• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.2
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• pp.65-71
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• 2014

In recent years, strong typhoons have passed South Korea almost every year and severe damages were incurred directly and indirectly. However, instances where wave and wind data were procured from the offshore approach path of the typhoon are very rare and thus researchers are experiencing difficulties in obtaining calibration and verification data of typhoon-generated wave modeling. This paper provides a synthesis of records of observations by the Korea Meteorological Administration and Korea Institute of Ocean Science and Technology on storm waves generated by the typhoons SONGDA, NABI, and SHANSHAN that passed from 2004 to 2006 in order to help researchers interested in typhoon-generated wave numerical modeling. Although the trajectories of typhoon NABI and SHANSHAN were east of the Korea Strait, a significant wave height of 8.3 m was measured at Namhyeongjedo located east of Geojedo. Moreover, an unprecedented significant wave height of 12.2 m was measured for both typhoons at a station 1.4 km away from Yeongil Bay breakwater. Meanwhile, a comparative analysis of data obtained with a ocean data buoy at Geojedo and a Directional Waverider at Namhyeongjedo showed maximum wave heights that were similar but considerably different significant wave heights.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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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.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.6
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• pp.375-382
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• 2016

In the present study, the wave hindcasting has been performed, and then the characteristics of storm waves at Gangnueng port was investigated, in which the high waves are observed. Comparing the numerical results with the wave measurements at Gangneung port, Niigata, and Hamada, there were good agreements between them. In particular, the Pearson correlation coefficients of significant wave heights and peak periods at Gangneung port were 0.92 and 0.72, respectively. Then the extreme wave analysis on the significant wave heights was carried out for the estimation of the frequency of storm waves. In this analysis, the storm waves over the threshold were fitted to GPD(Generalized Pareto Distribution). According to this analysis, the return period of the storm wave on February, 24, 2008, one of the large storm waves at Gangneung port, was 8.2 months. Among the computed significant wave heights larger than one-year wave, 58.3% of them were resulted from the storm, while the others were from the typhoon. Additionally, the regression analysis on the waves larger than one-month wave has been conducted, and then the relationship between the computed significant wave heights and the significant wave period, $T_{1/3}=7H_s^{0.25}$ was obtained.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.227-234
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• 2004

Recently huge typhoons had attacked to the coastal waters in Korea and caused disastrous casualties in those area. There are some discussions on correction to the design parameters for the coastal structures. Wave transformation computations with the extreme waves are of value in planning and constructing engineering works, especially in coastal regions. Prediction of typhoon surge elevations is based primarily on the use of a numerical model in this study, since it is difficult to study these events in real time or with use of physical models. Wave prediction with a two dimensional numerical model for a site with complicated coastal lines and structures at the period of typhoon 'Maemi' is discussed. In order to input parameters for the extreme wave conditions, we analyzed the observed and predicted typhoon data. Finally we applied the model discussed above to the storm surge and extreme wave problem at Busan Harbor, the southeast coast of Korea. Effects of water level variation and transformation of the extreme waves in relation with the flooding in coastal waters interested are analyzed. We then mack an attempt to presen a basic hazard map for the corresponding site.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.219-225
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• 2004

Following a preceding study if Shin et al.(2004), wave fields for a month if September if 2003 are simulated based on the modified WAM cycle 4 model that enables the precise wave hindcasting with fine spatial meshes, and characteristics of extreme waves at the south roast if Koreo are analyzed The accuracy if applied wave model is verified by comparing computed wave parameters and corresponding ones measured at Ieodo ocean research station. The wave hindasting if typhoon 'Maemi' with an hour time interval reveals the extreme wave characteristics at 4 primary locations if south coast of Korea as follows: 1) At the front sea of Chaguido in the south of Jeju-do, the maximum significant wave height, moon wave period and mean wave direction appear to be 7.41m, 13.65s and $6.4^{\circ}$, respectively at 16:00 KST if Sep. 12, 2003. 2) At the entrance of Masan Bay, 12.50m, 13.65s and $1.2^{\circ}$ at 21:00 KST if Sep. 12. 3) At the front sea of Suyoung Bay, 13.85m, 13.81s and $0.2^{\circ}$ at 22;00 KST if Sep. 12. 4) At the front sea of Ulsan port, 11.00m, 13.25s and $28^{\circ}$ at 23:00 KST if Sep.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.5
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• pp.351-362
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• 2020

Numerical simulations of the storm surge and waves induced by the Typhoon Maemi incident on the south sea of Korea in 2003 are performed using the JMA-MSM forecast weather field, NCEP-CFSR reanalysis weather field, ECMWF-ERA5 reanalysis weather field, and the pressure and wind fields obtained using the best track information provided by JTWC. The calculated surge heights are compared with the time history observed at harbours along the coasts of Korea. For the waves occurring coincidentally with the storm surges the calculated significant wave heights are compared with the measured data. Based on the comparison of surge and wave heights the assessment of the reliability of various weather fields is performed. As a result the JMA-MSM weather fields gives the highest reliability, and the weather field obtained using JTWC best track information gives also relatively good agreement. The ECMWF-ERA5 gives in general surge and wave heights weaker than the measured. The reliability of NCEP-CFSR turns out to be the worst for this special case of Typhoon Maemi. Based on the results of this study it is found that the reliable weather fields are essential for the accurate simulation of storm surges and waves.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.745-751
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• 2004

