1. Estimating Ozone Production Efficiency from Space Matthew Cooper 1, Randall Martin 1,2, Bastien Sauvage 3, Chris Boone 4, Kaley Walker 4,5,Peter Bernath 4,6, Chris McLinden 7, Doug Degenstein 8, Andreas Volz-Thomas 9, Catherine Wespes 10 5 th International GEOS-Chem Meeting Harvard University May 2, 2011 1. Dalhousie University2. Harvard-Smithsonian Center for Astrophysics3. University of Waterloo 4. University of Toronto5. University of York 6. Environment Canada7. University of Saskatchewan 8. Université de Toulouse9. Forschungszentrum Juelich10. Université Libre de Bruxelles

2. Convective outflow: No HNO 3, some initial O 3, NO x Ozone Production Efficiency OPE represents the nonlinear dependence of O 3 on NO x GEOS-Chem predicts high ozone production efficiency – This has not been confirmed by measurements in the tropical troposphere – We can estimate OPE using satellite retrievals of O 3 and HNO 3 concentrations

3. Observations Solar occultation instrument measuring IR Global coverage in tropics over several years (2004-2010) Measures O 3, HNO 3, 30+ others Evaluation against aircraft, ozonesondes [Cooper et al., JGR, in press] – 10-13% high bias for O 3 – 15% for HNO 3 ACE-FTS PEM Tropics A (1996) and B (1999) PRE-AVE (2004) and CR-AVE (2006) Tropospheric O 3 and HNO 3 observations between 8-12 km used here Aircraft

4. Testing the Method using GEOS-Chem How does calculating OPE from concentrations compare to direct calculation from production rates? Assumed similar O 3, HNO 3 loss Some HNO 3 scavenging occurs, leads to OPE overestimation OPE from concentrations is an upper limit estimate!

5. Ozone Production Efficiency from ACE-FTS OPE given by slope OPE = 196 (+34, -61) mol/mol Agrees with tropical mean OPE from GEOS-Chem (190 mol/mol) First estimate of OPE using satellite data Uncertainty sources – Slope error ± 8 – ACE bias ± 5 – Method (upper limit) -53 – Regional pollution ±33 ACE-FTS (11.5 km) in Tropics (±20°)

6. OPE from ACE-FTS, Aircraft and GEOS-Chem Over South Pacific region: GEOS-Chem agree with both data sets within uncertainties Tropics (±20° at 11.5 km) OPE (mol/mol) ACE-FTS223 (+41, -69) Aircraft232 (+41, -71) GEOS-Chem188 (+42, -63) GEOS-Chem ACE-FTS Aircraft

7. OPE Variability Whole TropicsTropical AtlanticTropical Pacific OPE from GC P-rates13193196 OPE from ACE –FTS196 (+34, -61)146 (+16, -41)249 (+21, -68) Number of Points3686265 Error – slope (mol/mol)81419 Error –variability (mol/mol)3264 0 50 100 150 200 250 300 Ozone Production Efficiency (mol/mol)

8. Summary Estimation of Ozone Production Efficiency possible from ACE- FTS measurements – A new application for satellite measurements Upper limit tropical mean OPE = 196 (+34,-61) mol/mol using ACE-FTS measurements In agreement with values calculated from GEOS-Chem output Regionally defined values possible from ACE-FTS – show same features seen in GEOS-Chem