Radiometrs-polarimeters: principles of design and applications for sea surface microwave Emission Polarimetry

On The Effect of Atmospheric Emission upon the Passive Microwave Polarimetric Response of an Azimuthally Anisotropic Sea Surface

“…Airborne campaigns and analyses of SSM/I measurements have indicated that ocean brightness temperatures can vary over azimuthal angles relative to the wind direction by a few degrees Kelvin [7][8][9][10]. These experimental evidences have been supported by theoretical studies about the sensitivity of the polarimetric passive signature, that is the observed Stokes vector, over an azimuthally-anisotropic surface [11][12][13].…”

“…Then, we have evaluated the parameters of an equivalent homogeneous atmosphere. The atmospheric transmittance was computed by integrating along a vertical or a slanted path the extinction coefficient k e , while the mean radiative temperatures have been derived from the brightness temperature given by the model using equations (7) and (8). In this computation we have imposed the boundary condition at the Earth surface by assigning the physical temperature and a surface emissivity different for vertical and horizontal polarizations and derived from the outputs of the polarimetric emission model (note that in this case the interaction between the surface and the atmosphere influences T UP also).…”

Scattering and Thermal Emission from a Two Dimensional Periodic Surface

“…However, these six sets of equations are restricted to four by the divergenceless condition of plane wave fields. Using the x and y components of these equations and substituting in the Fourier series expansions (15)(16)(17)(18) results in the following matrix equation:…”

“…In a more recent application, theories and experiments involving passive remote sensing of one dimensional periodic surfaces [11][12][13][14][15][16] have conclusively demonstrated the existence of a third Stokes parameter component of the thermal emission, U B . Assumed to be non-zero only in polarimetric passive remote sensing, U B is known to respond to the azimuthal anisotropy of the medium under view [17] and thus is currently being investigated for application to remote sensing of wind direction over the ocean [18][19][20][21].…”

Stokes Antenna Temperatures

“…Polarimetric capabilities have enabled the sensing of ocean-surface wind directions, as well as the enhanced measurements of wind speed, among other applications. Airborne radiometers based on polarization combiners and analog and digital correlators were used to make some of the first nonnadir polarimetric measurements of the sea surface, e.g., [1]- [4]. The first spaceborne polarimeter for Earth observation, called WindSat, was designed for oceansurface wind-vector remote sensing and has produced compelling results [5].…”