Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 7 2 2007 10.5194/acpd-7-5595-2007 http://www.atmos-chem-phys-discuss.net/7/5595/2007/ http://www.atmos-chem-phys-discuss.net/7/5595/2007/acpd-7-5595-2007.html http://www.atmos-chem-phys-discuss.net/7/5595/2007/acpd-7-5595-2007.pdf 5595 5615 2007-04-26 CALIPSO observations of stratospheric aerosols: a preliminary assessment L. W. Thomason l.w.thomason@nasa.gov M. C. Pitts D. M. Winker NASA Langley Research Center, Hampton, VA, USA We have examined the 532-nm aerosol backscatter coefficient measurements by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for their use in the observation of stratospheric aerosol. CALIPSO makes observations that span from 82° S to 82° N each day and, for each profile, backscatter coefficient values reported up to ~40 km. The possibility of using CALIPSO for stratospheric aerosol observations is demonstrated by the clear observation of the 20 May 2006 eruption of Montserrat in the earliest CALIPSO data in early June as well as by observations showing the 7 October 2006 eruption of Tavurvur (Rabaul). However, the very low aerosol loading within the stratosphere makes routine observations of the stratospheric aerosol far more difficult than relatively dense volcanic plumes. Nonetheless, we found that averaging a complete days worth of nighttime only data into 5-deg latitude by 1-km vertical bins reveals a stratospheric aerosol layer centered near an altitude of 20 km, the clean wintertime polar vortices, and a small maximum in the lower tropical stratosphere. However, the derived values are clearly too small and often negative in much of the stratosphere. 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