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1 Korean Journal of Remote Sensing, Vol.23, No.4, 2007, pp.311~321 Development K d (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea Jee-Eun Min*, **, Joo-Hyung Ryu*, Yu-Hwan Ahn*, and Kyu-Sung Lee** *Ocean Satellite Research Group, Korean Ocean Research & Development Institute (KORDI) **Department of Geoinformatic Engineering, Inha University Abstract : The diffuse attenuation coefficient for down-welling irradiance (K d (l)), which is the propagation of down-welling irradiance at wavelength l from surface to a depth (z) in the ocean, and underwater visibility are important optical parameters for ocean studies. There have been several studies on K d (l) and underwater visibility around the world, but only a few studies have focused on these properties in the Korean sea. Therefore, in the present study, we studied K d (l) and underwater visibility around the coastal area of the Yellow Sea, and developed K d (l) and underwater visibility algorithms for ocean color satellite sensor. For this research we conducted a field campaign around the Yellow Sea from 19 ~ 22 September, 2006 and there we obtained a set of ocean optical and environmental data. From these datasets the K d (l) and underwater visibility algorithms were empirically derived and compared with the existing NASA SeaWiFS K d (l) algorithm and NRL (Naval Research Laboratory) underwater visibility algorithm. Such comparisons over a turbid area showed small difference in the K d (l) algorithm and constants of our result for underwater visibility algorithm showed slightly higher values. Key Words : Diffuse attenuation coefficient for down-welling irradiance (K d (l)), Underwater visibility, Yellow Sea, Case-II water. K d l K d l K d l K d l K d l jhryu@kordi.re.kr 311

Satellite Research Group, Korean Ocean Research & Development Institute (KORDI) **Department of Geoinformatic Engineering, Inha University Abstract : The diffuse attenuation coefficient for

2 Korean Journal of Remote Sensing, Vol.23, No.4, 2007 K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l K d l 312

3 Development K d (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea K d l K d K d Fig. 1. Map of the Saemangeum coastal area showing sampling points/stations during 19~22 September,

4 Korean Journal of Remote Sensing, Vol.23, No.4, 2007 Table 1. Summary of measurements. Measurements A, C, D line sampling (<chl>, SS) optic (ASD) B line sampling (<chl>, SS) optic (ASD, TriOS, visibility) * <chl>: Chlorophyll concentration SS: Suspended sediment concentration ASD: Field spectroradiometer measurement for surface TriOS: UV/VIS spectrometer measurement for water profile visibility: vertical and horizontal visibility using secchi disk obtained by diver L u E u E d E d E u L u L wt Fig. 2. Diver view of a secchi disk for horizontal visibility at a depth of 1m. E d L sky ml ml ml 314

concentration SS: Suspended sediment concentration ASD: Field spectroradiometer measurement for surface TriOS: UV/VIS spectrometer measurement for

5 Development K d (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea <chl> (mg/m 3 ) = C v (1) V C = 11.85E _ E _ E 630 V ml ml E d (z) = E d (0 _ )e _ z2 z1 dzk d (z) (2) z K d l E d K d = ln[ ] _ 1 E d (z 2 ) (3) (z _ 2 z 1 ) E d (z 1 ) E d K d l K d l L w K d l K d l L w R rs K d l L w R rs K d l K d K d l K d l K d K d L w (l 1 ) K d (490) = K w (490) + A( )B L w (l 2 ) l l K w K d L K d (490) = K w (490) ( w (490) )_ (5) L w (550) K w R rs E d L w E K d (490) = ( d (490) R rs (490) )_ (6) E d (550) R rs (550) K d E d E d K d (490) = ( )_ 1.03 R rs (490) (7) R rs (550) R rs K d l K d l e K d (l) = K w (l) + (l)chl e(l) (8) R rs a b b K d l K d l K d l (4) 315

l K d l K d K d L w (l 1 ) K d (490) = K w (490) + A( )B L w (l 2 ) l l K w K d L K d (490) = K w (490) + 0.15645( w (490) )_ 1.5401 (5) L w (550) K w R rs E d L w E K d (490) = 0.016 + 0.

