• Title/Summary/Keyword: Astronomical Tide

Search Result 23, Processing Time 0.028 seconds

Analysis on the estimation errors of the lowest and highest astronomical tides for the southwestern 2.5 GW offshore wind farm, Korea

  • Ko, Dong Hui;Jeong, Shin Taek;Cho, Hong-Yeon;Kang, Keum-Seok
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • v.10 no.1
    • /
    • pp.85-94
    • /
    • 2018
  • For the design of wind-power facilities, the highest and lowest astronomical tides (HAT and LAT, respectively) are needed for the tidal-water levels regarding international designs; however, the approximate highest high water and approximate lowest low water AHHW and ALLW, respectively, have been used in Korea. The HAT and LAT in the wind-farm test-bed sea should be estimated to satisfy the international standard. In this study, the HAT and LAT are therefore estimated using the hourly tidal-elevation data of the Eocheongdo, Anmado, Younggwang, Gunsan, Janghang, and Seocheon tidal-gauging stations that are located in the adjacent coastal sea. The nodal variation patterns of the major lunar components, such as $M_2$, $O_1$, and $K_1$ are analyzed to check the expected long-term lunar cycle, i.e., 18.61 year's nodal-variation patterns. The temporal amplitude variations of the $M_2$, $O_1$, and $K_1$ clearly show the 18.61-years periodic patterns in the case of the no-nodal correction condition. In addition, the suggested HAT and LAT elevations, estimated as the upper and lower confidence limits of the yearly HAT and LAT elevations, are 50 cm greater than the AHHW and 40 cm lower than the ALLW, respectively.

Characteristics of Tidal Flow Simulation of Real Tide in West-South Coastal Waters of Korea (실조석에 의한 한국 서남해 연안역에서 해수유동의 재현특성)

  • Jeong, Seung-Myong;Park, Il-Heum
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.26 no.5
    • /
    • pp.531-541
    • /
    • 2020
  • In this study, a computed tide of a real tide was introduced to improve the numerical solutions for tides and tidal flow simulations. The real tide was defined considering the nodal modulation amplitude, phase correction factor, astronomical argument, and tidal harmonic constants of all the constituents. The numerical simulation was performed using the real tide parameters for the west-south coastal waters of Korea, where the observation data for tides, tidal currents, waves, and winds over two seasons exist. The tidal flow simulation of the real tide was simulated successfully. The correlation coefficient between the observed and calculated values was 1.0, which indicated both accurate amplitude and phase. The U- and V-components of the tidal current obtained for the real tide had average valid correlations of 0.83 and 0.936, respectively. The speed error for the residual current was 0.006 m/s on the average, which indicated an insignificant difference, and the directional behavior of the residual current was very similar. In addition, the velocity error was attributed to various weather effects, such as high waves and wind storms. Therefore, this model is expected to improve current solutions provided that weathering forces, such as waves and winds, are considered.

TIDAL EVOLUTION OF LUNAR ORBIT AND EARTH ROTATION

  • Na, Sung-Ho
    • Journal of The Korean Astronomical Society
    • /
    • v.45 no.2
    • /
    • pp.49-57
    • /
    • 2012
  • In this study, I calculate the past and future dynamical states of the Earth-Moon system by using modified Lambeck's formulae. I find that the ocean tidal effect must have been smaller in the past compared to its present amount. Even though the Moon is already in the spin-orbit synchronous rotational state, my calculation suggest that it will not be in geostationary rotational state in the next billion years or so. This is due to the associated Earth's obliquity increase and slow retardation of Earth's spin and lunar orbital angular velocities. I also attempt to calculate the precessional period of the Earth in the future. To avoid uncertainties in the time scale, the future state is described by using the Earth-Moon distance ratio as independent parameter. Effects due to solar tidal dissipation are included in all calculations.

