NARSTO PM Assessment Chapter 5: Spatial and Temporal Pattern TOC Introduction Data Global Pattern NAM Dust NAM Smoke NAM Haze NAM Total PM Local PM Dust over North America - PowerPoint PPT Presentation

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NARSTO PM Assessment Chapter 5: Spatial and Temporal Pattern TOC Introduction Data Global Pattern NAM Dust NAM Smoke NAM Haze NAM Total PM Local PM Dust over North America

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Higher levels also cover the Caribbean Islands and S. Florida. ... b. Contour map of the PM10 concentration on April 29, 1998. ... – PowerPoint PPT presentation

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Title: NARSTO PM Assessment Chapter 5: Spatial and Temporal Pattern TOC Introduction Data Global Pattern NAM Dust NAM Smoke NAM Haze NAM Total PM Local PM Dust over North America


1
NARSTO PM AssessmentChapter 5 Spatial and
Temporal PatternTOC Introduction Data Global
Pattern NAM Dust NAM Smoke NAM Haze NAM Total
PM Local PM Dust over North America
  • Section Contents
  • Fine Dust Concentration
  • Sahara Dust Plume in July
  • Sahara Events over the Gulf Coast
  • Seasonal and Secular Trends of Sahara Dust over
    the US
  • Global Scale Dust Transport The April 1998
    Asian Dust Event
  • Asian Dust Impact on NAM A Spatial and Temporal
    Perspective
  • Dust Generated within in North America??

Direct questions to Rudolf B. Husar
rhusar_at_me.wustl.edu
2
Sahara Dust Plume in July
  • Based on TOMS Satellite. Work of Herman,
    Prospero.
  • In July (1998) elevated levels of absorbing
    aerosol (Sahara Dust) reaches the Gulf of Mexico
    and evidently, enters the continent .
  • High TOMS dust levels are seen along the
    US-Mexican borders, reaching New Mexico. Higher
    levels also cover the Caribbean Islands and S.
    Florida.
  • Another patch of absorbing aerosol (local dust?)
    is seen over the Colorado Plateau, well separated
    from the Sahara dust.

3
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5
Fine Dust Concentration
  • Based on IMPROVE
  • See Sisler Malm
  • The year average Fine Dust is highest over the
    Gulf region (gt 1 ug/m3).
  • In Texas and the West, Fine Dust accounts for
    10-25 of the Fine Mass.

6
Fine Particle Dust Concentration Over the East
Coast
  • Seasonal Pattern of Dust from IMPROVE
  • Strong peak in July. Dust trace extends to
    Shenandoah
  • Dust is highly episodic 90 percentile is gtgt
    median
  • Lots of previous work by Prospero, Cahill, Malm

7
Seasonal and Secular Trends of Sahara Dust over
the US
  • Daily dust levels at 6 IMPROVE sites over the SE
    US were averaged to indicate regional values.
  • Regional Sahara Dust events occur several times
    each summer (as shown by Prospero, Cahill,
    Malm.)
  • Seasonal pattern peaks sharply in July when the
    Sahara plume swings to ne North into the
    Caribbean.
  • The July average dust declines from 7 ug/m3 in S
    Florida to about 1 ug/m3 in Shenandoah.

8
Sahara Events over the Eastern US
PM10 in Sahara Dust Events
  • Based on PM10 data in EPAs AIRS. Previous work
    by Prospero, Cahill, Malm
  • Scanning the AIRS PM10 database several
    regional-scale PM10 episodes over the Gulf Coast
    (gt 80 ug/m3)
  • Three such episodes are shown on the right for
    July 5, 1992, June 30, 1993 and June 21, 1997.
  • Speciation data (IMPROVE) show that during the
    events, the fine particle dust exceeds 20 ug/m3.
  • The Sahara dust impact on PM10 is not confined to
    fluke events. In fact, the regional PM10
    concentrations over the entire Eastern US (90th
    percentile) occur in July over the Gulf Coast
  • Hence, Sahara dust is the dominant contributor to
    peak PM10 levels over the Gulf Coast (and over
    the EUS NW Mexico?).
  • The Sisler Malm analysis also shows that Fine
    Dust over the entire US is highest over the
    Sahara impact region.
  • Issue Can this be true????RBH

9
Global Scale Dust Transport The April 1998 Asian
Dust Event
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.
  • 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.