6 Korean Journal of Remote Sensing, Vol.23, No.4, 2007 a b b K d l K d l R rs a b b K d = m 0 a + m 1 (1 _ m 2 e _ m a 3 ) b b (9) m 0 q a q a m m m R rs R rs L w K d l dl = _ (a + b)l + L * dr (10) L _ T L B C o = (11) L r a b L * C o L T L B C r = C o e [_ (c + Kcosq)r] (12) C r r r _ ln( Cr ) C r = o (13) c + Kcosq 4.0 r vertical = (14) c + K 4.8 r horizontal = (15) c c K d l l L B K d l 316

m m R rs R rs L w K d l dl = _ (a + b)l + L * dr (10) L _ T L B C o = (11) L r a b L * C o L T L B

7 Development Kd (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea Fig. 3. Spectral diffuse attenuation coefficient (Kd) for each stations. 각 정점별로 수심 0 m와 20 m의 Ed 관측 값을 수식 (2) 에 적용하여 Kd(l)값을 유추하였다. 각 정점별로 비슷한 형태의 스펙트럼 값을 나타내는 것을 알 수 있었다. 전 체적인 형태는 575 nm를 중심으로 파장이 짧아질수록 Fig. 5. Comparison between in-situ Kd(490) and SeaWiFS Kd(490). 값이 증가하였고, 또한 파장이 길어질수록 증가하는 패 턴을 나타내었다. 575 nm 이후 파장대에서의 증가 패 SeaWiFS Kd(490)값을 비교한 그래프이다. 현장 관측 턴은 순수한 해수의 Kd(l)스펙트럼의 일반적인 성격으 값에 비해 SeaWiFS Kd(490)이 조금 높은 값을 보였지 로 설명될 수 있다(Smith and Baker, 1981). 575 nm 만 전체적으로 상관관계가 0.7로서 비교적 높은 상관관 이전의 파장대 부분의 파장이 짧아질수록 증가하는 패 계를 보이는 것을 알 수 있었다. 턴은 우리나라 서해 연안의 클로로필과 부유물질 및 용 현장에서 얻어진 Kd(l)와 LwN값을 이용하여 Kd(l) 알 존유기물질 등의 높은 농도로 인한 흡광 특성이라고 볼 고리즘을 개발하였다. 아래의 수식 (16)은 본 연구를 통 해 개발된 Kd(490) 알고리즘을 나타낸다. 이 결과를 수 있다. 이렇게 얻어진 Kd(l)값을 SeaWiFS의 Kd(490) 자료 와 비교하여 보았다. Fig. 4는 2006년 9월 21일에 획득 NASA의 SeaWiFS Kd(490) 알고리즘과 비교하여 보았 다(Fig. 6). 된 SeaWiFS로부터 얻어진 Kd(490) 영상이다. 이 자료 에서 각각의 정점에 해당하는 값을 추출하여 현장관측 값과 비교하여 보았다. Fig. 5는 현장관측 Kd (490)값과 Fig. 4. SeaWiFS Kd(490) Product obtained at 21 September Fig. 6. Comparison of Kd(490) versus the ratio of normalized water-leaving radiances (LwN) at 490 and 555 nm (solid line represent Kd(490) algorithm for this study and dot line represent the SeaWiFS Kd(490) algorithm developed by NASA). 317

값이 증가하였고, 또한 파장이 길어질수록 증가하는 패 턴을 나타내었다. 575 nm 이후 파장대에서의 증가 패 SeaWiFS Kd(490)값을 비교한 그래프이다. 현장 관측 턴은 순수한 해수의 Kd(l)스펙트럼의 일반적인 성격으 값에 비해 SeaWiFS Kd(490)이 조금 높은 값을 보였지 로 설명될 수 있다(Smith and Baker, 1981).

8 Korean Journal of Remote Sensing, Vol.23, No.4, 2007 L K d (490) = ( wn (490) )_ (R 2 = 0.67)(16) L wn (555) L wn L wn K d L wn L wn L wn L wn L wn L wn K d K d K d Fig. 7. In-water horizontal visibility (1 m depth from surface) and in-water (Vertical (0-)) & out-water (Vertical (0+)) vertical visibility at surface along the transect (B line). K d l c 6.9 r vertical = (17) c + K d 5.8 r horizontal = (18) c K d l r vertical = _ K d (490) (R 2 = 0.71) (19) r horizontal = _ K d (490) (R 2 = 0.75)(20) 318

In-water horizontal visibility (1 m depth from surface) and in-water (Vertical (0-)) & out-water (Vertical (0+)) vertical visibility at

9 Development K d (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea Fig. 8. Relationship graph for horizontal & vertical visibility with K d (490). K d l K d l K d l K d l K d l K d l 319

