How do aerosols affect air quality, the human environment, and natural ecosystems

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How do aerosols affect air quality, the human
environment, and natural ecosystems?
Many others
and

• For AeroCenter Update, March 8, 2008 (Year of the
  Rat)

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Aerosol affects air quality Emission,
transport, and amount of surface particulate
matter
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PM air quality

• Aerosol particles, also called particulate matter
  (PM) in air quality terms, exert health and
  environmental problems when in high concentrations

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Sources of PM

• Local/Regional
• Power plants, automobiles, fires, dust, and other
  natural sources (trees, volcanoes)
• Transboundary transport from outside
• Pollutants, smoke, and dust generated from other
  regions that can be transported into region of
  interest
• The extent of impact of long-range transport and
  regional emissions on air quality depends on the
  amount emitted locally and the vertical locations
  of PM from outside regions

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Sources and transport from observations and models
From Yoram Kaufman
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What can satellite data tell us about the long
range transport of pollution beyond pretty
pictures?

• A Satellite-based assessment of trans-Pacific
  transport of pollution aerosol
• Hongbin Yu, Lorraine Remer, Mian Chin, Huisheng
  Bian, Richard Kleidman, Thomas Diehl, JGR in
  press, 2008
• (Kaufman special issue)

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Anthropogenic (pollution smoke) AOD over oceans
derived from MODIS
Yoram Kaufmans formula

• Wheret, ta and tm are total, anthropogenic, and
  maritime aerosol optical thickness
• ft, fd, fm, fa are fractions of fine mode, dust,
  maritime, and anthropogenic aerosol optical
  thicknesses
• ta is derived using a modified/ improved Kaufman
  method
• Using vertical information from GLAS and CALIPSO,
  RH data from AIRS, and mass extinction efficiency
  from field measurements to convert ta to mass flux

From Hongbin Yu (Yu et al., 2008)
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Measurement-based estimate of transpacific
transport of anthropogenic aerosols

• Using aerosol products from multiple satellite
  sensors (MODIS, GLAS, CALIPSO, AIRS) and from
  field measurements
• 18 Tg/year pollution aerosol is exported from
  East Asia (and its upwind regions) to NW Pacific
• 4.5 Tg/year (25) reaches the west coast of
  North America
• This imported amount is about 15 of the total
  anthropogenic emissions in U.S. and Canada
• GOCART and GMI model simulations show similar
  magnitudes with satellite-based estimate, which
  is the total column amount

Export
Import
From Hongbin Yu (Yu et al., 2008)
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The above study is an estimate of total column
flux how does this transport affect the surface
air quality?

• Intercontinental transport of pollution and dust
  aerosols Implications for regional air quality
• (A modeling study)
• Mian Chin, Thomas Diehl, Paul Ginoux, William
  Malm, ACP 2007

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The impact is critically dependent on vertical
extent of transported aerosol plume
GOCART model study
Leaving Asia
Entering N. Am.

• Asian pollution
• Max in at surface leaving Asia
• Max above surface (1.5 4 km) entering North
  America
• Requiring downward mixing to send stuff to North
  American surface

• European pollution
• Contributing 10 50 in the Asian outflow!

Ratio of imported to locally emitted athropogenic
fine mode PM at surface - From 14 in NW to
3 in SE U.S.
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Other studies showing the importance of aerosol
vertical profiles to map the column amount to
surface PM

• Using GEOS-CHEM model to map MISR data to surface
  PM2.5 Y. Liu, Kourtakis, R. Kahn, et al, JAWMA
  2007
• 3-D Air Quality System project R. M. Hoff, K.
  McCann, H. Zhang, A. Prados, and J. Engel-Cox
• Using Giovanni tool to map MODIS AOD to surface
  PM2.5 A. Prados and Greg Leptoukh

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MISR GEOS-Chem Mapping near-surface
pollution(Liu, Krukakis, Kahn et al., 2007)

• MISR provides total-column AOT over land to
  constrain model
• MISR also gives particle shape to separate dust
  spherical particles --gt much better result
• GEOS-CHEM provides aerosol vertical distribution
  detailed spherical-particle chemical speciation

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3-D Air Quality System (R. Hoff et al.)

• Integrate NASA satellite sensor and lidar data
  into EPAs air quality data systems
• Provide greater accessibility and usability of
  satellite and lidar data to users of these
  systems
• Enable monitoring in horizontal and vertical
  dimensions for forecasting and retrospective
  analysis

Remapped MODIS 12x12 CMAQ Gridded AOD product
MODIS 10x10 granule AOD product
Calipso and UMBC Lidar data mapped to EPA PM sites
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Assessing U.S Air Quality with Giovanni (Ana
Prados and Greg Leptoukh)

• Data sets MODIS Terra and Aqua AOD, EPA PM2.5,
  CALIOP, OMI NO2 and Aerosol Index
• Services include AOD/PM2.5 correlation maps and
  scatter plots, and image loops for examining long
  range transport of pollutants

May 22nd, 2007 Smoke over north Carolina. High
AOD and low PM2.5 (r0.54). There is also haze in
the southeast Improved correlation over this
region when excluding smoke areas (r0.80)
Level-3 MODIS AOD
Giovanni data sets and tools help provide a more
complete understanding of the origin, evolution,
and vertical distribution of aerosol pollution
over the continental U.S.
EPA PM2.5 (ug/m3)
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Remarks on aerosol impact on air quality

