5 October 2007 Maximum entropy regularization strategies for inferring aerosol vertical distribution from light scattering measurements
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Abstract
A methodology is presented for obtaining information on aerosol vertical structure, a key variable in studies of aerosol climate forcing and atmospheric correction of satellite ocean-color imagery. The methodology employs ground-based angular measurements of atmospheric radiance, total or polarized, in the oxygen A-band centered on 763 nm. The radiance measured at different zenith angles is sensitive to different atmospheric layers, and the measurements can be inverted to retrieve the vertical profile of aerosol concentration. To solve the inverse problem, in which small errors in the data may yield large errors in the reconstructed profile, an iterative regularization scheme, robust to noise and perturbing effects (e.g., due to multiple scattering and non-null surface reflectance), is developed. Maximum entropy regularized solutions are introduced. The methodology is tested on atmospheric radiance data simulated for typical aerosol profiles and aerosol types. The retrieved aerosol profiles agree with the prescribed ones, indicating that the inversion scheme is efficient in achieving a proper balance between goodness-of-fit to the data and stability of the solution. The methodology has the potential to extend and complement surface observations of aerosol vertical structure made by lidar networks. This perspective is significant, since current information on aerosol vertical structure is insufficient to constrain and verify key assumptions in global aerosol models. The complementary information would contribute, via assimilation, to improving predictions of aerosol radiative forcing and to reducing uncertainties in model simulations of climate change. In addition, the methodology would help to evaluate the retrievals of aerosol vertical structure from space-borne lidars, and would be useful to check the atmospheric correction of satellite ocean-color imagery and develop improved correction algorithms in the presence of absorbing aerosols.
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Bruno Pelletier, Bruno Pelletier, Robert Frouin, Robert Frouin, Philippe Dubuisson, Philippe Dubuisson, } "Maximum entropy regularization strategies for inferring aerosol vertical distribution from light scattering measurements", Proc. SPIE 6680, Coastal Ocean Remote Sensing, 668005 (5 October 2007); doi: 10.1117/12.738168; https://doi.org/10.1117/12.738168
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