Shaw J A
Environmental Technology Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80303-3328, USA.
Appl Opt. 1999 May 20;38(15):3157-65. doi: 10.1364/ao.38.003157.
Infrared radiances from water become partially polarized at oblique viewing angles through both emission and reflection. I describe computer simulations that show how the state of polarization for water varies with environmental conditions over a wavelength range of 3-15 microm with 0.05-microm resolution. Polarization at wavelengths longer than approximately 4 microm generally is negative (p, or vertical) and increases with incidence angle up to approximately 75 degrees, beyond which the horizontally polarized reflected atmospheric radiance begins to dominate the surface emission. The highest p polarization (approximately 4-10%) is found in the atmospheric window regions of approximately 4-5 and 8-14 microm. In the 3-5-microm spectral band, especially between 3 and 4 microm, reflected atmospheric radiance usually is greater than surface emission, resulting in a net s polarization (horizontal). The results of these simulations agree well with broadband measurements of the degree of polarization for a water surface viewed at nadir angles of 0-75 degrees.
通过发射和反射，来自水体的红外辐射在倾斜视角下会部分偏振。我描述了计算机模拟，展示了在3至15微米波长范围内，以0.05微米分辨率，水体的偏振状态如何随环境条件变化。波长大于约4微米时的偏振通常为负（p，即垂直），并随着入射角增加至约75度而增大，超过该角度后，水平偏振的反射大气辐射开始主导表面发射。最高的p偏振（约4 - 10%）出现在约4 - 5微米和8 - 14微米的大气窗口区域。在3 - 5微米光谱带，特别是在3至4微米之间，反射大气辐射通常大于表面发射，导致净s偏振（水平）。这些模拟结果与在0至75度天底视角下观测到的水体表面偏振度的宽带测量结果非常吻合。
