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Tropospheric ozone and its precursors over the United States:

Tropospheric ozone and its precursors over the United States: Sources and intercontinental influence. Rynda Hudman Postdoctoral Fellow University of California, Berkeley. Lawrence Livermore National Lab June 17, 2010. = NO x. Alt (km).

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Tropospheric ozone and its precursors over the United States:

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  1. Tropospheric ozone and its precursors over the United States: Sources and intercontinental influence Rynda HudmanPostdoctoral Fellow University of California, Berkeley Lawrence Livermore National Lab June 17, 2010

  2. = NOx Alt (km) INTERCONTINENTAL INFLUENCE OF OZONE (1) primary constituent of smog in surface air [NRC, 1991] (2) 3rd most important greenhouse gas [IPCC, 2007] 10 Greenhouse gas 8 hn O3 NO NO2 6 Hemispheric Pollution 4 OH HO2 Direct Intercontinental Transport (1 week) 2 CO, VOCs Air quality Air quality CONTINENT 1 CONTINENT 2 OCEAN

  3. NOx HAS OTHER WIDESPREAD CONSEQUENCES hrs - 1 day • Acidification of soils and waterways • Eutrophication of waterways • Forest die-back • impacts carbon sequestration • Secondary organic aerosol formation • Impacts GHG lifetimes through its effect on OH NO2 HNO3 NO

  4. SOURCES OF NOx *Numbers from IPCC [2007] • Can we better constrain the magnitude of these sources? • Can we go beyond previous work and understand the physical processes governing biogenic sources? Lightning: 1-6 TgN/yr Natural Soils: 5-8 TgN/yr FF: 21-28 TgN/yr BB: 6-12 Tg N/yr Agr: 0.5-2 TgN/yr Natural Soils Biomass Burning Agriculture Fossil Fuel BIOGENIC SOURCES ANTHROPOGENIC SOURCES

  5. Do we understand nitrogen transformations in the atmosphere? Can we constrain magnitude and processes governing N sources over North America? Anthropogenic Lightning Soils Biomass Burning What are the impacts on hemispheric ozone and air quality? OUTLINE

  6. 1. TRANSPACIFIC TRANSPORT OF ASIAN POLLUTION AND IMPACT ON U.S. AIR QUALITY NO2 HNO3 (soluble) PAN (insoluble, thermally unstable) NOy NO AIR QUALITY IMPACTS SOURCES CHEMICAL EVOLUTION ASIA UNITED STATES OCEAN

  7. NOAA ITCT-2k2: APRIL – MAY 2002 Monterey, CA Flight path: Sampled several Asian pollution plumes

  8. High PAN PAN  NOx  HNO3 TWO FOSSIL FUEL POLLUTION PLUMES OF ASIAN ORIGIN Primarily Anthropogenic, but very different pathways 5-7 km High CO Moderate Ozone May 5th 2-4 km High CO High Ozone May 17th Hudman et al., [2004]

  9. LARGE PAN DRIVEN OZONE PRODUCTION ~50% of ozone produced from PAN decomposition Observational Estimate: 17 ppbv ozone produced from 320 pptv PAN Ozone production per unit NOx ~ 50

  10. PAN DRIVEN OZONE PRODUCTION IN SUBSIDING TROPOSPHERIC POLLUTION PLUMES Hudman et al., [2004]

  11. WHY WERE NO PLUMES SEEN AT THE SURFACE? Model vs observations at Trinidad Head (April – May 2002) [Goldstein et al.,2004] Observations: 38 ± 7 ppb (unfiltered), GEOS-Chem model: 39 ± 5 ppb 41 ± 5 ppb (filtered against local influence) Analogy to dust: X10 dilution as plume entrained to boundary layer 20 ppbv ozone enhancement  2 ppbv enhancement at the surface Likely very different at mountain sites, due to greater exposure to FT!

  12. 2. CONSTRAINING ANTHROPOGENIC SOURCES OF NOx ICARTT Campaign July-August 2004 Full mapping of Eastern U.S. and North Atlantic • Lightning, Soils • NEI 99 FF Emiss • Daily biomass burning inventory GEOS-CHEM SIMULATION OCEAN

  13. LARGE DISCREPENCY IN SURFACE NOx and CO Mean comparison along the flight tracks BL bias in CO and NOx Hudman et al. [2007] Measurements: CO (J. Holloway), NOx (T. Ryerson)

  14. ICARTT OBSERVATIONS CONFIRM LARGE DECREASE SINCE 1999 IN INDUSTRY/POWER SOURCE Large overestimate powerplant/industry dominated Midwest and in the South Model / Observed NOx (0-2 km) DC-8 Midwest Observed Simulated Improved Simulation [ratio] 50% reduction in power and industry source due to SIP Call [Frost et al., 2006] Hudman et al. [2007] Measurements (WP-3D, DC-8):T. Ryerson (NO2), Ron Cohen/Tim Bertram (NO2)

