Geophysical Fluid Dynamics Laboratory Transport of Asian ozone pollution into surface air over the western U.S. in spring Meiyun Lin Lin, M., A. M. Fiore, L. W. Horowitz, O. R. Cooper, V. Naik, J. S. Holloway, B. J. Johnson, A. M. Middlebrook, S. J. Oltmans, I. B. Pollack, T. B. Ryerson, J. Warner, C. Wiedinmyer, J. Wilson, and B. Wyman (2012), J. Geophys. Res., doi: /2011JD016961, in press. HTAP, NASA JPL, 2/2/2012

Process-oriented analysis of multi- platform observations with a new, global high-resolution chemistry-climate model Sondes AQS/CASTNet GFDL AM3 Problems: 1) Coinciding ozone maxima of stratospheric and anthropogenic origin [e.g. Stohl and Trickl 1999; Cooper et al 2004; Ambrose et al., 2011] 2) Limitations of tropospheric CTMs in capturing observed dynamic variability in ozonesondes [e.g. Jaegle et al., 2003; Liang et al., 2007; Jonson et al., 2010] 3) Prior multi-model evaluations on campaign /monthly mean basis [e.g. Dentener et al 2006; Stevenson et al., 2006; Fiore et al., 2009] Our Approach: 1) Global high-res (50 km) with fully coupled strat+trop chemistry [Donner et al., 2011]; Nudged to GFS 2) Analyze transport events on daily basis, leveraging intensive measurements from CalNex 2010

 Maximum in the western U.S. (4-7 ppb)  Large-scale conclusions independent of resolution  High-res spatially refines estimates: 1-2 ppbv (~20%) higher over the high- altitude areas Diagnosed as difference between pairs of simulations: Base – Zero Asian anthrop. Mean Asian impacts on U.S. surface O 3 in spring: high-resolution model spatially refines estimates Daily max 8-h average O 3 in surface air, May-June 2010 average C48 (~200 km) C180 (~50 km) How good is the model? Emissions: Asian INTEX-B scaled to 2010, US NEI2005, ACCMIP elsewhere

The GFDL AM3 model explains 50-90% of observed daily O 3 variability in Point Reyes sonde Cooper et al., 2011 Lin, M et al., in prep, 2012 CalNex sondes All sites: 30-90% Sonde AM3/C180 (~50 km) AM3/C48 (~200 km) < 3 km 3-6 km 6-9 km  Source attribution?

Trans-Pacific transport of Asian pollution plumes to WUS often coincides with ozone injected from stratosphere Observed GFDL AM3 Zero Asian emissionsO 3 -strat ~50% from O 3 -strat 20-30% from Asia Ozone (ppbv) Improved stratospheric ozone tracer (O 3 -strat), w/ tropopause diagnosed by the e90 tracer of Prather et al. [2010]

 How much does Asian pollution contribute to surface high-O 3 events?  Careful attribution of O 3 sources in continental inflow  Necessitate a model representing dynamic variability of UT/LS O 3 and STE Observed GFDL AM3 Zero Asian emissions O 3 -strat Full chemistry AM3 captures the interleaving and mixing of Asian pollution and stratospheric air Primarily strat

Obs (CASTNet/AQS) AM3/C180 total ozone AM3/C180 Asian ozone Asian pollution contribution to high surface O 3 events, confounding to attain tighter standard in WUS June June Tighter standard… harder to attain with domestic control Max daily 8-h average

Transport of Asian pollution on the isentropic surfaces to the lower troposphere over the LA Basin Previously identified isentropic transport mechanism [Brown- Steiner and Hess, 2011] Asian enhancements to trop column O 3 on May 8, 2010 Vertical cross-section of Asian O 3 along California coast θ [K] [ppb] Asian ozone available to be intercepted by the elevated terrain or entrained into the daytime boundary layer (~1-4 km in depth)

The Asian enhancement increases for total O 3 in the ppb range over Southern California, Arizona 25th

