• 대한원격탐사학회지
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• 제39권6_2호
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• pp.1523-1528
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• 2023

Geostationary Ocean Color Imager-II (GOCI-II)는 2020년 2월 성공적으로 발사된 이후 본격적인 검보정 활동을 통해, 산출물 정확도 향상을 위한 다양한 연구들이 진행 중이다. 본 특별호는 GOCI-II 자료의 검보정 및 알고리즘 개선 연구가 시작된 지 2년이 되어가는 현재 시점에서의 GOCI-II 자료 품질 관리 알고리즘을 점검하고, 정확도 향상 및 활용 진행 사항과 관련 연구결과를 소개한다. GOCI-II 영상 자료의 지속적인 검보정 활동을 통해 정확도 높은 자료가 제공되고 활용되기를 기대한다.

• 대한원격탐사학회지
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• 제32권1호
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• pp.25-38
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• 2016

With the increasing need for high temporal resolution satellite imagery for monitoring land surfaces, this study evaluated the temporal resolution of the NDVI composites from Geostationary Ocean Color Imager (GOCI) data. The GOCI is the first geostationary satellite sensor designed to provide continuous images over a $2,500{\times}2,500km^2$ area of the northeast Asian region with relatively high spatial resolution of 500 m. We used total 2,944 hourly images of the GOCI level 1B radiance data obtained during the one-year period from April 2011 to March 2012. A daily NDVI composite was produced by maximum value compositing of eight hourly images captured during day-time. Further NDVI composites were created with different compositing periods ranging from two to five days. The cloud coverage of each composite was estimated by the cloud detection method developed in study and then compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua cloud product and 16-day NDVI composite. The GOCI NDVI composites showed much higher temporal resolution with less cloud coverage than the MODIS NDVI products. The average of cloud coverage for the five-day GOCI composites during the one year was only 2.5%, which is a significant improvement compared to the 8.9%~19.3% cloud coverage in the MODIS 16-day NDVI composites.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.187-190
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• 2007

The Geostationary Ocean Color Imager (GOCI) is under development to provide a monitoring of ocean-color around the Korean Peninsula from geostationary platforms. It is planned to be loaded on Communication, Ocean, and Meteorological Satellite (COMS) of Korea. The GOCI has been designed to provide multi-spectral data to detect, monitor, quantify, and predict short term changes of coastal ocean environment for marine science research and application purpose. The target area of GOCI observation covers sea area around the Korean Peninsula. Based on the nonlinear radiometric model, the GOCI calibration method has been derived. The nonlinear radiometric model for GOCI will be validated through ground test. The GOCI radiometric calibration is based on on-board calibration devices; solar diffuser, DAMD (Diffuser Aging Monitoring Device). In this paper, the GOCI radiometric error propagation is analyzed. The radiometric model error due to the dark current nonlinearity is analyzed as a systematic error. Also the offset correction error due to gain/offset instability is considered. The radiometric accuracy depends mainly on the ground characterization accuracies of solar diffuser and DAMD.

• 대한원격탐사학회지
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• 제26권2호
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• pp.167-173
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• 2010

본 논문은 통신해양기상위성에 탑재된 해양탑재체의 관측자료를 지상에서 처리하는 영상전처리 시스템을 소개하는 것으로, 주요 기능, 개발 과정, 운영 계획으로 나누어 기술한다. 해양탑재체 영상전처리시스템은 주 시스템과 백업 시스템이 해양위성센터 (한국해양연구원)와 위성운영센터 (한국항공우주연구원)에 각각 설치되어 있으며, 현재 모든 시험을 완료하고 위성 발사 전의 최종 시험 운영 중에 있다. 해양탑재체 영상전처리시스템이 제공할 통신해양기상위성의 해양데이터는 정지궤도에서 연속적으로 한반도 주변을 관측한 것으로서, 해수 온도 변화나 해양 생태계 등의 해양환경연구에 중요한 자료로 활용 가능할 것으로 기대되고 있다.

• 대한원격탐사학회지
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• 제39권6_2호
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• pp.1577-1589
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• 2023

해양의 모니터링을 위해서는 변화를 예측하는 과정이 필요하다는 것은 널리 인정되고 있다. 이 연구에서는 Geostationary Ocean Color Imager (GOCI) 자료를 이용하여 해양의 변화를 지시할 수 있는 반사도의 시계열 예측을 수행하였다. 이를 위해 다중 규모 Convolutional Long-Short-Term-Memory (ConvLSTM) 모델을 제안하였으며, GOCI-I 자료를 이용하여 모델을 학습하였다. 취득 기간이 다른 GOCI-II 자료를 이용하여 모델의 성능을 검증하였으며, 기존의 ConvLSTM 모델과 성능을 비교하였다. 비교 결과, 제안한 모델은 시공간적 특성을 모두 고려하여 반사도의 변화 경향성을 파악하는데 있어 가장 우수한 결과를 보였다. 장기 예측 결과를 통해 모델이 학습한 반사도의 시간적 변화 경향을 확인하였으며, 이를 이용한 주기적 변화 탐지가 가능할 것으로 기대된다.