  15. Measurments: A. Goldstein Chebogue Point (surface) BOTH AIRCRAFT AND SURFACE DATA CO EMISSIONS ARE 2.5 TIMES TOO HIGHERROR IN OTHER SPECIES Measurments: J. Holloway, G. Sachse, A. Goldstein SIMULATED (anthro CO reduced by 60%) SIMULATED (NEI99) OBSERVED Measurments: J. Holloway, G. Sachse Aircraft (0-1.5 km) Hudman et al. [2008]

  16. OZONE REDUCTIONS RESULTING FROM DECREASE IN NOx EMISSIONS Bias reduces previous model of 5- 15 ppbv Hudman et al. [2009]

  17. 3. LIGHTNING SOURCES OF NOx Ozone FT bias 5-10 ppbv Large UT NOx bias

  18. UT NOx OBSERVATIONS POINT TO A LARGER THAN EXPECTED LIGHTNING NOx SOURCE UT NOx (8 – 12 km) DC-8 GEOS-Chem X4 [ppbv] Hudman et al. [2007] NO: W. Brune, NO2: R. Cohen/T Bertram

  19. FLASH RATES WELL SIMULATED IN SOUTH POINTING TO A LARGER YIELD/FLASH AT NORTHERN MIDLATITUDES Flash Comparison (flashes/km2/s) GEOS-Chem Lightning parameterization in model (flashes/km2/s): Land: ~CTH4.9 , Ocean: ~CTH1.73 CTH= Cloud Top Height Price and Rind [1992] NLDN 0.22 0.33

  20. OZONE COMPARISON INTEX-NA SOUTHEAST U.S.Increasing lightning yield X4 to 500 mol/flash has ~10 ppbv effect on ozone O3 NO2 2004 was not an anomalous lightning year Observed Simulated Improved Simulation …suggests great sensitivity of ozone to climate change Hudman et al. [2007]

  21. SUMMERTIME NORTH AMERICAN OZONE ENHANCEMENTS Can use to develop radiative forcing estimates ICARTT DC-8 ~ Equal contributions for lightning and anthropogenic emissions in free troposphere and to NH burden NA Enhancement to Hemispheric Ozone Biomass Lightning Anthropogenic Simulated Observed All Hudman et al. [2009]

  22. SPRING KEY RESULTS SUMMER Alt (km) INFLOW SOURCES AND EXPORT BBNA FFLightning 10 NOx/flash 4X larger than previously thought! Subsidence Over E Pacific 8 Asian Plume PANNOxHNO3 strong O3 6 Export well constrained 4 2 NOx stationary sources 22%  effects on O3 & OPE X10 Dilution Anthropogenic CO 60% O3 (ppbv)  Asia  Europe North America

  23. 3. SPACE BASED CONSTRAINTS ON SOIL NOx Most of what we know about processes responsible for soil NOx emissions is based on point measurements.

  24. NO is a low-yield product of nitrifying bacteria Processes not well understood, HUGE spatial variability, but best correlation soil moisture (precip), T, N avail. [Meixner and Yang, 2006] ATMOSPHERE N2O(g), N2(g), NO(g) BIOSPHERE

  25. WHERE TO EXPECT LARGE NITRIC OXIDE EMISSIONS: Fertilized fields and monsoon regions Pulsing : Release of soil NO following rain event, due N-buildup & reactivation of water-stressed bacteria • Monsoon: • SW U.S./Mexico • Africa/ITCZ • Southeast Asia • Fertilized Fields: • United States • Europe

  26. LARGE SOIL NOx SOURCE INFERRED FROM SATELLITES Regional Distribution of soil NOx • GLOBAL: 8.9 Tg N/yr • MIDLATITUDES: 3.9 Tg N/yr [Jaeglé et al., PNAS, 2005]

  27. OZONE MONITORING INSTRUMENT (OMI) HAS MUCH FINER SCALE RESOLUTION AND DAILY GLOBAL COVERAGE OMI NO2 Column Aug 4, 2004 • 2600 km swath width providing daily global coverage • 1:45 pm equatorial overpass time • 14 x 24 km pixel size at nadir We examine interannual variability in soil NO emissions and our understanding of pulsing behavior over the Agricultural Great Plains

  28. SOIL NOx “EVENTS” pulsing over freshly fertilized Montana fields after rain event [Bertram et al., GRL, 2005]

  29. CAN SOIL NOx EMISSIONS BE ROUTINELY VIEWED FROM SPACE? ENOx 2005-2008 [Bertram et al., GRL, 2005] We extend this work to include U.S.: daily NARR Temp & Precip MODIS Landtype Fertilizer emissions [Ramankutty] Hudman et al. [2010]

  30. MODELED SOIL NOx EMISSIONS Dry, warm conditions  anomalously high modeled June 2006 soil emissions Hudman et al. [2010]

  31. SOIL EMISSION CONTRIBUTION TO NO2 COLUMN GEOS-Chem global CTM (2x2.5) June 2006 SOIL COLUMN / TOTAL COLUMN SOIL S.D. / COLUMN S.D. SOIL COLUMN = TOTAL COLUMN – NO SOIL COLUMN We should be able to see anomalies in soil NOx and day-to-day variability over Great Plains Hudman et al. [2010]

