The Dependence of TOA Reflectance Anisotropy on Cloud Properties Inferred from ScaRaB Satellite Data

Abstract An angular dependence model (ADM) describes the anisotropy in the reflectance field. ADMs are a key element in determining the top-of-the-atmosphere (TOA) albedos and radiative fluxes. This study utilizes 1-yr satellite data from the Scanner for Radiation Budget (ScaRaB) for overcast scenes to examine the variation of ADMs with cloud properties. Using ScaRaB shortwave (SW) overcast radiance measurements, an SW mean overcast ADM, similar to the Earth Radiation Budget Experiment (ERBE) ADM, was generated. Differences between the ScaRaB and ERBE overcast ADMs lead to biases of ∼0.01–0.04 in mean albedos inferred from specific angular bins. The largest biases are in the backward scattering direction. Overcast ADMs for the visible (VIS) wavelength were also generated using ScaRaB VIS measurements. They are very similar to, but a little smaller at large viewing angles and a little larger at nadir, than the SW overcast ADMs. To evaluate the effect of cloud properties on ADMs, ScaRaB overcast observation...

摘要 角度依赖模型（ADM）描述了反射场中的各向异性。ADM是确定大气顶部（TOA）反照率和辐射通量的关键要素。本研究利用辐射收支扫描仪（ScaRaB）针对阴天场景的1年卫星数据来研究ADM随云特性的变化。利用ScaRaB短波（SW）阴天辐射测量值，生成了一个类似于地球辐射收支实验（ERBE）ADM的短波平均阴天ADM。ScaRaB和ERBE阴天ADM之间的差异导致从特定角度区间推断出的平均反照率存在约0.01 - 0.04的偏差。最大偏差出现在后向散射方向。还利用ScaRaB可见光（VIS）测量值生成了可见光波长的阴天ADM。它们与短波阴天ADM非常相似，但在大视角时略小，在天底时略大。为了评估云特性对ADM的影响，ScaRaB阴天观测……