Exceptional Event Analysis

1. Exceptional Event Analysis Draft, July 13, 2005 rhusar@me.wustl.edu

2. Exceptional PM25 Events • Exceptional air pollution events are due to sources outside the jurisdiction of control agencies (??) • Exceptional PM25 events are primarily due to biomass (forest,grass) smoke and windblown dust • The composition of smoke is dominated by organic carbon (OCf) as shown in the pie chart [ yes for Quebec fire…. What about other fires, including those in other regions, or closer by] • Windblown dust is composed of crustal elements, Si, Al, FE, Ca etc. • A robust way of identifying smoke events is by the unusually high OC fraction of PM25 mass, such as the Quebec Smoke event, compared to the average.

3. Event Dates and Locationsi.e. event days as proposed by GA? IMP & STN 14 site avg 470654001 • IMPROVE and STN chemical data available for 2003 • Events are analyzed using three station configurations: • STN site 470654001, Chattanooga • IMPROVE site COHU1 • Aggregate of 14 IMP&STN sites [ we may need to describe how interpolation is done. It affects assumed region > 50] COHU1

4. Chemical Pattern at Chattanooga STN 470654001 PM25 OC • In 2003, at Chattanooga STN 470654001 site, the chemical data are available for four ‘event’ days • The four days represent high PM2.5 concentrations (>40 35? ug/m3) at the Chattanooga site • The time series for total organics shows that the ‘event’ days are among the highest for the 2002-03 period • On the same event days, the fine particle sulfate concentration is also high except on April 15, 2003 • The organic fraction of PM2.5 during the event days was below 20% except on April 15, 2003 SO4 OC/PM25 Nice chart. Important points about April 15!

5. IMPROVE COHU1 PM25 OC • The closest IMPROVE site to Chattanooga is at Cohu which has six “event days” in 2003. (any in common with the earlier 4? Particularly April 15) • The six days represent high PM2.5 concentrations (~30 ug/m3) at the Cohu site • The time series for total organics shows that the ‘event’ days are among the highest for the 2002-03 period • On the same event days, the fine particle sulfate concentration is also high (~15 ug/m3) • The organic fraction of PM2.5 during the event days was below 20% SO4 OC/PM25

6. IMPROVE & STN 14 Sites PM25 OC • The regional aerosol chemistry pattern is examined by aggregating? 14 IMPROVE/STN sites. • Aggregation = spatially interpolated value, or simple average? • The seven event days in 2003 (represented by aggregated days?) have high PM2.5 concentrations (20-40 ug/m3) • The total organics data show moderate to high regional OC levels (5-10ug/m3) during the ‘event’ days • On the same event days, sulfate concentration is also high (8-16ug/m3) • The organic fraction of PM2.5 during the event days was about 20% except on April 15, 2003 (~30%) • Thus, it is evident, that the regional OC is relatively low, (important point) SO4 OC/PM25

7. April 15, 2003 Individual Event Analyses (only seven days so far) • There will be a set pattern for the individual exceptional day analysis, e.g. the list of images and discussion at the left for April 15, 2003 • Each image is linked to the viewer for more detailed browsing, comparison etc., as shown below • The structured ‘story’ for each exceptional day/event will be added to the images • The use of the tools is/will be explained through web-based tutorials, e.g. Introduction to DataFed Catalog and browser (Flash presentation with sound)