Preprints
https://doi.org/10.5194/amt-2021-322
https://doi.org/10.5194/amt-2021-322

  20 Nov 2021

20 Nov 2021

Review status: this preprint is currently under review for the journal AMT.

Aerosol models from the AERONET data base. Application to surface reflectance validation

Jean-Claude Roger1,2, Eric Vermote2, Sergii Skakun1,2, Emilie Murphy1,2, Oleg Dubovik4, Natacha Kalecinski1,2, Bruno Korgo3, Christopher Justice1, and Brent Holben5 Jean-Claude Roger et al.
  • 1Department of Geographical Sciences, University of Maryland, College Park, MD, 20742, USA
  • 2Terrestrial Information System Branch-Code 619, NASA/GSFC, Greenbelt, MD, 20771, USA
  • 3Laboratoire d’Optique Atmosphérique, Université de Lille 1, Villeneuve d’Ascq, 59665, France
  • 4Laboratory of Thermal and Renewable Energy, University Joseph KI-ZERBO, Ouagadougou, Burkina Faso
  • 5Biospheric Science Branch-Code 618, NASA/GSFC, Greenbelt, MD, 20771, USA

Abstract. Aerosols play a critical role in radiative transfer within the atmosphere, and they have a significant impact on climate change. As part of the validation of atmospheric correction of remote sensing data affected by the atmosphere, it is critical to utilize appropriate aerosol models as aerosols are a main source of error. In this paper, we propose and demonstrate a framework for building and identifying an aerosol model. For this purpose, we define the aerosol model by recalculating the aerosol microphysical properties (Cvf, Cvc, %Cvf, %Cvc, rvf, rvc, σr, σc, nr440, nr650, nr850, nr1020, ni440, ni650, ni850, ni1020, %Sph) based on the optical thickness at 440 nm τ440 and the Ångström coefficient α440–870 obtained from numerous AERosol RObotic NETwork (AERONET) sites. Using aerosol microphysical properties provided by the AERONET dataset, we were able to evaluate our own retrieved microphysical properties. The associated uncertainties are up to 23 %, except for the challenging, imaginary part of the refractive index ni (about 38 %). Uncertainties of the retrieved aerosol microphysical properties were incorporated in the framework for validating surface reflectance derived from space-borne Earth observation sensors. Results indicate that the impact of aerosol microphysical properties varies 3.5 × 10−5 to 10−3 in reflectance units. Finally, the uncertainties of the microphysical properties yielded an overall uncertainty of approximately of 1 to 3 % of the retrieved surface reflectance in the MODIS red spectral band (620–670 nm), which corresponds to the specification used for atmospheric correction.

Jean-Claude Roger et al.

Status: open (until 25 Dec 2021)

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Jean-Claude Roger et al.

Jean-Claude Roger et al.

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Short summary
From measurements of sky performed by a network of robots around the world (AERONET), we determined the properties of the atmospheric particles (aerosols) for each AERONET site using the aerosol concentration and its variation over the visible spectrum. This allow us to determine an aerosol model useful for (but not only) the validation of the surface reflectance satellite product. The impact of the aerosol model uncertainties on the surface reflectance validation has been found as 1 to 3 %.