1. National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory Princeton, NJ 08542 http://www.gfdl.noaa.gov Evolution of Stratospheric Temperature and Ozone in GFDL Climate Model Simulations John Austin and R. John Wilson

2. GFDL climate model, coupled chemistry 48L model, upper boundary ~ 0.002 hPa Horizontal resolution 2 x 2.5 deg. Finite Volume dynamical core Comprehensive stratospheric chemistry; simplified tropospheric chemistry 3 member ensemble (1) 1960-2005 with observed forcings (2) 1990-2100 with A1B etc. forcings and SSTs from GFDL IPCC runs. AMTRAC: Description and runs

3. Decadally averaged total ozone, 1960-1999

4. TOMS Decadal total ozone, 1980-2002

5. TOMS vs. model Decadal total ozone, 1980-2002

6. Mean Ozone trend 1980-1999

7. Observed ozone trends 1980-1999 (Randel pers. comm., 2005)

8. AMTRAC polar spring lower stratosphere temperature evolution 1960-1999

9. AMTRAC polar lower stratospheric temperature evolution, 12-month running mean

10. AMTRAC (colored lines) and observed (black line) global average temperature for 1960 to 2005 weighted in the vertical by the MSU4 weighting function.

11. SOCOL MSU-4 equivalent temperature (25 months running mean) courtesy Schnadt et al.

12. Conclusions Past ozone trends are in reasonable agreement with observations for the period 1980-2000, but about 2%/decade larger than observed in the total column. The Antarctic ozone hole developed rapidly in the model from the late 1970s and peak depletion occurred by about 2000-2005. Ozone recovery was slow with the Antarctic ozone hole becoming negligible by about 2065 but not disappearing entirely until 2075 or so. Arctic ozone recovered to 1980 values by about 2040 It is suggested that the change in ozone recovery time from 2065 at the S. Pole to 2040 at the N. Pole reflects climate change (temperature change and changes in the Brewer- Dobson ciculation).

13. Acknowledgements V. Ramaswamy and the GFDL Global Atmosphere Model Development Team