Radiative transfer model for the computation of radiance and polarization in an ocean–atmosphere system: polarization properties of suspended matter for remote sensing

Abstract

A radiative transfer code termed OSOA for the ocean-atmosphere system that is able to predict the total and the polarized signals has been developed. The successive-orders-of-scattering method is used. The air-water interface is modeled as a planar mirror. Four components grouped by their optical properties, pure seawater, phytoplankton, nonchlorophyllose matter, and yellow substances, are included in the water column. Models are validated through comparisons with standard models. The numerical accuracy of the method is better than 2%; high computational efficiency is maintained. The model is used to study the influence of polarization on the detection of suspended matter. Polarizing properties of hydrosols are discussed: phytoplankton cells exhibit weak polarization and small inorganic particles, which are strong backscatterers, contribute appreciably to the polarized signal. Therefore the use of the polarized signal to extract the sediment signature promises good results. Also, polarized radiance could improve characterization of aerosols when open ocean waters are treated.

Retrieval of the Eyjafjallajökull volcanic aerosol optical and microphysical properties from POLDER/PARASOL measurements

“…We assume a Lambertian reflectance model for the ocean surface reflectance, since the errors introduced by this assumption are small. We evaluated the effects of this assumption by using a radiative transfer code that allows to simulate the total and polarized radiances emerging from a coupled ocean-atmosphere system (Chami et al, 2001). The effects of the water-leaving radiance on the signal modeled at TOA can be safely ignored at 865 nm and are small at 670 nm.…”

OSOAA: a vector radiative transfer model of coupled atmosphere-ocean system for a rough sea surface application to the estimates of the directional variations of the water leaving reflectance to better process multi-angular satellite sensors data over the ocean

“…As mentioned in section 1, the development of the OSOAA model that includes the rough sea surface has been inspired by a former radiative transfer code, so-called OSOA [11], which was initially developed for a flat sea surface. We briefly review below the main characteristic of the OSOA model (section 2.1) prior to focusing on the implementation of the rough sea surface to obtain the OSOAA model (section 2.2).…”

“…The OSOA radiative transfer model [11] solves the vector radiative transfer equation of the coupled atmosphere-ocean system for a flat sea surface using the successive orders of scattering methods. The OSOA model thus predicts the components of the Stokes vector I, Q and U [28] at a few levels of the atmosphere-ocean system, e.g.…”

“…Many vector radiative transfer models have been proposed to predict the radiance and degree of polarization of the light using various numerical methods such as the successive orders of scattering method [11][12][13], the discrete ordinate method [14,15], the Monte Carlo method [16], the adding doubling method [17][18][19][20]. Because the sea surface is usually rough, a realistic radiative transfer model should be able to account for the roughening effect of the wind onto the sea surface to better simulate the propagation of the light across the air-sea interface.…”

“…Chami et al [11] had developed a vector radiative transfer code of the coupled oceanatmosphere system for a flat sea surface using the successive orders of scattering methods (socalled "Ordres Successifs Océan Atmosphère" -OSOA model). As mentioned above, the flat sea surface assumption limits the application of the OSOA model especially if sophisticated inverse algorithms need to be developed for analyzing the future satellite multidirectional and polarimetric data (e.g.…”