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Intercontinental Transport of Tropospheric Ozone and Precursors at Northern Midlatitudes: Implications for Surface Air Q

This study explores the transport of ozone and its precursors across continents and its impact on surface air quality and global climate change. It discusses the role of anthropogenic emissions, the stratosphere, and natural sources in influencing ozone levels. The study also highlights the implications for air quality standards and the potential for transatlantic pollution transport.

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Intercontinental Transport of Tropospheric Ozone and Precursors at Northern Midlatitudes: Implications for Surface Air Q

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  1. INTERCONTINENTAL TRANSPORT OF TROPOSPHERIC OZONE AND PRECURSORS AT NORTHERN MIDLATITUDES:IMPLICATIONS FOR SURFACE AIR QUALITY AND GLOBAL CHANGE Daniel J. Jacob, Arlene M. Fiore, Qinbin Li, Randall V. Martin, Loretta J. Mickley, Paul I. Palmer, Rokjin Park

  2. OZONE TREND AT EUROPEAN MOUNTAIN SITES, 1870-1990 Marenco et al. [1994] Preindustrial ozone models }

  3. 1750-2000 radiative forcing from tropospheric ozoneis less well constrained than implied by IPCC 2001 report(and could be greatly underestimated) 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. GLOBAL MEAN TEMPERATURE CHANGE SINCE 1750 DRIVEN BY MODEL TROPOSPHERIC OZONE CHANGE and compared to temperature changes from equal radiative forcings (0.45 W m-2) by uniformly mixed ozone and CO2 (GISS GCM 2’) Compared to an equivalent CO2 radiative forcing, tropospheric ozone gives less tropospheric warming and more stratospheric cooling CO2 Uniform ozone Ozone Loretta Mickley, In preparation

  5. 1980-1984 1994-1998 1980-1984 1994-1998 SURFACE OZONE IN U.S. INCLUDES A 20-40 ppbv BACKGROUND THAT HAS INCREASED BY ~3 ppbv OVER THE PAST 20 YEARS 8-h daily maximum ozone probability distribution at rural U.S. sites [Lin et al., 2000]

  6. THIS OZONE BACKGROUND IS A SIZABLE INCREMENT TOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDS(even more so in Europe!) Europe (8-h avg.) Europe (seasonal) U.S. (8-h avg.) U.S. (1-h avg.) 0 20 40 60 80 100 120 ppbv preindustrial present background

  7. Simulated increase in mean U.S. surface ozone (ppbv) from tripling of Asian emissions (1985 to 2015)with other emissions held constant Enough to offset the benefits of 25% reductions in domestic emissions! Jacob et al. [1999]

  8. GEOS-CHEM global model of tropospheric chemistry(www-as.harvard.edu/chemistry/trop/geos) • assimilated meteorological data from NASA DAO, 1988-2001 • 1ox1o- 4ox5o horizontal resolution, 20-48 layers in vertical • used by groups at Harvard, Duke, U. Washington, Rutgers, JPL, BNL, EPFL, Toulouse, Aquila; standard versions and benchmarks maintained at Harvard RECENT AND CURRENT APPLICATIONS: • Tropospheric ozone : global budget, Asian outflow, U.S. air quality, Middle East, transatlantic transport, tropics (TOMS), interannual variability, trends • Carbon monoxide: global and regional budgets, interannual variability • Aerosols: sulfate-organics-dust-sea salt • Stratospheric ozone: coupling with troposphere • Carbon dioxide: source/sink information from correlations with chemical tracers • Organics: budgets of hydrocarbons, oxygenated organics, nitriles, methyl halides • Satellite retrievals, inversions, chemical data assimilation: CO, CO2, ozone, formaldehyde, NO2 • Chemical forecasting: TRACE-P

  9. SUMMER 1995 AFTERNOON OZONE IN SURFACE AIR Fiore et al. [2001] AIRS observations GEOS-CHEM (r2 = 0.4, bias=3 ppbv) “Background ozone” produced outside the North American boundary layer contributes 15-35 ppbv to mean surface air concentrations in the model

  10. 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 (clean conditions) Background (pollution episodes) Fiore et al. [2001] Pollution coordinate

  11. RANGE OF ASIAN/EUROPEAN POLLUTION SURFACE OZONE ENHANCEMENTS OVER THE U.S. IN SUMMERasdetermined from a simulation with these emissions shut off Subsidence of Asian pollution + local production Max Asian/European pollution enhancements (up to 14 ppbv) occur at intermediate ozone levels (50-70 ppbv) stagnation tropical air MAJOR CONCERN IF OZONE STANDARD WERE TO DECREASE! Fiore et al. [2001]

  12. NORTH AMERICAN OZONE OUTFLOW IN SURFACE AIR (GEOS-CHEM model results for 1997) APRIL L H L JULY H Li et al. [2001]

  13. ORIGIN OF SURFACE OZONE AT BERMUDA IN SPRING (S. Oltmans) Production over U.S. is the dominant source of ozone at Bermuda; stratosphere contributes less than 5 ppbv Li et al. [2001]

  14. Observed [Simmonds] OZONE DATA AT MACE HEAD, IRELAND Model vs. observed stats, 1993-1997 Time series, Mar-Aug 1997 GEOS-CHEM model N.America pollution events in model Li et al. [2001]

  15. 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. [2001]

  16. FORECASTING TRANSATLANTIC TRANSPORT OF NORTH AMERICAN POLLUTION TO EUROPE WITH THENORTH ATLANTIC OSCILLATION (NAO) INDEX NAO index = normalized surface P anomaly between Iceland and Azores NAO Index North American ozone pollution enhancement At Mace Head, Ireland (GEOS-CHEM model) r = 0.57 Li et al. [2001] Greenhouse warming a NAO index shift a change in transatlantic transport of pollution

