1. Observational Evidence: Ozone and Particulate Matter EMEP SB, 13 September 2010 http://www.htap.orghttp://www.htap.org - summary Chapter 2 Kathy Law LATMOS-CNRS, France David Parrish NOAA, USA

2. Key issue – where is O3 imported into downwind receptor regions? From Cooper, chapter A1, HTAP ΔO3  climate (5-14km) ΔO3  regional AQ/inter-continental transport (0-3km)  TF-HTAP

3. O 3 & PM Observational Evidence Asian anthropogenic plume seen at Mount Batchelor on west coast US, April 2004 (Jaffe et al., 2005) Aerosol signal equivalent to 20 μg m -3 Pollution events at surface sites

4. Ozone measurements on west coast of continents show levels approaching or exceeding levels of ambient standards or objectives O 3 imported into receptor regions Baseline ozone record (local anthrop. influences removed) Mace Head (west coast Ireland) 1987-2009 WHO 8-hr health guideline vegetation guideline

5. MOZAIC data collected on commercial aircraft at Frankfurt during 2003 from 0-12km (1080 profiles) [courtesy Zebinden, Thouret] Troposphere is full of plumes January July 0 km 12 km December

6. Plumes only account for 1-2% of air masses All NH influenced by anthrop. pollution (even at remote sites) « background » often defined as only natural sources - not a very useful concept (especially for O 3 ) Receptor regions see broad spectrum of concentrations Vertical CO and O3 profiles - MOZAIC aircraft @ 2-10km over west coast USA, summer

7. Analysis of natural, inter-continental and local contributions to surface O 3 (site in southern England), Derwent et al. (2008) Issue – how to distinguish imported ozone from local or regional influences?

8. HTAP Ozone Trends Seasonal averages calculated from monthly mean data (provided by PIs or original hourly/daily data Linear fit if quadratic term not significant Spring (MAM) trends strongest Seasonal trends: different O3 behaviour in different seasons – cancellation of different trend signals in annual trends Surface & altitude (LT) sites – comparison linear/quadratic fits spring-time ozone trends at remote or high-altitude sites HTAP 2010

9. The Main Messages Troposphere is full of plumes giving broad distribution of concentrations Clear observational evidence exists for inter-continental transport of O 3 precursors (satellite, aircraft, surface) Measurements often exceed AQ/health standards for O 3 at west coast sites of downwind receptor regions (at least 25% from inter-continental transport) Rising trends in NH O 3 especially downwind of Asia – mixed signatures in other regions General Conclusions

10. Following slides from Toulouse ozone trends meeting shows figures from updated David’s updated analysis

11. NH ozone trends for TF-HTAP Surface: Europe (Mace Head*, Zingst-Arkona – Baltic Sea), N. America - Pacific MBL* (several sites) and Japanese MBL (3 sites) Altitude sites: Europe (Hohenpeissenberg(1km), Arosa (1.8km), Jungfrau(3.6km), Zugspitze(3.0km)), N. America (Lassen (1.8km), MOZAIC (3-8km) – spring only), Japan (Mt. Happo(1.9km)) * MH and Pacific MBL are baseline concentrations – local continental influences removed HTAP 2010

12. Linear fit trends for the seasons and periods indicated Sites in the interior of Europe were only fit up to 2000. All error bars indicate 95% confidence limits. Generally all trends are positive and statistically significant – except North America in autumn Some indication of increasing trend with altitude. Japan (downwind of east Asia) has stronger trends Seasonal ozone trends: linear fits

13. Baseline record – local influences removed using particle dispersion model & trace gas data Spring/winter O3 concs. much higher than summer/autumn Strongest trend in winter, trends slowing LinearQuadratic

14. Winter ozone increasing, at least up to 2000 Indications for ozone levelling off or decreasing since 2000 Spring ozone becoming higher than summer (?) and winter higher than autumn (?) - shift in seasonal cycle? 1.0 km a.s.l. central Europe

15. Quadratic fits were made to Plot of coefficient of the second order term from quadratic fits. Generally decreasing trends in Europe and North America, although some not statistically significant, especially North America Japan - no statistically significant indication of changing trends. Rate of change in trends (ppbv/yr/yr)

16. Summary & Open Issues Motivation from TF-HTAP perspective – analysis of measurements O 3 downwind from emission regions Increasing trends in Japan, slowing trends in Europe (LT), North America less clear Changing seasonal cycles? Quadratic fits more useful – entire record Issues – diagnosis of imported fraction

17. Some additional figures from HTAP Chapter 2 Plus recommendations

18. O 3 & PM Observational Evidence Forest fire and anthropogenic CO plumes seen by MOPITT Satellite in July 2004 (NRC, 2010) O 3 precursors: plume events

19. O 3 & PM Observational Evidence Tropospheric ozone column satellite data - mix of long-range Transport, chemical production/loss and natural sources (stratosphere) [Ziemke et al., 2006] Satellite tropospheric O 3

20. Future Directions Main Recommendations Continued and improved measurement networks for detection of inter-continental pollution (O 3, precursors, PM components) – in particular vertical profile data Development of finger printing techniques for source attribution (e.g. isotopes, VOC ratios) Dedicated field experiments, measurements and modelling to improve currently poor understanding about import of pollution into downwind receptor regions