Global Distribution and Transport of Air Pollution

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Global Distribution and Transport of Air Pollution
Presented at The Haagen-Smit Symposium From Los
Angeles to Global Air Pollution Lake Arrowhead,
April 9-12, 2001 Rudolf Husar CAPITA,
Washington University, St. Louis
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Background

• Global-scale air pollution existed since..
• The difference is that now we can observe it!
• Outline of Presentation
• Major pollutant sources and emissions
• Observation-based global chemical climatology of
  major gases and aerosols
• Illustration of global-scale dust and smoke
  events
• Opportunities and challenges of the the 21st
  century

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Industrial Sulfur Emission Density
Regional hot-spots for industrial sulfur
emissions Eastern North America, Europe East
Asia

• The regional hot-spots for industrial sulfur
  emissions are in
• E. North America,
• Europe and
• E. Asia

• Long Term Trends
• North America roughly constant for the past
  century
• Europe Rise after WW II but leveled off since
  1990
• East Asia Sharp rise since the 1960s.

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Satellite Fire Detection
ESA
Fires are major sources of atmospheric trace
gases and aerosols. Savanna region of Africa
Thousands of small fires every year in the
December-February dry season. Fires are Seasonal
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Columnar NO2 GOME Satellite
Burrows et al., 1999
January Highest NO2 are over northern
industrialized regions, and Sub-Saharan Africa
September High NO2 over the subtropical S
America, Africa and Indochina
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Tropospheric Ozone (Total TOMS Stratospheric)
Fishman and Brackett, 1997

• Jun Jul Aug High O3 over industrial N.
  Hemisphere
• Sep Oct Nov Elevated O3 over the southern
  subtropics

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POLDER Aerosol Index (Depolarization)
Douze et al 2001
January High aerosol index over West Africa,
India and China.
June High aerosol levels over Central Africa,
India and China and C. America
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Continental Surface Visibility (Human Observers)

• NOAA NCDC Global Summary of the Day (SOD) 7000
  Observations

Low Visibility
High Visibility
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Extinction coefficient (visibility) for SE Asia
Sep, Oct, Nov
Dec, Jan, Feb

• The most intense and persistent regional haze is
  over India

During 1997 biomass fires in Indonesia caused
unusually intense haze
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Extinction coefficient (visibility) for N. America
Dec, Jan, Feb
Jun, Jul, Aug

• The haze over N. America is modest compared to
  hazy regions of Africa, E. Asia and S. America

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Aerosol Optical Depth (AVHRR-Backscattering)
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Fusion of Satellite and Surface Visibility Data

• Satellite data over the oceans and visibility
  data over land can be combined
• In Jun Jul Aug, the highest aerosol levels are
  over India, Africa
• The aerosol levels over the industrial E.N.
  America, Europe and E. Asia are moderate

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Oceanic Visibility from Ships McDonald 1938

• The 1938 visibility maps are remarkably similar
  to the satellite-derived visibility maps for the
  1990s.

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Absorbing Aerosol Index (TOMS 0.3 mm abs.)

• Herman et. al., 1997

Dust
???
Smoke
July
TOMS is sensitive to dust and smoke in elevated
layers Sahara dust is the he most pronounced
feature of the TOMS index
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Sahara Dust Transport to N America, July
Sahara Dust Plume
Sahara Dust Plume

• 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.

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Sahara and Local Fine Dust Apportionment
Based on their respective Al/Si ratios.
Annual
July

• The annual fine Sahara dust is about 1 mg/m3
• In Florida, the local Sahara dust are similar
• At Big Bend Sahara is lt 25 of local fine dust.

• In July the Sahara dust contributes 4-8 mg/m3
• In the Southeast, fine Sahara dust is 2-4 times
  the local fine dust.

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Satellite Data on Sahara Dust(SeaWiFS 8 chan.,
0.4-0.9 mm)

• Truecolor image of Sahara dust cloud
  approaching Florida
• Dust cloud covers Florida
• SeaWiFS and other satellite data allow
• Daily dust tracking
• Quantitative analysis
• Climatological dust studies.

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Water Removal Rate and Lifetime

• Precipitation/Water Vapor 1/mm
• - a measure of water lifetime in the atmosphere.
  

