An experimental evaluation of theoretical sea surface reflectance factors relevant to above-water radiometry

• Published in: Optics Express
• Main Author: ZIBORDI Giuseppe
• Language: English
• Published: OPTICAL SOC AMER 2016
• Subjects: Aerosol Robotic Network
• Online Access: https://publications.jrc.ec.europa.eu/repository/handle/JRC98128; https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-6-A446; https://doi.org/10.1364/OE.24.00A446

Determination of the water-leaving radiance Lw through above-water radiometry requires knowledge of accurate reflectance factors rho of the sea surface. Publicly available rho relevant to above-water radiometry include theoretical data sets generated: i. by assuming a sky radiance distribution accounting for aerosols and multiple scattering, but neglecting polarization, and quantifying sea surface effects through Cox-Munk wave slope statistics; or differently ii. accounting for polarization, but assuming Rayleigh sky radiance distribution, and quantifying sea surface effects through modeled wave elevation and slope variance spectra. The impact on above-water data products of differences between those factors rhos quantified through comparison of Lw from the Ocean Color component of the Aerosol Robotic Network (AERONET-OC) with collocated Lw from in-water radiometry. Results, specific for measurements of radiance from the sea performed with 40 degrees viewing angle and 90 degrees azimuth offset with respect to the sun plane, indicated a better agreement between above- and in-water LW determined for wind speeds tentatively lower than 4 m s-1 with rho computed neglecting polarization effects, but accounting for aerosols and multiple scattering. Nevertheless, analysis performed by partitioning the investigated data set also indicated that actual rho values would exhibit dependence on sun zenith comprised between those characterizing the two sets of reflectance factors considered in this study. JRC.D.2 - Water and Marine Resources