• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.47-53
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• 2012

A coastal flood area was predicted using the empirical superposition of the typhoon surge level and typhoon wave height along the Busan coastal area. The historical typhoon damages were reviewed, and the coastal topography was measured using VRS-GPS. A FEMA formula was applied to estimate the coastal flood area in a typhoon case when the measured and predicted data of typhoon waves are not available. The results in the area of Haeundae beach and Gwangalli beach were verified using the flood area data from the case of Typhoon Maemi (2003). If a Hurricane Katrina class typhoon were to pass through the Maemi trajectory, the areathat would be flooded along theBusan coastal area was predicted and compared with the results of the Maemi case. Because of the lack of ocean environment data such as data for the sea level, waves, bathymetry, wind, pressure, etc., it is hard to improve the prediction accuracy for the coastal flood area in the typhoon case, which could be reflected in the policy to mitigate a typhoon's impact. This paper discusses the kinds of ocean environment information that is needed to predict a typhoon's impact with better accuracy.

• Ocean Science Journal
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• v.41 no.4
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• pp.245-254
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• 2006

Long term wave climate of both extreme wave and operational wave height is essential for planning and designing coastal structures. Since the field wave data for the waters around Korean peninsula is not enough to provide reliable wave statistics, the wave climate information has been generated by means of long-term wave hindcasting using available meteorological data. Basic data base of hindcasted wave parameters such as significant wave height, peak period and direction has been established continuously for the period of 25 years starting from 1979 and for major 106 typhoons for the past 53 years since 1951 for each grid point of the North East Asia Regional Seas with grid size of 18 km. Wind field reanalyzed by European Center for Midrange Weather Forecasts (ECMWF) was used for the simulation of waves for the extra-tropical storms, while wind field calculated by typhoon wind model with typhoon parameters carefully analyzed using most of the available data was used for the simulation of typhoon waves. Design wave heights for the return period of 10, 20, 30, 50 and 100 years for 16 directions at each grid point have been estimated by means of extreme wave analysis using the wave simulation data. As in conventional methodsi of design criteria estimation, it is assumed that the climate is stationary and the statistics and extreme analysis using the long-term hindcasting data are used in the statistical prediction for the future. The method of extreme statistical analysis in handling the extreme vents like typhoon Maemi in 2003 was evaluated for more stable results of design wave height estimation for the return periods of 30-50 years for the cost effective construction of coastal structures.

• Ocean and Polar Research
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• v.43 no.4
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• pp.205-217
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• 2021

A shallow channel between Jeju and Udo Islands, which is located in the northeastern Jeju Island, is influenced by storm- or typhoon-induced currents and surface waves as well as strong tidal currents. This study examines the typhoon-induced current and wave patterns in the channel, using Acoustic Doppler Current Meter (ADCP) measurements and an ocean-wave coupled modeling experiment. Three typhoons were chosen - Chaba (2016), Soulik (2018), and Lingling (2019) - to investigate the responses of currents and waves in their pathways. During the pre-typhoon periods, dominant northward flow and wave propagation were observed in the channel due to the southeasterly winds before the three typhoons. After the passage of Chaba, which passed over the eastern side of Jeju Island, the northward flow and wave propagation were totally reversed to the opposite direction, which was attributed to the strong northerly winds on the left side of the typhoon. In contrast, in the cases of Soulik and Lingling, which passed over the western side of Jeju Island, strong southerly winds on the right side of the typhoons continuously intensified the northward current and wave propagation in the channel. The model-simulated current and wave fields reasonably coincided with observational data, showing southward/northward flow and wave propagation in response to the right/left side of the typhoon pathways. Typhoon-induced downwind flows, and surface waves could enhance up to 2m/s and 3m due to the strong winds that lasted for more than 12 hours. This suggests that the flow and wave patterns in the Udo channel are highly sensitive to the pathway of typhoons and accompanying winds; thus, this may be a crucial factor with regard to the movement of seabed sediments and subsequent coastal erosion.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.5
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• pp.340-350
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• 2020

A rapid refresh wave forecasting system has been developed using the sea wind on the Korea Local Analysis and Prediction System. We carried out a numerical experiment for wind-wave interaction as an important parameter in determining the forecasting performance. The simulation results based on the seasons of with typhoon and without typhoon has been compared with the observation of the ocean data buoy to verify the forecasting performance. In case of without typhoon, there was an underestimate of overall forecasting tendency, and it confirmed that an increase in the wind-wave interaction parameter leads to a decrease in the underestimate tendency and root mean square error (RMSE). As a result of typhoon season by applying the experiment condition with minimum RMSE on without typhoon, the forecasting error has increased in comparison with the result without typhoon season. It means that the wave model has considered the influence of the wind forcing on a relatively weak period on without typhoon, therefore, it might be that the wave model has not sufficiently reflected the nonlinear effect and the wave energy dissipation due to the strong wind forcing.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.26-38
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• 2020

