• Title, Summary, Keyword: High tide

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Tidal Influence on Physical Parameters and Phytoplankton Size Structure in Youngsan River Estuary during Neap Tide (조석에 따른 영산강 하구의 물리적 환경 및 식물플랑크톤 크기구조: 소조기)

  • Park, Geon-Woo;Lee, Da-Hye;Shin, Yongsik
    • Journal of Environmental Science International
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    • v.26 no.3
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    • pp.325-334
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    • 2017
  • To understand the changes in physical parameters and phytoplankton size structure caused by tides, a fixed station in the Youngsan River estuary was monitored at 2-h intervals, on April 28, 2012 and August 12, 2012. No clear relationship was observed between the temperature and salinity changes and tidal levels in April. However, in August, temperature decreased during the ebb tide and increased during the flood tide, while salinity showed the opposite trend. In addition, there was no specific change in the phytoplankton biomass corresponding to tidal levels in April. In August, the total chlorophyll a and the biomass of net phytoplankton (>$20{\mu}m$) increased almost 20 times during the ebb tide and decreased during the flood tide. The biomass of nanophytoplankton (<$20{\mu}m$) showed a similar variation in response to tidal level changes. In April, the relationship between percent contributions of phytoplankton size structure and tidal levels was not clear. In August, the net phytoplankton was dominant in the early stage and nanophytoplankton was dominant in the later stage, while contribution of nanophytoplankton and net phytoplankton increased at high tide and low tide, respectively. Therefore, in April, other factors such as freshwater discharge were more important than the tide, whereas in August, when no freshwater discharge was recorded, the changes in semidiurnal tides influenced the physical parameters and phytoplankton dynamics. These results could contribute to the understanding of phytoplankton dynamics in the Youngsan River estuary.

Application of unmanned aerial image application red tide monitoring on the aquaculture fields in the coastal waters of the South Sea, Korea (연근해 양식장 주변 적조 모니터링을 위한 무인항공영상 적용 연구)

  • Oh, Seung-Yeol;Kim, Dae-Hyun;Yoon, Hong-Joo
    • Korean Journal of Remote Sensing
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    • v.32 no.2
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    • pp.87-96
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    • 2016
  • Red tide, causes aquaculture industry the damages in Korea every summer, was usually detected by using satellite, aquaculture information was difficult to detect by using satellite. Therefore, we suggests the method for detecting the red tide using the coastal observation and the product from the unmanned aerial Vehicle. As a result, we obtained the high resolution unmanned aerial Vehicle images, detected the red tide by using the unsupervised classification from the true color images and the simple algorithm from the RGB color images. Compared the previous color images, unmanned aerial Vehicle images were clearly classified the ocean color, we were able to identify the red tide distribution in sea surface. These methods were determined to accurately monitor the red tide distribution on the aquaculture fields in the coastal waters where is established the aquaculture.

The Change of Suspended Sediment Concentration in the Seomjin River Estuary during Fall and Winter Months (추계와 동계 섬진강하구 부유퇴적물농도 변화)

  • Lee, Byoung-Kwan;Lee, Su-Woong;Kim, Seok-Yun
    • Journal of Korean Society on Water Environment
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    • v.27 no.4
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    • pp.542-550
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    • 2011
  • Changes of suspended sediment concentration in the Seomjin river estuary located in south sea of the Korea peninsula were investigated during the spring tide in autumn (i.e. 25 hours in October) 2000 and winter (i.e. 25 hours in February) 2001. The changes of temperature and salinity during the spring tide in October 2000 showed larger variations than the those in February 2001. During the spring tide in October 2000, currents at bottom layer were observed to be stronger than during the spring tide in February 2001, showing that both of the two periods had ebb currents-predominant tide asymmetries. The suspended sediment concentrations in October 2000 were larger than the those in February 2001. At the time of the maximum of tide currents or after about one hour of the maximum during the autumn months, the suspended sediment turbidity was observed to be maximum. Another observation station at Hadong upstream from the Seomjin river estuary showed about one hour delay in tide phase, Thereby, the suspended sediment concentration showed high turbidity after two hours at bottom and three hours at surface layer, in particular, in October 2000. This results can be explained by the facts that river discharge increased significantly after the summer rainy season, causing also increase of erosion processes by strong current velocity at bottom layer.

