• 대한원격탐사학회지
• /
• 제34권2_2호
• /
• pp.339-349
• /
• 2018

황해 녹조 대발생은 2008년 이후 매년 여름 대규모로 발생하고 있으며, 인공위성 분석을 통해 녹조 규모를 추정하기 위한 연구가 활발하게 진행되고 있다. 하지만 정확한 녹조 면적 산출을 위한 위성영상 선택 기준이 마련되어 있지 않은 실정이다. 따라서 이 연구에서는 위성영상의 공간해상도에 따른 녹조 면적 산출 결과의 차이를 알아보고, 녹조 면적 산출에 적합한 위성영상을 제시하고자 한다. 이 연구에서 이용한 위성영상은 Landsat ETM+, MODIS, GOCI로 영상의 공간해상도는 각각 30, 250, 500 m 이다. NDVI 알고리즘을 적용하여 녹조 픽셀을 분류하였고, 임계값에 따른 녹조 면적 산출 결과를 비교하였다. 또한, Linear Spectral Unmixing(LSU) 기법을 이용하여 한 픽셀 내에 녹조가 차지하는 비율을 추정하였고, 녹조 비율의 차이가 면적 계산에 미치는 영향을 평가하였다. NDVI 알고리즘을 이용한 녹조 면적 산출 결과, 공간해상도가 낮을수록 녹조 면적이 과대추정되는 경향을 보였고, 최대 1.5배 차이를 보였다. 또한, LSU 분석 결과에서 픽셀 내의 녹조 비율이 0.1(10%) 미만인 픽셀이 대부분이었고, 0.5(50%) 이상 녹조 비중을 차지하는 픽셀은 세 타입의 영상 모두에서 약 2% 수준으로 극히 적었다. 즉, NDVI 분석 결과에서 녹조로 분류된 픽셀의 경우 한 픽셀의 공간을 녹조가 100% 채우고 있지 않더라도 모두 동일 면적으로 간주되기 때문에 실제보다 과대추정되는 것으로 생각되고, 이러한 현상은 공간해상도 차이에 의해 심화되는 것으로 나타났다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
• /
• pp.324-327
• /
• 2006

This research is about the optical characteristic of red tide which is collected from Nam-Hae for basic research of red tide remote sensing technique development. 21 kinds of red tide organisms are cultivated to investigate optical characteristic of them on the level of laboratory, and chlorophyll specific absorption coefficient($a^*$) and backscattering coefficient($b_b^*$) are estimated by using spectrophotometer. Absorption spectrums according to species are appeared diversely from 0.005 to 0.06 (mg/ $m^2$), and the shapes of spectrums are also different. The range of $b_b^*$ are appeared $10^{-2}{\sim}10^{-4}$ mg/ $m^2$, which have around 100 times differences between species, and the shape of spectrum also have significant difference between species. These results are able to use as an input data of inverse model from ocean color.

• 한국측량학회지
• /
• 제36권5호
• /
• pp.343-353
• /
• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• 한국해안·해양공학회논문집
• /
• 제26권6호
• /
• pp.352-358
• /
• 2014

국내 서해안과 남해안의 조위자료로부터 조석-해일 비선형효과에 대한 발생실태를 조사한 결과 부산을 제외한 모든 해역에서 비선형성이 확인되고 있으며 특히 목포 및 완도를 중심으로 한 서남해안에서 두드러지게 나타나고 있다. 대규모 해일이 드물기 때문에 창조집중에 대한 사례는 흔치 않은 반면 저조시 조위편차가 커지는 조석변조해일은 빈번하게 발생하고 있다. 또한 낙조우세가 심한 목포해역의 경우 새로운 형태의 조석-해일 비선형성에 의해 낙조시 해일고가 크게 나타나는 현상을 확인하였다. 조위편차 산정과정에서 비선형성과 관련된 오류를 해소하는 방안으로 편기해일고 산정방법에 대해서도 검토하였다.

• 한국어업기술학회:학술대회논문집
• /
• 한국어업기술학회 1998년도 수산관련공동학술대회발표요지집
• /
• pp.382.2-383
• /
• 1998

