Preliminary study of the development of Korea Ocean Satellite Center

본 연구는 통신해양기상위성 개발에 따라 해양 탑재체 자료의 효율적인 이용을 위해 반드시 필요한 해양위성센터 구축을 위한 종합계획을 수립하기 위하여 수행되어졌다. 이를 위해 해양연구에 사용되는 위성의 종류와 활용분야에 대해 조사하였으며, 국외의 해양위성 관련기관을 알아보고 현 우리나라의 위성관련 기관과 비교해봄으로서 해양위성센터의 필요성을 인식하였다. 또한 해양위성센터의 임무에 대해 분석함으로서 업무 범위를 파악하였으며 관련 유사기관과의 업무 분담을 고려한 해양위성센터의 추진방향을 제시하였다. 해양위성센터 구축을 위하여 입지조건분석을 분석하고 다양한 건립안을 제시하고 이들의 장단점을 비교・분석하였다. 조직 및 인력, 시설, 시스템에 대한 추진계획안을 제시하였으며 추진내용과 관련된 예산을 수립하였다. 그리고 운영계획과 해양위성센터 설립에 따른 추후 추진사항에 대해서도 조사하였다. 이 기획연구의 결과는 해양위성센터를 설립하는데 있어 기본자료로 활용될 것이다.2

Ocean color research activities in Korea: Prospective from space

Since the end of 1970's, measurements from space-borne satellite sensors had demonstrated that ocean color remote sensing is a powerful tool for understanding oceanic biological and physical processes. Several ocean color sensors including CZCS (Nimbus-7 Coastal Zone color scanner) have contributed much in understanding these complex oceanic processes. Since a decade, Korea has been conducting basic and applied research in the field of optical oceanography and ocean color remote sensing and designing of several indigenous satellite ocean color payloads and ground-based instruments. Of these, Korea Multi-Purpose Satellite (KOMPSAT-1) OSMI, which is worldwide ocean color monitoring for the study of biological oceanography. It generates six-band ocean color images with 800 km swath width and 1 km ground sample distance by whiskbroom scanning. In the same series, KOMPSAT-2 will carry Multispectral Camera (MSC) of very high spatial resolution (4m) and spectral resolution corresponding to Landsat-5 Thematic Mapper, which will enable enhanced understanding of intricate and striking patterns of small-scale biological and physical phenomena, especially in coastal ocean. Korea’s major ocean color mission is Geostationary Ocean Color Imager (GOCI), the first geostationary ocean color sensor, which is planned to be operated in a staring-frame capture mode onboard its Communication Ocean and Meteorological Satellite and tentatively scheduled for launch in 2008. The mission concept includes eight visible and two NIR bands, 1 km pixel resolution, and a coverage region of 2500  2500km centered at 36N and 130E. The instrument is expected to provide SeaWiFS quality observations with the frequencies in acquisition of the imagery 8 times during daytime and 2 times during nighttime. In co-ordination with the other institutes and organizations such as KORDI, MOMAF and MOST, KARI takes a major step towards designing and deploying such instruments in space orbits. Apart from the r1

Korean Ocean Color Mission in Geostationary Orbit

GOCI, the first Geostationary Ocean Color Imager, shall be operated in a staring-frame capture mode onboard its Communication Ocean and Meteorological Satellite and tentatively scheduled for launch in 2008. The mission concept includes eight visible-to-near-infrared bands, 0.5km pixel resolution, and a coverage region of 2500  2500km centered at 36N and 130E. The instrument measured the solar reflected radiation in eight spectral bands in the visible and near-infrared parts of the spectrum has had the scope of its objectives broadened to understand the role of the oceans and ocean productivity in the climate system, biogeochemical variables, geological and biological response to physical dynamics and to detect and monitor toxic algal blooms of notable extension and hazardous materials, such as oil spills through observations of ocean color. The instrument is expected to provide SeaWiFS quality observations with the frequencies in acquisition of the imagery 8 times during daytime and 2 times during nighttime. The ocean color imager shall have a special feature to enable imaging any portion of the globe. In order to achieve the goal of the mission, the different radiometric and geometric requirements have been refined by taking into account the constraints imposed by a geo-orbiting platform and the technical capabilities of the imager. Since being the geo-orbiting platform and a wide aerial coverage, the mode of operation of the instrument remains a challenging issue and shall be finalized in the forthcoming RFP. Korea Aerospace Research Institute (KARI) and Korea Ocean Research and Development Institute are coordinating sensor characterization, design and performance. The GOCI shall be expected to complement measurements of ocean color with the high spatial, spectral, temporal and radiometric resolutions.1

