind plays a more significant role in predicting high wave events. Nevertheless, the numerical model optimized in this study highlighted some limitations in predicting high waves that rise rapidly in time caused by meteorological events. This suggests that further research is necessary to enhance the accuracy of wave prediction in various climate conditions, such as extreme weather.

• 대기
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• 제19권1호
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• pp.93-106
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• 2009

Analysis has been made on the wind wave characteristics in terms of significant wave height ($H_s$) near the Korean marginal seas in the 2006 - 2007 year using the third generation wave model, WAVEWATCH - III model. In order to evaluate its performance, its results were compared with the observed data using KMA ocean buoy. The two year average RMSE between modeled and observed Hs shows reasonably small value of about 0.37 m. The accuracy of predicted values in the year 2007 is increased mainly due to finer model grid size and better accurate wind field. The model used in this study predicts very well the characteristics ($H_s$) of wind waves near the Korean Peninsular. Simulated monthly wind waves show the evident seasonal variations due to Typhoons in summer season. When Typhoons approach to Korean Peninsular, the accuracy of wind waves predictions is lower than that of annual mean value.

• 한국항해항만학회지
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• 제28권9호
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• pp.815-820
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• 2004

In this paper, after analyzing other models with their advantages and disadvantages, we proposed a simple parametric model for calculating wind speed & direction and wave height & direction at any location around the typhoon at sea. The proposed wind-field model of typhoon is asymmetric, and consists of a circular symmetric wind-field caused by the pressure gradient of stationary typhoon and a moving wind-field caused by the movement of typhoon. By verifying this model through observed data, we found that it is accurate enough to develop the simulation software for training students and seafarers so as to take appropriate actions while being faced with the typhoon at sea.

• Ocean and Polar Research
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• 제43권3호
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• pp.179-192
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• 2021

In this study, an integrated wave model from global to coastal scales was developed to improve the operational wave prediction performance of the Korean Meteorological Administration (KMA). In this system, the wave model was upgraded to the WaveWatch III version 6.07 with the improved parameterization of the source term. Considering the increased resolution of the wind input field and the introduction of the high-performance KMA 5^th Supercomputer, the spatial resolution of global and regional wave models has been doubled compared to the operational model. The physical processes and coefficients of the wave model were optimized for the current KMA global atmospheric forecasting system, the Korean Integrated Model (KIM), which is being operated since April 2020. Based on the sensitivity experiment results, the wind-wave growth parameter (β_max) for the global wave model was determined to be 1.33 with the lowest root mean square errors (RMSE). The value of β_max showed the lowest error when applied to regional/coastal wave models for the period of the typhoon season when strong winds occur. Applying the new system to the case of August 2020, the RMSE for the 48-hour significant wave height prediction was reduced by 13.4 to 17.7% compared to the existing KMA operating model. The new integrated wave prediction system plans to replace the KMA operating model after long-term verification.

• 한국해양공학회지
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• 제24권6호
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• pp.7-15
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• 2010

Analyses of wind wave characteristics near the Korean marginal seas were performed in 2008 and 2009 by comparisons of an operational wind wave forecast model and ocean buoy data. In order to evaluate the model performance, its results were compared with the observed data from an ocean buoy. The model used in this study was very good at predicting the characteristics of wind waves near the Korean Peninsula, with correlation coefficients between the model and observations of over 0.8. The averaged Root Mean Square Error (RMSE) for 48 hrs of forecasting between the modeled and observed waves and storm surges/tide were 0.540 m and 0.609 m in 2008 and 2009, respectively. In the spatial and seasonal analysis of wind waves, long waves were found in July and September at the southern coast of Korea in 2008, while in 2009 long waves were found in the winter season at the eastern coast of Korea. Simulated significant wave heights showed evident variations caused by Typhoons in the summer season. When Typhoons Kalmaegi and Morakot in 2008 and 2009 approached to Korean Peninsula, the accuracy of the model predictions was good compared to the annual mean value.

