The role of the critical angle in brightness reversals on sunglint images of the sea surface
The role of the critical angle in brightness reversals on sunglint images of the sea surface
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DOI：
10.1029/2009jc006037
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发表时间：
2010-09
影响因子：
--
通讯作者：
C. Jackson;W. Alpers
中科院分区：
文献类型：
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作者：
C. Jackson;W. Alpers
[1]在海面的光学图像上，在太阳反辉区及其周围经常观察到各种各样的海洋和大气现象。这些现象的出现强烈地依赖于观察几何形状，海面上比背景更粗糙（或更平滑）的区域根据它们相对于镜面反射点的位置而看起来比背景更亮或更暗。为了了解这些海面签名的变化，本文介绍了一个关键的传感器视角的概念，定义为传感器天顶角，在不同的海面粗糙度的变化产生相同的太阳反辉辐射。当成像几何形状过渡通过临界角时，表面特征经历亮度反转。了解这种转变发生的地点对于正确解释这些现象的海面特征十分重要。理论背后的临界角的概念，然后应用到太阳反辉图像从太空中获得的中分辨率成像光谱仪机载美国宇航局的Aqua和Terra卫星。
[1] A wide variety of oceanic and atmospheric phenomena are often observed in and around the sunglint region on optical images of the sea surface. The appearance of these phenomena depends strongly on the viewing geometry with areas on the sea surface that are rougher (or smoother) than the background appearing as either brighter or darker than the background depending on their position relative to the specular point. To understand these sea surface signature variations, this paper introduces the concept of a critical sensor viewing angle, defined as the sensor zenith angle at which different sea surface roughness variances produce identical sunglint radiance. It is when the imaging geometry transitions through the critical angle that a surface feature goes through a brightness reversal. Knowledge of where this transition takes place is important for properly interpreting the characteristics of the sea surface signature of these phenomena. The theory behind the concept of the critical angle is presented and then applied to sunglint imagery acquired over the ocean from space by the Moderate Resolution Imaging Spectroradiometer onboard NASA's Aqua and Terra satellites.