Articles | Volume 8, issue 22
Atmos. Chem. Phys., 8, 6617–6626, 2008
Atmos. Chem. Phys., 8, 6617–6626, 2008

  17 Nov 2008

17 Nov 2008

Steady-state aerosol distributions in the extra-tropical, lower stratosphere and the processes that maintain them

J. C. Wilson1, S.-H. Lee2, J. M. Reeves1, C. A. Brock3, H. H. Jonsson4, B. G. Lafleur1, M. Loewenstein5, J. Podolske5, E. Atlas6, K. Boering7, G. Toon8, D. Fahey3, T. P. Bui5, G. Diskin9, and F. Moore10 J. C. Wilson et al.
  • 1Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, 80208-0177, USA
  • 2Department of Chemistry, Williams Hall, Kent State University, Kent, OH 44240, USA
  • 3NOAA ESRL CSD, 325 Broadway, Boulder, CO 80305, USA
  • 4CIRPAS/Naval Postgraduate School, Marina, CA 93933, USA
  • 5NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035-1000, USA
  • 6University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
  • 7Department of Chemistry, Room 419 Latimer Hall, University of California, Berkeley, CA 94720-1460, USA
  • 8Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, Ca 91109, USA
  • 9Chemistry and Dynamics Branch, MS 483, NASA Langley Research Center, Hampton, VA 23681, USA
  • 10NOAA ESRL GMD, 325 Broadway, Boulder, CO 80305, USA

Abstract. Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and sedimentation of particles in the extra-tropical overworld north of 45 N are found to maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. Exchange with the troposphere is important in understanding aerosol evolution there. Size distributions of volcanically perturbed aerosol are included to distinguish between volcanic and non-volcanic conditions. This analysis suggests that model failures to correctly predict OCS and aerosol properties below 20 km in the Northern Hemisphere extra tropics result from inadequate descriptions of atmospheric circulation.

Final-revised paper