Analysis of Flood due to Storm Surge at Masan Bay (마산만에서 고조로 인한 침수원인 분석)

  • 황호동;이중우;권소현
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2004.04a
    • /
    • pp.217-224
    • /
    • 2004
  • Open-coast storm surge computations 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. A simple quasi-two dimensional numerical model for storm surge is considered. In order to understand the model's underlying assumptions, range of validity, and application, we discussed several aspects of typhoons and the physical factors governing storm generation processes. We also followed the basic governing equation, together with the assumption generally taken in their development, to see the principle characteristics of the model from a physical as well as a mathematical point of view. The equations consistent with the model described here are reduced forms of the basic equations and their effects on the resulting numerical scheme are discussed. Finally we applied the model discussed above to a storm surge problem at Masan Bay, the south coast of Korea Effects of astronomical tide, initial water level, and atmospheric pressure setup are considered. We then analyzed the flood at the coastal city and proposed a reasonable way of flood control.

  • PDF

Hindcasting of Storm Surge at Southeast Coast by Typhoon Maemi

  • KAWAI HIROYASU;KIM DO-SAM;KANG YOON-KOO;TOMITA TAKASHI;HIRAISHI TETSUYA
    • Journal of Ocean Engineering and Technology
    • /
    • v.19 no.2 s.63
    • /
    • pp.12-18
    • /
    • 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.

The Establishment and Application of Hydraulic Channel Routing Model on the Nakdong River (II) Model Application (낙동강 유역 수리학적 하도추적 모형 구축 및 적용 (II) 홍수사상의 적용)

  • Lee, Eul Rae;Kim, Sang Ho
    • Journal of Wetlands Research
    • /
    • v.8 no.1
    • /
    • pp.83-96
    • /
    • 2006
  • In this study, hydraulic flood routing is performed by 1-Di. unsteady flow model, FLDWAV on the downstream of Nakdong river. For input information, KOWACO Rainfall-Runoff Model is used and resonable boundary condition is constructed. As the result of the application about the past flood event, good agreement of comparison with observed and calculated values are show in the interesting sites, Jindong and Samrangjin. Additionally, estuary barrage's WSL evaluation procedure is enhanced to accurate calculation, and it is defined by downstream boundary condition in Nakdiong river. The new regressive equation to calculate the predicted tide value is developed by considering the astronomical tide and past observed tide value at Nakdong estuary barrage. The guideline's construction of the new application and flood forecasing system of other river basins is possible by using this studied results.

  • PDF

Estimation of the Lowest and Highest Astronomical Tides along the west and south coast of Korea from 1999 to 2017 (서해안과 남해안에서 1999년부터 2017년까지 최저와 최고 천문조위 계산)

  • BYUN, DO-SEONG;CHOI, BYOUNG-JU;KIM, HYOWON
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
    • /
    • v.24 no.4
    • /
    • pp.495-508
    • /
    • 2019
  • Tidal datums are key and basic information used in fields of navigation, coastal structures' design, maritime boundary delimitation and inundation warning. In Korea, the Approximate Lowest Low Water (ALLW) and the Approximate Highest High Water (AHHW) have been used as levels of tidal datums for depth, coastline and vertical clearances in hydrography and coastal engineering fields. However, recently the major maritime countries including USA, Australia and UK have adopted the Lowest Astronomical Tide (LAT) and the Highest Astronomical Tide (HAT) as the tidal datums. In this study, 1-hr interval 19-year sea level records (1999-2017) observed at 9 tidal observation stations along the west and south coasts of Korea were used to calculate LAT and HAT for each station using 1-minute interval 19-year tidal prediction data yielded through three tidal harmonic methods: 19 year vector average of tidal harmonic constants (Vector Average Method, VA), tidal harmonic analysis on 19 years of continuous data (19-year Method, 19Y) and tidal harmonic analysis on one year of data (1-year Method, 1Y). The calculated LAT and HAT values were quantitatively compared with the ALLW and AHHW values, respectively. The main causes of the difference between them were explored. In this study, we used the UTide, which is capable of conducting 19-year record tidal harmonic analysis and 19 year tidal prediction. Application of the three harmonic methods showed that there were relatively small differences (mostly less than ±1 cm) of the values of LAT and HAT calculated from the VA and 19Y methods, revealing that each method can be mutually and effectively used. In contrast, the standard deviations between LATs and HATs calculated from the 1Y and 19Y methods were 3~7 cm. The LAT (HAT) differences between the 1Y and 19Y methods range from -16.4 to 10.7 cm (-8.2 to 14.3 cm), which are relatively large compared to the LAT and HAT differences between the VA and 19Y methods. The LAT (HAT) values are, on average, 33.6 (46.2) cm lower (higher) than those of ALLW (AHHW) along the west and south coast of Korea. It was found that the Sa and N2 tides significantly contribute to these differences. In the shallow water constituents dominated area, the M4 and MS4 tides also remarkably contribute to them. Differences between the LAT and the ALLW are larger than those between the HAT and the AHHW. The asymmetry occurs because the LAT and HAT are calculated from the amplitudes and phase-lags of 67 harmonic constituents whereas the ALLW and AHHW are based only on the amplitudes of the 4 major harmonic constituents.