A Study on Standing Crops in Phragmitis communis Communities and their Environmental Factors (갈대군락의 현존량과 환경요인에 관한 연구)

  • 김철수
    • Journal of Plant Biology
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    • v.18 no.3
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    • pp.129-134
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    • 1975
  • It was studied of relation between biomass of reed communities (Phragmitis communis) and several environmental factors concerned with such as chlor ine, pH, humus content in soil and depth of seawater submerged. Two sites where were the different geographical conditions were set up. One site had two plots: H plot, at theshallows of seawater, was not submerged except at full tide or at heavy rainfall, and M plot, at medium depth of seawater, submerged at every common tide at inside of a bank along the west seashore of Mu-An-peninsula. The other site also two plots: M' plot, at medium depth, submerged about 10 hours at each tide, and L plot, at deep seawater submerged every tims at tide at the outside of a bank along the eastside estuary of Youngsan river. Maximum standing crop of the reed community was shown on 25th of June: biomass at H M, M' and L plot were respectively 4.65, 3.60, 0.98, and 0.67 kg dry weight per $m^2$. Density of individual at H, M, M' and L plot was 67, 78, 244 and 333 plants per $m^2$. Net production of the terrestrial parts of rred community on the outside of the bank were lesser as much as a sixth than that on inside, but the density of the plant on outside of the bank was higher as much 4 or 5 times than that on inside. It was assumed that the growth of reed plant was inhibited by high chlorine, high pH, less humus in soil and submergence of seawater for long period.

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Characteristics of Meteorological and Marine Environments for the Red Tide Occurrence in Mid-South Sea of Korea (한국 남해중부해역의 적조발생에 관한 기상 및 해양환경 특성)

  • 윤홍주;김승철;박일흠
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.323-328
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    • 2003
  • This study deals with the relationship between the red tide occurrence and the meteorological and marine factors, the prediction of areas where the red tide is likely to occur based on the information, and the satellite monitoring for the red tide in mid-South Sea of Korea. From 1990 to 2001, the red tide was observed every year and the number of occurrences increased as well. The red tide mostly occurred in July, August, and September. The most important meteorological factor governing the mechanisms of the increase in the number of red tide occurrences is found to be a heavy precipitation. It was found that the favorable marine environmental conditions for the red tide formation are some of marine factors such as the warm water temperature, the low salinity, the high suspended solid, the low phosphorus, and the low nitrogen. The necessary conditions for the red tide occurrence are found to be the heavy precipitation (23.4∼54.5 mm) for 2∼4 days, the warm temperature (24.64-25.85 $^{\circ}C$), proper sunshine (2∼10.3 h), and light winds (2∼4.6 m/s & SW) for the day in red tide occurrence. It was possible to monitor the spatial distributions and concentration of the red tide using the satellite images. It was found from this study that the likely areas for red tide occurrence in August 2000 were Yosu ∼ Dolsan coast, Gamak bay, Namhae coast, Marado coast, Goheung coast, and Deukryang bay.

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Characteristics of Meteorological and Marine Environments for the Red Tide Occurrence of Mid-South Sea in Korea (한국 남해중부해역의 적조발생에 관한 기상 및 해양환경 특성)

  • 윤홍주;김승철;박일흠
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.4
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    • pp.845-852
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    • 2003
  • This study deals with the relationship between the red tide occurrence and the meteorological and marine factors, the prediction of areas where the red tide is likely to occur based on the information, and the satellite monitoring for the red tide in mid-South Sea of Korea. From 1990 to 2001, the red tide was observed every year and the number of occurrences increased as well. The red tide mostly occurred in July, August, and September. The most important meteorological factor governing the mechanisms of the increase in the number of red tide occurrences is found to be a heavy precipitation. It was found that the favorable marine environmental conditions for the red tide formation are some of marine factors such as the warm water temperature, the low salinity, the high suspended solid, the low phosphorus, and the low nitrogen. The necessary conditions for the red tide occurrence are found to be the heavy precipitation (23.4-54.5 mm) for 2∼4 days, the warm temperature $(24.6∼25.9^{\circ}C)$, proper sunshine (2∼10.3 h), and light winds (2∼4.6 m/s & SW) for the day in red tide occurrence. It was possible to monitor the spatial distributions and concentration of the red tide using the satellite images. It was found that the likely areas for red tide occurrence in August 2000 were Yosu - Dolsan coast, Gamak bay, Namhae coast, Marado coast, Goheung coast, and Deukryang bay.

