• Atmosphere
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• v.23 no.2
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• pp.205-220
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• 2013

Upper ocean response to typhoon Ewiniar (0603) and its impact on the following typhoon Bilis (0604) are investigated using observational data and numerical experiments. Data used in this study are obtained from the Ieodo Ocean Research Station (IORS), ARGO, and satellite. Numerical simulations are conducted using 3-dimensional Princeton Ocean Model. Results show that when Ewiniar passes over the western North Pacific, unique oceanic responses are found at two places, One is in East China Sea near Taiwan and another is in the vicinity of IORS. The latter are characterized by a strong sea surface cooling (SSC), $6^{\circ}C$ and $11^{\circ}C$ in simulation and observation, under the condition of typhoon with a fast translation speed (8m $s^{-1}$) and lowering intensity (970 hPa). The record-breaking strong SSC is caused by the Yellow Sea Bottom Cold Water, which produces a strong vertical temperature gradient within a shallow depth of Yellow Sea. The former are also characterized by a strong SSC, $7.5^{\circ}C$ in simulation, with a additional cooling of $4.5^{\circ}C$ after a storm's passage mainly due to enhanced and maintained upwelling process by the resonance coupling of storm translation speed and the gravest mode internal wave phase speed. The numerical simulation reveals that the Ewiniar produced a unfavorable upper-ocean thermal condition, which eventually inhibited the intensification of the following typhoon Bilis. Statistics show that 9% of the typhoons in western North Pacific are influenced by cold wakes produced by a proceeding typhoon. These overall results demonstrate that upper ocean response to a typhoon even after the passage is also important factor to be considered for an accurate intensity prediction of a following typhoon with similar track.

• Journal of the Korean Institute of Navigation
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• v.15 no.1
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• pp.49-65
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• 1991

It is of great importance for any vessel under way, especially in rough sea, to be maneuvered safely with proper seakeeping performance. In this paper, the author aims to develope a navigational safety evaluation system in rough sea by analyzing ship's with the theory of wave spectrum using random process analysis and the theory of evaluating the seakeeping performance. The scope and the method of this study are as follows ; (1) Modelized typhoon mathematically to represent the sea condition in rough sea. (2) Estimated sea conditions by getting wave spectrum, supposing that the wave by typhoon is fully developed short crest irregular wave. (3) Defined evaluation factor of vessel's seakeeping performance and obtained response amplitude operators thereby. (4) Obtained the response spectrum of factors on seakeeping performance. (5) Defined and obtained evaluation index, dangerousness, relative and maximum dangerousness of factors on seakeeping performance. (6) Analyzed the calculated dangerousness of evaluation index and picked the vertical acceleration out of 7 factors as the presentative factor on seakeeping performance. (7) Carrid out the judgement of danger by obtaining dangerousness value according to steaming hour, course alteration and speed change. By synthesizing the above items, the authors suggests a computer model of navigational safety evaluation system and examined the validity of the model by computer simulation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.4
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• pp.84-94
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• 2023

The wave height and period regression curve is widely used to estimate the design wave period. In this study, the parameters of the curves are estimated, compared, and evaluated using the linear, robust linear, and nonlinear regression methods, respectively. The data used in the design wave height estimation are the annual maxima (AM) wave height and period data sets divided by typhoon and non-typhoon conditions, provided by the Ministry of Oceans and Fisheries (2019). The estimation parameters show significant differences in the local coastal waters and the estimation methods. The estimation parameters based on the Suh et al. (2008, 2010) method show the apparent bias, under-estimation in the intercept (scale) parameter, and over-estimation in the slope (exponent) parameter, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.917-920
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• 2007

In this research, a typhoon model has been reproduced on the Masan area which had a great damage caused by a tidal wave of the typhoon "MAEMI" at that time. In addition, after calculating the highest level of a tide that happens in the case, it can be compared with one in a real situation, and the accuracy of the typhoon model could be analyzed as well by comparing the actual overflow area with the greatest overflow area computed by the data of the highest level of a tide. This research is to provide some fundamental and primary materials for the design of stable harbor structure by predicting such as tidal changes that follow some typhoon matrixes hereafter.

• 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.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.273-283
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• 2020

Numerical simulations of the storm surge and waves induced by the Typhoon Bolaven incident on the west sea of Korea in 2012 are performed using the JMA-MSM weather field provided by the Japan Meteorological Agency, and the calculated surge heights are compared with the time history observed at harbours along the various coasts of Korea. For the waves occurring coincidentally with the storm surges the calculated significant wave heights are compared with the data measured using the wave buoys operated by the Korea Hydrographic and Oceanographic Agency and the Korea Meteorological Administration. Additional simulations are also performed based on the pressure and wind fields obtained using the best track information provided by the Joint Typhoon Warning Center, and the calculated results are compared and analyzed. The waves and storm surges calculated using JMA-MSM wether field agree well with the observations because of the better reflection of the topography and the pre-background weather field. On the other hand, the calculated results based on the weather fields produced using the JTWC best track information show some limitations of the general trend of the variations of wave and surge heights. 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.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.309-316
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• 2003

In this paper, The statistical properties of ocean waves in the sea area of Hong-do, Korea are examined based on 1998-2002's wave data from a directional wave buoy. Wave data aquisition rate, mean wave heights, frequency of wave direction are summarized. Wave height and period scatter diagrams and n-years return period wave heights are estimated. Wave periods of maximum wave heights are also estimated. Large amplitude wave characteristics during the typhoon Prapiroon in 2000, Rusa in 2002 are also examined.

• Magazine of the Korean Society of Hazard Mitigation
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• v.5 no.4 s.19
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• pp.106-114
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• 2005

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.211-218
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• 2004

The WAM wave model has been widely used for wave hindcasting in the ocean by many domestic and foreign researchers due to its relative simplicity and high accuracy. As this model was originally developed for the condition cf deepwater and comparatively coarse grid size covering wide area, it might produce in a fault result mused by the improper distribution of directional spreading. We extensively investigated involved problems based on WAM Cycle 4 model and suggested the improved WAM model so that it is applicable to both shallow water sea and fine mesh wave simulation. The modified WAM model is verified here by comparing the computed result with and the observed data at Ieodo Ocean Research Station for September of 2003.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.557-564
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• 2004

The WAM wave model has been widely used for wave hindcasting in the ocean by many domestic and foreign researchers due to its relative simplicity and high accuracy. As this model was originally developed for the condition of deepwater and comparatively coarse grid size covering wide area, it might produce in a fault result caused by the improper distribution of directional spreading. We extensively investigated involved problems based on WAM Cycle 4 model and suggested the improved WAM model so that it is applicable to both shallow water sea and fine mesh wave simulation The modified W AM model is verified here by comparing the computed result with and the observed data at Ieodo Ocean Research Station for September of 2003.