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 µm with 0.05-µm resolution. Polarization at wavelengths longer than approximately 4 µm generally is negative (p, or vertical) and increases with incidence angle up to approximately 75°, beyond which the horizontally polarized reflected atmospheric radiance begins to dominate the surface emission. The highest p polarization (∼4–10%) is found in the atmospheric window regions of approximately 4–5 and 8–14 µm. In the 3–5-µm spectral band, especially between 3 and 4 µm, 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°.
© 1999 Optical Society of AmericaFull Article | PDF Article
C. R. Zeisse, C. P. McGrath, K. M. Littfin, and H. G. Hughes
J. Opt. Soc. Am. A 16(6) 1439-1452 (1999)
James L. Cogan
Appl. Opt. 24(7) 1030-1036 (1985)
M. D. Mermelstein, E. P. Shettle, E. H. Takken, and R. G. Priest
Appl. Opt. 33(25) 6022-6034 (1994)