OSIRIS limb scattered sunlight spectra are used to retrieve vertical profiles of stratospheric aerosol extinction at 750 nm. All the spectra obtained with a single vertical scan of the spectrograph line of sight are used together to retrieve an extinction profile with approximately 1.5 km vertical resolution. A wavelength ratio of 750 nm to 470 nm is used to characterize the effect of the Mie scattering signal. Hydrated sulphuric acid particle microphysics, including a size distribution for typical background aerosol, are assumed to calculate the scattering cross section and phase functions required to retrieve the aerosol extinction.
This retrieval is regularly processed at the University of Saskatchewan for all OSIRIS stratospheric limb scan measurements. Data from November, 2001, to the current date is available for download as an OSIRIS Level 2 Product in HDF-EOS5 format. OSIRIS remains fully operational and processing of this algorithm will be maintained into the foreseeable future.
Figure from Bourassa, A. E., D. A. Degenstein, B. J. Elash, and E. J. Llewellyn, Evolution of the stratospheric aerosol enhancement following the eruptions of Okmok and Kasatochi: Odin-OSIRIS measurements, J. Geophys. Res., 115, D00L03, doi:10.1029/2009JD013274, 2010.