10 Korean Journal of Remote Sensing, Vol.23, No.4, 2007 Austin, R. W. and T. J Petzold, The determination of the diffuse attenuation coefficient of sea water using the coastal zone color scanner, Oceanography From Space, Springer, New York. Austin, R. W. and T. J. Petzold, Spectral dependence of the diffuse attenuation coefficient of light in ocean waters, Optical Engineering, 25: Chang, G. C. and T. D. Dickey, Coastal ocean optical influences on solar transmission and radiant heating rate, Journal of Geophysical Research, 109: C01020, doi: /2003jc Jeffrey, S. W. and Humphrey, G. F., New spectrophotometric equations for determining chlorophylls a, b and c in higher plants, algea and natural phytoplankton, Biochemie Physiologie Pflanzen, 167: Kirk, J. T. O., Light and Photosynthesis in Aquatic Ecosystems, Cambridge Univ. Press, New York. Lee, Z. P., K. L. Carder, and R. Armone, Deriving inherent optical properties from water color: A multi-band quasi-anayltical algorithmfor optically deep waters, Applied Optics, 41: 5, Lee, Z. P., M. Darecki, K. L. Carder, C. O. Davis, D. Stramski, and W. J. Rhea, Diffuse attenuation coefficient of downwelling irradiance: An evaluation of remote sensing methods, Journal of Geophysical Research, 110: C02017, doi: /2004jc Lewis, M. R., M. Carr, G. Feldman, W. Esaias, and C. McMclain, Influence of penetrating solar radiation on the heat budget of the equatorial pacific ocean, Nature, 347: Marra, J., C. Langdon, and C. A. Knudson, Primary production, water column changes, and the demise of a Phaeocystis bloom at the Marine Light-Mixed Layers site (59_N, 21_W) in the northeast Atlantic Ocean, Journal of Geophysical Research, 100: 6,633-6,644. McClain, C. R., K. Arrigo, K.-S. Tai, and D. Turk, Observations and simulations of physical and biological processes at ocean weather station P, , Journal of Geophysical Research, 101: 3,697-3,

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11 Development K d (l) and Visibility Algorithm for Ocean Color Sensor Around the Central Coasts of the Yellow Sea Mishra, D. R., S. Narumalani, and M. Lawson, Characterizing the vertical diffuse attenuation coefficient for downwelling irradiance in coastal waters: Implications for water penetration by high resolution satellite data, ISPRS Journal of Photogrammetry & Remote Sensing, 60: Morel, A. and Prieur, L., Analysis of variations in ocean colour, Limnology and Oceanography, 22: Morel, A., Optical modeling of the upper ocean in relation to its biogenous matter content (case 1 waters), Journal of Geophysical Research, 93: 10,749-10,768. Morel, A. and D. Antoine, Heating rate within the upper ocean in relation to its bio-optical state, Journal of Physical Oceanography, 24: 1,652-1,665. Morel, A. and S. Maritorena, Bio-optical properties of oceanic waters: A reappraisal, Journal of Geophysical Research, 106: 7,163-7,180. Mueller, J. L., SeaWiFS algorithm for the diffuse attenuation coefficient, K(490), using water-leaving radiances at 490 and 555 nm, SeaWiFS Postlaunch Calibration and Validation Analyses, part 3: Mueller, J. L. and C. C. Trees, Revised SeaWiFS prelaunch algorithm for diffuse attenuation coefficient K (490), NASA Tech. Memo., TM , 41: Museler, E. A., A comparison of in-situ measurements and satellite remote sensing of underwater visibility, Master s thesis, Naval Postgrauate School, Monterey, CA, Platt, T., S. Sathyendranath, C. M. Caverhill, and M. Lewis, Ocean primary production and available light: Further algorithms for remote sensing, Deep Sea Research, 35: Preisendorfer, R. W., Hydrologic optics, U.S. Department of Commerce, 1: 218. Rasmus, K. E., W. Graneli, and S. -A. Wangberg, Optical studies in the Southern Ocean, Deep-Sea Research Part II, 51: 2,583-2,597. Sathyendranath, S., T. Platt, C. M. Caverhill, R. E. Warnock, and M. R. Lewis, Remote sensing of oceanic primary production: Computations using a spectral model, Deep Sea Research, 36: Smith, R. C. and K. S. Baker, Optical properties of the clearest natural waters, Applied Optics, 20: Zaneveld, J. R. V., J. C. Kitchen, and H. Pak, The influence of optical water type on the heating rate of a constant depth mixed layer, Journal of Geophysical Research, 86: 6,426-6,

Photogrammetry & Remote Sensing, 60: 48-64. Morel, A. and Prieur, L., 1977. Analysis of variations in ocean colour, Limnology and Oceanography, 22: 709-722. Morel, A., 1988.

0특-04문정언(f5.16)(189~207)

0특-04문정언(f5.16)(189~207) Korean Journal of Remote Sensing, Vol.26, No.2, 2010, pp.189~207 Development of Ocean Environmental Algorithms for Geostationary Ocean Color Imager (GOCI) Jeong-Eon Moon*, **, Yu-Hwan Ahn*, Joo-Hyung Ryu*,