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Vertical Distribution of Aerosols Space-borne
Lidar
Winker et., al. 1995

• Long rang transport occurs mostly in elevated
  layers
• Elevated layers mix with BL air
• Cloud interaction is clearly discernable

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Vertical Distribution of Aerosols Space-borne
Lidar
Topography restricts the dispersion of smoke on
continental scales.
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Aerosols as Indicators of Biogeochemical Processes
Urban/Industrial Activities
Fires
Dust storms
Volcanoes
Each source type has a unique signature size,
composition or optical properties. Aerosols can
be easily detected by passive visible
sensors. Space-based aerosol sensors already
exist to monitor the global daily aerosol pattern.
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Haze over ChinaSeaWiFS

• Industrial haze covers most of Eastern China
• Haze is confined to low-lying areas and valleys

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The Asian Dust Event of April 1998
Mongolia
China
Korea
On April 19, 1998 a major dust storm occurred
over the Gobi Desert The dust cloud was seen
through SeaWiFS, TOMS, GMS, AVHRR satellites The
dust transport was followed on-line by an an
ad-hoc international group
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SeaWiFS/TOMS data for April 21 shows dust
transport to the Pacific
Japan
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Trans-Pacific Dust Transport
The dust cloud traversed the Pacific in 6 days at
about 4 km altitude
As the dust approached N. America, it subsided to
the ground
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Asian Dust Cloud over N. America
Reg. Avg. PM10
100 mg/m3
Hourly PM10
On April 27, the dust cloud rolled into North
America. The regional average PM10 increased to
65 mg/m3 In Washington State, PM10 exceeded 100
mg/m3
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Fine Particle Dust Concentrations (IMPROVE)
April 25, 1998 April 29, 1998
May 2, 1998
On April 25, the western U.S. was virtually
dust-free. Highest concentration was an April
29. On May 2, the high levels moved (?) to the
Colorado Plateau.
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Smoke from Central American Fires
May 14, 98
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SeaWiFS, TOMS, Bext May 15, 1998
May 15, 98
DMSP Night Light
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SeaWiFS, TOMS, Bext May 16, 1998
May 16, 98
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Topography Limits Smoke Dispersion
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Smoke Aerosol and Ozone Inverse Relationship
Extinction Coefficient (visibility)
Surface Ozone
Surface ozone is generally depressed under the
smoke cloud
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PM10 Concentrations During the Smoke Event

• A füstfelho útjában mindehol a megengedett érték
  feletti aeroszol koncentrációt okozott, és a
  levego homályossága gátolta a légiforgalmat

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Summary of Global Air Pollution and Transport

• The global sulfur emissions have shifted from N.
  America and Europe to East Asia.
• The industrial belt, 30-60 deg N, is dominated
  by anthropogenic SOx, NOx and O3. This conforms
  to the conventional wisdom since the 1970s.
• Recent satellite data show that NOx, HC and
  aerosols are dominated by biomass burning in the
  subtropics and the southern hemisphere. ??
• The radiatively active global aerosol is
  dominated by smoke and dust, rather then by
  industrial sulfates as we have presumed.
• Episodic trans-continental transport of dust and
  smoke (ozone?) can now be detected and modeled
  routinely.
• Such extra-jurisdictional pollution events
  cause significant episodic impact on the air
  quality of N. America.

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On the Future of Global Air Chemistry

• Chris Junge, a pioneer of global atmospheric
  chemistry
• To find something interesting in the 1950s, all
  we had to do is look.
• Now, in the 21st century, looking, particularly
  for changes will be even more interesting.
• May you live in interesting times
• We are in the midst of an observational
  revolution (satellites, monitoring networks).
• The global distribution and transport of some
  pollutants can be monitored daily.

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Global Monitoring Situation and Future

• Many useful satellite products are
  serendipitous developed after deployment (TOMS
  AAI, AVHRR, SeaWiFS).
• Each sensor/system measures different aspect of
  atmospheric chemistry.
• Data from multiple satellites AND surface
  observations needs to be reconciled and fused.
• Such massive data analysis/interpretation job can
  only be accomplished by
• Open flow of data/knowledge.
• International collaboration.
• Scientific value-adding chains .

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ChallengePutting together theBIG PICTURE

• Increasing amount of satellite-derived
  information about air, land and sea are helping
  scientists to study how they are interconnected
  to form a finely balanced system.
• National Geographic, Oct 2000
• Will we put together the Big Picture?

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Challenge Sensory-Motor Response to Changes
All living organisms use sensory-motor feedback
system to maintain their existence in a changing
environment.
Sensing and recognition (monitoring)
Reasoning and explaining (sciences)
Challenge 21 Science Management Link
Decision making, action (management)

The above three steps are necessary for
sustainable development in an ever-changing
world.
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The Perfect Gobi Dust Storm April 7, 2001An
evolving presentation by a virtual community

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