• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.316-319
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• 2006

Monthly-mean aerosol parameters derived from the 1998-2004 SeaWiFS observations over East Asian waters are analyzed. SeaWiFS GAC Level 1 data covering the Northeast Asian area are collected and processed by the standard atmospheric correction algorithm released by the SeaWiFS Project to produce daily aerosol optical thickness (AOT) and ${{\AA}}ngstr{\ddot{o}}m$ exponent imageries. Monthly mean AOT and ${{\AA}}ngstr{\ddot{o}}m$ exponent values are extracted from the daily composite images for six study areas chosen from the surrounding waters of Japan. A slight increasing trend of ${{\AA}}ngstr{\ddot{o}}m$ exponent is found and interpreted as about 4-5% increase in submicron fraction of aerosol optical thickness at 550nm. Two cloud screening methods, including the standard cloud masking method of SeaWiFS and the one based on the local variance method, are applied to the SeaWiFS data processing, in an attempt to inspect the influence to the observed statistical uptrend which probably induced by different cloud mask algorithms. The variability comes from the different cloud masking algorithms are discussed.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 춘계학술대회 논문집
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• pp.83-86
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• 2006

이어도 종합해양과학기지의 스펙트로미터로 측정된 해색 스펙트럼 자료들과 SeaWiFS 해색센서로부터 측정된 스펙트럼 자료들을 계절별로 비교 분석하여 해색영상 자료를 처리하는데 사용된 대기보정 알고리즘이 제주도 남쪽 해역과 동중국해 해역에서 어느 정도의 오차를 가지고 있는지 연구하였다. 또한 분석된 자료들을 이용하여 SeaWiFS에서 측정한 스펙트럼 자료들을 보정하고자 하였으며, 이것은 인공위성에서 측정한 클로로필 농도값이 현장관측자료와 비교했을 때 갖는 오차의 범위를 줄여줄 수 있을 것으로 생각된다. 이와 같은 연구결과들은 차후 운용될 COMS 위성의 GOCI 해색센서에 사용될 대기보정 알고리즘과 해양환경 분석 알고리즘을 개발하는데 많은 도움이 될 것으로 생각한다.

• 대한원격탐사학회지
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• 제18권5호
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• pp.299-303
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• 2002

Many ocean color sensors are being operated at present and will be continued to operatein the coming years. However, these ocean color sensors have different spectral bands locations and higher level product algorithms. Thus the continuity of ocean color data from the satellite with different missions will be important for monitoring of oceanographic variation with long term research. In this study, CZCS band and algorithm are compared with OCTS and SeaWiFS algorithm for estimating chlorophyll. Missing bands of OCTS and CZCS for chlorophyll algorithm are estimated by linear-interpolation using SeaWiFS data. We were able to evaluate the effectiveness of the correction methods using linear interpolation method. Surprisingly, linear interpolation gave a better result than those of other bands.

• 대한원격탐사학회지
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• 제19권3호
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• pp.201-208
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• 2003

Much effort has been made in the radiometric calibration of the ocean scanning multispectral imager (OSMI) since after the successful launch of KOMPSAT-1 in 1999. A series of calibration coefficients for OSMI detectors were obtained in collaboration with the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary (SIMBIOS) project office. In this study, we ompare the OSMI level-2 products (e.g., chorophyll-a concentration) calculated from the NASA cross-calibration coefficients with the SeaWiFS counterparts. Sample study areas are some of diagonostic data sites recommended by the SIMBIOS working group. Results of this study show that the OSMl-derived chlorophyll-a concentration agrees well with the SeaWiFS counterpart in Case 1 water; however, differences become larger in Case 2 water.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.913-916
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• 2006

Spatial distribution, seasonal and interannual variability of chlorophyll a concentration in Okhotsk Sea from SeaWiFS data between 2001 and 2004 were describe. An Empirical Orthogonal Function method was applied for analysis data. The ten modes described about 85% of total variance. Two maxima were defined - more intensive in spring and weaker in autumn. The first mode showed zones with chlorophyll a concentration during maximum bloom. The second mode specified timing of spring bloom in various regions in Okhotsk Sea. Analysis of SeaWiFS data indicated connection between highest chlorophyll a concentration and sea surface temperature limits during spring bloom. Similar relation was not found during fall bloom.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 2004년도 GIS/RS 공동 춘계학술대회 논문집
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• pp.241-246
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• 2004

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 755 and 865nm fails due to backscattering by suspended mineral particles. Therefore, the near infrared channels 765 and 865nm used fur 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 largely introduced due to light interaction through the complex atmosphere carried several aerosol and gaseous components and at the air-sea interface.interface.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.909-912
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• 2006