• Key quantities Vertical distribution
  composition and particle size
• Current satellite data have limited information
  on these quantities
• There are innovative methods to estimate the
  transport and retrieve surface PM from current
  satellite observations but with large
  uncertainties
• Future satellite mission should focus on
  improving capabilities on observing the key
  quantities with adequate spatial coverage and
  accuracy

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Aerosol affects human environment Global
dimming/brightening
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Multi-decadal change of solar radiation reaching
the surface

• Solar radiation reaching the surface (Ssfc) is
  the primary energy source for life, and any
  change of this radiation could substantially
  affect the climate, hydrological cycle, and
  ecosystems
• Surface water evaporation
• Soil moisture
• Crop yield
• CO2 uptake

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Multi-decadal change of solar radiation reaching
the surface global dimming/brightening

• Long-term observations of Ssfc have shown a
  decline in solar radiation up to 1990 at several
  different regions of the world (dimming)
• Recent measurements have indicated an increase of
  Ssfc since about 1990 over many regions of the
  world (brightening)
• Anthropogenic emission change mirrors the change
  of Ssfc, suggesting possible roles of aerosols
• Many other factors can also contribute to the
  Ssfc change, such as clouds
• Global or regional or local?

Total
Other regions
East Asia
Former USSR
Eastern Europe
OECD Europe
U.S.A.
From David Streets (Streets et al., 2004, 2006)
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Long-term variations of AOD (1979
2006)(Preliminary GOCART results)

• Using time-varying anthropogenic emission 1979 -
  2006 from David Streets
• Compiling volcanic, biomass burning,
  aircraft/ship emissions (T. Diehl)
• Calculating dust and sea-salt emissions as a
  function of wind speed and surface conditions

Global ocean avg AOD, 60S 60N
Global land avg AOD, 60S 60N
Figure from Thomas Diehl
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What is the relationship between aerosol
emission, AOD, and Ssfc? (Preliminary GOCART
results annual avg)
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Remarks on aerosol impact on surface radiation

• Key quantities direct and diffuse SW solar
  radiation at the surface, under both cloudy and
  clear skies, and aerosol amount and optical
  properties
• Current satellite retrieval of surface radiation
  (e.g. from ISCCP or CERES) suffers from
  difficulties in specify aerosol amount and
  optical properties
• Current surface radiation networks are limited
  for adequate global assessment
• Long-term monitoring of surface radiation and
  aerosols from ground-based network is needed
• Better retrieval of surface radiation from space
  requires much better knowledge of aerosol
  properties

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Aerosol affects natural ecosystem Dust and
ocean productivity
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Connection between dust and ocean biology

• Iron supply is a limiting factor on phytoplankton
  growth over vast areas of the ocean
• Deposition of dust transported from deserts is
  believed to be the main source of iron to the
  open ocean
• However, dust-marine productivity connection
  depends on the amount of soluble iron, Fe(II)

Global iron and dust connections
From Jickells et al., Science 2005
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Dust as a Tracer of Climate Change in Antarctica
and as modulator of Phytoplankton Activity

• Phytoplankton activity is very sensitive to
  changes in nutrient availability (particularly in
  the Southern Ocean)

Artificially seeded Fe in the Southern Ocean
Visible chlorophyll enhancement afterwards
Soiree Experiment, Edward et al, Nature 2000)
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Global distributions of Chl. and aerosol

• Satellite retrieves both ocean Chl. (e.g. MODIS
  and SeaWiFS) and dust aerosols (e.g. MODIS coarse
  mode, MISR non-spherical), which can be
  potentially used to link dust to ocean
  productivity
• But absorbing aerosols (dust, smoke) remain
  problematic in ocean color data processing

Chlorophyll Concentration
January 2001
From W.E. Esaias
Aerosol Optical Thickness
April 2001
From C. McClain
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A combination of MODIS and OMI observations shows
dust traveling a long way in the South Atlantic
Gassó Stein, GRL 2007

• Observation of dust in the SO is very difficult
  because
• Very cloudy --- gt very few clear sky retrievals
  ----- gt sampling problem
• Dust activity is episodic and in pulses.
• Only a combination of satellite retrievals and
  surface (ship) can help to understand dust
  transport and detection in the SO as this example
  shows.

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Dust deposition over Atlantic Ocean derived from
Terra Aqua MODIS
Yoram Kaufmans method

• Obtain dust AOD td
• Estimate vertical profiles using virtual lidar
  correlations with the NCEP winds
• Convert dust AOD to mass
• Using wind speed and Terra/Aqua dust mass
  differences to estimate the dust mass transport
• Derive dust deposition

Estimated dust flux, Kaufman et al., JGR 2005

• Kaufman et al. 2005 estimated
• 240 80 Tg of dust are transported annually from
  Africa to Atlantic
• 50 Tg fertilize the Amazon Basin
• 50 Tg reach the Caribbean
• 20 Tg return to Africa and Europe

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Remarks on aerosol impact on ocean biology

• Key quantities dust aerosol amount and
  deposition, soluble iron, ocean
  phytoplankton/chlorolphyll
• Current satellite retrievals of ocean color
  requires accurately accounting for aerosol
  interference
• It is very difficult to observed dust when clouds
  present
• It is even more difficult to know if iron from
  dust is active
• Future satellite observation should have a better
  capability to detect dust even in cloudy
  conditions with adequate spatial coverage
• Although dust deposition cannot be directly
  observed by satellites, it can be derived with
  higher temporal satellite coverage (several
  times/day) to see aerosol moving and change