INTERCONTINENTAL TRANSPORT OF OZONE: LINKING AIR QUALITY AND CLIMATE ISSUES

1. INTERCONTINENTAL TRANSPORT OF OZONE:LINKING AIR QUALITY AND CLIMATE ISSUES Daniel J. Jacob

2. WELL-DOCUMENTED TREND IN TROPOSPHERIC OZONE BACKGROUND OVER 20th CENTURYmodels seem unable to reproduce it quantitatively Observations from European mountain sites [Marenco et al., 1994]

3. UNCERTAINTY IN PREINDUSTRIAL OZONE: MODELS ARE HIGHER THAN 19th CENTURY OBSERVATIONSRadiative forcing from ozone could be much higher than given by IPCC! Global simulation of late 19th century ozone observationswith the GISS GCM Standard model: DF = 0.44 W m-2 “Adjusted” model (lightning and soil NOx decreased, biogenic hydrocarbons increased): DF = 0.80 W m-2 [Mickley et al., 2001]

4. INTERCONTINENTAL TRANSPORT OF OZONE POLLUTION:SURFACE OZONE ENHANCEMENTS CAUSED BYANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTS GEOS-CHEM model, July 1997 North America Europe Asia Li et al. [2002]

5. OZONE BACKGROUND OVER U.S. IS GENERALLY DEPLETED DURING REGIONAL POLLUTION EPISODESdue to deposition and chemical loss under stagnant conditions Observed (J.W. Munger) model (GEOS-CHEM) model background O3 vs. (NOy-NOx) At Harvard Forest, Massachusetts background 2.5km N American boundary layer BACKGROUND Clean conditions Polluted conditions Fiore et al. [2002] Pollution coordinate

6. FREQUENCY DISTRIBUTION OF AFTERNOON BACKGROUND OZONE CONCENTRATIONSIN U.S. SURFACE AIR IN SUMMER 1995 (model)summer ensemble vs. pollution episodes Convection upwind occasionally results in high background during pollution episodes

7. Subsidence of Asian pollution + local production stagnation tropical air U.S. standard European standards SURFACE OZONE ENHANCEMENTS OVER U.S. IN SUMMERDUE TO ASIAN & EUROPEAN ANTHROPOGENIC EMISSIONSGlobal 3-D model results (GEOS-CHEM) sampled for ensemble of summer days over the U.S. Fiore et al. [2002]

8. 50% NOx 2030 A1 2030 B1 50% NOx 50% CH4 50% CH4 2030 A1 2030 B1 1995 (base) 50% NMVOC 50% NMVOC Combined effects of future anthropogenic emission trendson U.S. ozone air quality and on global climate: importance of methane! Ozone pollution Fiore et al. [2002]

9. NORTH AMERICAN OZONE OUTFLOW IN SURFACE AIR Simulated concentrations and fluxes of North American pollution ozoneGEOS-CHEM results for 1997 L APRIL H L JULY H Li et al. [2002]

10. (GEOS-CHEM) r = 0.82, bias –1.8 ppbv model source attribution TRANSPORT OF U.S. OZONE POLLUTIONTO BERMUDA IN SPRING Observations from S. Oltmans Observations (S. Oltmans) GEOS-CHEM model (S. Oltmans) Most of surface ozone over Bermuda in spring originates from the U.S. (outflow behind cold fronts); stratosphere contributes less than 5 ppbv Li et al. [2002]

11. OZONE PROFILE AT BERMUDA, APRIL 1996(SEASONAL MAXIMUM) Stratospheric source of ozone is unimportant throughout tropospheric column Ozonesonde data (n = 28) from S. Oltmans Li et al. [2002]

12. Ozonesonde observations (1988-2000) GEOS-CHEM model (1996) APRIL OZONE CLIMATOLOGY OVER NORTH AMERICA Model can reproduce observations without invoking stratospheric influence Li et al. [2002]

13. PREVIOUS ARGUMENT FOR HIGH-ALTITUDE SOURCE OF OZONE AT BERMUDA FROM TRAJECTORY ANALYSES • Oltmans and Levy [1994]: “On days with high ozone … the trajectories all come from north of 50°N and altitudes near 600 mb.” • Moody et al. [1995]: “High-ozone events are associated with high-speed subsident flow of North American continental origin” Moody et al. [1995]

14. GEOS-CHEM SIMULATION REPRODUCES ASSOCIATION OF HIGH OZONE AT BERMUDA WITH SUBSIDING TRAJECTORIES FROM NW March 18, 1996 event: 290 K back-trajectory Subsiding air Cold front Ozone pollution NORTH AMERICA BERMUDA Continental ozone pollution mixes with subsiding air behind cold fronts Li et al. [2002]

15. ANOTHER EXAMPLE: GEOS-CHEM SIMULATION OF APRIL 13, 1996 EVENT Li et al. [2002]

16. GEOS-CHEM SIMULATION REPRODUCES OBSERVED CORRELATIONS OF OZONE WITH 7Be AND 210Pb AT BERMUDA AND TENERIFE (3 km) BERMUDA + for both 7Be and 210Pb: consistent with Huang et al. [JGR 1999] TENERIFE + for 7Be, - for 210Pb: consistent with Prospero et al. [GRL 1995] Ozone at Tenerife is mostly produced in middle troposphere Li et al. [2002]

