• Title, Summary, Keyword: High tide

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Numerical Experiment on Sea Prince Oil Spill Incident Using a High Resolution Ocean Circulation Model (고해상도 해양순환모형을 이용한 씨프린스호 유류유출 사고 수치실험)

  • Kim, Ye-Sol;Lee, Ho-Jin;Jung, Kyung-Tae;Park, Jae-Hun;Lee, Hyun-Jung
    • Ocean and Polar Research
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    • v.34 no.3
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    • pp.337-348
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    • 2012
  • This study investigates the effects of tide, wind and oceanic currents on oil spill dispersions through a series of numerical floats tracking experiments on the Sea Prince oil spill incident occurred in 1995 using a 3-dimensional high resolution ocean circulation model. For that, a total of four experimental cases (experiment with tide, wind and oceanic currents, experiment with tide and oceanic currents, experiment with wind and oceanic currents, and experiment with tide and wind) were compared. It could be seen that results from experiment involving all external forces showed better agreement with the observed pattern of oil slick movement than other cases. The oceanic currents acted to drive floats to move to the western channel of the Korea straits and wind accelerated the eastward movement of floats in the early stage of the incident. Tidal currents played significant role in the horizontal dispersion of floats.

Red Tide Detection through Image Fusion of GOCI and Landsat OLI (GOCI와 Landsat OLI 영상 융합을 통한 적조 탐지)

  • Shin, Jisun;Kim, Keunyong;Min, Jee-Eun;Ryu, Joo-Hyung
    • Korean Journal of Remote Sensing
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    • v.34 no.2_2
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    • pp.377-391
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    • 2018
  • In order to efficiently monitor red tide over a wide range, the need for red tide detection using remote sensing is increasing. However, the previous studies focus on the development of red tide detection algorithm for ocean colour sensor. In this study, we propose the use of multi-sensor to improve the inaccuracy for red tide detection and remote sensing data in coastal areas with high turbidity, which are pointed out as limitations of satellite-based red tide monitoring. The study area were selected based on the red tide information provided by National Institute of Fisheries Science, and spatial fusion and spectral-based fusion were attempted using GOCI image as ocean colour sensor and Landsat OLI image as terrestrial sensor. Through spatial fusion of the two images, both the red tide of the coastal area and the outer sea areas, where the quality of Landsat OLI image was low, which were impossible to observe in GOCI images, showed improved detection results. As a result of spectral-based fusion performed by feature-level and rawdata-level, there was no significant difference in red tide distribution patterns derived from the two methods. However, in the feature-level method, the red tide area tends to overestimated as spatial resolution of the image low. As a result of pixel segmentation by linear spectral unmixing method, the difference in the red tide area was found to increase as the number of pixels with low red tide ratio increased. For rawdata-level, Gram-Schmidt sharpening method estimated a somewhat larger area than PC spectral sharpening method, but no significant difference was observed. In this study, it is shown that coastal red tide with high turbidity as well as outer sea areas can be detected through spatial fusion of ocean colour and terrestrial sensor. Also, by presenting various spectral-based fusion methods, more accurate red tide area estimation method is suggested. It is expected that this result will provide more precise detection of red tide around the Korean peninsula and accurate red tide area information needed to determine countermeasure to effectively control red tide.

Effect of the Freshwater Discharge on Seawater and Sediment Environment in a Coastal Area in Goheung County, South Korea

  • Nguyen, Hoang Lam;Jang, Min-Seok;Cho, Hyeon-Seo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.3
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    • pp.270-276
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    • 2014
  • Seasonal characteristics of water and sediment qualities and potential effects of the freshwater discharge from a small tide embankment interior in a coastal area in Goheung county were investigated from May to September in 2012. Chemical oxygen demand values (COD) were mostly higher than 2 mg/L in summer ebb tide, which exceed the standard value of water quality criteria II of acceptable level for aquaculture activities. Nitrogen and phosphorus were found as the limiting nutrients for algae growth in summer and fall and in spring, respectively. Nitrogen was the limiting nutrient for diatom growth in the whole studied period. The sudden high values of COD, ammonia, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) were found in water sample collected from station 5 which located in front of the tide embankment sluice gate during spring ebb tide. The freshwater discharge form the tide embankment interior maybe affected the survey areas during a short time interval. Mean values of eutrophication index of the surveyed coastal region in spring, summer and fall were all bigger than 1. Water quality was mostly considered at level II which acceptable for aquaculture activities. Sediment quality in this study was generally in the range of standard for fisheries environment.

