041026 Icap Transp Quant


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041026 Icap Transp Quant

  1. 1. <ul><li>The Dust Community </li></ul>Intercontinental Dust and Smoke over North America: Quantitative Tools an Results ?? July Dust Local Sahara Dust 10 0 5
  2. 2. Observational Tools Establishing Aerosol Origin ( Egen, 1835) <ul><li>Modern Methods – similar to century-old approaches but with more data </li></ul><ul><li>Direct Evidence. Photographic, satellite or compelling visual evidence of origin </li></ul><ul><li>Aerosol Composition. Chemical fingerprinting of different source types (speciation, traces) </li></ul><ul><li>Temporal pattern. Chemical Physical property analysis (satellite, ASOS, PM2.5) </li></ul><ul><li>Spatial Pattern. Chemical </li></ul><ul><li>Transport Pattern. Forward, backward trajectory, residence time analysis </li></ul><ul><li>Chemistry with Transport . Combining chemical fingerprinting and transport (CATT) </li></ul><ul><li>Dynamic modeling . Simulation model (forward, inversion) quantifying origin/transport </li></ul><ul><li>Historical Methods </li></ul><ul><li>Source attribution methods have been used for the past 2 centuries </li></ul><ul><li>A list of methods was given my Egen, 1835. See paper and PPT </li></ul>Direct Evidence Spatial Pattern Wind Pattern Composition Temporal Pattern Trajectory
  3. 4. Origin of Fine Dust Events over the US Gobi dust in spring Sahara in summer US-scale fine dust events are mainly from intercontinental transport Fine Dust Events, 1992-2003 ug/m3
  4. 6. Sahara and Local Dust Apportionment: Annual and July • The maximum annual Sahara dust contribution is about 1  g.m 3 • In Florida, the local and Sahara dust contributions are about equal but at Big Bend, the Sahara contribution is < 25%. The Sahara and Local dust was apportioned based on their respect ive Al/Si ratios. • In July the Sahara dust contributions are 4 - 8  g.m 3 • Throughout the Southeast, the Sahara dust exceeds the local source contributions by w wide margin (factor of 2 - 4) Annual July
  5. 7. Combined Aerosol-Trajectory Tool (CATT) <ul><li>High dust concentration (>7 ug/m3) in July all originate from Sahara </li></ul><ul><li>Lower concentration form local sources </li></ul>
  6. 8. Seasonal Average Fine Soil (VIEWS database, 1992-2002) <ul><li>Fine soil concentration is highest in the summer over Mississippi Valley, lowest in the winter </li></ul><ul><li>In the spring, high concentrations also exists in the arid Southwest (Arizona and Texas) </li></ul><ul><li>Evidently, the summer Mississippi Valley peak is Sahara dust while the Spring peak is from local (and Asian) sources </li></ul>Sahara
  7. 9. Sahara Dust Impact Events AIRS PM10 Concentration July 5 1992 June 30, 1993 June 21, 1997
  8. 10. Eastern US PM25 Event Composition <ul><li>The largest EUS PM25 events (as RCFM) are simultaneously ‘events’ in sulfate, organics and soil! </li></ul><ul><li>Some EUS PM25 events are single species events </li></ul><ul><li>Some PM25 events are not events in any species; their reinforcing combination causes the PM25 event </li></ul>
  9. 11. Aerosol Event Catalog: Web pages <ul><li>Catalog of generic ‘web objects’ – pages, images, animations that relate to aerosol events </li></ul><ul><li>Each ‘web object’ is cataloged by location, time and aerosol type. </li></ul>
  10. 12. Summary of Quantification Techniques <ul><li>Intercontinental Transport Analysis Methods </li></ul><ul><li>Direct evidence – satellite images </li></ul><ul><li>Chemical tracers of Sahara, Gobi & Local dust (Al, Si, Fe, K) </li></ul><ul><li>Temporal analysis – spikes are IC transport events </li></ul><ul><li>Spatial analysis – excess dust in the dust transport path </li></ul><ul><li>Spatio-temporal-chemical analysis with backtrajectories </li></ul><ul><ul><li>Results </li></ul></ul><ul><li>The chemical, temporal and spatial analyses indicate a consistent estimate of 0.3 ug/m 3 (2 ug/m 3 in July) of fine dust over the SE US. </li></ul>