NARSTO PM Assessment Chapter 5: Spatial and Temporal Pattern Dust over North America

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NARSTO PM AssessmentChapter 5 Spatial and
Temporal PatternDust over North America

• Section Contents
• Chapter Goal
• Policy Issues
• Chapter Structure

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Fine Soil Concentration

• IMPROVE
• Sisler Mam

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Sahara Dust Plume in July

• TOMS
• Prospero

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Sahara Events over the Gulf Coast
PM10 in Sahara Dust Events

• The highest regional PM10 concentrations in July
  (90 percentile of occur over the Gulf Coast
• During Sahara dust events, speciation data
  (IMPROVE) show that the fine particle dust
  exceeds 20 ug/m3
• Hence, Sahara dust is the dominant contributor to
  peak PM10 levels over the Gulf Coast.

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Trend of Sahara Events over the SE US

• Daily data show high dust concentrations over
  large regions
• Regional events occur several times each summer
  season.

• Seasonal Pattern July Peak
• In July, monthly average dust declines from 7
  ug/m3 in S Florida to about 1 ug/m3 in Shenandoah.

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Trans-Pacific Dust Transport
Approximate location of the April 19 dust cloud
over the Pacific Ocean based on daily SeaWiFS,
GMS5/GOES9/GOES10 and TOMS satellite data. Over
the Pacific Ocean, the dust cloud followed the
path of the springtime East-Asian aerosol plume
shown by the optical thickness derived from AVHRR
data.
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Dust over the West Coast of North America

• a. GOES 10 geostationary satellite image of the
  dust taken on the evening of April 27.
• The dust cloud, marked by the brighter
  reflectance covers the entire northwestern US and
  adjacent portions of Canada.
• A dust stream is also seen crossing the Rocky
  Mountains toward the east.

b. Contour map of the PM10 concentration on April
29, 1998. Note the coincidence of high PM10 and
satellite reflectance over Washington
c. Regional average daily PM10 concentration over
the West Coast. The sharp peak on April 27-30 is
due to the Asian dust.
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Dust Map over the West Coast
The PM2.5 dust concentration data from the
IMPROVE speciated aerosol network show virtually
no dust on April 25th, high values over the West
Coast on April 29th and dust further inland on
May 2. Evidently, on April 25th the dust layer
seen by the sun photometers was still elevated
since the surface dust concentration was low.
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The April 98 Asian dust - A unique Event over N.
America.

• The average PM2.5 dust concentration at three
  IMPROVE monitoring sites over the 1988-98 period
  was well below 1 mg/m3
• On April 29, 1998 the sites show simultaneous
  sharp rise to 3-11 mg/m3.
• Evidently, the April 1998 Asian dust event caused
  2-3 times higher dust concentrations then any
  other event during 1988-1998.

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Dust Generated in North America

• Buds, can you spare some of your ideas?
• This section needs ideas!
• There must be dust in the dust belt of NAM but
• Where
• When
• How much
• How do we document it?

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Summary

• Point 1
• Point 2
• Point 3

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Resource Links

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• Comment and Feedback Page
• References