Integration model of POSP measurement spatial response function

The particulate observing scanning polarimeter (POSP) measurement spatial response function (SRF) relates to the weighted contribution of each location within the measurement footprint, which is determined by the percentage of the dwell time of each location on the Earth surface to the overall sampling integration time. The SRF resulting from a combination of the equally weighted instantaneous field of view (IFOV) during integration is required for an accurate modeling. Simply using a mean value SRF assuming an equivalent weight at each sampling position instead of the actual SRF will inevitably introduce errors. Considering the data fusion between POSP and high spatial resolution sensors, a discrete integration method that takes the effect of actual weights into account is proposed in this paper. The simulation results of the integral model and the mean value model show that the larger the intensity change in the sampling area covered by the IFOV of the POSP during a single sampling, the more significant the difference between the two results. Meanwhile, the integration SRF is validated by resampling the simultaneous imaging polarization camera (SIPC) data, which is compared with POSP data acquired at the same time in an aerial experiment. The results show that the integration SRF model is more accurate to characterize the details of POSP measurement than the mean value SRF model. The proposed SRF reduces the root mean square error (RMSE) of convolved results and measurements by 5∼30% with different radiance contrast scene.

Analysis of the spectral and angular response of the vegetated surface polarization for the purpose of aerosol remote sensing over land

A precise estimate of the polarization induced by the surface in reflected radiation is crucial for remote sensing applications dedicated to monitoring the atmosphere. Here we present airborne observations acquired during a field campaign in the North of France over vegetated surfaces. Polarized reflectances were measured in four spectral bands in the range between 0.67 and 2.2 μm and for scattering angles between 75° and 145°. Our results confirm that the polarization generated by the reflection of vegetated surfaces can be understood as being primarily a specular reflection process. It is not possible from our measurements to see any spectral dependence of the surface polarization in the given spectral channels. The surface polarization is well fitted by existing surface models which have two degrees of freedom that allow the magnitude and angular behavior of the surface-polarized reflectance to be adjusted.