Odin-OSIRIS stratospheric aerosol data product and SAGE III intercomparison Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada
12 Jan 2012
Received: 05 July 2011 – Published in Atmos. Chem. Phys. Discuss.: 16 September 2011 Abstract. The scattered sunlight measurements made by the Optical Spectrograph and
InfraRed Imaging System (OSIRIS) on the Odin spacecraft are used to retrieve
vertical profiles of stratospheric aerosol extinction at 750 nm. The
recently released OSIRIS Version 5 data product contains the first publicly
released stratospheric aerosol extinction retrievals, and these are now
available for the entire Odin mission, which extends from the present day
back to launch in 2001. A proof-of-concept study for the retrieval of
stratospheric aerosol extinction from limb scatter measurements was
previously published and the Version 5 data product retrievals are based on
this work, but incorporate several important improvements to the algorithm.
One of the primary changes is the use of a new retrieval vector that greatly
improves the sensitivity to aerosol scattering by incorporating a forward
modeled calculation of the radiance from a Rayleigh atmosphere. Additional
improvements include a coupled retrieval of the effective albedo, a new
method for normalization of the retrieval vector to improve signal-to-noise,
and the use of an initial guess that is representative of very low background
aerosol loading conditions, which allows for maximal retrieval range.
Furthermore, the Version 5 data set is compared to Stratospheric Aerosol and
Gas Experiment (SAGE) III 755 nm extinction profiles during the almost four
years of mission overlap from 2002 to late 2005. The vertical structure in
coincident profile measurements is well correlated and the statistics on a
relatively large set of tight coincident measurements show agreement between
the measurements from the two instruments to within approximately 10%
throughout the 15 to 25 km altitude range, which covers the bulk of the
stratospheric aerosol layer for the mid and high latitude cases studied here.
Revised: 04 January 2012 – Accepted: 05 January 2012 – Published: 12 January 2012
Citation: Bourassa, A. E., Rieger, L. A., Lloyd, N. D., and Degenstein, D. A.: Odin-OSIRIS stratospheric aerosol data product and SAGE III intercomparison, Atmos. Chem. Phys., 12, 605-614, doi:10.5194/acp-12-605-2012, 2012.