Following a preceding study of Shin et al.(2004), wave fields for a month of September of 2003 are simulated based on the modified WAM cycle 4 model that enables the precise wave hindcasting with fine spatial meshes, and characteristics of extreme waves at the south coast of Korea are analyzed The accuracy of applied wave model is verified by comparing computed wave parameters and corresponding ones measured at Ieodo ocean research station. The wave hindcasting of typhoon 'Maemi' with an hour time interval reveals the extreme wave characteristics at 4 primary locations of south coast of Korea as follows: 1) At the front sea of Chaguido in the south of Jeju-do, the maximum significant wave height, mean wave period and mean wave direction appear to be 7.41m, 13.65s and $6.4^{\circ}$ respectively at 16:00 KST of Sep. 12, 2003. 2) At the entrance of Masan Bay, 12.50m, 13.65s and $1.2^{\circ}$ at 21:00 KST of Sep. 12. 3) At the front sea of Suyoung Bay, 13.85m, 13.81s and $0.2^{\circ}$ at 22;00 KST of Sep. 12. 4) At the front sea of Ulsan port, l1.00m, 13.25s and $2.8^{\circ}$ at 23:00 KST of Sep. 12.

• Ocean and Polar Research
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• v.43 no.4
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• pp.307-320
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• 2021

Udo Rhodolith Beach is a small-scale, mixed sand-and-gravel beach embayed on the N-S trending rocky coast of Udo, Jeju Island, South Korea. This study analyzes the short-term topographic changes of the beach during the extreme storm conditions of four typhoons from 2016 to 2020: Chaba (2016), Soulik (2018), Lingling (2019), and Maysak (2020). The analysis uses the topographic data of terrestrial LiDAR scanning and drone photogrammetry, aided by weather and oceanographic datasets of wind, wave, current and tide. The analysis suggests two contrasting features of alongshore topographic change depending on the typhoon pathway, although the intensity and duration of the storm conditions differed in each case. During the Soulik and Lingling events, which moved northward following the western sea of the Jeju Island, the northern part of the beach accreted while the southern part eroded. In contrast, the Chaba and Maysak events passed over the eastern sea of Jeju Island. The central part of the beach was then significantly eroded while sediments accumulated mainly at the northern and southern ends of the beach. Based on the wave and current measurements in the nearshore zone and computer simulations of the wave field, it was inferred that the observed topographic change of the beach after the storm events is related to the directions of the wind-driven current and wave propagation in the nearshore zone. The dominant direction of water movement was southeastward and northeastward when the typhoon pathway lay to the east or west of Jeju Island, respectively. As these enhanced waves and currents approached obliquely to the N-S trending coastline, the beach sediments were reworked and transported southward or northward mainly by longshore currents, which likely acts as a major control mechanism regarding alongshore topographic change with respect to Udo Rhodolith Beach. In contrast to the topographic change, the subaerial volume of the beach overall increased after all storms except for Maysak. The volume increase was attributed to the enhanced transport of onshore sediment under the combined effect of storm-induced long periodic waves and a strong residual component of the near-bottom current. In the Maysak event, the raised sea level during the spring tide probably enhanced the backshore erosion by storm waves, eventually causing sediment loss to the inland area.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.122-133
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• 2005

The change of surface sediment composition, shoreline and transection of geography were studied to investigate the Typhoon(Maemi) effect in Naa Beach located in the south area of East sea. In the backshore the volume of gravel is do creased, and increased in the volume of sand. The erosion in the sediment occurred to 4 m in the thickness and effected to 10 m in depth. And the coastline retreated to 12 m after typhoon. During typhoon conditions, higher amplitude waves deepen the wave base, causing much of the lower beach face and the offshore. The upper beach face is extensively eroded during typhoon and sand sediment is redeposited.

• Proceedings of the KSRS Conference
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• v.1
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• pp.390-393
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• 2006

It is well known that synthetic aperture radar (SAR) provides information on ocean winds and surface waves. SAR data are of particularly high value in extreme weather conditions, as radar is able to penetrate the clouds providing information on different ocean surface processes. In this presentation some recent results on SAR observation of extreme wind and ocean wave conditions is summarised. Particular emphasize is put on the investigation of typhoons and extratropical cyclones in the North Pacific. The study is based on the use of ENVISAT ASAR wide swath images. Wide swath and scansar data are well suited for a detailed investigation of cyclones. Several examples like, e.g., typhoon Talim will be presented, demonstrating that these data provide valuable information on the two dimensional structure of the both the wind and the ocean wave field. Comparisons of the SAR observation with parametric and numerical model data will be discussed. Some limitations of standard imaging models like, e.g., CMOD5 for the use in extreme wind conditions are explained and modifications are proposed. Finally the study summarizes the capabilities of new high resolution TerraSAR-X mission to be launched in October 2006 with respect to the monitoring of extreme weather conditions. The mission will provide a spatialresolution up to 1m and has full polarimetric capabilities.