Observing%20Air%20Quality%20from%20Space

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Observing Air Quality from Space

• Randall Martin, Aaron van Donkelaar, Lok Lamsal,
  Chulkyu Lee, Carolyn Verduzco

With contributions from Mike Brauer University
of British Columbia Ralph Kahn, Rob Levy NASA
Goddard Paul Villeneuve UofT, Health Canada
Undergraduate Science Conference 25 September
2010 Dalhousie University
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A Group Effort
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Major Air Pollutants and Health Effects
(AQHI)
Key Pollutants that Contribute to Respiratory and
Cardiovascular Illness Fine Aerosol (PM2.5),
Ozone (O3), Nitrogen Dioxide (NO2)
Health Canada, Health Effects of Air Pollution
Smog Alert, Toronto
AQHI f(NO2, O3, PM2.5)
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Sources of Major Air Pollutants
NO2
H2O, sunlight
sunlight
Nitric oxide (NO) Carbon monoxide (CO),
Volatile organics (VOCs)
Hydroxyl (OH)
Ozone (O3)
Nucleation, Condensation,Coagulation
oxidation
Ammonia (NH3), Sulfur dioxide (SO2), NO, VOCs
NH3, H2SO4, HNO3 Semivolatile Organics
Aerosol
Fires
Biosphere
Human activity
Mineral Dust
Sea Salt
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Large Regions Have Insufficient In Situ
Measurements for Air Quality Assessment
Canada Wide Standard (CWS) 3-year average of
annual 98th percentile of the daily 24-hour
average PM2.5 lt 30 ug m-3 WHO standard 10 ug m-3
in annual mean
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Sun-synchronous Polar Orbiting Geometry
Sun-synchronous Polar Orbit
14 orbits / day
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Visible
Photographs in the
Ultraviolet
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Satellite Observations of Tropospheric NO2
Method Solar backscatter
l2
l1
Scattering by Earth surface and atmosphere
SCIAMACHY 2003-2005
Tropospheric NO2 (1015 molecules cm-2)
Idealized NO2 absorption spectrum
Martin et al., JGR, 2006
l1
l2
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Visibility Impeded by Aerosol LoadingWaterton
Lakes/Glacier National Park
7.6 ug m-3
12 ug m-3
22 ug m-3
65 ug m-3
Malm, 1999
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Aerosol Remote Sensing
For dark scenes
Aerosol Reflectance for specific wavelength and
geometry
surface
measured
molecular
For small ?a
Aerosol optical thickness
single scattering albedo P(T) phase function
Pollution haze over East Coast
Dust off West Africa
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Aerosol Optical Thickness (t) from
SatelliteUsing MODIS and MISR Instruments over
2001-2006
0.3 0.25 0.2 0.15 0.1 0.05 0
t unitless
van Donkelaar et al., EHP, 2010
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Chemical Transport Model (GEOS-Chem) Simulation
of Aerosol Optical Depth
Aaron van Donkelaar
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Ground-level PM2.5 ? t
? affected by vertical structure, aerosol
properties, relative humidity Obtain ? from
aerosol-oxidant model (GEOS-Chem) sampled
coincidently with satellite obs
GEOS-Chem Simulation of ? for 2001-2006
van Donkelaar et al., EHP, 2010
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Significant Agreement with Coincident In situ
Measurements
r
MODIS t 0.40
MISR t 0.54
Combined t 0.63
Combined PM2.5 0.78
Annual Mean PM2.5 µg/m3 (2001-2006)
Satellite Derived
Satellite-Derived µg/m3
In-situ
In-situ PM2.5 µg/m3
van Donkelaar et al., EHP, 2010
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Global Climatology (2001-2006) of PM2.5
Evaluation with measurements outside Canada/US
Number sites Correlation Slope Bias (ug/m3)
Including Europe 244 0.86 0.83 1.15
Excluding Europe 84 0.84 0.91 -2.5
Better than in situ vs model (GEOS-Chem)
r0.52-0.62, slope 0.63 0.71
van Donkelaar et al., EHP, 2010
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van Donkelaar et al., EHP, 2010
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van Donkelaar et al., EHP, 2010
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Data Valuable to Assess Health Effects of PM2.5

• 30 of Asia exposed to gt50 µg/m3 in annual
  mean
• 0.610.20 years lost per 10 µg/m3 Pope
  et al., 2009
• Estimate decreased life expectancy due to PM2.5
  exposure

Population
PM2.5 Exposure µg/m3
van Donkelaar et al., EHP, 2010
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Simulated (GEOS-Chem) Sulphate Transport
Aaron van Donkelaar
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Challenges
Encouraging Prospects for Satellite Remote
Sensing of Air Quality
Remote Sensing Improved algorithms to
increase accuracy and observe other pollutants
Modeling Comprehensive assimilation
capability Develop representation of processes
Measurements Research quality
measurements for validation and
process-level understanding
Acknowledgements Health Canada NSERC
NASA