• Title, Summary, Keyword: High tide

Search Result 430, Processing Time 0.037 seconds

A Study on Red Tide Detection Algorithm Based on Two Stage filtering - Application to MODIS Chlorophyll Information - (2단계 필터링 기반 적조 탐지 알고리즘에 관한 연구 - MODIS 클로로필 정보에 적용 -)

  • Kim, Yong-Min;Kim, Hyung-Tae
    • Korean Journal of Remote Sensing
    • /
    • v.24 no.4
    • /
    • pp.325-331
    • /
    • 2008
  • We propose an algorithm to detect large Cochlodinium polykrikoides red tide event that was appeared in Korean coastal waters. This algorithm is based on two-stage filtering using MODIS chlorophyll information. Most of the red tide detection studies generally use assumption that sea water having high chlorophyll concentration is red tide events because of high correlation and red tide. However, these methods generate many commission errors such as turbid water by detecting inactive sea water of red tide. Therefore, we eliminated commission errors by applying two stage filtering and verified the algorithm's effectiveness by detecting large Cochlodinium polykrikoides red tide event that was appeared in Korean coastal waters.

Screening of Differentially Expressed Genes in Heterosigma akashiwo, a Red-Tide Causing Organism, Induced by Exposure to High Light

  • Ko, Young-Seok;Cho, Kyung-Je;Moon, Byoung-Yong
    • Journal of Photoscience
    • /
    • v.8 no.3_4
    • /
    • pp.93-97
    • /
    • 2001
  • Heterosigma akashiwo has been reported as red-tide causing phytoplankton in the Korean coastal area during summer when they are exposed to high light. It also shows photosynthetic adaptability to strong light during culture in the laboratory. On the basis of these observations, we tried to find out some genes specifically expressed in Heterosimga akashiwo during exposure to high light, assuming that they might have some resistant mechanisms associated with light adaptation. For this purpose, we carried out DD-PCR to detect differentially expressed mRNAs from cells that had been illuminated under high light for 3 days. We found eight cDNA clones that had been expressed specificically for high light. When they were further screened by reverse Northern hybridization, three of them were identified to be positive cDNA clones. When these cDNA fragments were subjected to DNA sequencing and then their base sequences were compared to GenBank database, one of them showed sequence homology 86% identical to the partial sequence of 16S rRNA gene of eubacterium CRO-18.

  • PDF

Study on Application Program Preparation of the High Tide Prediction for the Electronic Computer (전지계산기에 의한 해일을 예측하는 수치계산 Program 개발에 관한 연구)

  • 김치홍
    • Water for future
    • /
    • v.13 no.2
    • /
    • pp.55-62
    • /
    • 1980
  • It is very important thing that the high tide prediction along the sea-side before the typhoon landing. In Korea, every year somewhere of the near sea-shore has been suffered much damages by the high tide during typhoon season, and the governement has to spend much of the reserved budget to rescue and reconstruction the damaged facilities in the seas-shore area. In this point of view, as none of the high tide prediction program in Korea, the author aims to develope this kind of study, so that this application program may dedicate the concerned organizations such as Ministry of Construction, Commerce and Industry, and Agriculture Forestry and Fishery, etc. Due to developed the software of high speed electronic computer in recently, the complicated numerical analysis can be solve very conviniently. So the author tries to prepare the high tide predecation program using the equation of motion and continous in the fluide dynamics by the constant time and distance of the differentation method. The input data for this program are the weather chart and depth data of the mattered bay, inner-sea or outer-sea. This program has been applied on the Pohan inner harbor as a model and find ort the program computation results is coincide with the observed values of "FRAN" typhoon in 1976 at the Pohang harbor.ng harbor.