Population Structure and Reproduction of Padina concrescens Thivy(Dictyotales: Phaeophyta) in Southwest Baja California Peninsula, Mexico

  • Rafael, Riosmena-Rodriguez;Consuelo, Ortuno-Aginrre
    • ALGAE
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    • v.24 no.1
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    • pp.31-38
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    • 2009
  • The brown algae padina concrescens is widely distributed in the northwestern Pacific Mexico. We described the population of P. concrescens based on population parameters such as cover, density and size structure and reproduc-tion at two levels tide at the intertidal area in the southwestern Baja. California Peninsula. Monthly visits from January to December 2003 were done. Both cover and density were measured in situ by quadrants method. Samples were collected to obtain size structure and percentage of reproductive fronds. Our results show there is sparial vari-ation in the population structure more than temporal. Thus, cover and density peak were at different months ineach tide level studied, the lower tide level shows the high values in cover as well as density. The frond develop-ment was observed in height/width ratio this relation was consistent only in the low tidal zone. Size class distribu-tion has consistently small size plants in both tide levels.Reproduction was seasonal in the tide channel but in both tide levels all the reproductive plants were tetrasporophyte. Our results suggest that this population is pseudopere-nial and it strongly as a consequence of the intense competition in the intertidal zone.

The Outbreak of Red Tides in the Coastal Waters off Kohung, Chonnam, Korea: 1. Physical and Chemical Characteristics in 1997 (전남 고흥 해역의 유해성 적조의 발생연구: 1.물리${\cdot}$화학적인 특성)

  • Yang, Jae-Sam;Choi, Hyun-Yong;Jeong, Hae-Jin;Jeong, Ju-Young;Park, Jong-Kyu
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.1
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    • pp.16-26
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    • 2000
  • Physical characteristics and nutrient distributions in seawater were investigated to understand the mechanism of red tide outbreak in coastal waters off Kohung area. To identify any physical and chemical differences before, during and after the red tide outbreaks, 6 times of field observations have been carried out from May to October, 1997. We found that major environmental properties of the seawater in the study area were determined not by the local meteoric conditions or nearby-land influences, but by the intrusion of seawater from offshore. In particular, extreme environmental variations in seawater were found during the period of red tide outbreak from August to September. Before the red tide outbreak, high concentrations of DIN(Dissolved Inorganic Nitrogen)were found in seawater, but they decreased during the outbreak. Whereas no significant variations of DIP(Dissolved Inorganic Phosphate) were found. For the water mass in the semienclosed northern part of the study area, local nutrient sources originated from nearby-lands were estimated to cover 70% of total DIN input, but the rest part of the water mass in the study area, sporadic intrusion of offshore water mass could account for the major source of DIN supply. An offshore water mass influenced by Yangtze river effluent was suggested as one of the candidates with its high nitrate contents, high seawater temperature and low salinity. A red tide related phytoplankton, Gyrodinium impudicum, was found in seawater on the 21th day of August and, on the same day, a unique water mass with high temperature and extremely low salinity suddenly appeared in the study area. On the 22th day of September, after one and half month duration of red tide we found that red tide had disappeared simultaneously with the intrusion of new water mass with different characteristics.

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Tide And Tidal Current In The Estuary Of The Nakdong River (낙동강 하구의 조석과 유동)

  • Ryu, Cheong-ro;Chang, Sun-duck
    • 한국해양학회지
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    • v.14 no.2
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    • pp.71-77
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    • 1979
  • Tidal waves and the fluctuation of current are studied by use of observed data on tidal level, flow velocity and river discharge in the estuarine region of the Nakdong River. Observed data on the tidal level at five stations are used to obtain the fluctuation of amplitude and phase of tides, and the change of the wave speed versus distance from the river mouth. Comnining these tidal data with the vertical distribution of horizontal velocity data, some characteristics of the periodic tidal flow are deduced: (1)Diminishing rates of the tidal amplitude ratio η / η$\_$0/ at high tide were 0.058η$\_$0H/ /Km at neap tides. The constant of phase change, K, was 0.035rad/km. (2)While proceeding landward, the shape of the tidal wave changes from symmetrical to asymmetrical. The traveling speed of the tidal wave crest was estimated to be 3.6∼5.2m/sec, while that of the tidal wave trough was 2.4∼ 3.5m/sec. (3)The flowing speed of the water varies periodically in accordance with the tidal period. The maximum speed of landward flow appeared approximately at two hours before the high tide, while that of seaward flow at two hours before the low tide. (4)The upstream boundary is deduced approximately to be 50km at spring tide and 44km at neap tide from the tidal velocity decreasing. the tidal influence area is estimated approximately to be 65km from the tidal amplitude damping.

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Analysis of the Characteristics of Water Quality Difference Occurring between High Tide and Low Tide in Masan Bay (만조와 간조시 마산만 수질의 농도차 발생 특성의 분석)