10
The Asian Dust Event over NAM A Spatial and
Temporal Perspective
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.
  • 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.

11
Size and Composition of the Global Dust
  • Both the aged Sahara and East Asian dusts have
    fixed composition.
  • East Asian dust is enriched in Fe, CA and K
    compared to the Sahara dust.
  • Volume (mass) size distribution of long range
    transported global-scale dust.
  • MMD 2-3 um.

12
Dust Generated within in North America??
  • Buds, can you spare some of your ideas? This
    section really needs ideas!
  • There must be dust generated in different parts
    of North America.
  • But
  • Where
  • When
  • How much
  • How do we document it?

13
Summary of Dust Pattern over North America
  • Sahara, Sahara, Sahara
  • Occasional Asian Dust
  • Some local NAM dust but
  • Where
  • When
  • How much
  • OK, Are YOU provoked yet?

14
NARSTO PM AssessmentChapter 5 Spatial and
Temporal PatternTOC Introduction Data Global
Pattern NAM Dust NAM Smoke NAM Haze NAM Total
PM Local PM Speciated Seasonal Fine Dust
Percentiles over the Eastern US
  • The seasonal aerosol aerosol pattern at the
    IMPROVE sites is examined using two
    methodologies
  • Seasonal Percentile Frequency Charts

15
Method 2 Seasonal Percentiles, 1992-99
  • The charts depict the magnitude of seasonal and
    synoptic variation
  • The synoptic-scale variation (day-to-day) can be
    measured by the 20-80 percentile spread

Great Smoky Mtn.
Lye Brook
Dirty days, 80-90
Dirty days, 80-90
Clean days (20)
Clean days (20)
  • At Lye Brook, VT, the clean days (20 percentile)
    corresponds to 4 ug/m3 throughout the year
  • The dirty days are (80-90-ile) have 2-5 times
    higher concentration than the clean days.

At the Smoky Mtn, the clean days in the winter
are also 4 ug/m3. However in the summer, even
the clean days have 14 ug/m3 PM2.5. The dirty
days are have 2-3 times higher than the clean
days through out the year.
16
Regional Grouping of Sites
  • For this presentation the IMPROVE sites were
    grouped as follows
  • New England ()
  • Mid-Atlantic ()
  • Central EUS ()
  • Peripheral ()
  • For each region, the seasonality is displayed
    for
  • Chemical Mass Balance
  • Carbonaceous Mass Balance
  • Fine Particle Mass Percentiles
  • Coarse Mass Percentiles
  • Sulfate Percentiles
  • Fine Soil Percentiles
  • Tot. Carbon. 'Unknown' Percentiles
  • Smoke Organics Percentiles

17
New England Fine Soil Percentiles
Acadia
Lye Brook
  • Fine Dust

18
Mid-Atlantic Fine Soil Percentiles
Washington DC
Brigantine
Shenandoah
Dolly Sods
Jefferson
  • Fine dust

19
Central EUS Fine Soil Percentiles
Upper Buffalo
Mammoth Cave
Shining Rock
G.Smoky Mtn.
Sipsy
  • Fine dust

20
Peripheral Sites Fine Soil Percentiles
Voyageurs
Acadia
Badlands
Big Bend
Everglades
  • Fine Dust

21
New England Coarse Mass Percentiles
Moosehorn
Acadia
Lye Brook
  • Coarse mass

22
Mid-Atlantic Coarse Mass Percentiles
Washington DC
Brigantine
Shenandoah
Dolly Sods
Jefferson
  • Coarse mass

23
Central EUS Coarse Mass Percentiles
Upper Buffalo
Mammoth Cave
Shining Rock
G.Smoky Mtn.
Sipsy
  • Coarse mass

24
Peripheral Sites Coarse Mass Percentiles
Voyageurs
Acadia
Badlands
Big Bend
Everglades
  • Coarse mass
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