2 research outputs found
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Synergistic angular and spectral estimation of aerosol properties using CHRIS/PROBA-1 and simulated Sentinel-3~data
A method has been developed to estimate Aerosol Optical Depth (AOD), Fine Mode Fraction (FMF) and Single Scattering Albedo (SSA) over land surfaces using simulated Sentinel-3 data. The method uses inversion of a coupled surface/atmosphere radiative transfer model, and includes a general physical model of angular surface reflectance. An iterative process is used to determine the optimum value of the aerosol properties providing the best fit of the corrected reflectance values for a number of view angles and wavelengths with those provided by the physical model. A method of estimating AOD using only angular retrieval has previously been demonstrated on data from the ENVISAT and PROBA-1 satellite instruments, and is extended here to the synergistic spectral and angular sampling of Sentinel-3 and the additional aerosol properties. The method is tested using hyperspectral, multi-angle Compact High Resolution Imaging Spectrometer (CHRIS) images. The values obtained from these CHRIS observations are validated using ground based sun-photometer measurements. Results from 22 image sets using the synergistic retrieval and improved aerosol models show an RMSE of 0.06 in AOD, reduced to 0.03 over vegetated targets
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Improvements in Aerosol Optical Depth Estimation Using Multiangle CHRIS/PROBA Images
A method has been developed to estimate aerosol optical
depth (AOD) over land surfaces using high spatial resolution,
hyperspectral, and multiangle Compact High Resolution Imaging
Spectrometer (CHRIS)/Project for On Board Autonomy (PROBA)
images. The CHRIS instrument is mounted aboard the PROBA
satellite and provides up to 62 bands. The PROBA satellite allows
pointing to obtain imagery from five different view angles within
a short time interval. The method uses inversion of a coupled
surface/atmosphere radiative transfer model and includes a general
physical model of angular surface reflectance. An iterative
process is used to determine the optimum value providing the
best fit of the corrected reflectance values for a number of view
angles and wavelengths with those provided by the physical model.
This method has previously been demonstrated on data from
the Advanced Along-Track Scanning Radiometer and is extended
here to the spectral and angular sampling of CHRIS/PROBA.
The values obtained from these observations are validated using
ground-based sun-photometer measurements. Results from
22 image sets show an rms error of 0.11 in AOD at 550 nm, which
is reduced to 0.06 after an automatic screening procedure