In this paper a method for remotely-sensed assessment of eutrophication was experimented. The water samples were collected for analysis of COD (chemical oxygen demand) and nutrients concentration, and the remote sensing reflectance data at the sampling points were synchronously measured using above-water method in two cruises, which were conducted in the Pearl River Estuary in January 2003 and January 2004 respectively. Based on the in-situ data the local algorithms for estimation of concentration of nutrients (P and N) and COD were developed by Partial Least Squares (PLS) regression. The algorithms were then applied to atmospheric-corrected SeaWiFS data and the COD and nutrients concentration in Pearl River Estuary were estimated. And then the assessment of eutrophication was carried out by comparison of the estimated nutrients and COD value with the water quality standard. The results show that the whole estuary is seriously in eutrophication.

• 대한원격탐사학회지
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• 제16권4호
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• pp.315-325
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• 2000

Observations were made to validate ocean color algorithms in the Ulleung Basin, East Sea in May 2000. Small scale and meso-scale surveys were conducted for the validation of ocean color products (nLw: normalized water-leaving radiance and chlorophyll concentration). There were discrepancies between SeaWiFS and in situ nLw showing the current aerosol models of standard SeaWiFS processing software are less than adequate (Gordon and Wang, 1994). Applying the standard SeaWiFS in-water algorithm resulted in an overestimation of chlorophyll concentration. This is because that CDOM absorption was higher than the estimated chlorophyll absorption. TSS concentration was also high. Therefore, the study region deviated from Case 1 waters. The source of these materials seems to be the entrainment of coastal water by the Tsushima Warm Current. Study of the bio-optical properties in other season is desirable.

• 대한원격탐사학회지
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• 제24권6호
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• pp.535-549
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• 2008

위성 센서의 대리 검정은 다양한 표적을 이용하여 모의된 대기 상단의 복사휘도를 이용하여 수행된다. 본 연구에서는 인도양과 태평양상에 있는 다섯 개의 해양 표적을 통해 대기상단 가시영역에서의 복사휘도를 계산하고, 위성 센서 검보정에의 활용 가능성에 대해서 알아보았다. 복사전달모델인 65를 통해 계산된 대기상단의 복사휘도를 MODIS/Terra와 SeaWiFS 관측 값과 비교하였으며, 모의를 위하여 이들 위성의 기하정보와 복사계의 특징들이 사용되었다. MODIS/Terra의 에어로솔 광학적 두께 (AOT: Aeroso) Optical Thickness)와 SeaWiFS의 pigment concentrations, OMI의 오존 자료가 모델 입력 값으로 사용되었고 NCEP/NCAR 재분석 자료로부터 바람과 총가강수량에 대한 정보를 얻었다. 전 표적 지역에 대해서 5일 평균한 결과, 2005년 한 해 동안 계산된 복사휘도와 관측된 복사휘도와의 백분율 차이는 약 ${\pm}5%$의 수준으로 나타났고 이것은 계산된 복사휘도가 위성에서의 관측 값과 잘 일치함을 의미한다. 또한 동일 알고리즘으로 약 ${\pm}5%$의 오차수준 이내의 결과를 SeaWiFS를 통해 얻을 수 있었다. 이러한 결과는 위성의 가시채널 검보정이 본 연구의 복사휘도 모의 방법을 통해서 ${\pm}5%$의 오차범위 안에서 이루어질 수 있음을 보여준다.

• 한국지리정보학회지
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• 제4권1호
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• pp.27-33
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• 2001

본 연구에서는 시화호, 경기만, 천수만, 진해만에서 SeaWiFS 밴드영역을 가진 수중광학측정장비에 의해 얻어진 자료를 바탕으로 투명도 알고리듬이 구성되었다. 이를 현장관측치와 비교하여 가장 높은 상관계수를 나타내는 밴드를 찾았다. 수중광 반사도 밴드비율은 $R_{rs}$(490/665)의 밴드비율이 실측치와 가장 좋은 상관관계($R^2$=0.8188)를 나타냈다. 현장조사에 의해 얻어진 수중 광학 알고리듬을 위성자료에 적용하기 위해 SeaWiFS 보다 비교적 연안해역을 모니터링하기에 용이한 공간해상력을 가진 Landsat TM의 반사도 자료를 계산하고, 이를 동일시점의 현장관측자료와 비교하였다. 하지만, Landsat TM을 적용한 결과는 실측치와 낮은 상관관계를 나타냈고, 이에 대한 문제점을 제시하였다.