• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.4
• /
• pp.344-353
• /
• 2016

The cause of abnormal tidal residuals was examined by analyzing sea levels, sea surface atmospheric pressures, winds at ten tide stations, and current, measured at the coast of the Yellow Sea from the night of November $24^{th}$ to the morning of the $25^{th}$ in 2013, along with weather chart. Additionally, the cross-correlations among the measured data were also examined. The 'abnormal tidal residuals' mentioned in this study refer to differences between maximum and minium tidal residuals. The largest abnormal tidal residual was identified to be a difference of 176 cm occurring over 4 hours and 1 minute at YeongJongDo (YJD) with a maximum tidal residual of 111 cm and minimum of -65 cm. The smallest abnormal tidal residual was 68 cm at MoSeulPo (MSP) during 8 hours 52 minutes. The cause of these abnormal tidal residuals was not a meteo-tsunami generated by an atmospheric pressure jump but wind generated by the pressure patterns. The flow speed due to these abnormal tidal residuals as measured at ten tide stations was not negligible, representing 16 ~ 41 % of the annual average ebb current speed. From the cross correlation among the tidal residuals, winds, and tidal residual currents, we learned the northern flow, due to southerly winds, raised the sea level at Incheon when a low pressure center located on the left side of the Korean Peninsula. After passing the Korean Peninsula, a southern flow due to northerly winds decreased the sea level.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.6
• /
• pp.561-569
• /
• 2013

EOF analysis of tidal residual derived from 2003~2009 tide data was used to identify the spatio-temporal variability. The effect of sea surface air pressures and winds on the tidal residual was also investigated by the correlation analysis. The first mode accounting for 68 % of the total variance represented concurrent sea level rise or fall, and the second mode accounting for 21 % of the total variance explained alternative sea level rise and fall between West Sea coast and both South Sea and East Sea coasts. While northerly and southerly winds dominated the tidal residual in the eastern coast of Yellow Sea, the effect of sea surface air pressures on the tidal residual increased along the coastal regions from South Sea to East Sea.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.165-171
• /
• 2013

The fact that tidal residuals are detected greatly at the tide-dominated region implies that tide component has still remained in the tidal residual. Auto-correlation function analysis also show that the auto-correlation coefficients are conspicuous near tidal periods at the Western Coast. A wavelet method was used to analyze characteristics of the short period or tide-relevant residuals. Considering the results that tidal period is prominent at the tide-dominated region, that seasonal variation is trivial at the short periods, and that shallow tidal period is conspicuous at Mokpo, the short period can be considered to be correlated with tide modulated surge. The result also shows short period components stem mainly from tide-forecasting error and tide-surge interaction. Thus tide modulated surge must be distinguished from meteorological surge.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.1
• /
• pp.1-9
• /
• 2012

Tidal residual is being an important factor by the influence of the climate change in terms of the coastal safety and defense. It is one of the most important factor for the determination of the reference sea level in order to check the safety and performance of the coastal structures in company with the typhoon intensity variation. The probability density function (pdf) of tidal residuals in the Korean coasts have a non-ignorable skewness and high kurtosis. It is highly restricted to the application of the normal pdf assumption as an approximated pdf of tidal residuals. In this study, the pdf of tidal residuals estimated using the Kernel function is suggested as a more reliable and accurate pdf of tidal residuals than the normal function. This suggested pdf shows a good agreement with the empirical cumulative distribution function and histogram. It also gives the more accurate estimation result on the extreme values in comparison with the results based on the normal pdf assumption.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.22 no.4
• /
• pp.279-285
• /
• 2010

In the process of the probabilistic-based design on the coastal structures, the probability density function (pdf) of tidal elevation data is assumed as the normal distribution function. The pdf shape of tidal elevation data, however, is better-fitted to the double-peak normal distribution function and the equivalent mean and standard deviation (SD) estimation process based on the equivalent normal distribution is required. The equivalent mean and SD (equivalent parameters) are different with the mean and SD (normal parameters) estimated in the condition that the pdf of tidal elevation is normal distribution. In this study, the difference, i.e., estimation error, between equivalent parameters and normal parameters is compared and analysed. The difference is increased as the tidal elevation and its range are increased. The mean and SD differences in the condition of the tidal elevation is ${\pm}400cm$ are above 100 cm and about 80~100 cm, respectively, in Incheon station. Whereas, the mean and SD differences in the condition of the tidal elevation is ${\pm}60cm$ are very small values in the range of 2~4 cm, in Pohang station.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.2
• /
• pp.72-80
• /
• 2014