Lessons learned: 1) Conduct process-oriented analysis of factors contributing to model differences 2) High-resolution model analysis of continental inflow processes 3) Evaluate models with high temporal frequency observations 4) A common emission inventory across models Recommendations for TF HTAP: Ongoing work relevant for TF HTAP: 1)Mixing of pollution and stratospheric air in continental inflow  Necessitate models representing key features for accurate attribution 2)Asian emissions can contribute ~8-15 ppb to observed high-O 3 events  Implications for attaining more stringent standards 3) Potential to forecast intercontinental O 3 transport events from space  Require further work to be quantitative 1)Stratospheric contribution to high surface O 3 events in WUS (Poster) 2)Historical variability, trends, and source attribution for … Stratospheric exchange, fires, emissions, and climate (e.g. ENSO)

Extra slides

The new GFDL CM3/AM3 chemistry-climate model AM3 cubed sphere grid  C48 (~200x200 km 2 )  C180 (~50x50 km 2 ) M. Lin, et al., JGR, 2012 Donner et al., Golaz et al., Griffies et al., J. Climate, 2011 Naik et al., in prep 48 vertical levels Surface  86 km Atmospheric Chemistry 86 km 0 km Atmospheric Chemistry 86 km 0 km Atmospheric Dynamics & Physics Radiation, Convection (includes wet deposition of tropospheric species), Clouds, Vertical diffusion, and Gravity wave Atmospheric Dynamics & Physics Radiation, Convection (includes wet deposition of tropospheric species), Clouds, Vertical diffusion, and Gravity wave Chemistry of gaseous species (O 3, CO, NO x, hydrocarbons) and aerosols (sulfate, carbonaceous, mineral dust, sea salt, secondary organic) Dry Deposition Aerosol-Cloud Interactions Chemistry of O x, HO y, NO y, Cly, Br y, and Polar Stratospheric Cloud (PSC) Forcing Solar Radiation Well-mixed Greenhouse Gas Concentrations Volcanic Emissions Forcing Solar Radiation Well-mixed Greenhouse Gas Concentrations Volcanic Emissions Ozone–Depleting Substances (ODS) Modular Ocean Model version 4 (MOM4) & Sea Ice Model Modular Ocean Model version 4 (MOM4) & Sea Ice Model Pollutant Emissions (anthropogenic, ships, biomass burning, natural, & aircraft) Land Model version 3 (soil physics, canopy physics, vegetation dynamics, disturbance and land use) Land Model version 3 (soil physics, canopy physics, vegetation dynamics, disturbance and land use) SSTs/SIC from observations or CM3 CMIP5 Simulations GFDL-CM3 GFDL-AM3 AM3 option to nudge to “reanalysis winds”  How good is the model?

Transpacific transport of Asian pollution: the view from satellite (10 18 molecules cm -2 ) AIRS retrievals of CO total columns (version 5.2 level 3 daily 1ºx1º gridded products, McMillan et al., 2011)

Potential for developing space-based “indicators” for day-to- day variability in Asian ozone pollution over WUS? r  Advanced warning of Asian impacts on WUS surface O 3 ?  Qualitatively promising… but short data set, need further testing Grand Canyon NP Correlation of Asian ozone pollution enhancement at Grand Canyon NP in GFDL AM3 with AIRS CO columns, considering time lags of 1-3 days, May-June 2010

Asian enhancements to MDA8 O 3 at WUS National Parks peak 1-2 days after AIRS CO averaged over NE Pacific  Qualitatively promising… but short data set  Need further test for a quantitative relationship and extending to other years? AIRS CO over NE Pacific (10 18 molec cm -2 ) AM3 Asian O 3 at 3 WUS sites (ppb)

 Distinguish “stratospheric” vs. “tropospheric” air masses using the e90 tracer proposed by Prather et al. [2010]; allowing double tropopause  Set O 3 -strat identical to O 3 in “stratospheric” air masses; subject to chemical and depositional loss in “tropospheric” air masses  Transport of O 3 -strat and e90 both driven by meteorology Stratospheric ozone tracer