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First Stage of Recovery in the Stratospheric Ozone
Layer
Eun-Su Yang/Ga TechDerek M. Cunnold/Ga Tech
Ross J. Salawitch/JPLM. Patrick McCormick/Hampton
UJames Russell III/Hampton U
Joseph M. Zawodny/LaRCSamuel Oltmans/CMDL
Michael J. Newchurch/UAH
AGUSpring Meeting23-27 May 2005
New Orleans, LA
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Equivalent Effective Stratospheric Chlorine
EESC peak in ~1997.
Timing adjusted for transport to the stratosphere in WMO [2003] .
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Fractional Ozone loss
calculated in PC model.
Peak loss during Pinatubo, as expected.Larger losses at higher latitudes.Consistent with loss expected from EESC record.
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Residual ozone columnfrom SAGE and
HALOE above 18km
60S-60N
[O3]t = + t + [Seasonal terms] +
[QBO terms] + γ [F10.7]t +
a1Nt-1 + tCumulative sum of SAGE residual, ,,departures from projected trend line 1997-2005.
2-Sigma envelope (dotted).
Constant level (green).
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Residual total ozone column
from
Dobson/Brewer 30S-60N (top)
and
merged TOMS/SBUV 60S-60N (bottom).
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Cumulative sum total ozone columnDobson/Brewer 30S-60N (top)andMerged TOMS/SBUV 60S-60N (bottom)residuals from projected trend line 1997-2005.
Total columns recover more than 18 km-TOA due to gains between tropopause – 18 km.
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SAGE/HALOE (black) stratospheric ozone column (TP+2km to TOA)60S-70S
Temperature effects removed,and saturation effect shown to be negligible north of 70S (not negligible at 90S).
Also shows clear chlorine signature (red) ~1997 inflection and slight increasing afterward [Yang et al., accepted, GRL, 2005]
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Middle stratospheric ozone data from SAGE (pre 91) and HALOE (post 93) in black.
EESC regression onto ozone (blue).
Ozone expected from observationally constrained PC model calculations (red).
Consistent results.
Time series (top)
CUSUMs (bottom)
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Middle stratospheric ozone data from ozonesondes 18-25 km agree with SAGE/HALOE andEESC regression.
Time series (top)
CUSUMs (bottom)
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EESC influence on Lower
Stratosphere: moderate
EESC influence on Middle
stratosphere: strong
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PV influence on Lower Stratosphere:
moderate
Similar for Tropopause Height
Tropopause – 18 km 18-25 km
PV influence on Middle
Stratosphere: none
Similar for Tropopause Height
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CONCLUSIONS
The decline in the global stratospheric ozone layer has stopped.
3 independent satellite sensors: SAGE, HALOE, merged TOMS/SBUVand 2 ground networks: Dobson/Brewer and ozonesondes,all show consistent results in ozone trends and recovery signatures.
Most (81%) of the ozone loss occurred above 18 km.Half of the recovery occurred tropopause-18km.
Chlorine signature expected from the Montreal Protocoland Amendments is clear in ozone improvement in the middle and upper stratosphere.
Dynamics, not chlorine, controls ozone behavior in lower stratosphere.
Climate change interactions and potential stratospheric aerosol injections will influence the ozone recovery signature.
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http://nsstc.uah.edu/atmchem/
Acknowledgements
WOUDC NASA/ESE
NOAA/NGDCSwiss Met Service
Steve Montzka/CMDLNASA/LaRC data centerNASA/GSFC data center
International ozonesonde programs
This work is dedicated to the memory of
Professor Greg Reinsel