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

Equivalent Effective Stratospheric Chlorine

EESC peak in ~1997.

Timing adjusted for transport to the stratosphere in WMO [2003] .

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.

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).

Residual total ozone column

from

Dobson/Brewer 30S-60N (top)

and

merged TOMS/SBUV 60S-60N (bottom).

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.

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]

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)

Middle stratospheric ozone data from ozonesondes 18-25 km agree with SAGE/HALOE andEESC regression.

Time series (top)

CUSUMs (bottom)

EESC influence on Lower

Stratosphere: moderate

EESC influence on Middle

stratosphere: strong

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

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.

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