Composition and Chemistry
Detection of optical path in spectroscopic space-based observations of greenhouse gases: Application to GOSAT data processing
Article first published online: 22 JUL 2011
Copyright 2011 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 116, Issue D14, 27 July 2011
How to Cite
2011), Detection of optical path in spectroscopic space-based observations of greenhouse gases: Application to GOSAT data processing, J. Geophys. Res., 116, D14304, doi:10.1029/2010JD015352., , , and (
- Issue published online: 22 JUL 2011
- Article first published online: 22 JUL 2011
- Manuscript Accepted: 29 APR 2011
- Manuscript Revised: 25 APR 2011
- Manuscript Received: 18 NOV 2010
 We present a method to detect optical path modification due to atmospheric light scattering in space-based greenhouse gas spectroscopic sounding. This method, which was applied to the analysis of radiance spectra measured by the Greenhouse Gases Observing Satellite (GOSAT), is based on the path length probability density function (PPDF) and on retrieval of PPDF parameters from radiance spectra in the oxygen A-band of absorption at 0.76 μm. We show that these parameters can be effectively used to characterize the impact of atmospheric light scattering on carbon dioxide retrieval in the atmospheric carbon dioxide (CO2) absorption bands at 1.6 μm and 2.0 μm. The threshold for PPDF parameters is set so that the optical-path modification is negligible, and these settings are recommended as a basic guideline for selecting the clearest atmospheric scenarios. An example of data processing for six global GOSAT repeat cycles in April and July 2009 shows that PPDF-based selection efficiently removes CO2 retrieval biases associated with subvisible cirrus and sandstorm activities.