Publication Abstracts

Mishchenko and Travis 1997

Mishchenko, M.I., and L.D. Travis, 1997: Satellite retrieval of aerosol properties over the ocean using measurements of reflected sunlight: Effect of instrumental errors and aerosol absorption. J. Geophys. Res., 102, 13543-13553, doi:10.1029/97JD01124.

A major task of several currently existing and planned satellite instruments is to provide accurate global of the distribution and properties of tropospheric aerosols using radiance and/or polarization measurements of the reflected sunlight. We use advanced computer simulations of radiative transfer in a realistic atmosphere-ocean model at a wavelength of 865 nm to examine the sensitivity of several widely used and recently developed retrieval techniques to aerosol absorption and instrumental errors. We assume that nonabsorbing (e.g., sulfate) and strongly absorbing (e.g., soot) aerosol components are mixed externally and that the scattering matrix of the mixture is that of of the nonabsorbing component, while the only effect of the absorbing component is to reduce the single-scattering albedo. We show that neither algorithms using multiple-viewing-angle radiance measurements nor analogous polarization measurements or their combination can retrieve the aerosol single-scattering albedo with sufficient accuracy. However, accurate retrievals of the aerosol optical thickness, refractive index, and effective radius using polarization measurements do not require a precise knowledge of the aerosol single-scattering albedo, whereas potential uncertainties in the single-scattering can strongly influence the accuracy of aerosol retrievals based on intensity measurements alone. Another important conclusion is that the accuracy of aerosol retrievals based on intensity and/or polarization measurements of the reflected sunlight is strongly corrupted by instrumental errors. We show that nonzero measurement errors can result in the best fit of model computations to measurement data being obtained with aerosol parameters far different from the actual ones. Our results emphasize the importance of accurate and stable instrumental calibration and suggest that the absolute radiometric uncertainty should be constrained to about ±4% or better and the absolute polarization accuracy should be kept to within ±0.2%. However, less accurate polarization measurements can still be used to estimate the aerosol refractive index and effective radius with reasonable accuracy. The results of our previous paper [Mishchenko and Travis, 1997] and this one demonstrate the limited capabilities of aerosol retrieval techniques based on intensioty measurements alone and suggest that high-precision spaceborne polarimetry may potentially be the only way of retrieving aerosol characteristics with accuracy needed for long-term monitoring of global climate forcings and feedbacks.

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BibTeX Citation

@article{mi06000k,
  author={Mishchenko, M. I. and Travis, L. D.},
  title={Satellite retrieval of aerosol properties over the ocean using measurements of reflected sunlight: Effect of instrumental errors and aerosol absorption},
  year={1997},
  journal={J. Geophys. Res.},
  volume={102},
  pages={13543--13553},
  doi={10.1029/97JD01124},
}

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RIS Citation

TY  - JOUR
ID  - mi06000k
AU  - Mishchenko, M. I.
AU  - Travis, L. D.
PY  - 1997
TI  - Satellite retrieval of aerosol properties over the ocean using measurements of reflected sunlight: Effect of instrumental errors and aerosol absorption
JA  - J. Geophys. Res.
VL  - 102
SP  - 13543
EP  - 13553
DO  - 10.1029/97JD01124
ER  -

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