  • PDF

Change in Abundance of Coilia spp. Larvae by the Tidal Cycle in the Han River Estuary, Korea (한강하구에서 조석주기에 따른 웅어속 자치어의 출현량 변동)

  • Kim, Ji-Hye;Song, Tae-Yoon;Kim, Byung-Gi;Kim, Byung-Pyo;Han, Kyung-Nam
    • Korean Journal of Ichthyology
    • /
    • v.28 no.3
    • /
    • pp.192-199
    • /
    • 2016
  • The Seokmo and Yeomha channels are representative areas of high tidal energy in the Han River estuary. Surveys of environmental variables and abundance of Coilia spp. larvae, an anadromous fish, were carried out following the tidal cycle in August 2007 and August 2008. It was found that mean water temperature varied by <$1^{\circ}C$ across flood and ebb tides. A clear difference in salinity was observed between tides, with a high of 15.1 psu during flood tide, and a low of 0.8 psu during ebb tide. Coilia spp. larvae were significantly more abundant during the ebb tide than the flood tide (p<0.05). Since Coilia spp. larvae are anadromous fish, it seems that they use the ebb tide as a Selective tidal stream transport (STST) for horizontal movement in order to settle in the estuary (cultivation area), following hatching in the upper/middle courses of the Han River. A high percentage of larvae with improved swimming ability (measuring ${\geq}13.6mm$ in length) was observed during the ebb tide.

Hydrodynamic Characteristics of Tide-Adapting Low-Crested Structure (조위차 극복형 저마루 구조물의 수리특성)

  • Hur, Dong-Soo;Jeong, Yeon-Myeong;Lee, Woo-Dong
    • Journal of Ocean Engineering and Technology
    • /
    • v.33 no.1
    • /
    • pp.68-75
    • /
    • 2019
  • A low-crested structure (LCS) is an excellent feature not only because it provides shore protection but also because it is fully submerged. However, in order to properly control waves, it is necessary to maintain a certain range of crest height and width in consideration of the wave dimensions at the installation area. According to previous studies, an LCS has some wave breaking effect when the crest width is more than a fourth of the incident wavelength and the crest depth is less than a third of the incident wave height. In other words, if the crest width of the LCS is small or the crest depth is large, it cannot control the wave. Therefore, when an LCS is installed in a large sea area with a great tidal range in consideration of the landscape, waves cannot be blocked at high tide. In this study, the hydraulic performances of a typical trapezoidal LCS with a constant crest height and a low-crested structure with an adjustable crest height, which was called a tide-adapting low-crested structure (TA-LCS) in this study, were compared and evaluated under various wave conditions through hydraulic experiments. It was found that the wave transmission coefficients of the TA-LCS at high tide were lower than the values for the typical LCS based on empirical formulas. In addition, the hydraulic performances of the TA-LCS for wave reflection control were 12.9?30.4% lower than that of the typical LCS. Therefore, the TA-LCS is expected to be highly effective in controlling the energy of incoming waves during high tide even in a macro-tidal area.

The Characteristics of Tidal Current and Water Mass in the Narrow Channel 1. Tidal Current and Water mass in the Chungmu Channel (협수로의 수리 특성과 수괴구조 1. 충무수로의 조류와 수괴구조)

  • Park, Byung-Soo
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.13 no.2
    • /
    • pp.168-177
    • /
    • 2001
  • The flow pattern and water mass structure in the Chungmu channel were investigated using the field observations during June and July, 2001. The currents in the channel may be regarded as a hydraulic current decided by difference of tide levels between two sides in the channel. The strongest current in the channel occurs around in high water and low water. The coefficient C to be determined the characteristics of velocity in the channel was obtained from an equation, $u=C{\sqrt{2gh}}$ and ranges from 0.37 to 0.65 in the Chungmu Channel at the spring tide and from 0.23 to 0.37 at the neap tide. Eastward tidal transport is usually larger than that of westward transport in Chungmu the Channel. Sea water exchange rates are 39.2% in spring tide and 20.5% in neap tide respectively. The water mass structure in the channel is changed by the speed of the tidal current. The water mass is well mixed at the high water when the current is strong and is stratified at slack water when the current is weak.

  • PDF

Study on monitoring and prediction for the occurrence of red tide in the middle coastal area in the South Sea of Korea 1. The relationship between the occurrence of red tide and the meteorological factors (원격탐사를 이용한 한국 남해 중부해역에서의 적조 예찰 연구1. 적조발생과 기상인자간의 상관성 연구)

  • 윤흥주;김영섭;윤양호;김상우
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.6 no.6
    • /
    • pp.843-848
    • /
    • 2002
  • It is studied on the relationship between the occurrence of red tide and the meteorological factors(precipitation, air temperature, sunshine and winds) in the middle coastal area in the South Sea of Korea. In summer and early-fall which frequently occurred the red tide, the precipitation had directly influence on the occurrence of red tide because it carried the nutritive substances which originated from the land into the coastal areas. Then air temperature kept up generally high values, and sunshine and winds showed not directly the relationship on the occurrence of red tide.

