大亚湾水体后向散射比率的光谱变化

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。

Spectral variability of particulate backscattering ratio in the Daya Bay

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.