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					Springtime Airmass Transport Pathways to the US
     Dust and Smoke Transport to the US.
       Global-Scale Dynamic Modeling.

            Prepared by: Rudolf B. Husar and Bret Schichtel
       CAPITA ,Washington University, Saint Louis, Missouri 63130

               Submitted to:   Angela Bandemehr
       for presentation at the: ITAP Working    Group Meeting
                                June 27, 2000
• Anthropogenic and natural pollutants generated in one country are regularly
  transported to other countries adding to their air quality burden.
• On the average, transboundary pollutants transport to the US small but
  favorable emission and transport conditions may cause transport episodes.
• This work begins to assess the transboundary transport to the US by
  backward airmass histories during the Spring season of 1999.
• This work complements the companion analysis “Modeling the Episodic
  Transport of Air Pollutants from Asia to North America” by Hanna et al.,
• Overall Goal of Work: Create visualizations of transboundary airmass
  transport to the United States
Springtime Airmass Transport Pathways to the US

Airmass history (Backtrajectory) Analysis

                                            • Backtrajectories are
                                            aggregated by counting the
                                            hours each „particle‟ resided in
                                            a grid cell.

                                            The „residence time‟, i.e. hours
                                                  the Seattle, WA back
                                             trajectories resided over each
                                                        grid cell
                    Airmass Transport to the West Coast

 Seattle, WA
Prob. of Airmass
Traversing Asia =

 San Francisco, CA

Prob. of Airmass
Traversing Asia
= 0.08
                                                   • The most probable
                                                   long range transport
                                                   to the West Coast
 San Diego, CA                                     occurs across the
                                                   Pacific from the
Prob. of Airmass
Traversing Asia                                    Russian coast
= 0.045
                         Airmass Transport to the Midwest
                                                      • AtMinneapolis, the
 Minneapolis, MN                                      springtime transport is
                                                      from Canada.
Prob. of Airmass                                      • Transport to St.
Traversing Asia =
                                                      Louis is mostly from
                                                      the North with some
                                                      southerly contribution.
 St. Louis, MO                                        • San Antonio,
                                                      receives the transport
Prob. of Airmass                                      from the Gulf of
Traversing Asia =                                     Mexico with some
                                                      contributions from the
                                                      Great Plains and the
                                                      West Coast.
  San Antonio, TX
Prob. of Airmass
Traversing Asia = 0.02
                         Airmass Transport to the East Coast

                                                       • The springtime
  Boston, MA                                           transport to Boston is
                                                       from Eastern Canada.
Prob. of Airmass
Traversing Asia = 0.01                                 • Transport to Norfolk
                                                       is also mostly from the
                                                       North with some
  Norfolk, VA                                          contribution to from
                                                       the South Atlantic
Prob. of Airmass                                       sates.
Traversing Asia =
                                                       • Miami receives its
                                                       air from the Caribbean
                                                       with some
  Miami, FL                                            contribution from the
                                                       the Eastern US.
Prob. of Airmass
Traversing Asia = 0.01
Transport Simulation of the April 1998
      Asian Dust Event

      April 16, 1998 SeaWiFS image
                         Trans- Pacific Transport April 19-23

           CAPITA Monte Carlo Model              TOMS Aerosol Index
             Blue Particles < 1 km, Red > 7 km

April 20

April 21

April 22

April 23
           Trans- Pacific Transport April 24-28

April 24

April 25

April 26

April 27

April 28
        GOES Satellite Image and West Coast PM10 Concentration During the
                            April 98 Asian Dust Event

•Regional average PM10 levels reached 65 µg/m3 compared to typical values of 10-25 µg/m3
•On April 29, the PM10 exceeded 100 µg/m3 over parts of Washington and Oregon
      IMPROVE Fine Particle Dust Concentrations
    April 25, 1998            April 29, 1998          May 2, 1998

On April 25, the western U.S. was virtually dust-free, but reached high
concentrations by April 29. On May 2, the elevated dust concentrations
moved over the Rocky Mountains and the Colorado Plateau
Fires are Major Contributors to Global Atmospheric Chemistry
Vegetation fires are important to the ecology of many
terrestrial systems because they cycle many trace
Fires are also major sources of atmospheric trace
gases and aerosols.
Nowadays vegetation fires are initiated mostly by
humans for land clearing, agricultural harvest
clearing, savanna burning for nomadic agriculture.
Over the sub-Sahara savanna region has thousands of
small fires every year in the December-February
Fires are routinely monitored by several satellites
using the AVHRR, DMSP and GOES sensors
Central American Smoke over Eastern N. America
3D Rendering of Satellite Data of the C. American Smoke
                     Daily Global Aerosol Modeling
                       D. Westphal, Naval Research Lab.

Currently, there is an
   operation global
   aerosol model that
   simulates the daily
   aerosol concentration
On any given day, the
   global aerosol
   distribution is
   dominated by
   industrial sulfates,
   windblown dust and
   biomass smoke.
   POPs Modeling Issues for Future Consideration

• The transport pattern depend on season. Need a full year transport
climatology to the US
• Some regions of the U.S. may be particularly sensitive, I.e. Alaska

• Develop new methods for quantifying and displaying 3D transport e.g.
separate examination of high and low elevation transport
• Where do the POPs come from? Global distribution of POPs sources
• What is the lifetime/transport distance of POPs? 5-10 days? More?
• How do POPs deposit from the atmosphere? Precipitation over the US
and along the transport path.
• Dynamic exchange of POPs between air and vegetation, soil, water
• Are there easily measurable and better understood surrogates for POPs?
How good are aerosols and ozone as tracers?

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