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Springtime Airmass Transport Pathways to the US
Prepared by: Rudolf B. Husar and Bret Schichtel
CAPITA ,Washington University, Saint Louis, Missouri 63130
Submitted to: Angela Bandemehrfor presentation at the: ITAP Working Group Meeting
June 27, 2000
Dust and Smoke Transport to the US.
Global-Scale Dynamic Modeling.
Introduction
• 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., 1999
• Overall Goal of Work: Create visualizations of transboundary airmass transport to the United States
Springtime Airmass Transport Pathways to the US
• 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 history (Backtrajectory) Analysis
Airmass Transport to the West Coast
Seattle, WA
San Francisco, CA
San Diego, CA
Prob. of Airmass Traversing Asia = 0.08
Prob. of Airmass Traversing Asia = 0.08
Prob. of Airmass Traversing Asia = 0.045
• The most probable long range transport to the West Coast occurs across the Pacific from the Russian coast eastward.
Airmass Transport to the Midwest
Minneapolis, MN
St. Louis, MO
San Antonio, TX
Prob. of Airmass Traversing Asia = 0.01
Prob. of Airmass Traversing Asia = 0.01
Prob. of Airmass Traversing Asia = 0.02
• At Minneapolis, the springtime transport is from Canada.
• Transport to St. Louis is mostly from the North with some southerly contribution.
• San Antonio, receives the transport from the Gulf of Mexico with some contributions from the Great Plains and the West Coast.
Airmass Transport to the East Coast
Boston, MA
Norfolk, VA
Miami, FL
Prob. of Airmass Traversing Asia = 0.01
Prob. of Airmass Traversing Asia = 0.01
Prob. of Airmass Traversing Asia = 0.01
• The springtime transport to Boston is from Eastern Canada.
• Transport to Norfolk is also mostly from the North with some contribution to from the South Atlantic sates.
• Miami receives its air from the Caribbean with some contribution from the the Eastern US.
Transport Simulation of the April 1998
Asian Dust Event
April 16, 1998 SeaWiFS image
April 20
April 21
April 22
April 23
TOMS Aerosol Index
Trans- Pacific Transport April 19-23
CAPITA Monte Carlo ModelBlue Particles < 1 km, Red > 7 km
April 24
April 25
April 26
April 27
April 28
Trans- Pacific Transport April 24-28
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 elements.
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 season.
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 ModelingD. 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?