POLREF: A new simulator for Polarized Reflection Coefficients over ocean
Zagolski, F.; Santer, R.; Barker, K.; Huot, J.-P. (2012). POLREF: A new simulator for Polarized Reflection Coefficients over ocean. ParBleu Technologies/Adrinord/Argans: St Jean-sur-Richelieu, Lille and Plymouth. 1 poster pp.
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Document type: Poster
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| Authors | | Top |
- Zagolski, F.
- Santer, R., more
- Barker, K., more
- Huot, J.-P.
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| Abstract |
In the validation of the algorithm for the MERIS (MEdium Resolution Imaging Spectrometer) atmospheric corrections over ocean, the water reflectance derived from in-situ measurements represents a key element. The water-leaving radiance needs to be corrected for the sky dome Fresnel reflection. In the standard protocol, this correction is achieved with an approximate value of the Fresnel reflection coefficient of sea surface applied to the measurement of the sky radiance. The latter ignores the polarized nature of both the atmospheric scattering and the surface reflection. The introduction of the polarization requires a radiative transfer code (RTC) which deals with the Stokes parameters, to compute the total radiance fields at bottom of the atmosphere (BOA). The successive orders (SO) of scattering code (Lenoble et al., 2007) was a good opportunity to analyze the impact of the polarization in the reflected sky dome radiance over ocean. This study has been fully reported in Santer et al., 2012.A simulator, namely POLREF (POLarization REFlection coefficient), has then been developed to produce a new set of Fresnel reflection coefficients at the 15 MERIS wavelengths. It relies on a pre-computed synthethic database (SEAPOL), which includes MERIS look-up tables (LUTs) of atmospheric scattering functions at BOA. These LUTs have been generated with the SO vector code using as inputs, the same spectral bandset, the same aerosols, the same atmospheric and surface conditions, and the same set of Sun/view geometries, as for the «OceanAerosol» auxiliary data file (ADF) used in the last 3rd MERIS reprocessing. Thus, the POLREF simulator is perfectly in-line with the MERIS instrument facilities processor (IPF). |
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