Pope et al. (2007) Ultraviolet Absorption Spectrum of Chlorine Peroxide, ClOOCl, Francis D. Pope, Jaron C. Hansen, Kyle D. Bayes, Randall R. Friedl, and Stanley P. Sander, J. Phys. Chem. A, 111, 4322-4332, 2007 ClO + ClO + M ClOOCl + M (1a) ClOOCl + h ClOO + Cl (2) ClOO + M Cl + O 2 + M (3) 2 [Cl + O 3 ClO + O 2 ] (4) Net: 2O 3 3O 2
Antarctic Ozone Loss Oct. 1 Box model chemistry using JPL (2006) at 80˚S, 50 hPa Vary J(ClOOCl) From sondes we know that O 3 is ~0 by early Oct., adopting the Pope et al. (2007) rate results in less than 50% O 3 loss Plot from Randy Kawa NASA/GSFC Polar chemistry workshop for evaluating the new Pope et al. J rate to be held at Cambridge, UK (17-19 June, 2008)
What is EESC? Equivalent effective stratospheric chlorine (EESC) was developed to relate this halogen evolution to tropospheric source gases in a simple manner (Daniel et al., 1995) EESC represents the levels of Cl & Br in the stratosphere that can lead to ozone loss.
CFC-11 Emissions for 1960-2100 Qing Liang NASA/GSFC Global averaged surface CFC-11 mixing ratio GEOS CCM Emission & CFC-11 lifetime = 56 years WMO A1 Emission & CFC-11 lifetime = 45 years 2040 2032 Note: Assuming total CFC-11 production is the same, the difference between WMO A1 emission and model backed-out flux is due to differences in CFC-11 lifetimes and uncertainty in the remaining bank estimate. We spread the difference evenly between 2005-2100 for a modified emission estimate. Emission vs. mixing ratio forcings of CCMs Lifetime problem with CFC-11
Summary If the new lab measurements of Cl 2 O 2 photolysis are correct, then we must make seriously revise our current paradigm of polar ozone loss. Our future chlorine scenarios are critically dependent on lifetimes of ozone depleting substances. Revision of the CFC-11 lifetime alone will alter our projections of recovery. The acceleration of the stratospheric circulation is based upon model simulations, not observations. A changing circulation will affect both ozone and trace gas distributions