동해에서 해색위성를 이용한 중규모 에디에 의한 생물학적 분포 연구

A mesoscale anticyclonic eddy influencing spatial and temporal aspects of biological variability was detected from satellite ocean color observations in the East Sea, typical of Case-1 waters. This eddy formed in spring and summer apparently altered the optical properties of water column by enhancing chlorophyll concentrations from 0.5 to 8 mg/m3. Enhanced chlorophyll concentrations may be attributed to high levels of nutrients transported from coastal regions and from deep waters by the action of eddy. Satellite measurements of chlorophyll were supplemented with AVHRR sea surface temperature data and with ship-based observations using CTD and other optical sensors to better understand the characteristics of the anticyclonic eddy feature in the East Sea. Horizontal distribution of potential temperature () and salinity (S) of water off the Southeast coast exhibited cold and low saline surface water (12C; S>34.4) at 75dBar, corroborating the northeastward intrusion of Tsushima Warm Current (TWC) along the Tsushima Strait and the northward branch of East Korean Warm Current (EKWC) along the Korean east coast. The EKWC separated from the coast at about 37-38 N and formed a mesoscale anticyclonic eddy feature off the Korean east coast during spring and summer. The process of such mesoscale anticyclonic eddy feature might have produced interior upwelling that could have shoaled and steepened the nutricline, enhancing phytoplankton population by advection or diffusion of nutrients in the vicinity of Ulleungdo in the East Sea. By late summer and fall when antheropogenically-influenced coastal water supported high chlorophyll biomass, the northward EKWC instead of influencing the anticyclonic eddy circulation would entrain chlorophyll from an adjacent eddy/upwelling and coastal areas, forming a conveyer-belt transport process to inject coastal biota into the open-ocean r1

Comparison of red tide detection by a new red tide index method and standard dio-optical algorithm applied to SeaWiFS imagery in optically complex Case-II waters

Various methods to detect the phytoplankton/red tide blooms in the oceanic waters have been developed and tested on satellite ocean color imagery since the last two and half decades, but accurate detection of blooms with these methods remains challenging in optically complex turbid waters, mainly because of the eventual interference of absorbing and scattering properties of dissolved organic and particulate inorganic matters with these methods.1

탁수의 remote reflectance 모델과 부유물 알고리즘 개발

위성에 의한 탁수 원격탐사 알고리즘 개발을 위하여 탁수발생 해역의 remote reflectance를 광합성 색소인 클로로필, 부유물, 용해유기물 농도 등으로 모델화 하였다. 반사도 모델 검정하기 위하여 현장의 관측 값과 비교하였으며, 반사도 모델에 의한 알고즘과 현장에서 얻어진 통계적 관계와 비교하였다. 모델의 탁도 알고리즘과 현장의 탁도 알고리즘 사이에는 조금의 차이가 있었으나 거의 유사한 결과를 얻을 수 있었다. 개발된 알고리즘을 SeaWiFS 위성자료에 적용하여 한 빈도 주변해역의 해수 탁도를 분석한 결과 현장 관측치와 잘 일치하는 아주 우수한 결과를 보여주었다.33Nkciothe

Geometrical analysis of redtide & water quality in the Korean coastal waters

한반도 주변해역에서 적조 및 수질의 공간적 변화에 관한 지리적 정보를 DB화하여 이들이 시공간적으로 어떻게 변화되는지를 통계적 분석을 하였다.2

Spatial and temporal patterns in satellite-derived chlorophyll-a concentration and their relation to oceanic processes in the East China Sea and Yellow Sea

