Sydor Michael, Gould Richard W, Arnone Robert A, Haltrin Vladimir I, Goode Wesley
Department of Physics, University of Minnesota, Duluth, Duluth, Minnesota 55812, USA.
Appl Opt. 2004 Apr 1;43(10):2156-62. doi: 10.1364/ao.43.002156.
We examine the problem of uniqueness in the relationship between the remote-sensing reflectance (Rrs) and the inherent optical properties (IOPs) of ocean water. The results point to the fact that diffuse reflectance of plane irradiance from ocean water is inherently ambiguous. Furthermore, in the 400 < lambda < 750 nm region of the spectrum, Rrs(lambda) also suffers from ambiguity caused by the similarity in wavelength dependence of the coefficients of absorption by particulate matter and of absorption by colored dissolved organic matter. The absorption coefficients have overlapping exponential responses, which lead to the fact that more than one combination of IOPs can produce nearly the same Rrs spectrum. This ambiguity in absorption parameters demands that we identify the regions of the Rrs spectrum where we can isolate the effects that are due only to scattering by particulates and to absorption by pure water. The results indicate that the spectral shape of the absorption coefficient of phytoplankton, a(ph)(lambda), cannot be derived from a multiparameter fit to Rrs(lambda). However, the magnitude and the spectral dependence of the absorption coefficient can be estimated from the difference between the measured Rrs(lambda) and the best fit to Rrs(lambda) in terms of IOPs that exclude a(ph)(lambda).
我们研究了海水遥感反射率（Rrs）与固有光学特性（IOPs）之间关系的唯一性问题。结果表明，海水对平面辐照度的漫反射本质上是不明确的。此外，在光谱的400＜λ＜750nm区域，Rrs(λ)还因颗粒物质吸收系数和有色溶解有机物吸收系数在波长依赖性上的相似性而存在不确定性。吸收系数具有重叠的指数响应，这导致不止一种IOPs组合可以产生几乎相同的Rrs光谱。吸收参数的这种不确定性要求我们确定Rrs光谱中能够分离仅由颗粒散射和纯水吸收所产生影响的区域。结果表明，浮游植物吸收系数a(ph)(λ)的光谱形状不能通过对Rrs(λ)进行多参数拟合得到。然而，吸收系数的大小和光谱依赖性可以根据测量的Rrs(λ)与在排除a(ph)(λ)的IOPs条件下对Rrs(λ)的最佳拟合之间的差异来估计。
