A SPARC Success Story:

The Role of Halogen Chemistry inPolar Stratospheric Ozone Depletion

An Update on the Initiative Sponsored by theStratospheric Processes and their Role in Climate (SPARC) Project

of the World Climate Research Programme

Initiative Co-Chairs:Michael J. Kurylo (UMBC/GEST)

Björn-Martin Sinnhuber (U. Bremen)

WCRP SPARC Scientific Steering Group17th SessionKyoto, Japan

26-30 October 2009

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Cox and Hayman (1988) Burkholder et al. (1990) DeMore and Tschuikow (1990) Vogt and Schindler (1990) Molina et al. (1990) Huder and DeMore (1995) Bloss et al. (2001) McKeachie et al. (2004) JPL 2006

ClOOCl Spectral and Absorption Cross-Section Data Available for the JPL 06-2 Evaluation

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Cox and Hayman (1988) Burkholder et al. (1990) DeMore and Tschuikow (1990) Vogt and Schindler (1990) Molina et al. (1990) Huder and DeMore (1995) Bloss et al. (2001) McKeachie et al. (2004) JPL 2006 Pope et al. (2007)

A Greater Problem Arises

Models Using Pope et al. Cross SectionsYield Less O3 Loss than Observed:

Antarctic simulation using CLAMS model

JPL 2006

Burkholder 1990

Pope 2007

Huder & DeMore 1994

von Hobe et al., ACP, 2007

ObservedOzone

JPL 2006

Figure 4-17, WMO 2007, adapted from Frieler et al., GRL, 2006Updated to include Pope et al. cross section by R. Schofield, M. Rex, T. Canty and R. Salawitch

JPL 2006

Observed OzoneLoss, Match

Calculated Ozone Loss for ModelConstrained by SOLVE Measurements

of ClO+2×ClOOCl

Modeled Ozone Loss for: GREEN DASHED: Pope et al. (2007), BrO from CH3Br & Halons GREEN SOLID : Pope et al. (2007), measured BrO

Modeled Ozone Loss for: BLACK : JPL 02 Kinetics, BrO from CH3Br & Halons BLUE DOTTED : JPL 02 Kinetics, BrOx from measured BrO BLUE DASHED: JPL 02 Kinetics except Burkholder et al. (1990) cross section BLUE SOLID : Burkholder et al. (1990) cross section and measured BrO

Models Using Pope et al. Cross SectionsYield Less O3 Loss than Observed:

Arctic simulation using box modelconstrained by observed ClOx

0 pptv Bry

22 pptv Bry

Kinnison, Brasseur, Orlando, Garcia, Tilmes

Pope et al. cross sections in MOZART3/WACCM1b yield half as much ozone loss as Burkholder et al. cross sections

Huder and DeMore, 1995

JPL 2006

Burkholder et al., 1990

Pope et al., 2007

ClO

OC

l Cro

ss S

ect

ion

(cm

2)

von Hobe et al., 2008

The UV/Vis Absorption Spectrum of Matrix-IsolatedDichlorine Peroxide, ClOOCl

M. von Hobe, F. Stroh, H. Beckers, T. Benter, and H. Willner

Phys. Chem. Chem. Phys., 2009, 11, 1571 - 1580, DOI: 10.1039/b814373k

More Recent Published Gas Phase Spectra

Chen et al., UV Absorption Cross Sections of ClOOCl are Consistent with Ozone Degradation Models, Science, 324, 781,

8 May 2009.

NASA / JPL Data Panel Interim Recommendation - 2009

"Chemical Kinetics and Photochemical Data for Use

in Atmospheric Studies”

Evaluation Number 16 of the NASA Panel for Data

Evaluation", JPL Publication 09-XX (2009).

S. P. Sander, R. R. Friedl,D. M. Golden, M. J. Kurylo,

P. H. Wine, J. Abbatt,J. B. Burkholder, C. E. Kolb, G. K. Moortgat, R. E. Huie,

and V. L. Orkin

Soon to be available at http://jpldataeval.jpl.nasa.gov/.

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NASA / JPL 09: Estimated Error Limits Revised

“Chlorine-Catalyzed Ozone

Destruction:Cl Atom

Production from ClOOCl

Photolysis”D. M. Wilmouth, T. F.

Hanisco, R. M. Stimpfle, and J. G. Anderson

J. Phys. Chem.(in press)

Available for download on the

J. Phys Chem A ASAP website:

http://pubs.acs.org/doi/pdf/10.1021/jp9053204

“Chlorine-Catalyzed Ozone Destruction:Cl Atom Production from ClOOCl Photolysis”

Wilmouth et al., J. Phys. Chem. (in press)

“Chlorine-Catalyzed Ozone Destruction:Cl Atom Production from ClOOCl Photolysis”

Wilmouth et al., J. Phys. Chem. (in press)

“UV Absorption Spectrum of the ClO Dimer (Cl2O2)between 200 and 420 nm”

D. K. Papanastasiou, V. C. Papadimitriou, D. W. Fahey,and J. B. Burkholder

J. Phys. Chem. (in press)

“UV Absorption Spectrum of the ClO Dimer (Cl2O2)between 200 and 420 nm”

D. K. Papanastasiou, V. C. Papadimitriou, D. W. Fahey,and J. B. Burkholder

J. Phys. Chem. (in press)

Comparison of wavelength dependent Cl2O2 atmospheric photolysis rate coefficients, J(λ), calculated for a solar zenith angle (SZA) of 86 at an altitude of 20 km

“UV Absorption Spectrum of the ClO Dimer (Cl2O2)between 200 and 420 nm”

D. K. Papanastasiou, V. C. Papadimitriou, D. W. Fahey,and J. B. Burkholder

J. Phys. Chem. (in press)

Upper Frame: Integrated atmospheric photolysis rate coefficients, J, calculated for Cl2O2 as a function of solar zenith angle (SZA). Lower Frame: Same data relative to the values obtained using the NASA/JPL recommended Cl2O2 cross section data.