• Ocean and Polar Research
• /
• 제30권1호
• /
• pp.1-10
• /
• 2008

In order to find the effect of intertidal sediments on nutrient cycle in coastal environment, we measured ammonia, nitrate, phosphate, and silicate concentrations every hour during at least 12 hours in the entrance of Keunso Bay during four seasons. The content of ammonia and silicate do not change considerably with season, but nitrate shows large seasonal variation. In summer, nitrate concentration was much lower than in other seasons, which resulted from large biological uptake and active denitrification in intertidal sediments during summer. Phosphate also exhibit seasonal variations, but not that large like nitrate. N/P and N/Si ratios were lower in summer than in other seasons, which was due to active denitrification in the intertidal sediments during summer. For all seasons, ammonia concentrations were higher at low tide than at high tide, but nitrate concentrations were higher at high tide. Dissolved inorganic nitrogen concentrations measured in spring, summer, and winter were higher at high tide than at low tide, but in fall, they were higher at low tide than at high tide. For spring and winter, phosphate and silicate concentrations were higher at low tide than at high tide, while in summer and fall, they were higher at high tide than at low tide. In Keunso Bay, intertidal sediments affect significantly the nutrient cycle around the coastal areas. The intertidal sediments act as a source for ammonia and silicate, but as a sink for nitrate. However, phosphate is not considerably influenced by intertidal sediments.

• 수산해양기술연구
• /
• 제47권4호
• /
• pp.338-343
• /
• 2011

To obtain the effective sampling estuarine fauna by a passive net in the West Sea of Korea occurring strong tide, catch were collected by bag nets with various sampling trials off Ganghwa Island in November 2009. We compared the difference of community structures (on spring tide vs. neap tide, total sample vs. subsample and 4 nets vs. 1 net) with each species composition as a sampling unit by the Pearson chi-square test. Number of individual at the spring tide was more abundant than that at the neap tide (p<0.0001) although number of species at the spring tide was not significantly different with that at the neap tide (p=0.174). Both number of species (p=0.138) and number of individual (p=0.096) were not significantly different between total sample and random subsample. Number of species was not significantly different between the subsample by 1 net and the subsample by 4 nets (p=0.515), but number of individual was a little different on both samples (p=0.024). In conclusion, we suggest the subsample by 1 net at spring tide as the effective sampling estuarine fauna by a passive net in the West Sea occurring strong tide.

• 대한원격탐사학회지
• /
• 제28권5호
• /
• pp.531-548
• /
• 2012

남해안에서 발생한 Cochlodinium polykrikoides 적조를 적조인 경우와 아닌 경우(satellite high chlorophyll water)로 부터 분류하기 위해서, 본 연구는 Son et al.(2011)의 spectral classification 방법을 세계 최초 해색위성인 GOCI 파장에 맞도록 개선했다. C. polykrikoides 적조인 경우와 아닌 경우는 네 가지 단계를 거쳐서 분리했다. 첫 번째 단계는 적조 발생 가능지역으로 555nm와 680nm (fluorescence peak)에서 피크를 보이는 지역을 선택했다. 두 번째 단계는 적조 발생 가능 지역 중에서 용존유기물/부유물질 함량이 높은 지역과 낮은 지역을 구분했다. 세 번째와 네 번째 단계는 blue-to-green 밴드비를 이용하여 적조 발생 지역과 아닌 지역을 구분했다. 네 가지 단계를 적용한 결과 적조의 스펙트럼은 증가된 식물성 플랑크톤과 용존유기물(부유물질)의 흡광 때문에 짧은 파장에서는 낮은 기울기를 보이고, 증가된 부유물질 때문에 긴 파장에서는 상대적으로 증가된 기울기를 나타냈다. GOCI를 위해 개선된 spectral classification 방법은 C. polykrikoides 적조인 경우와 적조가 아닌 경우에 대해서 높은 user accuracy를 보이고, 다양한 해양환경에서 신뢰성 있는 적조 탐지 가능성을 보이고 클로로필 농도를 이용한 방법이나 기존의 다른 적조 탐지 방법보다 좋은 결과를 보였다. 남해안 C. polykrikoides 적조는 2012년 7월 말에서 8월 초까지 나로도와 통영 부근 해상에서 탐지 되었고, 2012년 8월 중순에는 완도에서 거제도까지 남해안 전체에 걸쳐 발생했다.

• 수산해양기술연구
• /
• 제12권1호
• /
• pp.19-24
• /
• 1976

A series of physical oceanographic investigations of the circulation in the Kwang Bay' were carried out seven times from May 1974 to May 1975 every other month. The average water transports through the southern entrance of the' Kwang Yang Bay were approximately $1,014{\times}I0^6m^3$/half-tide in ebb current and $278{\times}10^6m^3$$405.6{\times}I0^6m^34/half-tide in ebb current, and $282{\times}10^6m^3 $/half-tide in flood current, at the maximum current intensity. The water from Seomjin River flows into the bay at an annual average rate of $84{\times}I0^6m^3$/half-tide, the rate being fluctuated from month to month from $6.0\times}10^6m^3 $to $11. 5{\times}I0^6m^3 $per half-tide.

• 해양환경안전학회지
• /
• 제20권3호
• /
• pp.270-276
• /
• 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.