• 대한원격탐사학회지
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• 제29권3호
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• pp.337-349
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• 2013

Communication Ocean Meteorological Satellite (COMS) for the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service was launched onto Geostationary Earth Orbit on June 27, 2010 and it is currently under normal operation service on $128.2^{\circ}$ East of the geostationary orbit since April 2011. In order to perform the three missions, the COMS has 3 separate payloads, the meteorological imager (MI), the Geostationary Ocean Color Imager (GOCI), and the Ka-band antenna. The MI and GOCI perform the Earth observation mission of meteorological observation and ocean monitoring, respectively. For this Earth observation mission the COMS requires daily mission commands from the satellite control ground station and daily mission is affected by the satellite control activities. For this reason daily mission planning is required. The Earth observation mission operation of COMS is described in aspects of mission operation characteristics and mission planning for the normal operation services of meteorological observation and ocean monitoring. And the first one-year normal operation results after the In-Orbit-Test (IOT) are investigated through statistical approach to provide the achieved COMS normal operation status for the Earth observation mission.

• 대한원격탐사학회지
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• 제30권1호
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• pp.137-147
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• 2014

세계 최초의 정지궤도 해양관측위성인 천리안 해양관측위성(Geostationary Ocean Color Imagers;GOCI)의 자료 품질을 유지하면서도 용량을 줄임으로써 자료 배포 서비스를 향상시키기 위한 방법을 검토하였다. 레벨-2 자료는 압축만으로도 약 92.9%의 용량 절약을 할 수 있지만, 레벨-1 자료는 압축으로 인한 용량 절약이 약 20.7%에 그치기 때문에 또 다른 접근 방식이 필요하였다. 이 연구에서는 위성 영상 자료의 양자화 비트 수(12비트)가 레벨-1 자료의 픽셀 당 비트 수(32비트)보다 작게 설정되어 있다는 점에 착안하여, 레벨-1 자료에 대해 최적화된 픽셀 당 비트 수를 찾고자 하였다. $R^2$와 변조전달함수(Modulation Transfer Function, MTF)를 이용한 실험 결과, 레벨-1 자료의 픽셀 당 비트 수를 14비트까지 줄이더라도 위성 영상자료의 품질 저하가 없다는 것을 정량적으로 확인하였다. 또한, Ns2 (Network Simulator 2)를 이용한 네트워크 평가 결과, 레벨-1 자료의 경우 픽셀 당 비트 수를 14비트까지 줄였을 때 배포시간을 약 57.7% 줄일 수 있었고, 레벨-2 자료의 경우 압축을 이용하여 92.9%까지 파일 크기를 줄였을 때 배포시간을 약 92.5% 줄일 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.467-470
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• 2006

Geostationary Ocean Color Imager (GOCI) onboard its Communication Ocean and Meteorological Satellite (COMS) is scheduled for launch in 2008. GOCI includes the eight visible-to-near-infrared (NIR) bands, 0.5km pixel resolution, and a coverage region of 2500 ${\times}$ 2500km centered at 36N and 130E. GOCI 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 through observations of ocean color. To achieve these mission objectives, it is necessary to develop an atmospheric correction technique which is capable of delivering geophysical products, particularly for highly turbid coastal regions that are often dominated by strongly absorbing aerosols from the adjacent continental/desert areas. In this paper, we present a more realistic and cost-effective atmospheric correction method which takes into account the contribution of NIR radiances and include specialized models for strongly absorbing aerosols. This method was tested extensively on SeaWiFS ocean color imagery acquired over the Northwest Pacific waters. While the standard SeaWiFS atmospheric correction algorithm showed a pronounced overcorrection in the violet/blue or a complete failure in the presence of strongly absorbing aerosols (Asian dust or Yellow dust) over these regions, the new method was able to retrieve the water-leaving radiance and chlorophyll concentrations that were consistent with the in-situ observations. Such comparison demonstrated the efficiency of the new method in terms of removing the effects of highly absorbing aerosols and improving the accuracy of water-leaving radiance and chlorophyll retrievals with SeaWiFS imagery.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.56-59
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• 2006

In this paper, Korea's first geostationary Communication, Ocean and Meteorological Satellte(COMS) program is introduced. COMS program is one of the Korea National Space Programs to develop and operate a pure civilian satellite of practical-use for the compound missions of meteorological observation and ocean monitoring, and space test of experimentally developed communication payload on the geostationary orbit. The target launch of COMS is scheduled at the end of 2008. COMS program is international cooperation program between KARI and ASTRIUM SAS and funded by Korean Government. COMS satellite is a hybrid satellite in the geostationary orbit, which accommodates multiple payloads of MI(Meteorological Imager), GOCI(Geostationary Ocean Color Imager), and the Ka band Satellite Communication Payload into a single spacecraft platform. The MI mission is to continuously extract meteorological products with high resolution and multi-spectral imager, to detect special weather such as storm, flood, yellow sand, and to extract data on long-term change of sea surface temperature and cloud. The GOCI mission aims at monitoring of marine environments around Korean peninsula, production of fishery information (Chlorophyll, etc.), and monitoring of long-term/short-term change of marine ecosystem. The goals of the Ka band satellite communication mission are to in-orbit verify the performances of advanced communication technologies and to experiment wide-band multi-media communication service mandatory.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.104-107
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• 2005

COMS(Communication, Ocean, and Meteorological Satellite) is the geostationary satellite for the mission of satellite communication, ocean monitoring, and meteorological service. It is scheduled to be launched at the end of 2008. Ocean payload of COMS named as GOCI(Geostationary Ocean Color Imager) observes ocean color and derives the chlorophyll concentrlition, the concentration of dissolved organic material and so on. In operational oceanography, satellite derived data products are used to provide forecasting and now casting of the ocean and coastal water state. In this work, conceptual design of structural part of GOCI is carried out and two baseline concepts are proposed. The one is dioptric module that uses lens system and the other is TMA(Three Mirror Anastigmat) module that uses mirror system. Trade-off studies between two concepts are investigated by considering optical and mechanical performances. Finally, on-going tasks and future development plan are briefly discussed.