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09JPL 09 . JPL Est Error IUPAC (2007) .Pope et al (2007) .von Hobe et al (2009) .Chen et al (2009) .Wilmouth et al (2009) .Papanastasiou et al(2009)

JPL 09 Recommendation & Most Recent Lab Studies

Conclusions

The ClOOCl cross section has been perhaps the largest source of uncertainty in our description of polar ozone loss.

The laboratory measurement of the ClOOCl cross section by Pope et al. (2007) fell outside the range of uncertainty defined by prior laboratory studies, leading to much discussion, deliberation, and debate within the atmospheric chemistry community.

The community met in Cambridge, England (June 2008) to examine our understanding of polar ozone loss (laboratory, theory, field observations, and modelling) in light of the Pope et al. study. A detailed report from that workshop is available electronically at:

http://www.atmosp.physics.utoronto.ca/SPARC/index.html

Several subsequent laboratory studies (published or about to be published) have failed to reproduce the Pope et al. ClOOCl cross sections and provide strong support for our understanding of chlorine-catalyzed ozone loss in the polar stratosphere.

The SPARC Initiative played an important role in fostering this new work!

JPL-09 Recommendations on theClO + ClO ClOOClEquilibrium Constant

"Chemical Kinetics and Photochemical Datafor Use in Atmospheric Studies”

Evaluation Number 16 of the NASA Panel for Data Evaluation", JPL Publication 09-XX (2009).

S. P. Sander, R. R. Friedl, D. M. Golden, M. J. Kurylo,P. H. Wine, J. Abbatt, J. B. Burkholder, C. E. Kolb,

G. K. Moortgat, R. E. Huie, and V. L. Orkin

Soon to be available at http://jpldataeval.jpl.nasa.gov/.

Lab Data Used in the JPL 2009 Recommendation for KEQ Over the Temperature Range 180<T/K<300

Lab Data Together with Various Fits for KEQ

Over the Temperature Range 180<T/K<300

JPL 2006 and JPL 2009 Recommendations for KEQ

Together with Various Fits from 180 < T/K < 225

Salawitch / Canty Analysis of Field DataFiltered for SZA > 105 Displayed on the Previous Plot

“Constraining the ClO/ClOOCl Equilibrium Constant from Aura Microwave Limb Sounder Measurements of Nighttime

ClO”

M. Santee, S. Sander, N. Livesey and L. Froidevaux

(to be submitted to PNAS Special Issue on Atmospheric Chemistry)

Acknowledgements

• NASA/JPL Panel for Data Evaluation– esp. D. Golden & J. Burkholder

• New Lab Studies– D. Wilmouth & J. Anderson (Harvard U.)

– J. Burkholder (NOAA-ESRL)

Interface betweenLaboratory Kinetics and the

2010 WMO/UNEP Ozone Assessment

Lifetimes for Long-Lived Compounds and VSLS’s for Chapters 1 and 5

Based on the most currentJPL 2010 and IUPAC Evaluations

"Chemical Kinetics and Photochemical Datafor Use in Atmospheric Studies”

Evaluation Number 17 of the NASA Panel for Data EvaluationJPL Publication 10-XX (2010).

S. P. Sander, R. R. Friedl, D. M. Golden, M. J. Kurylo,P. H. Wine, J. Abbatt, J. B. Burkholder, C. E. Kolb,

G. K. Moortgat, R. E. Huie, and V. L. Orkin

Available Spring 2010 at http://jpldataeval.jpl.nasa.gov/

Influence of JPL 09-XX Recommendationson Model Simulations of NOy and O3

Charles Jackman and Eric FlemingSeptember 29, 2009

GSFC Fully Coupled 2-D Model Computationsof Constituent Diurnal Cycles

1) Compare with UARS odd nitrogen (NO,NO2,HNO3,ClONO2) 2) Compare with Total Ozone Measurements (1988-2002)

3) Total Ozone (1980, 2000, time series)

1) Compare with UARS odd nitrogen (NO, NO2, HNO3, ClONO2)NO+NO2 at Sunset; HNO3+ClONO2 for 24-hour average

Model with JPL-09 higher than with JPL-06[due to increased N2O + O(1D) 2NO reaction]

2) Compare with Total Ozone Measurements (1988-2002)Total Ozone 1988-2002 average

Model with JPL-09 lower than with JPL-06Largest impact in polar spring, especially SH

[~One-half of change due to increased N2O + O(1D) 2NO reaction]

-15 DU

-10 DU

3) Total Ozone (1980, 2000, time series)

Model with JPL-09 has less ozone

than with JPL-06(higher Cl sensitivity in polar

regions with JPL-09)

Ozone recovery delayed by ~1 year