OSIRIS stratosphere

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 at 750 nm. This retrieval is regularly processed at the University of Saskatchewan for all OSIRIS stratospheric limb scan measurements.

Example result / latest result (if near-real time)


Satellite: Odin (ESA Third Party Mission)
Instrument(s): OSIRIS (Canada)
Instrument/algorithm PI: Adam Bourassa (Algorithm), University of Saskatchewan
Contact details: adam.bourassa[at]usask.ca
Parameter(s): Stratospheric aerosol extinction coefficient at 750 nm from 10-35 km altitude at 2 km resolution
Aerosol algorithm: MART
Cloud screening: Cloud-tops
Aerosol model:

Hydrated sulphuric acid

Retrieval assumptions:

Log-normal particle size distribution; 80 nm mode radius, 1.6 mode width; horizontal homogeneity

Retrieval limitations: Extinction threshold approximately 10-6 to 10-2 km-1
Spatial, temporal coverage: 2002-2014 / global, weekly
Spatial, temporal resolution: 2 km vertical resolution; 500 km along track sampling
Operations status: Fully processed
Validation status: Validated against SAGE III occultation, ongoing with SAGE II
Quality control:

Precision estimate reported with retrievals

last algorithm version:


last validation: 2015