A Study on the establishment of Korean maritime boundaries (우리나라의 해양경계 설정에 관한 연구)

  • Kim, Baek-Su;Choe, Yun-Su;Kim, Ho-Gyun;Jeon, Chang-Dong
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
    • /
    • 2007.04a
    • /
    • pp.11-16
    • /
    • 2007
  • Since public awareness on the importance of sea is increasing, a number of states have ratified the United Nations Convention on the Law of the Sea. However several problems on marine boundary making are raising due to the ambiguity of law and importance of sea area. The purpose of this study is to find a logical principal through overall consideration on decision of baseline points which is a criteria of maritime boundary delimitation. Accordingly, this paper considers the current status, problems and measures for marine boundary making and then presents an alternative on it.

  • PDF

Application of Oil Spill Model to the South Sea of Korea (누유확산 모델의 남해안 적용)

  • Hong Keyyong;Lee Moonjin
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.1 no.1
    • /
    • pp.56-65
    • /
    • 1998
  • An oil spill model, Green Sea Ranger(GSR) based on trajectory and fate modeling of spilt oil behavior is introduced. The various physical models on weathering processes are reviewed and those adopted by GSR are described. A database for currents, which is necessary for the real-time simulation of oil spill, is generated on the south sea of Korea. The real-time prediction of tidal currents in the South Sea of Korea is carried out. Four major constituents (M₂, S₂, K₁, O₁ tide) are employed in the prediction, and those angular speeds and phases are determined from the astronomical arguments. The harmonic constants of the constituents are computed by solving shallow-water tide equations. The GSR has user-freiendly GUI and flexible framework which makes it easy to expand the database for sea environments in Korean coastal waters. The GSR is validated by the simulation of O-Sung oil spill caused by a grounded oil tanker in coastal sea near Maemol-do. The simulated trajectory is compared with observed one and it is shown that the GSR gives reasonable estimation on spilt oil bahavior.

  • PDF

Effect of a Barrier on Tides in the Youngsan Estuary (영산강하구(榮山江河口)의 방조제건설(防潮堤建設) 조위변화(潮位變化))

  • Choi, Byoung Ho
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.4 no.2
    • /
    • pp.113-124
    • /
    • 1984
  • This study represents results of analysis of sea level record at Mokpo for the years 1956~1982. The results are believed to be the first detailed analysis for the Port of Mokpo. The tidal constants are obtained from separate yearly extended harmonic analysis. The variability of these yearly analysis gives estimates of effects on astronomical tide due to Youngsan Barrier. Multiple statistics of sea level record for the years 1965~1980 and 1981~1982 are presented separately to evaluate the distribution of sea level frequency due to the construction of Barrier. Some of preliminary results are presented and indication of further studies are discussed.

  • PDF