Study on monitoring and prediction for the red tide occurrence in the middle coastal area in the South Sea of Korea II. The relationship between the red tide occurrence and the oceanographic factors (원격탐사를 이용한 한국 남해 중부해역에서의 적조 예찰 연구 II. 적조발생과 해양인자간의 상관성 연구)

  • 윤홍주;남광우;조한근;변혜경
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.8 no.4
    • /
    • pp.938-945
    • /
    • 2004
  • On the relationship between the red tide occurrence and the oceanographic factors in the middle coastal area in the South Sea of Korea, the favorable oceanographic conditions for the red tide formation are considered as follows; the calm weather increases sea water temperature in summer and early-fall which the red tide occurs frequently, and the heavy precipitation brings some riverine water to ween: low salinity, high suspended solid, low phosphorus and high nitrogen, respectively. We decided the potential areas in the coastal zones vulnerable to the red tide occurrence based on the limited factors controlling the growth of phytoplankton. By using GIS through the overlap for three subject figures (phosphorus, nitrogen and suspended solids), it was founded that the potential areas are the Yeosu∼Dolsan coast, the Gamak bay, the Namhae coast, the Narodo coast, the Goheung and Deukryang bay. This result has very well coincided to the results of the satellite and in-situ data.

Sea Level Change due to Nonlinear Tides in Coastal Region (연안해역에서 비선형 조석으로 인한 해수면 변화)

  • Jung, Tae Sung
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.29 no.5
    • /
    • pp.228-238
    • /
    • 2017
  • In coastal region, tidal harmonic constants of semi-diurnal tides and nonlinear tides were collected. The observed tide data of KHOA were analyzed by a tide harmonic analysis method. In the southwestern coasts and Han river estuary, nonlinear tides are clearly generated. The generation of tide non-linearity and tide asymmetry is closely related with tide form factor in Korean coastal zone. Tide non-linearity and asymmetry in Mokpo harbour have increased by a series of coastal development projects. The increase has caused rise of high water level and drop of low water level, and increase of tidal range. In Kunsan Outport, tidal range has been declined due to inter-annual change of nonlinear tides after completion of Samangeum sea-dyke.

Research of the West Coasts` Plant Community in Korea ( I ) (한국 서해안 해변식물 군락의 연구 (제 1 보))

  • 홍원식
    • Journal of Plant Biology
    • /
    • v.1 no.1
    • /
    • pp.17-24
    • /
    • 1958
  • The author investigated the plant sociological studies on the flora of Inchon districts coast area. (It contains also province of Buchun, Kumpo, and Hwasung, the island of Kanghwa.) The scenery of the west coast in Korea is very curious, because the soil in this area contains comapratively large amount of mud and small sand. Some parts of this area is covered with only mud, and the area between the line of high tije and line of low tide is very vast. When a low tide was appearel, there were vast moddel places appeared about 10 km in length. The author could distinguish $\varepsilon$ different types of communties in this zone. (1) Suaeda jatonica community (2) Statice japonica community (3) Scirtus triqueier community (4) Zoy_ia community (5) Phragmites community (6) Carex Pumilla community (7) Atriolex subsodata community (8) Rosa rugasa community (1), (2), (3), (4) communities can grow under the high tide. (When the high tide comes they soaked in the sea water.) (1) Suaeda community is the most popular type of the Yellow sea. It is very wonderful scene that the vast area (the length of 10 km) is covered with this Suaeda, and it looks like to be painted with blood. (2) Staice (3) Scirpus (4) Zoysia community is can fully maintain their glorious life in the sea water. It is due to the this plants tolerance of salt. (1), (2), (3), (4) communities are very strong to the tolerance of salt, especially the Suaeda is remarkable. The structure and some sucession I trend of each community were studied in detail and the mutual relations among the communites were also concluded.

  • PDF