041026 Icap Transp Quant
- 1. The Dust Community Intercontinental Dust and Smoke over North America: Quantitative Tools an Results ?? July Dust Local Sahara Dust 10 0 5
- 2. Observational Tools Establishing Aerosol Origin ( Egen, 1835) Modern Methods – similar to century-old approaches but with more data Direct Evidence. Photographic, satellite or compelling visual evidence of origin Aerosol Composition. Chemical fingerprinting of different source types (speciation, traces) Temporal pattern. Chemical Physical property analysis (satellite, ASOS, PM2.5) Spatial Pattern. Chemical Transport Pattern. Forward, backward trajectory, residence time analysis Chemistry with Transport . Combining chemical fingerprinting and transport (CATT) Dynamic modeling . Simulation model (forward, inversion) quantifying origin/transport Historical Methods Source attribution methods have been used for the past 2 centuries A list of methods was given my Egen, 1835. See paper and PPT Direct Evidence Spatial Pattern Wind Pattern Composition Temporal Pattern Trajectory
- 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
- 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
- 7. Combined Aerosol-Trajectory Tool (CATT) High dust concentration (>7 ug/m3) in July all originate from Sahara Lower concentration form local sources
- 8. Seasonal Average Fine Soil (VIEWS database, 1992-2002) Fine soil concentration is highest in the summer over Mississippi Valley, lowest in the winter In the spring, high concentrations also exists in the arid Southwest (Arizona and Texas) Evidently, the summer Mississippi Valley peak is Sahara dust while the Spring peak is from local (and Asian) sources Sahara
- 9. Sahara Dust Impact Events AIRS PM10 Concentration July 5 1992 June 30, 1993 June 21, 1997
- 10. Eastern US PM25 Event Composition The largest EUS PM25 events (as RCFM) are simultaneously ‘events’ in sulfate, organics and soil! Some EUS PM25 events are single species events Some PM25 events are not events in any species; their reinforcing combination causes the PM25 event
- 11. Aerosol Event Catalog: Web pages Catalog of generic ‘web objects’ – pages, images, animations that relate to aerosol events Each ‘web object’ is cataloged by location, time and aerosol type.
- 12. Summary of Quantification Techniques Intercontinental Transport Analysis Methods Direct evidence – satellite images Chemical tracers of Sahara, Gobi & Local dust (Al, Si, Fe, K) Temporal analysis – spikes are IC transport events Spatial analysis – excess dust in the dust transport path Spatio-temporal-chemical analysis with backtrajectories Results 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.