A Study on the Characteristics of Summer Water Temperature Fluctuations by Spectral Analysis in Coast of Korea in 2016 (스펙트럼 분석을 통한 2016년 하계 한국연안의 수온변동 특성에 관한 연구)

  • Seo, Ho-San;Jeong, Yong-Hyun;Kim, Dong-Sun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.2
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    • pp.186-194
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    • 2020
  • In this study, spectral analysis was conducted to identify environmental factors af ecting short-term changes in water temperature in the East, West and South coasts of Korea. The data used in the spectrum analysis is the 2016 summer water temperature, air temperature, tide level and wind data provided by Korea Hydrographic & Oceanographic Agency. In power spectrum results, peaks of water temperature and tide level were observed at same periods in West Sea (Incheon, Pyeungteak, Gunsan and Mokpo) and South Sea (Wando, Goheung, Yeosu, Tongyeong and Masan) where mean tidal range was more than 100 cm. On the other hand, periodicity of water temperature did not appear in East Sea and Busan where the mean tidal range was small. Coherence analysis showed that water temperature was highly correlated with tide in West Sea and three stations(Wando, Goheung and Tongyeong) of South Sea. Especially, correlation between water temperature and tide level in Wando and Tongyeong presented 0.96 at semi-diurnal period. Water temperature in Yeosu seems to have influenced by tide and inflow of fresh water. In Masan, water temperature is influenced by south wind, tide and inflow of fresh water. In East Sea, influence of tide on water temperature is small due to current and small tidal range. As a result of comparing the time series graph, stations where the correlation between water temperature and tide is high show that relatively cold water was inputted at flood tide and flow out at ebb tide. short-term variation of water temperature was affected by tide, but long-term variation over a month was affected by air temperature.

Some Characters of Students' Understandings about Tide Concept (조석개념에 대한 학생들의 이해 특성)

  • Kook, Dong-Sik
    • Journal of The Korean Association For Science Education
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    • v.15 no.4
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    • pp.429-436
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    • 1995
  • The purpose of this study is to identify students' alternative frameworks about tide concept, to investigate some characters of them and students' understanding types with increasing grade in secondary school earth science course. The objective questionnaire method was used, and the subjects of this study are 528 students selected randomly in secondary school. The results are as follow. 1) Thirteen alternative frameworks about tide concept, related to the phase change of the moon and the motion of the earth are identified. 2) The alternative frameworks needed mechanical and causal reasoning have the trend reinforced or sophisticated with increasing the grade. And alternative frameworks needed phenomenal and mechanical, phenomenal and causal reasoning are changed little but ones needed phenomenal, variative and basic reasoning change scientifically. The rates of the alternative frameworks needed definitional, empirical, phenomenal reasoning decrease at the learning grade of that concept but increase after that grade. 3) Middle school students have the definitional, phenomenal, empirical and qualitative understanding types but high school students have the causal, analytic, quantitative and mechanical ones on tide concept.

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Realtime Tide and Storm-Surge Computations for the Yellow Sea Using the Parallel Finite Element Model (병렬 유한요소 모형을 이용한 황해의 실시간 조석 및 태풍해일 산정)

  • Byun, Sang-Shin;Choi, Byung-Ho;Kim, Kyeong-Ok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.1
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    • pp.29-36
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    • 2009
  • Realtime tide and storm-surge computations for the Yellow Sea were conducted using the Parallel Finite Element Model. For these computations a high resolution grid system was constructed with a minimum node interval of loom in Gyeonggi Bay. In the modeling, eight main tidal constituents were analyzed and their results agreed well with the observed data. The realtime tide computation with the eight main tidal constituents and the storm-surge simulation for Typhoon Sarah(1959) were also conducted using parallel computing system of MPI-based LINUX clusters. The result showed a good performance in simulating Typhoon Sarah and reducing the computation time.

A Study of a Method for Detecting Marine Pollution Using X-band Radar (X-Band 레이더를 이용한 해양오염 관측기법에 관한 연구)

  • Park, Seung-Geun;Yang, Young-Jun;Park, Jun-Soo;Kwon, Sun-Hong
    • Journal of Ocean Engineering and Technology
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    • v.24 no.2
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    • pp.53-56
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    • 2010
  • Oil spills and red tide can be very damaging to the environment and fishery farming. These catastrophic accidents must be detected as quickly as possible. In this paper, we report the results of applying the wavelet transform to SAR or marine radar images for the detection of the boundaries of an oil spill or red tide. The application of the wavelet transform to these phenomena looks quite promising in detecting the boundaries of oil spills and red tide areas.