  17. SURFACE OZONE ENHANCEMENTS CAUSED BYANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTS GEOS-CHEM model, July 1997 North America Europe Asia Li et al. [2001]

  18. QUANTIFYING INTERCONTINENTAL TRANSPORTTHROUGH INTEGRATION OF OBSERVATIONS AND MODELS SATELLITE OBSERVATIONS Global and continuous but few species, low resolution Source/sink inventories 3-D CHEMICAL TRACER MODELS SURFACE OBSERVATIONS high resolution but spatially limited Assimilated meteorological data AIRCRAFT OBSERVATIONS High resolution, targeted flights provide critical snapshots for model testing Chemical and aerosol processes INTERCONTINENTAL TRANSPORT: CONCENTRATIONS, FLUXES, BUDGETS

  19. INTERCONTINENTAL TRANSPORT EXPERIMENT – NORTH AMERICA (INTEX-NA) A NASA Global Tropospheric Experiment (GTE) mission OBJECTIVES: • To quantify the North American import and export of (1) atmospheric oxidants and their precursors, (2) aerosols and their precursors, (3) long-lived greenhouse gases • To relate this import/export to surface sources/sinks and to continental boundary layer chemistry TWO AIRCRAFT:NASA DC-8 and P-3 • TWO PHASES: • Summer 2004: • active photochemistry, biosphere • aerosol radiative forcing • carbon uptake • Spring 2006: • maximum Asian inflow • contrast with summer

  20. INTEX NOMINAL FLIGHT TRACKS FOR PHASE A (SUMMER) RL BG WL AZ DR BR NO HI DC-8 P-3B Ozonesonde sites

  21. ATMOSPHERIC COLUMNS OF NO2 AND FORMALDEHYDE (HCHO) MEASURED FROM GOMEBY SOLAR BACKSCATTERALLOW MAPPING OF NOx AND HYDROCARBON EMISSIONS GOME SATELLITE INSTRUMENT Tropospheric NO2 column ~ ENOx Tropospheric HCHO column ~ ENMHC ~ 2 km hn (420 nm) BOUNDARY LAYER hn (340 nm) NO2 NO HCHO CO OH hours O3, RO2 hours NMHC 1 day HNO3 Emission Deposition Emission NITROGEN OXIDES (NOx) NON-METHANE HYDROCARBONS

  22. 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 Martin et al. [2001]

  23. GOME RETRIEVAL OF TROPOSPHERIC NO2vs. GEOS-CHEM SIMULATION (July 1996) Martin et al. [2001] GEIA emissions scaled to 1996

  24. FORMALDEHYDE COLUMNS FROM GOME:July 1996 means Palmer et al. [2001] BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO IN U.S. IN SUMMER

  25. GOME DETECTS THE ISOPRENE “VOLCANO” IN THE OZARKS Palmer et al. [2001]

  26. CORRELATION WITH SURFACE TEMPERATUREOF GOME HCHO COLUMNS OVER THE OZARKS Temperature dependence of isoprene emission (GEIA) Palmer et al. [2001]

  27. MAPPING OF ISOPRENE EMISSIONS FOR JULY 1996 BY SCALING OF GOME FORMALDEHYDE COLUMNS [Palmer et al., 2001] GOME COMPARE TO… GEIA (IGAC inventory) BEIS2

  28. ONGOING WORK AT HARVARD FOR PHASE I OF OAR/OAQPS CLIMATE CHANGE MODELING INITIATIVE(Arlene Fiore, Rokjin Park, Brendan Field, Daniel Jacob) • OBJECTIVES: • Determine the global impacts of future changes in anthropogenic emissions on • surface ozone in N. America, Europe, and Asia; • surface ozone background; • tropospheric oxidizing capacity; • radiative forcing (CH4 and O3). • Develop coupled ozone-aerosol simulation capability in GEOS-CHEM for nesting with CMAQ/Models-3 • APPROACH: • Conduct global GEOS-CHEM simulations with • 50% global reductions in emissions; • realistic future emission scenarios (Streets) • Implement GEOS aerosol simulation from Mian Chin (NASA/GSFC) into GEOS-CHEM model

  29. IMPACTS OF 50% REDUCTIONS IN ANTHROPOGENIC EMISSIONS Simulations are for 7/94-12/95 (first 6 mos. for initialization) with 4ox5o resolution

  30. NEXT STEP: NESTING OF GEOS-CHEM WITH MODELS-3in collaboration with EPA/OAQPS and ORD • One-way nesting: use GEOS-CHEM global model fields as time-dependent boundary conditions for simulation of ozone, aerosols, and their precursors in Models-3 • First application: Texas 2000 field campaign • Two-way nesting: develop better simulation of regional effects on global atmospheric chemistry including intercontinental transport and radiative forcing

  31. SOME PRIORITY QUESTIONS FOR PHASE II OF OAR/OAQPS CLIMATE CHANGE MODELING INITIATIVE • How can we develop an integrated modeling framework to assess the effects of specific perturbations (e.g., anthropogenic emissions) on local surface air quality and global change in a consistent manner? • Development of nested aerosol-chemistry models • How can we design an observational strategy to evaluate model assessments of intercontinental transport? • Use models to define the observations needed to test them • How can we extract information from satellite observations on intercontinental transport of pollution? • Integration with in situ observations and models, development of inverse modeling tools • How can we better understand the climate forcings of ozone and aerosols? • Development of coupled aerosol-chemistry-climate models

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