Discussion of Natural Event Documentation High Winds, Corcoran and Bakersfield, California September

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Discussion of Natural Event DocumentationHigh
Winds, Corcoran and Bakersfield,
CaliforniaSeptember 22, 2006

• Rudolf B. Husar
• March 10, 2006

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Key Evidence High Winds -gt High PM10

• The SJV APCD makes a good case that high winds
  and high PM10 occurred in Corcoran Bakersfield

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MODIS Terra, 1030 Local Time
MODIS Terra, 1330 Local Time
MODIS Terra shows some pollution/smoke in the
Southern SJV
MODIS Aqua, 3 hours later shows that the
pollution/smoke has been cleared by the high winds
Neither image shows evidence of dust not
surprising since dust is hard to see over land
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AIRNOW PM2.5, Sep. 22, 2006, Local time
2006-09-2214
2006-09-2216
2006-09-2218
2006-09-2220
2006-09-2222
2006-09-2300
2006-09-2302

• AIRNOW data are available along the SJ Valley

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AIRNOW PM2.5
The dust peak is progressing from 1200 in
Modesto to 2000 in Bakersfield Transport speed
0f 25 MPH would do it
Sacramento, ?? peak
Modesto, 1200 peak
Corcoran, 1600 peak
Bakersfield, 2000 peak

• There is an issue with the absolute times dont
  match with the SJV report

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Surface Visibility (Bext), Winds Local Eastern
Time ??
2006-09-2216
2006-09-2222
2006-09-2218
2006-09-2220

• The high winds were also transported moving
  southward
• So, as the gust move southward it could create
  local dust wherever it peaks

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NAAPS Dust Model, Sep 22, 2006 (Times are GMT)
2006-09-22 0000
2006-09-22 0600
2006-09-22 1200
2006-09-22 1800
2006-09-23 0000
2006-09-23 0600

• High surface dust concentrations are forecasted
  for California
• In the early morning the highest winds surface
  dust conc. Highest in N. California
• By the afternoon, the winds surface conc.
  highest over S. California

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PM10-PM25 Obs from the SJV Report

• The PM10/PM2.5 ratio of 5-10 indicates fresh dust
• But the broad peak in Bakersfield suggests that
  the dust there has been dispersed..

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Tentative Conclusion

• Tentative Conclusions
• High winds were present to cause windblown dust
• Short-term PM10 peaks are indicative of windblown
  dust
• It was a Natural Dust Event

• Questions
• Why is PM10 highest in Corcoran-Bakersfield?
• Transport from the North is plausible

• Alternative Speculative Explanation by RBH (may
  be off)
• The high wind gusts were moving southward
• As the gust progressed, it kicked up local dust
  and caused the very high PM10