Evolution of Stratospheric Temperature and Ozone in GFDL Climate Model Simulations

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Evolution of Stratospheric Temperature and
Ozone in GFDL Climate Model Simulations

• John Austin and R. John Wilson

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AMTRAC Description and runs

• 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.

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

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Acknowledgements

• V. Ramaswamy and the GFDL Global Atmosphere Model
  Development Team