A statistical test was carried out on the IID (Independently and Identically Distributed) assumption of the AM (Annual Maxima) data used to estimate the design wave height. The test was divided into independence (randomness) test and homogeneity test, and each test was conducted on AM data of 210 and 310 stations in coastal and inner coastal grids in typhoon and non-typhoon (monsoon) conditions. As a result of the independence test, the rejection ratios of the test are in the range of 1.8~5.3% and 1.4~6.0% for the non-typhoon and typhoon data sets, respectively. On the other hand, in the distribution difference test of typhoon data and nontyphoon data, the same distribution hypothesis was found to be rejected in the range of 47~79% according to the test method for both coastal grid and inner coastal grid. Therefore, in estimating design wave height by extreme value analysis, the estimation process by dividing the typhoon and non-typhoon data is appropriate.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.12-18
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• 2005

Typhoon Maemi landed on the southeast coast of Korea and caused a severe storm surge in Jinhae Bay and Masan Bay. The tide gage in Masan Port recorded the storm surge of a maximum of more than 2m and the area of more than 700m from the Seo Hang Wharf was flooded by the storm surge. They had not met such an extremely severe storm surge since the opening of the port. Then storm surge was hindcasted with a numerical model. The typhoon pressure was approximated by Myers' empirical model and super gradient wind around the typhoon eye wall was considered in the wind estimation. The land topography surrounding Jinhae Bay and Masan Bay is so complex that the computed wind field was modified with the 3D-MASCON model. The motion of seawater due to the atmospheric forces was simulated using a one-layer model based on non-linear long wave approximation. The Janssen's wave age dependent drag coefficient on the sea surface was calculated in the wave prediction model WAM cycle 4 and the coefficient was inputted to the storm surge model. The result shows that the storm surge hindcasted by the numerical model was in good agreement with the observed one.

• 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 the Korean earth science society
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• v.25 no.4
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• pp.277-288
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• 2004

In this study, state of sea surface were analyzed comparatively for cases of low atmospheric pressure, which occurred in the middle area of China and moved eastward to the Korean Peninsula across the Yellow sea during April 9-12, 1999, and typhoons 'NEIL' May 1999 and 'OLGA' July 1999, which moved northward along the west coast of the Korean Peninsula. In cases of low pressure, wind speeds and phases were respectively stronger and faster in the center area than in the surrounding areas. The wave heights seem to a somewhat differing tendency from that of the wind speeds due to the influences of geometry. On the other hand, wave heights were lower under typhoon weather than under low pressures, except the instance of wave height over 5 m on Chilbal when typhoon Olga pass northward from the southern area. Storm surges also showed larger amplitudes under low pressures than under typhoons. The results suggest that wave sand storm surges may be larger for a slow passing synoptic low pressures than for a fast passing local typhoon.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.49-60
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• 2024

Recently, the frequency and intensity of typhoon-induced wave loading are increasing due to changed marine environments such as climate change. In addition, frequent earthquakes are causing a lot of damage around the world, including in Japan, Chile, Haiti, China, and Indonesia. In Korea, damage from typhoons has also been increasing since the 2000s, and the frequency and intensity of earthquakes are also increasing. Korea is surrounded by sea on three sides, so typhoons can cause a lot of damage to coastal structures, and earthquakes also cause a lot of damage to coastal structures. As such, the frequency and intensity of typhoon-induced wave loading and earthquakes are increasing both domestically and internationally, but there is no research linking typhoons and earthquakes. Therefore, in this study, numerical analysis was performed for a total of four cases by linking typhoon waves and earthquakes to the caisson breakwater. Numerical analysis was performed by applying wave loads in Case 1 and seismic wave in Case 2, seismic wave after wave loads in Case 3, and wave loads after seismic wave in Case 4. As a result of the numerical analysis, it was confirmed that in Case 3 and Case 4, which linked a typhoon and earthquakes, the damage caused by each load increased compared to Case 1 and Case 2 because the load was applied while the existing ground strength was reduced. In addition, it was confirmed that the greatest damage occurred in Case 3, in which seismic wave were applied after the wave loads.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.265-275
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• 2011

Estimation of wave height is the most important factor in the design of coastal structures such as breakwaters. In the present study, typhoon wind distribution was constructed by applying the parametric model of Holland (1980), and numerical simulations on the typhoon-generated waves were carried out using the WAM. The typhoons which affected the southern coast of the Korean Peninsula and several hypothetical typhoons were selected to construct the training sets. Design wave heights were estimated using the empirical simulation technique for various return periods and wave directions. The estimated design wave heights were compared with those by the peaks-over-threshold method and the results of KORDI(2005).