Spatial Pattern of Aerosols over N. America

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Spatial Pattern of Aerosols over N. America
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• Satellite Data
• PM 10
• PM2.5
• PMCoarse
• Visibility
• Contact Rudolf B. Husar (rhusar_at_me.wustl.edu)

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Seasonal Average Satellite Data (AVHRR)

• Satellite data provide consistent,
  continental-scale, multi-year coverage of the
  aerosol pattern
• AVHRR satellite data yields the optical
  thickness, EAOT over the oceans surrounding N.
  America
• The highest aerosol burden is in the springtime
  over the oceans east and west to Mexico
• In the summer, an elongated aerosol plume is
  emanating from E. US to the Atlantic

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Satellite Data over the Ocean and Land

• POLDER satellite data over the oceans and land
  shows the vertical burden of fine (polarizing)
  particles (smoke and fine haze)
• The most significant feature is the regional
  aerosol patch centered in S. Mexico-Guatemala.
• Both satellite data indicates the strong
  springtime aerosol peak due to biomass burning.

• The TOMS sensor provides a qualitative index of
  the columnar concentration of absorbing aerosols
  (smoke and dust)
• In May 1998 the fires produced more then the
  average springtime biomass smoke
• High springtime aerosol concentrations are found
  on both the Gulf and the Pacific side of Mexico,
  particularly at lower elevations

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PM10

• The EPA PM10 network provides that data for
  evaluation compliance with the NAAQS for PM10.
  The network begun operation in late 1986 using
  the Federal Reference Method (FRM)

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Annual PM10 Concentrations

• There are over 1000 PM10 monitoring stations in
  the US operating since the mid 1980s
• Data for 36 PM10 sites in 5 cities in Mexico are
  also available
• The highest PM10 is reported in the cities of
  Mexico (60-70 mg/m3)
• In the US, S. California has the highest annual
  PM10 in the dusty Imperial Valley, PM10 is gt50
  mg/m3
• The agricultural Nebraska-Kansas has annual value
  gt 35 mg/m3

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PM10 Seasonal Pattern
Falke and Husar (1998)

• PM10 concentration data are collected at gt1000
  sites as part of the EPA regulatory process
• The seasonal average PM10 concentration varies
  between from between 10 and 100 mg/m3
• Over the eastern US, the highest PM10 is in the
  summer (Q3) with 30-40 mg/m3 regional values
• In the mountainous West, the highest PM10 is
  recorded in the Fall and Winter (50-100 mg/m3).

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PM2.5

• The EPA PM2.5 network provides that data for
  evaluation compliance with the NAAQS for PM2.5.
  The network begun operation in late 1999 using
  the Federal Reference Method (FRM)

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Annual PM2.5 Concentration Estimates

• The map is based on AIRS PM2.5 data (as of
  January 01), the temporal coverage is uneven.
• The annual PM2.5 map spatial show
• A remarkably uniform regional distribution over
  the East (12-18 mg/m3).
• Urban-metropolitan areas over the East are
  slightly above (1-2 mg/m3) their surrounding
  region
• There are PM2.5 hot spots in the valleys of the
  West (San Joaquin and South Coast Air Basins)

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PM2.5 Annual Exceedance Regions CRUDE ESTIMATES
inadequate data

• Potentially significant exceedance (gt12 mg/m3)
• Georgia-E. Tennessee corridor
• San Joaquin and South Coast Air Basins
• Parts of the Ohio River Valley

• Potential PM2.5 exceedance regions (gt12 mg/m3)
• Entire non-coastal Eastern US (East of
  Mississippi)
• San Joaquin and South Coast Air Basins
• Specks of Montana, Texas

• Possible PM2.5 exceedance regions (gt12 mg/m3)
• Entire E. US except New England, Florida, Upper
  Midwest
• Parts of the Texas, Arizona, Oregon, Montana

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PM2.5 Seasonal Concentration Pattern

• The entire country shows pronounced seasonality
  summer peak in the East, fall/winter peak in the
  West
• The highest regional PM2.5 concentration is over
  the Southeast in the summer season (gt21 mg/m3).
• The regional Quarter 1 concentrations are highest
  around the Great Lakes, Georgia and California

gt40 mg/m3 ??
Jan, Feb, Mar
Apr, May, Jun
Jul, Aug, Sep
Oct, Nov, Dec
Note The spatial pattern are based on July
1999-June 2000 data. Preliminary analysis shows
that the second year of PM2.5 FRM data has a
different pattern over the East.
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Summary of PM2.5 FRM Network Data

• By January 2000 there were 600-700 FRM stations,
  100 sites with daily data
• The PM2.5 network is significantly clustered near
  urban-metro areas
• The annual PM2.5 map shows a remarkably uniform
  regional distribution over the East and hot
  spots over the West
• Virtually the entire Eastern US is in the
  vicinity of the annual NAAQS, (15 /- 3 mg/m3)
• Over the East, the seasonal concentration is
  highest in the summer, while the dirty Western
  valleys peak in the fall/winter.

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PM Coarse

• The EPA PM10 and PM2.5 networks provides data for
  evaluation compliance with the NAAQS. The spatial
  pattern of PMCoarse can be estimated by
  PM10-PM2.5 difference.

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PM2.5, PM10 and Estimated PM Coarse Maps

• Measured Annual PM2.5 Concentration based on the
  1999-2000 FRM network data

Measured Annual PM10 Concentration based on FRM
PM10 data in AIRS.
Estimated Annual PMCoarse Concentration
PMCoarse PM10 PM2.5 Difference of the
aggregated PM10 and PM2.5 Note Sampling methods
differ estimate uncertain.
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Haze (Visibility)

• Visibility is a welfare effect of PM
• Visibility data are also used as a surrogate for
  fine particle pattern analysis, preticularly for
  long-term trends.

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Seasonal Visibility Trends Maps 1980-1995

• In the period 1980-95, the visibility has
  improved gt 10
• The improvement was evident throughout the the
  US.
• The decline in haze was most pronounced in S.
  California (Q4) and the Eastern US (Q3)

 
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Eastern US Visibility Trends
90th Percentile - Top Trends 75th Percentile -
Bottom Trends

• Trends of the summertime 90th and 75th percentile
  light extinction for the eastern, northeastern
  and southeastern U.S. from 1980-95. The
  confidence level for each trend is based on the
  two sided Student's t-distribution.