Sunlight glitter on a wind-ruffled sea: further studies.
Time-averaged intensities are computed for the glitter pattern of sunlight on a wind-ruffled sea. In the present work the azimuthally asymmetric form of the wave-slope distribution measured by Cox and Munk is used, so that the glitter pattern depends on the wind direction as well as magnitude. Results are calculated for both a clean ocean surface and one covered with an oil film. The glitter pattern is quite different with the oil film due to the quieting action of the oil on the waves, the greater reflectivity of the surface when oil is on the surface, and the larger values of polarization for the reflected light at most typical angles in the glitter pattern. These effects are illustrated and discussed as possible methods for the detection of oil slicks. The glitter pattern observed at satellite altitudes is also calculated.
Path-radiance correction by polarization observation of Sun glint glitter for remote measurements of tropospheric greenhouse gases.
High-accuracy remote measurement of greenhouse gases is hampered by contamination of the field of view by the path radiance of solar radiation scattered from clouds and aerosols. A method is proposed for eliminating the effect of path radiance by differentiating two components of polarized light. The polarization of path radiance is measured directly at the wave-number region of strong water-vapor absorption. Using this measurement, we eliminate the components of path radiance involved in other bands, which are used for greenhouse gas measurements, by differentiating two components of the polarized light. It is shown that the effect of path radiance on retrieving the column amount of gases potentially can be reduced to below 0.1%.
Scattering of Light in the Lower Atmosphere
The optical scattering coefficient has been measured at Woomera at ground level, and at altitudes up to 14 000 ft, using two integrating nephelometers. The principle and the construction of a nephelometer are described. Results obtained over a period of 12 months are given.