17. Observed [Simmonds] OZONE DATA AT MACE HEAD, IRELAND:North American pollution signal is there but faint Model vs. observed stats, 1993-1997 Time series, Mar-Aug 1997 GEOS-CHEM model N.America pollution events in model Li et al. [2002]

18. EFFECT OF NORTH AMERICAN SOURCESON VIOLATIONS OF EUROPEAN AIR QUALITY STANDARD (55 ppbv, 8-h average) GEOS-CHEM model results, summer 1997 Number of violation days (out of 92) # of violation days that would not have been in absence of N.American emissions Li et al. [2002]

19. TRANSPORT OF U.S. POLLUTION TO EUROPE:CORRELATION WITH THE NAO INDEX NAO index = normalized surface P anomaly between Iceland and Azores North Atlantic Oscillation (NAO) Index North American ozone pollution enhancement At Mace Head, Ireland (GEOS-CHEM model) r = 0.57 Li et al. [2002] Greenhouse warming a NAO index shift a change in transatlantic transport of pollution

20. Enhancements in Asian surface ozone due to European anthropogenic emissions (GEOS-CHEM, 1996) Liu et al. [2002]

21. GLOBAL MODEL ANALYSIS OF OZONESONDE OBSERVATIONS ALONG THE PACIFIC RIM (1993-1997) Hong Kong, 1996 High UT variability at Hong Kong in winter-spring reflects alternance of tropical and stratospheric influences 300-120 hPa observations GEOS-CHEM model 700-300 hPa Spring enhancement from SE Asian biomass burning 850-700 hPa Liu et al. [2002]

22. ALTERNANCE OF TROPICAL AND STRATOSPHERIC INFLUENCES IN WINTER UT OVER HONG KONG:comparison of Dec 24, 1996 and Jan 6, 1997 Observed GEOS-CHEM Sonde and model profiles Model ozone concentrations and fluxes, 200 hPa Stratospheric ozone tracer at longitude of Hong Kong Liu et al. [2002]

23. SUMMER UT OZONE POLLUTION EVENT OVER HONG KONGAugust 21, 1996 Asian pollution Sonde and model profiles Observed GEOS-CHEM Model enhancement of ozone concentrations and fluxes due to Asian anthropogenic sources Liu et al. [2002]

24. LARGE MODEL OVERESTIMATE OF O3 OVER S. ASIA:aerosol effects are not enough to fix it MOZAIC aircraft observations (1995-99) GEOS-CHEM with full aerosol photochemistry GEOS-CHEM w/o radiative effects or uptake of HO2, NO2, or NO3 by aerosols Martin et al. [2002]

25. GOME RETRIEVAL OF TROPOSPHERIC NO2vs. GEOS-CHEM SIMULATION (July 1996) Martin et al. [2002] GEIA emissions scaled to 1996

26. CAN WE USE GOME TO ESTIMATE NOx EMISSIONS?TEST IN U.S. WHERE GOOD A PRIORI EXISTS Comparison of GOME retrieval (July 1996) to GEOS-CHEM model fields using EPA emission inventory for NOx GOME GEOS-CHEM (EPA emissions) BIAS = +3% R = 0.79 R = 0.78 Bias = +18% Martin et al. [2002]

27. FORMALDEHYDE COLUMNS FROM GOME:July 1996 means Palmer et al. [2001] BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO IN U.S. IN SUMMER GEIA isoprene emissions R = 0.83 Bias 14% Precision: 4x1015 cm-2

28. MODEL AS INTERMEDIARY FOR GOME VALIDATION:EVALUATE AGAINST IN SITU SURFACE OBSERVATIONS Mean daytime HCHO surface observations Jun-Aug 1988-1998 Model (1996) vs. observations Palmer et al. [2002]

29. SLANT COLUMNS OF HCHO FROM GOMEHigh values over southeast U.S. are due to biogenic isoprene emission Note “isoprene volcano” over the Ozarks Palmer et al. [2002]

30. DEPENDENCE OF GOME HCHO COLUMNSOVER THE OZARKS ON SURFACE AIR TEMPERATURE Temperature dependence of isoprene emission (GEIA) Palmer et al. [2002]

31. USING GOME HCHO COLUMNS TO MAP ISOPRENE EMISSIONS Displacement/smearing length scale 10-100 km hours hours HCHO hn, OH OH isoprene

32. GEOS-CHEM RELATIONSHIP BETWEEN HCHO COLUMNS AND ISOPRENE EMISSIONS IN N AMERICAUse relationship to map isoprene emissions from GOME observations NW NE GEOS-CHEM July 1996 Model HCHO column [1016 molec cm-2] SW SE model without isoprene Palmer et al. [2002] Isoprene emission [1013 atomC cm-2 s-1]

33. MAPPING OF ISOPRENE EMISSIONS FOR JULY 1996 BY SCALING OF GOME FORMALDEHYDE COLUMNS [Palmer et al., 2002] GOME COMPARE TO… GEIA (IGAC inventory) BEIS2 (official EPA inventory)

34. NEXT STEP: GLOBAL MAPPING OF VOC EMISSIONS FROM SPACE! T. Kurosu (SAO) and P. Palmer (Harvard) T. Kurosu (SAO) and P.I. Palmer (Harvard)