The impact of the un-polarized nature of chlorophyll fluorescence, which causes a dip in the degree of polarization of the underwater light field matching the fluorescence spectrum, led to the development of a theoretical relationship indicating that the resulting fractional reduction in observed polarization is linearly proportional to the magnitude of the fluorescence causing it. To evaluate this relationship, we used a vector radiative transfer code (VRTE) for the coupled atmosphere-ocean system using measured inherent optical properties (IOPs) for a variety of oligotrophic and eutrophic waters as inputs. The VRTE was used to simulate elastic components of the underwater reflectance as well as the degree of linear polarization (DoLP) for these different conditions. These values were compared with the underwater reflectances and the DoLPs measured by a multi-angular hyperspectral polarimeter to determine the magnitude of the fluorescence component in the reflectance spectra at 685 nm, and the decrease of the DoLP due to the fluorescence impact at the same wavelength. Fluorescence magnitudes retrieved from the differences between simulated and measured reflectances were found to match well the magnitudes estimated through the relationship based on the drop of the DoLP. It is noted that retrieval accuracies increase for both larger fluorescence and larger underlying DoLP values. Furthermore, a new method is evolved from the measured polarization analysis, Polarization-Curve Fluorescence Height (PCFH). Measured polarization were used to approximate the elastic signal and derive the inelastic un-polarized signal (fluorescence) from the difference in the fluorescence vicinity. These results open possibilities for estimating the magnitude of natural fluorescence using polarization measurements below or above the water surface, .in-situ, or remotely from aircraft or future satellites. Results of ongoing work on potential sensitivities and retrieval accuracies for these applications will be reported.

中文翻译：

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叶绿素荧光与偏振光场的关系：偏振-曲线荧光高度


叶绿素荧光的非偏振性质的影响，导致与荧光光谱匹配的水下光场的偏振程度下降，导致了一种理论关系的发展，表明观察到的偏振的分数减少与引起它的荧光的大小成线性比例。为了评估这种关系，我们使用矢量辐射传输码 （VRTE） 来耦合大气-海洋系统，使用测量的各种贫营养和富营养水域的固有光学特性 （IOP） 作为输入。VRTE 用于模拟水下反射率的弹性分量以及这些不同条件下的线性偏振度 （DoLP）。将这些值与水下反射率和多角度高光谱偏振仪测量的 DoLP 进行比较，以确定 685 nm 反射光谱中荧光分量的大小，以及由于相同波长的荧光影响而导致的 DoLP 降低。发现从模拟和测量反射率之间的差异中检索到的荧光幅度与通过基于 DoLP 下降的关系估计的幅度非常匹配。值得注意的是，对于较大的荧光和较大的潜在 DoLP 值，检索精度都会增加。此外，从测量的偏振分析演变出一种新方法，即偏振曲线荧光高度 （PCFH）。测得的偏振用于近似弹性信号，并从荧光附近的差异得出非弹性非偏振信号（荧光）。 这些结果为使用水面下方或上方、原位或远离飞机或未来卫星的偏振测量来估计自然荧光的大小提供了可能性。将报告有关这些应用程序的潜在灵敏度和检索准确性的持续工作结果。