1. 1 United States of America National Report on Surface- Based Ozone Research Seventh WMO/UNEP Ozone Research Managers Meeting Geneva, Switzerland 18-21 May, 2008

2. 2 US AGENCIES CONTRIBUTING National Aeronautics & Space Administration (NASA) National Oceanic & Atmospheric Administration (NOAA) National Science Foundation (NSF) Department of Agriculture (USDA) Environmental Protection Agency (EPA) SURFACE-BASED NETWORKS Dobson Ozone Spectrophotometer Network Ozonesonde Networks (including SHADOZ) Network for the Detection of Atmospheric Composition Change (NDACC) Advanced Global Atmospheric Gases Experiment (AGAGE) Network ESRL Global Monitoring Division Ozone-Depleting Gas Network Ultraviolet Radiation Networks

3. 3 OBSERVATIONAL ACTIVITIES OZONE Dobson Ozone Spectrophotometers (column and umkehr profiles - Part of GAW) – 16 global instruments plus the WMO World Standard instrument UV-Multi Filter Shadowband Radiometer (column) – 32 US, 2 Canadian, 1 New Zealand Brewer Spectrometer Network – 6 US Instruments Ozonesondes (profile) – 10 global sites plus additional near-annual balloon campaigns Miscellaneous Remote Profile Sensors - LIDAR, Microwave Radiometer, FTIR

4. 4 OBSERVATIONAL ACTIVITIES Ozone-Relevant Gases and Variables Aircraft and Balloon-borne – H 2 O, CFCs, HCFCs, HFCs, CH 3 CCl 3, CH 3 Br, CH 3 Cl Surface – Global measurements of 25 ozone- depleting gases for determination of equivalent effective chlorine (EECl) UV Visible spectrometers – NO 2, BrO, OClO FTIR spectrometers – HCl, HF, HNO 3, ClONO 2, NO

5. 5 OBSERVATIONAL ACTIVITIES UV BROADBAND & FILTER INSTRUMENTS: SURFRAD Network – 7 sites ESRL Network – Boulder and Mauna Loa (in conjunction with spectroradiometers) USDA UVB Monitoring Program – 34 sites SPECTRORADIOMETERS: SURFRAD UV spectroradiometers at Table Mountain NDACC spectroradiometers at Mauna Loa and Boulder (in collaboration with NIWA-New Zealand) NSF UV Monitoring Network - spectroradiometers at 7 sites, mainly in the polar regions ESRL/EPA Brewer Mark IV spectrometers at 6 US sites

6. 6 SIGNIFICANT RESULTS 1.CONTRIBUTIONS TO OZONE ASSESSMENTS 2.OZONE LOSS LINKED TO ANTARCTIC CLIMATE CHANGE 3.OZONE-DEPLETING GAS OBSERVATIONS 4.DOBSON TOTAL OZONE TRENDS 5.OZONE HOLE TRENDS AT SOUTH POLE 6.RECENT INCREASES IN HCFCs 7.CLIMATE BENEFITS OF THE MONTREAL PROTOCOL 8.RECENT AIRBORNE MEASUREMENTS OF TROPICAL BROMINE GASES 9.EVALUATING ODSs IN THE LABORATORY 10.UV RADIATION TRENDS

7. 7 Tropospheric Organic Chlorine

8. 8 Long-Lived Halocarbons Contributing to Equivalent Effective Cl ESRL

9. 9 1980 level Equivalent Effective Stratospheric Chlorine - Antarctica ODGI 2007 = 86 The Ozone Depleting Gas Index (ODGI) ODGI Recovery = 0 ODGI MAX = 100 (1994) HCFCs go away? ESRL EESC Observations Projection WMO 2006

10. 10 Dobson Ozone Trends – A New Look Dobson Ozone Trends Harris, J.M., S.J. Oltmans, P.P. Tans, R.D. Evans, and D.L. Quincy, Geophys. Res. Lett. 28, 4535, 2001 (updated) Smooth trend curves of monthly ozone values from selected Dobson stations (South Pole, continental US, and the tropics) are shown. Changes represented by the growth rate determined from differentiating these trend curves is an instantaneous measure of the rate of change of stratospheric ozone and thus represents various aspects of ozone layer recovery. ESRL No attempt to remove possible Pinatubo effects has been made

11. 11 Continental U.S. Total Column Ozone Growth Rate Instantaneous growth rate curve (± 2 SD) found from differentiating the trend curve Average growth rate 1968-1995: -2.16 %/decade Average growth rate 1996-2007: +1.73 %/decade

12. 12 South Pole Total Column Ozone Growth Rate Instantaneous growth rate curve (± 2 SD) found from differentiating the trend curve Average growth rate 1968-1995: -11.1 %/decade Average growth rate 1996-2007: -1.38 %/decade

13. 13 14 – 21 km total depletion region 2006 Antarctic Ozone Hole OMI Satellite Measurements – Sept. 24, 2006 South Pole Balloon-borne Measurements October 9, 2006

14. 14 Beginning of recovery? Probably Not South Pole 14-21 km Column Ozone From Balloon Ozonesondes ESRL ~1500 Balloon Flights

15. 15

16. 16 Recent Changes in HCFCs ESRL

17. 17 Ozone-Depleting Gases also Affect Climate CH4 N2O CFCs CH 4 N2ON2O CFCs CCl 4, CH 3 CCl 3

18. 18 0 -1 km ~ 17 km 4 - 8 km MeBr=31% Halons=34% S.Lived=35% MeBr=38% Halons=41% S.Lived=20% MeBr=47% Halons=46% S.Lived=7.5% Recent Airborne measurements define composition and distribution of organic bromine source gases in the tropical atmosphere

19. 19 Taken from IPCC Special Report (2005) Montreal Protocol Kyoto Protocol Evaluating Proposed Substitutes for ODSs Evaluation of the environmental impact of a compound from production to end-of-life. Laboratory studies are used to evaluate and quantify atmospheric removal, climate impact, and degradation products. Degradation Deposition What is a Good Substitute ? Zero ODP Short Atm. Lifetime Low GWP Minimal Impact of Degradation Products ESRL

20. 20 Preliminary analysis at eight sites shows changes in annual UV-B irradiance ranged from +6% to +14% over most of the US (orange bars) for the 10 year period 1994 to 2004. Purple bars show monthly variability. USDA UV-B Monitoring and Research Program

21. 21 Mauna Loa Observatory, Hawaii Boulder, Colorado UV Monitoring Local noon erythemal radiation calculated from UV spectroradiometers (1 nm resolution) at Mauna Loa, Hawaii and Boulder, Colorado and NIWAESRL

22. 22 SUMMARY Measurements of ozone-depleting gases show a decline in total ozone-depleting potential (EESC) heralding the potential beginning of ozone layer recovery (14% and 27% of the way to 1980 levels for Antarctica and mid-latitudes, respectively). To date, no clear indication of the beginning of ozone hole recovery has been observed at the South Pole. At mid-latitudes, ozone depletion has ceased increasing and may be in the first stages of recovery. The job is not completed. The ozone hole will last through most of the 21 st century. Continued support for long-term measurements of ozone and ozone-depleting substances is necessary. As we look to satellite measurements in the future, we must be vigilant that they are accompanied by accurate surface measurements. We are trying to observe a change of ~1% over a time period of ~10 years!