采用2007年5月大亚湾浮标定点航次采集的生物-光学数据, 分析了大亚湾水体后向散射比率的光谱变化及其影响因素。分析结果表明, 660nm处后向散射比率变化范围在0.0040—0.0245之间, 均值为0.0082±0.0032, 实测后向散射比率光谱波段间的相对变化不超过15%; 颗粒后向散射比率随着叶绿素a浓度增加呈减小的趋势, 高叶绿素浓度显著对应较低的后向散射比率; 粒径是影响大亚湾水体后向散射比率的重要因素之一, 随着水体中Junge粒级斜率的增大, 颗粒后向散射比率显著增大; 折射率的变化也对后向散射比率产生一定影响, 类似的水体粒径分布情况下, 浮游植物与非藻类物质相对贡献的变化将导致折射率的明显变化, 并将主导水体后向散射比率的变化。

Variability of particulate backscattering ratio and its interpretation were examined using in-situ measurements performed during May 2007 in the Daya Bay. The results indicated that the particulate backscattering ratio values range between 0.004 and 0.0245, with a mean value of 0.0082±0.0032. There was some spectral dependence of the particulate backscattering ratio, and less than 15% variability between wavelengths was estimated. A global decreasing of particulate backscattering ratio with increasing chlorophyll concentration was visible, and the low backscattering ratios were observed in water with high chlorophyll concentration. Particle-size distribution slope was the main factor controlling the variability of particles backscattering ratio: The particle backscattering ratio increased with particle-size distribution slope. Average particle refractive index was another influencing factor. With similar particle-size distribution, the amount of non-pigment material relative to phytoplankton that was characterized by the variability of refractive index had a strong effect on particulate backscattering ratio.

中国科学院重要方向性项目(KZCX2-YW-215); 国家自然科学基金项目(40906022; 40606011; 40906021;U0933005)

[1] MOBLEY C D, SUNDMAN L K, BOSS E. Phase Function Effects on Oceanic Light Fields[J]. Appl Opt, 2002, 41: 1035-1050.
[2] GORDON H R, BROWN O B, EVANS R H, et al. A semi-analytical radiance model of ocean color[J]. J Geophys Res, 1988, 93: 10909-10924.
[3] MOREL A, MARITORENA S. Bio-optical properties of oceanic waters: A reappraisal[J]. J Geophys Res, 2001, 106(C4): 7763-7780.
[4] ULLOA O, SATHYENDRANATH S, PLATT T. Effect of the particle size distribution on the backscattering ratio in seawater[J]. Appl Opt, 1994, 33: 7070-7077.
[5] TWARDOWSKI M S, BOSS E, MACDONALD J B, et al. A model for estimating bulk refractive index from the optical backscattering ratio and the implications for understanding particle composition in case I and case II waters[J], J Geophys Res, 2001. 106(C7): 14129-14142.
[6] MACDONALD J B, TWARDOWSKI M S, PEGAU W S, et al. Characterization of spectral backscattering in the Gulf of California[J]. In EOS Trans, AGU, 80, Ocean Sci Mett Suppl, 2000.
[7] CHAMI M, SHYBANOV E B, CHURILOVA T Y, et al. Optical properties of the particles in the Crimea coastal waters (Black Sea) [J]. J Geophys Res, 2005.110, C11020, doi: 10.1029/2005JC003008.
[8] MCKEE D, CUNNINGHAM A. Evidence for wavelength dependence of the scattering phase function and its implication for modeling radiance transfer in shelf seas[J]. Appl Opt, 2005, 44: 126-135.
[9] WHITMIRE A L, BOSS E, COWLES T J, et al. Spectral variability of the particulate backscattering ratio[J]. Opt Express, 2007, 15: 7019-7031.
[10] Spectral Absorption And Attenuation Meter Ac-S User’S Guide. (Revision J). WET Labs, Inc., Philomath, OR. 2009. pp.43
[11] PARSONS T R, MAITA Y, LALLI C M．A Manual of Chemical and Biological Methods for Seawater Analysis[M]. Oxford: Pergamon Press, 1984.
[12] BOSS E, TWARDOWSKI M S, HERRING S. Shape of the particulate beam attenuation spectrum and its inversion to obtain the shape of the particulate size distribution[J]. Appl Opt, 2001, 40: 4885-4893.
[13] BOSS E, PEGAU W S, LEE M, et al. The particulate backscattering ratio at LEO-15 and its use to study particle composition and distribution[J]. J Geophys Res, 2004, 109, C01014: 1-10.
[14] CHANG G C, BARNARD A, ZANEVELD R, et al. Bio-optical realtionships in the Santa Barbara Channel:   Implications for remote sensing[C]//Proceedings of the Ocean Optics XVII Conference. Frenmental, Australia, 2004: 1-12.
[15] LOISEL H, MERIAUX X, BERTHON J F, et al. Investigation of the optical backscattering to scattering ratio of marine particles in relation to their biogeochemical composition in the eastern English Channel and southern North Sea[J]. Limnol Oceanogr, 2007, 52(2): 739-752.
[16] SULLIVAN J M, TWARDOWSKI M S, DONAGHAY P L, et al. Use of optical scattering to discriminate particle types in coastal waters[J]. Appl Opt, 2005, 44: 1667-1680.
[17] MOREL A. Optical modeling of the upper ocean in relation to its biogenous matter content (case I waters) [J]. J Geophys Res, 1988, 93(C9): 10749-10768.
[18] STRAMSKI D, BRICAUD A, MOREL A. Modeling the light attenuation and scattering by spherical phytoplankton cells: a retrieval of the bulk refractive index[J]. Appl Opt, 1988, 27: 3954-3956.
[19] STRAMSKI D, MOBLEY C D. Effects of microbial particles on oceanic optics: A database of single-particle optical properties[J]. Limnol Oceanogr, 1997, 42(3): 538-549.
[20] AAS E. Refractive index of phytoplankton derived from its metabolic composition[J]. J Plankton Res, 1996, 18(12): 2223-2249.
[21] 周雯, 曹文熙, 李彩. 浮游植物吸收和散射特性: 理论模型[J]. 光学技术. 2007, 33(2): 177-180.
[22] VERITY P G, BEATTY T M, WILLIAMS S C. Visualization and quantification of phlankton and detritus using digital confocal microscopy[J]. Aquat Microb Ecol, 1996, 10: 55-67.
[23] LIDE D R. Physical and optical properties of minerals[M]. //CRC Handbook Of Chemistry And Physics.77th ed. CRC Press, 4130-4136.
[24] 周雯, 曹文熙, 李彩. 海水中矿物质颗粒物吸收和散射特性Mie理论分析[J]. 热带海洋学报. 2008, 27(1): 22-26.
[25] ZHOU WEN, CAO WENXI. Modeling the Influence of mineral particles and phytoplankton on chlorophyll estimation from ocean color remote sensing[J]. International Journal of Remote Sensing. 2008, 29(21): 6237-6248.