• 한국해안해양공학회지
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• 제19권1호
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• pp.57-65
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• 2007

천해파랑을 산정하기 위하여 천수, 굴절, 회절, 반사 및 쇄파 등의 파랑변형요소를 고려하는 대부분의 수치모델은 천해역에서의 바람장을 수치모델과 결합하여 천해파랑을 산정하고 있다. 그리고, 일반적으로 천해역에서 바람장을 산정하는 경우에 태풍모델로부터 얻어진 바람장을 해상풍으로 변환하여 사용하고 있다. 그러나, 이러한 해상풍 산정법은 해상풍의 평가에 중요한 요소로 작용될 수 있는 육상지형의 영향에 대해서는 고려하고 있지 않다. 본 연구는 천해역에서의 해상풍 산정에 대하여 육상지형의 영향을 고려함으로써, 결과적으로 정도 높은 천해파랑산정을 목적으로 한다. 먼저 지역적으로 차폐 및 개방되어 있는 해역을 대상으로 태풍모델로부터 얻어진 해상풍과 본 연구에서 적용하는 육상지형의 영향을 고려할 수 있는 MASCON모델로 산정된 해상풍의 결과를 상호 비교 검토한다. 그리고, 각 모델로부터 얻어진 해상풍을 SWAN모델에 적용하여 천해파랑을 산정하며, 이의 결과를 상호 비교 검토한다. 검토된 결과로부터 정도 높은 천해파랑산정을 위한 MASCON모델의 필요성을 논의한다.

• Wind and Structures
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• 제16권2호
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• pp.193-211
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• 2013

This paper presents results from a wind tunnel study that examined the drag coefficient and wind flow over an asymmetric wave train immersed in turbulent boundary layer flow. The modeled wavy surface consisted of eight replicas of a statistically-valid hurricane-generated wave, located near the coast in the shoaling wave region. For an aerodynamically rough model surface, the air flow remained attached and a pronounced speed-up region was evident over the wave crest. A wavelength-averaged drag coefficient was determined using the wind profile method, common to both field and laboratory settings. It was found that the drag coefficient was approximately 50% higher than values obtained in deep water hurricane conditions. This study suggests that nearshore wave drag is markedly higher than over deep water waves of similar size, and provides the groundwork for assessing the impact of nearshore wave conditions on storm surge modeling and coastal wind engineering.

• 한국해안·해양공학회논문집
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• 제24권5호
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• pp.333-342
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• 2012

파랑 모델에서 시공간적인 해상도의 변경은 결과에 많은 영향을 끼친다. 본 연구에서는 모델 입력장의 해상도 변경, 파랑 모델의 해상도 변경 그리고 물리적 옵션에 따른 모델의 민감도를 분석하였다. 모델의 분석을 위해서 전지구 부이관측자료와 위성자료를 이용하였다. 고해상도의 입력장을 사용할 경우 유의파고를 과대 산정하는 경향을 보였고, RSME는 약간 감소하였다. 고해상도의 파랑 모델을 수행할 경우 평균편향 및 RMSE가 약간 증가하였다. 또한, 유효 해상풍 계수를 기존의 값인 1.4보다 작게 설정할 경우 편향과 RMSE가 모두 감소하였다.

• 풍력에너지저널
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• 제14권3호
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• pp.25-33
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• 2023

In order to secure the safety of increasing offshore activities such as offshore wind farm maintenance and fishing, IMPACT, a mid-term marine weather forecasting system, was established by predicting marine weather up to 7 days in advance. Forecast data from the Korea Hydrographic and Oceanographic Agency (KHOA), which provides the most reliable marine meteorological service in Korea, was used, but wind speed and wave height forecast errors increased as the leading forecast period increased, so improvement of the accuracy of the model results was needed. The Model Output Statistics (MOS) method, a post-correction method using statistical machine learning, was applied to improve the prediction accuracy of wave height, which is an important factor in forecasting the risk of marine activities. Compared with the observed data, the wave height prediction results by the model before correction for 6 to 7 days ahead showed an RMSE of 0.692 m and R of 0.591, and there was a tendency to underestimate high waves. After correction with the MOS technique, RMSE was 0.554 m and R was 0.732, confirming that accuracy was significantly improved.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.229-234
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• 2004

A Typhoon wave is generated by wind fields during the Passage of Typhoon. Transporting wind field makes wind wave and swell in the open sea, and then, those wave components are transported in the shallow water. Typhoon waves in the shallow water is generated by Typhoon wind field and incident wave. Bisides, Incident waves to the shallow water are deformated by topographic conditions. This paper estimated the analysis of the Typhoon waves by wind fields and incident waves according to wave action balance equation model. As the result of wave numerical experiment, wave field during the passage of Typhoon 'Memi' in the shallow water is strongly effect by wind fields. Wave action balance equaion can be partially used for Typhoon wave simulations.