The approximately highest high water(AHHW), which has been used frequently as a basis of the design sea level, has not only ambiguous return period but also spatio-temporal problems induced by sea level rise and the spatial variability of tidal characteristics. The ratios of 4 major constituents with other constituents were investigated. In addition, tidal data were analyzed by probability density function. The temporal variability may be cured by using the latest tidal data. And the AHHW at summer was examined to lessen the spatial variability. The results show that the design sea levels need to increase by 10 cm or more at the Southern Coast and by 15~25 cm at the East Coast.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.6
• /
• pp.458-465
• /
• 2011

Characteristics of nearshore surge intensity were investigated by analyzing the tide data at 20 tidal stations. Statistical analysis of the surge data show that surge heights at the western coast are far greater than those at southern and eastern coasts, implying that each coast has its own classified characteristics. Surge height data greater than 30 cm were chosen and their intensities were calculated, and then, typhoon-induced surges were separated. The results show that while surge intensity at the western coast is conspicuous in winter due to the monsoon, it is conspicuous in summer due to the typhoon at other coasts. EOF analysis show that the 1st eigenvector at the western coast is prominent, which is considered to be consistent with above mentioned results.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.4
• /
• pp.200-206
• /
• 2013

Fourier analysis and a wavelet method were carried out to elucidate the characteristics of tidal residual components in coastal waters. The result of Fourier analysis shows tide-induced and monsoon-induced residuals are conspicuous at the short period and mid period, respectively. The tidal residuals were decomposed by period from 3 hours to 8 months and the characteristics of their components were shown by reconstituting them with short periods less than 24 hours, mid-periods between 1 day and 16 days and long periods longer than 1 month. The tidal residuals in the short period, i.e., tide-induced components, being based on the tidal elevation prediction errors, appear in the West Sea with high tidal ranges and do not have much seasonal fluctuation. Additionally, the period of typhoon induced surge ranges more or less than 12 hours. The mid-period components were clearly generated mainly in the West Sea during the winter and largely affected by monsoon. Accordingly, the pure surge height components were concentrated on the mid-period and had clear features for each coastal waters. The long period components show similar characteristics at all stations and are considered to stem from variations of mean sea levels.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2022.10a
• /
• pp.49-50
• /
• 2022

본 논문에서는 천문 및 기상에 의해 발생하는 조위 변동에 대한 이해를 높이고 나아가 이와 관련한 피해를 줄이고자 우리나라의 29개 조위관측소 자료를 바탕으로 크게 서해안, 남해안(제주 지역 포함), 동해안 지역으로 구분하여 지역별 조위의 특성과 태풍에 의한 영향을 분석하였다. 2000년부터 2021년까지의 조위 평균(표준편차)은 서해안은 628 cm(68 cm), 남해안은 270 cm, (35 cm), 동해안은 63 cm (15 cm)로 서해안이 가장 높고 동해안이 가장 낮은 편이다. 이러한 차이는 각 지역이 태풍의 영향권에(6월에서 10월 사이에 발생한 태풍의 진로 상 중심이 각 지역으로부터 10°반경 이내에 위치) 있을 때도 일관되게 나타난다. 서해안, 남해안, 동해안에서 특히 조위가 높게 나타나는 지역은 평택, 완도, 마산으로 태풍 영향 시에 각각 최대 1030 cm, 444 cm, 265 cm를 기록하였다. 다만, 서해안은 태풍의 영향을 받은 날과 그렇지 않은 날의 최대 조위 차이가 16 cm로 남해안의 108 cm나 동해안의 49 cm에 비해 뚜렷하게 떨어진다. 본 논문에서는 이렇듯 지역별 조위 특성의 차이 및 태풍에 의한 조위 변동을 정량적으로 분석하여 폭풍해일 특보 등 조위에 의한 피해 예방에 사용할 수 있는 참고 자료를 제시하였다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.9 no.3
• /
• pp.119-129
• /
• 2004

The surges caused by the typhoon “Maemi” which struck the southern coast of Korea are analysed in Kwangyang Bay on September 12, 2003. The deviations of the high water level were 93∼108 cm and the maximum deviations of the water level (maximum surges) were 176∼196 cm in Kwangyang Bay during the typhoon “Maemi”. The major parameters of the maximum deviations of the water level are as follows: Analysis shows that the pressure drop increased the sea level by 59 cm, the flood of the Sumjin River by 4-5 cm and the external surge propagation and wind setup by 113∼132 cm. During the typhoon “Maemi”, the highest high water recorded in Kwangyang Port (PT3) is 460 cm, which is higher by 5 cm than the highest high water (455 cm) with return period of 100 years estimated in planning the Kwangyang steelworks (POSCO) grounds and higher by 15 cm than the observed highest high water (445 cm) recorded during the typhoon “Thelma” on 1987. Thus, the highest high water caused by the typhoon “Maemi” is higher than the extreme highest high water for the last 20 years in Kwangyang Bay.