Re-examining the effect of particle phase functions on the remote-sensing reflectance

Xiong Yuanheng; Zhang Xiaodong; He Shuangyan; Gray Deric J.

摘要

Even though it is well known that both the magnitude and detailed angular shape of scattering (phase function, PF), particularly in the backward angles, affect the color of the ocean, the current remote-sensing reflectance (R-rs) models typically account for the effect of its magnitude only through the backscattering coefficient (b(b)). Using 116 volume scattering function (VSF) measurements previously collected in three coastal waters around the U.S. and in the water of the North Atlantic Ocean, we re-examined the effect of particle PF on R-rs in four scenarios. In each scenario, the magnitude of particle backscattering (i.e., b(bp)) is known, but the knowledge on the angular shape of particle backscattering is assumed to increase from knowing nothing about the shape of particle PFs to partially knowing the particle backscattering ratio (B-p), the exact backscattering shape as defined by (beta) over tilde (p)(gamma >= 90 degrees) (particle VSF normalized by the particle total scattering coefficient), and the exact backscattering shape as defined by the chi(p) factor (particle VSF normalized by the particle backscattering coefficient). At sun zenith angle = 30 degrees, the nadir-viewed R-rs would vary up to 65%, 35%, 20%, and 10%, respectively, as the constraints on the shape of particle backscattering become increasingly stringent from scenarios 1 to 4. In all four scenarios, the R-rs variations increase with both viewing and sun angles and are most prominent in the direction opposite the sun. Our results show a greater impact of the measured particle PFs on R-rs than previously found, mainly because our VSF data show a much greater variability in B-p, (beta) over tilde (p)(gamma >= 90 degrees) , and chi(p) than previously known. Among the uncertainties in R-rs due to the particle PFs, about 97% can be explained by chi(p), 90% by (beta) over tilde (p)(gamma >= 90 degrees) , and 27% by B-p. The results indicate that the uncertainty in ocean color remote sensing can be significantly constrained by accounting for chi(p) of the VSFs. (C) 2017 Optical Society of America

机译：尽管众所周知，散射（相位函数，PF）的幅度和详细角度，特别是在落后角度，影响海洋的颜色，目前的遥感反射率（R-RS）模型通常是帐户仅通过反向散射系数（B（b））仅对其幅度的影响。先前使用116体积散射功能（VSF）测量以前在美国的三个沿海水域中收集在北大西洋的水中，我们重新检查了四种情况下粒子PF对R-R的影响。在每种情况下，已知粒子反向散射（即，B（BP））的大小是已知的，但是假设关于粒子反向散射的角度形状的知识，以增加关于粒子PFS的形状以部分地知道粒子反向散射比而增加（bp），由曲线（p）（γ> = 90度）（γ> = 90度）（粒子总散射系数归一化的粒子Vsf）定义的精确背散射形状，以及由Chi定义的精确的反向散射形状（p ）因子（通过粒子后散射系数归一化的粒子VSF）。在Sun Zenith角度= 30度时，Nadir-View的R-RS将分别变化高达65％，35％，20％和10％，因为对粒子后散射形状的约束变得从场景1变得越来越严格4.在所有四种情况下，R-RS变化随着观察和太阳角度而增加，并且在阳光相对的方向上最突出。我们的结果表明，测量的粒子PFS对R-R的更大影响，而不是先前发现，主要是因为我们的VSF数据显示了BP，（Beta）over Tilde（P）（伽马> = 90度）和Chi的更大的变化（p）比以前已知。在粒子PFS引起的R-RS中的不确定因素中，约97％可以通过CHI（P），90％（β）通过薄层（P）（γ> = 90度）来解释，27％通过B-P。结果表明，海洋颜色遥感中的不确定性可以通过核算VSF的CHI（P）来显着限制。（c）2017年光学学会

Re-examining the effect of particle phase functions on the remote-sensing reflectance

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