Patterns in chlorophyll representing the spatial and temporal distribution of phytoplankton communities, which can reveal a great deal about the oceanic processes underlying their formation in the East China Sea (ECS) and Yellow Sea (YS), were investigated using the data assimilated from satellite sensors abroad. Sea surface temperature (SST) analyzed from Advanced Very High Resolution Radiometer (AVHRR) thermal infrared data were used to elucidate the physical factors responsible for the evolution of such patterns in the inner and outer shelves areas of the ECS. SeaWiFS-derived chlorophyll maps were used to examine intricate and striking patterns of phytoplankton blooms in the ECS and YS. Three different natures of phytoplankton assemblages were interpreted from the SeaWiFS ocean color data. The Chl-1 exhibited distinct pattern and persistent formation of dense phytoplankton blooms resulting from the Yangtze banks of the ECS during winter is thought to be associated with high nutrients derived from the Yangtze river. As previously investigated by Ahn et al. (2004), the winter blooms that originate from the Yangtze estuary led to the occurrence of the following stages-Infant Stage, Youth Stage, Mature Stage and Old Stage. The evolution of each of these stages is the result of the availability of nutrients, sunlight, nature of water mass and tidal and oceanic currents within the study region. As a part of this study, in situ data was collected along the pathway of the Jeju Warm Current, near Jeju-do Island, which confirmed the occurrence of phytoplankton assemblages along the direction of frontal system of the ECS during the evolution of mature stage. In contrast, hydrographic features and chlorophyll distribution maps led us to conclude that dense phytoplankton blooms (Chl-2) appearing off the shelf were closely linked with the upwelling, yielding high nutrients from the Kuroshio warm waters, exhibiting a short term variability during winter. The chlorophyll concent2

Extraction of the atmospheric path radiance in relation to retrieval of ocean color information from the TM and SeaWiFS imageries

The ocean signal that reaches the detector of an imaging system after multiple interactions with the atmospheric molecules and aerosols was retrieved from the total signal recorded at the top of the atmosphere (TOA). A simple method referred to as “Path Extraction” applied to the Landsat-TM ocean imagery of turbid coastal water was compared with the conventional dark-pixel subtraction technique. The shape of the path-extracted water-leaving radiance spectrum resembled the radiance spectrum measured in-situ. The path-extraction was also extended to the SeaWiFS ocean color imagery and compared with the standard SeaWiFS atmospheric correction algorithm, which relays on the assumption of zero water leaving radiance at the two NIR wavebands (765 and 865nm). The path-extracted water-leaving radiance was good agreement with the measured radiance spectrum. In contrast, the standard SeaWiFS atmospheric correction algorithm led to essential underestimation of the water-leaving radiance in the blue-green part of the spectrum. The reason is that the assumption of zero water-leaving radiance at 765 and 865nm fails due to backscattering by suspended mineral particles. Therefore, the near infrared channels 765 and 865nm used for deriving the aerosol information are no longer valid for turbid coastal waters. The path-extraction is identified as a simple and efficient method of extracting the path radiance introduced largely due to light interaction through the complex atmosphere carried several aerosol and gaseous components and at the air-sea interface.2

A depth-resolved primary production model for stratified water in the Yellow Sea

Despite some efforts to get better estimation of the primary production of the Yellow Sea, there is still uncertainty in the estimates. Extreme range of the environmental factors through seasons makes the estimation difficult. The high variability in environmental characteristics calls for using satellite data for better estimation of the primary production of the Yellow Sea. To achieve the goal with reasonable accuracy using satellite data, there are many problems to resolve such as retrieval of chlorophyll, diffuse attenuation coefficient of PAR, and vertical structure of chlorophyll in water column, and estimation of physiological parameters. Here we analyzed 66 vertical profiles of chlorophyll-a obtained during March-August in 1994-2001 period. Using some relationships among parameters, we attempt to retrieve subsurface chlorophyll profiles only from KPAR (downwelling attenuation coefficient of PAR) and surface chlorophyll-a values. Although uncertainty was high in predicting accurate shape of the profiles (e.g., exact depth of subsurface chlorophyll maximum), fairly good estimation of depth-integrated primary production was made. We also compared the estimates with those from VGPM (vertically generalized production model). VGPM gave much higher estimates than simulated in-situ depth-integrated primary production. The discrepancy resulted from that PBopt from VGPM formulation had large errors compared with in-situ PBopt. Adjusted VGPM gave better results than original VGPM. But the depth-resolved model was better than the adjusted VGPM in terms of fitness and bias.1