Correction of atmospheric scattering effects in space-based observations of carbon dioxide: Model study of desert dust aerosol
✍ Scribed by A. Bril; S. Oshchepkov; T. Yokota
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 447 KB
- Volume
- 109
- Category
- Article
- ISSN
- 0022-4073
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✦ Synopsis
We describe an original methodology for CO 2 retrievals using space-based measurements of reflected sunlight spectra. The effects of optical-path modification by aerosols were considered in terms of photon path-length statistics. First, the general approach was verified using a representative set of photon trajectories produced by the Monte Carlo technique. This method enabled accurate consideration of optical-path modification by aerosols and was effective in CO 2 retrievals if aerosol optical properties were assumed. The next approach involved a limited number of parameters that describe the photon path-length distribution function (PPDF) and which were retrieved simultaneously with the CO 2 amount. This approach was efficient under conditions of strong path modification by desert dust aerosol. The retrieval procedure included the following: estimation of PPDF parameters from radiance spectra in the O 2 A-band; the necessary correction to use these estimated parameters in the 1.6-mm band; and, finally, CO 2 retrievals from the 1.6-mm band. The procedure was verified by numerical simulations using an independent radiative transfer approach to produce radiance spectra expected for the Greenhouse Gases Observing Satellite (GOSAT) sensor.