TOPSE: Tropospheric Ozone Production About the Spring Equinox Elliot Atlas & TOPSE Science Team

1. TOPSE: Tropospheric Ozone Production About the Spring Equinox Elliot Atlas & TOPSE Science Team

2. Primary Objective of TOPSE To investigate the chemical and dynamic evolution of tropospheric chemical composition over mid- to high-latitude continental North America during the winter/spring transition, with particular emphasis on the springtime ozone maximum in the troposphere.

3. TOPSE Investigators:Measurements MeasurementInvestigators Remote Ozone/AerosolsBrowell et al., NASA Acidic Trace Gases/7-BeTalbot, Dibb, et al. UNH NMHC, Halocarbons, RONO2Blake et al., UCI NO2, PeroxynitratesCohen, Thornton et al., UCB Speciated PeroxidesHeikes, Snow, URI OH, H2SO4Eisele, Mauldin, NCAR HO2, RO2Cantrell, Stephens, NCAR HNO3Zondlo, NCAR NOx, NOy, OzoneRidley, Walega, NCAR CH2O, H2O2Fried, NCAR J valuesShetter, Lefer et al., NCAR PAN, PPNFlocke, Weinheimer, NCAR CO, N2OCoffey, Hannigan, NCAR Ultrafine Aerosols Weber, GIT Mission Scientists/P.I.sAtlas, Cantrell, Ridley, NCAR

4. TOPSE Investigators: Modeling/Collaboration Modeling/CollaborationInvestigators Regional/Forecast Model (HANK)Klonecki, Hess et al., NCAR Global Model AnalysisTie, Emmons et al., NCAR (MOZART)Brasseur et al., MPI Process and Radiation ModelsMadronich, Stroud et al., NCAR Global Model/Process StudiesJacob, Evans, Harvard U. Stratosphere/Troposphere Exch.Allen, Pickering, U. Md. Regional/other ModelsWang et al., Rutgers U. Meteorological Forecast/Moody, Cooper, Wimmers, U.Va. Remote Sensing Ozonesonde NetworkMerrill, URI; Fast, PNWL GOME BrORichter, Burrows, U. Bremen Met. Forecasts (UT/LS) Newman, NASA Polar Sunrise Expt., 2000Shepson, Purdue; Bottenheim, Can. Met. Serv.

5. TOPSE Flight Tracks

6. Some TOPSE Highlights • Seasonal variation in trace gases/aerosols • Evolution strong function of altitude and latitude • Decline in NMHC; Spring maximum in sulfate • PAN most significant odd-nitrogen component of NOy • Ozone evolution in the mid-troposphere • Increase about 20 ppb from Feb-May • Covariation in PANs, aerosols; no PV trend • Photochemical/surface sources implicated • Surface ozone depletion • Observations in early spring-May • Br-catalyzed ozone loss • Long-range transport of depleted air suggested • Transport processes • Most sampled air masses representative of • background mid-troposphere • Distant pollution sources were encountered in layers

7. Some TOPSE Highlights (cont’d) • In-situ photochemical processes • Measured radicals consistent with constrained models • Hydrogen peroxide 2 – 10 x lower than model • Formaldehyde photolysis significant HOX source at high latitudes • Calculated increase in in-situ ozone production in spring from increasing HOX sources and NO • Stratosphere-troposphere exchange • Remote sensing (satellite/lidar) indicate folds/streamers/STE(?) • In-situ encounters with lower stratosphere during flights • 7-Be measurements/models suggest significant fraction of tropospheric ozone is from stratosphere. Seasonal modulation by photochemistry with contribution by STE

8. Seasonal evolution of NMHC vs. latitude and altitude during TOPSE (Blake et al., UCI)

9. Formaldehyde vertical distributions vs. latitude: Feb – May, 2000 (Fried et al. – NCAR)

10. Evolution of Sulfate Aerosol Vertical Distribution 1 – 7 = Deployment number (Feb – May) (Scheuer, Talbot, Dibb – UNH)

11. Ozone vertical profile: Evolution during winter-spring (Ridley, Walega - NCAR)

12. Deployment 1 Deployment 3 Deployment 4 Deployment 5 Deployment 6 Deployment 7 Average Ozone Distributions During TOPSE (Browell et al., NASA)

13. PANs and ozone in the mid-troposphere (Cohen, Thornton – UCB Flocke, Ridley – NCAR)

14. 7Be measurements diagnose stratospheric O3 7Be/O3 correlation during TOPSE Observations of stratospheric influence: 7Be, HNO3, O3 (Dibb et al., UNH)

15. Chemical Transport Models (Global and Regional) Significant Model Differences: Model Similarities: Chemical Mechanisms, Emissions, Dry Deposition, Washout, Lightning (Emmons, Hess, et al. – NCAR)

16. Average of O3 for all flights All TOPSE flights: 40-85N, 235-300E, Surface to 350 hPa Good agreement between models and data until May

17. O3 Budget: 30o-90o North, Surface-350 hPaMOZART, HANK DESTRUCTION: HO2+O3->OH+2O2 OH+O3->HO2+O2 H2O+O(1D)->2OH PRODUCTION: HO2+NO->NO2+OH RO2+NO->NO2+RO

18. O3 Production and Loss Rates: 40-60NComparison with Steady-State Model constrained by TOPSE observations (Cantrell) Prod. Loss MOZART HANK SS-Model

19. ODE DIAL observations of surface ozone depletion over Hudson Bay (Browell et al. – NASA)

20. In-situ measurements over Hudson Bay: Observations of surface ozone depletion (Ridley-NCAR; Blake-UCI; Talbot-UNH)

21. Transport of ozone depleted surface air from Arctic to Hudson Bay: Evidence from measurements, models, satellite

22. Summary TOPSE characterized seasonal evolution of ozone and precursors over continental N.America Seasonal and altitude dependent transport Siberia/Europe vs. Asia Ozone background has strong stratospheric source, but growth in spring is primarily from in-situ chemistry in troposphere O3/aerosol/precursor relationships 7Be analysis/models (Surface ozone depletion widespread in Arctic…transport significant) Models capture many features of seasonal change after improvements from measurement comparison, but questions remain. Hydrogen peroxide Formaldehyde in UT etc….

23. Acknowledgments • TOPSE Science Team • Engineers, technicians, staff and pilots of NCAR Research Aviation Facility • Ground support at Churchill Airport and Thule Air Base • Financial support of the National Science Foundation • Atmospheric Chemistry • Polar Programs • NCAR Directors Fund • Administrative and logistical support of the Atmospheric Chemistry Division, Traffic Services