  • Yoo, Youngjin;Kim, Sung Jae
    • Journal of Wetlands Research
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    • v.21 no.2
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    • pp.102-113
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    • 2019
  • Slack-tide sampling was carried out at 6 stations at high and low tide for a tidal cycle during spring tide of the early summer (June) and summer (July, August) of 2016 to determine the difference of water quality according to tide in Masan Bay, Korea. The mixing regime of all the water quality components investigated was well explained through the correlation with SAL. In the early summer and summer, TURB, DSi and NNN which mainly flow into the bay from the streams and SS, COD, AMN and $H_2S$ which mainly indicate the internal sink and source materials have a property of conservative mixing and non-conservative mixing, respectively. The conservative mixing showed a good linear relationship of the water quality between high and low tide, and the non-conservative mixing showed a variation of different pattern each other. Factor analysis performed on the concentration difference data sets between high and low tide helped in identifying the principal latent variables for them. In early summer, multiple effects (tidal action, natural influx and internal sinks and sources etc.) acted in combination for the differences to be distributed evenly in four factors (VF1~4), since there were few allochthonous inputs as a low-water season. On the contrary, in summer, the parameters showing large concentration difference at ST-1 affected by stream water were concentrated in one factor (VF1) and clearly distinguished from the parameters affected by the internal sinks and sources. In fact, there is no estuary (bay) that always maintains steady state flow conditions. The mixing regime of an estuary might be changed at any time due to the change of flushing time, and furthermore the change of end-member conditions due to the internal sinks and sources makes the occurrence of concentration difference inevitable. Therefore, when investigating the water quality of the estuary, it is necessary to take a sampling method considering the tide to obtain average water quality data.

Saline Water Movement In The Estuary Of The Nakdong River (낙동강 하구의 염수운동)

  • Chang, Sun-duck;Ryu, Cheong-ro;Lee, Mun-ok;Lee, Jae Chul
    • 한국해양학회지
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    • v.16 no.1
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    • pp.31-37
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    • 1981
  • Saline water movements in relation to tidal condition and river discharge in the estuary of the Nakdong River are discussed on the basis of the observation data. The difference of salinity between the surface and the bottom layer was 1∼3 at spring tide forming a vertically homogeneous estuary, while at neap tide, it ranges up to 7∼15 indicating a sharp salt wedge. The maximum salinity appeared approximately at an hour after the high water, that is, three hours after the landward velocity maximum, while the salinity maximum at around an hour after the low water, that is, three hours after the seaward velocity maximum. The density current speed at a section located 10km landward from the river mouth was observed approximately to be 45cm sec$\^$-1/ at 8m layer.The relations between the salinity at Gupo and the river discharge at Jindong are estimated by means of the least square method. The maximum length of the salt wedge is calculated approximately to be 22km at neap tide and 16km at spring tide, which is in accordance with the observed data. The salinity influence area is deduced to be 45km at spring tide and 35km at neap tide. The diffusion coefficient of salinity was estimated approximately to be 1.5 10$\^$8/$\textrm{cm}^2$ sec$\^$-1/ at Samrak and 8 10$\^$5/$\textrm{cm}^2$ sec$\^$-1/ at Gupo at neap tide, while it was 1.4 10$\^$7/$\textrm{cm}^2$ sec$\^$-1/ at Dongwon at spring tide.

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Inter-annual Variation of Tides on the Western Coasts of Korea (서해 연안에서 조석특성의 경년변화)

  • Jung, Tae Sung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.2
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    • pp.81-91
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    • 2016
  • Harmonic analysis of tide data observed on the western coasts has been conducted. The changing trends of harmonic constants were reviewed. Overall, amplitudes of semidiurnal tide are not changed and present phases are faster than in the past. In Mokpo located in a semi-enclosed bay, the amplitudes have been greatly increased and the phases have become earlier due to construction of sea-dike and seawalls. Harmonic constants of diurnal tide have not been changed except Mokpo. In Mokpo the phases of diurnal tide have been earlier. Tidal ranges in spring tide and neap tide have not been significantly changed except Mokpo. In Mokpo tidal ranges have been increased and tidal flats widened. Approximate higher high water has been overall rising. Therefore, Korean western coasts can be easily inundated than before.

Flocculation and Algicidal Effect of Mixture of Red-soil or Clay and Chitosan against Harmful Green-Tide (유해 녹조에 대한 황토 및 점토와 키토산 혼합물의 응집 및 살조 효과)

  • Lee, Hyun-Su;Jeong, Gyeong-Won;Choi, Changyong;Ahn, Ginnae;Nah, Jae-Woon
    • Journal of Chitin and Chitosan
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    • v.22 no.1
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    • pp.47-53
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    • 2017
  • Currently, harmful green-tide is seriously occurred by water temperature rising by climate change and inflow of excessive nutritive salts in river. To remove these harmful green-tide, red-soil and clay are using in river. However, it is induced to high cost, damage of forestland, and destruction of ecosystem. In addition, only red-soil and clay are sunken to harmful green-tide, which is growth in bottom of river. It is cause of secondary pollution. To solve these problem, we prepared to red-soil/clay-mixed chitosan. In this study, characterization of chitosan was analyzed by $^1H-NMR$ and GPC-MALLS. Also, to confirm optimal concentration of flocculation, red-soil or clay of various concentration with chitosan of fixed concentration (5 mg/L) was treated in harmful green-tide. Moreover, its algicidal effect was analyzed by UV-vis spectrometer and, growth and chlorophyll a of harmful green-tide were decreased by red-soil/clay-mixed chitosan. Theses results suggest that red-soil/clay-mixed chitosan can be inhibit against harmful green-tide.