The variation of the polarized downwelling radiance distribution with depth in the coastal and clear ocean

The spectral polarized radiance distribution provides the most complete description of the light field that can be measured. However, this is a very difficult parameter to measure, particularly near the surface, because of its large dynamic range, changes in the skylight illumination, and waves at t...

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Published inJournal of Geophysical Research: Oceans Vol. 116; no. C7
Main Authors Bhandari, Purushottam, Voss, Kenneth J., Logan, Luke, Twardowski, Michael
Format Journal Article
LanguageEnglish
Published Washington Blackwell Publishing Ltd 01.07.2011
Subjects
Clear sky
Distribution
Downwelling
Geophysics
Image acquisition
Light fields
Light scattering
Marine
Oceanography
Oceans
optics
Polarization
Radiance
radiance distribution
Sky light
Skylights
Water circulation
Water column
Wavelengths
INE, USA, California, Santa Barbara Channel
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Summary:The spectral polarized radiance distribution provides the most complete description of the light field that can be measured. However, this is a very difficult parameter to measure, particularly near the surface, because of its large dynamic range, changes in the skylight illumination, and waves at the air‐sea interface. To measure the Stokes vector of the downwelling light field, which contains the polarization information, requires the combination of four images acquired simultaneously. To achieve this, we used the downwelling polarized radiance distribution camera system (DPOL) during the Radiance in a Dynamic Ocean (RaDyO) program Santa Barbara Channel and Hawaiian experiments. DPOL consists of four fisheye lenses and a spectral filter changer that allow us to capture the downwelling hemisphere of the polarized radiance distribution at seven wavelengths. Our measurements show that very near the surface, for clear sky conditions, the dominant source of polarization is the refracted sky light. As one progresses in the water column the polarization due to light scattering by the water increases and polarization due to light scattering in the water becomes dominant. Key Points Polarization in downwelling field, near the surface, determined by skylight Polarized scattering by water becomes important at greater depths Pattern of polarization plane remains fairly constant with depth
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ISSN:0148-0227
2169-9275
2156-2202
2169-9291
DOI:10.1029/2011JC007320