  32. OMI NO2 JUNE INTERANNUAL VARIABILITY FOLLOWS PREDICTED SOIL NOx Soil NO model June 2006 OMI June 2006 Anomaly June 2006 had lower than average lightning emissions, suggesting this was not a factor here Hudman et al. [2010]

  33. OMI NO2 JUNE INTERANNUAL VARIABILITY FOLLOWS SOIL NOx 2005 2006 2007 Suggests fertilizer induced emissions of soil NOx governs monthly variability in NO2 column over Great Plains… what about pulsing? Hudman et al. [2010]

  34. PULSING OVER EASTERN SOUTH DAKOTA We can use OMI to test understanding pulsing triggers Pulsing event reaches 4x1015 molec cm2, ~ 2 ppbv assuming 1km well mixed BL Hudman et al. [2010]

  35. KEY RESULTS • Space-based observations can offer constraints on soil NOx • Large scale behavior consistent with models. • Observed interannual anomaly is similar to model predictions. • Mechanistic details of pulses bear some resemblance, learning about the process of soil NOx emissions remains a challenge. • Because large scale features are well represented  ozone air quality  Asia  Europe North America

  36. MEAN MAXIMUM 8-HR OZONE ENHANCEMENT DUE TO SOIL NOx Ozone enhancement due to soil NOx emission doubles from 3  6ppbv, with events up to 16 ppbv! Comparable to decreases from power plant legislation discussed earlier. Hudman et al. [2010]

  37. 4. BIOMASS BURNING & CLIMATE During ICARTT, we were able to put some estimates on NOx emissions from fires…here we want to look at processes…. • What is the relationship between Area Burned and Meteorology/Moisture? • We can drive these relationships into the future using GCM  Future Area Burned • Develop future ozone and aerosol precursor emission estimates • Chemical transport model (driven by GCM winds)  impacts on air quality North America Hudman et al. , in prep.

  38. CANADIAN FIRE WEATHER INDEX MODEL WEATHER MOISTURE Drying time 2/3 day 15 day 52 day FIRE DANGER Severity Rating

  39. 500hPa GEOPOTENTIAL HEIGHT Height of pressure level above mean sea level Strong ridges are accompanied by warm and dry weather conditions at the sfc +60 Jul 1 – Aug 15 2004 Anomaly Strong Alaskan Ridge  record fires (Hudman et al., in prep)

  40. REGRESSIONS CAPTURE VARIABILITY OF AREA BURNED Regressions capture 74% of the variability in Canada and Alaska Major predictors: 500 mb GPH (large scale stagnation) and drought indices Hudman et al. , in prep.

  41. RAIN VS. STAGNATION  UNCERTAINTY IN RESPONSE 2000-2050 change in area burned 500 GPH changes ++ Rain 34% increase over Alaska, 8% (-34 to +118%)increase in Canada. Large regional variability. Hudman et al., in prep

  42. CHANGE IN SURFACE OZONE ENHANCMENT JUL-AUG Doubling of enhancement over Alaska, 1-2ppbv increase over populated Quebec cities and Midwest (20-40% increase) A decrease of ozone toward the Arctic (Hudman et al., in prep)

  43. PERCENT CHANGE IN SURFACE OC/EC JUL-AUG Preliminary Result [%] Transport of Black Carbon aerosol to the Arctic decreases by 40% (Hudman et al., in prep)

  44. KEY RESULTS • 500 mb GPH anomaly & fuel moisture are most important variables • Large regional variability in the response, due to dependence on rainfall vs. stagnation (highly GCM dependent). • Present day ozone enhancements due to wildfire 3-10 ppbv over Canada and Alaska. Future fire increases range from -2 - +4 ppbv. Large decreases of BC toward the Arctic. North America

  45. WHAT HAVE WE LEARNED? FUTURE DIRECTIONS? • TRANSFORMATION: PAN decomposition represents a major and possibly dominant component of the ozone enhancement in transpacific Asian pollution plumes. Dilution limits surface impacts. • ANTHROPOGENIC: NOx reduction legislation has been successful  4-8 ppbv decrease in summertime ozone. • CO emissions are overestimated in current inventories  impacts on other species estimates such as CO2 • LIGHTNING: Lightning at midlatitudes produces X4 more NOx/flash than midlatitude/subtropical storms  10-15 ppbv ozone, comparable to anthropogenic emissions • SOIL: Soil NOx emissions are highly dependent on temperature and precipitation, impacts on ozone ~6 ppbv (events reaching 16 ppbv), comparable to #2 above. • BIOMASS BURNING: Future fire activity likely depends on fuel moisture and atmospheric stability, both of which are highly variable in GCM projections.

  46. ACKNOWLEDGEMENTS Advisors: Ron Cohen, Daniel Jacob, Jennifer Logan, Loretta Mickley, Students and postdocs: Lee Murray, Dominick Spracklen, Ashley Russell, Luke Valin, Solene Turquety, Shiliang Wu, Dylan Millet, Agency: Mike Flannigan (CFS), Alan Cantin (CFS), Alice Gilliland (EPA) ITCT-2K2 & ICARTT, Science Teams AURA Science Team FUNDING: EPA, NASA, NOAA, NSF PhD Fellowship, AMS Graduate Fellowship Thanks for your attention!

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