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Transport Pathways for North American Pollution Outflow

Transport Pathways for North American Pollution Outflow. Qinbin Li, Daniel J. Jacob, Rokjin Park, Colette L. Heald, Yuxuan Wang, Rynda Hudman, Robert M. Yantosca Harvard University Mian Chin NASA/GSFC. I nternational C onsortium for A tmospheric R esearch on

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Transport Pathways for North American Pollution Outflow

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  1. Transport Pathways for North American Pollution Outflow Qinbin Li, Daniel J. Jacob, Rokjin Park, Colette L. Heald, Yuxuan Wang, Rynda Hudman, Robert M. Yantosca Harvard University Mian Chin NASA/GSFC International Consortium for Atmospheric Research on Transport and Transformation INTEX-NA ITCT-2K4 ITOP etc. Fall AGU, 12/10/2003 San Francisco

  2. Model Simulations and Observational Data GEOS-CHEM • Global 3-D model of tropospheric chemistry-aerosols. • Driven by GMAO GEOS-3 assimilated meteorology. • used in TRACE-P and ITCT-2K2 chemical forecasts. Model Simulations • Focused time period: June-August • Tagged CO (1998, 2000, 2001, 2002): 2°x2.5° • Full-chemistry (2000): 1°x1° ‘nested’ over North America 2°x2.5° Observations • MOPITT CO column • MODIS aerosol optical depth • AERONET aerosol optical depth

  3. H H H H 2000 1998 Deeper subtropical troughs in July and August than in June shift outflows to lower latitudes. El Nino; jet stream shifts southward in June → outflow at lower latitudes than “neutral” years. H H H H GEOS-3 Monthly Winds, 750 hPa (~2.5 km)

  4. H H 500 hPa 800 hPa Recirculation in the middle to upper troposphere. Recirculation in the middle to upper troposphere. H H GEOS-3 Monthly Winds, 500 & 800 hPa, 2000

  5. Climatology 2000 BB, July BB, July BB, August BB, August 2000: huge forest fires in NW (Montana, Idaho, Wyoming, etc.) North American Emissions unit: 10-12 molec/cm2/s FF BB, June Climatology: extensive boreal forest fires.

  6. June 2000 June 1998 Outflow at much lower latitudes in June 1998. Horizontal North American CO Flux Anthropogenic pollution outflow at 35ºN-50ºN, while biomass burning outflow at higher latitudes 45ºN-55ºN.

  7. Horizontal North American CO Flux July 2000 August 1998 Outflow in July is at lower latitudes than in June, while outflow in August shows features in between June and July.

  8. 1998 Outflow at lower latitudes in June 1998 than “neutral” Vertical and Zonal North American CO Flux, June 70ºW 300 hPa 70ºW 70ºW Line contour – fluxes Filled contour – concentrations Boundary layer and lower troposphere outflow; convective outflow in the middle to upper troposphere.

  9. 1998 Vertical and Zonal North American CO Flux, July 70ºW 300 hPa 70ºW 70ºW Line contour – fluxes Filled contour – concentrations Stronger convective transport than June and August.

  10. 1998 Vertical and Zonal North American CO Flux, August 70ºW 300 hPa 70ºW 70ºW Line contour – fluxes Filled contour – concentrations

  11. Monthly Average CO Column, July 2000 GEOS-CHEM v.s. MOPITT MOPITT GEOS-CHEM Model captures the spatial distribution but systematically overestimates CO column compared to MOPITT.

  12. Event June 9-13: WCB and Convective Outflow

  13. Event June 9-13: WCB, Convection from Midwest from southeast

  14. Event July 2-7: Outflow at Low Latitude

  15. Enhanced CO. Enhanced ozone and aerosols. Event July 2-7: Outflow at Low Latitude

  16. Recirculationin the Upper Troposphere North American Fossil Fuel CO 270 hPa, July 6-23, 2000 Deep convection in the SE U.S. followed by recirculation in the middle to upper troposphere; fairly aged air masses with high ozone but depleted NOy and aerosols upon leaving the continental U.S. (animation)

  17. Event July 9-14: Recirculation

  18. Enhanced CO in the upper troposphere. Enhanced ozone in the upper troposphere. Event July 9-14: Recirculation

  19. Event July 26-31: Outflow at Higher Latitude

  20. Event August 22-26: Biomass Burning Outflow

  21. Enhanced ozone but depleted aerosols and NOy. Recirculation in the upper troposphere. Event August 22-26: Another Example of Recirculation

  22. Asian and European Influences Detectable? • Asian and European influences dispersed into the background. • Asian plumes could be seen in strong transpacific transport. max concentration over 40 ppbv

  23. Summary and Conclusions • Main export pathways for N. American pollution over the N. Atlantic: 1. Outflow in the lower troposphere and in the boundary layer, at a large latitude range 30ºN-50ºN. This is the dominant export pathway. 2. Convective transport of eastern US pollution and large scale lifting (advection) of midwest pollution in the middle to upper troposphere. 3. Biomass burning outflow generally at higher latitudes (45ºN-55ºN) than anthropogenic outlfow. • Deep convection in SE US often is followed by recirculation in the middle to upper troposphere. • CO columns from MOPITT and aerosol optical depths from MODIS and AERONET provide useful insights in N. American pollution outflow. • Each and every synoptic system leads to continental outflow. • Wallops would be an ideal site for diagnosing N. American outflow and as aircraft base during the ICARTT missions.

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