Observing Air Quality from SpaceObserving Air Quality from Space

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

Undergraduate Science Conference25 September 2010

Dalhousie University

With contributions from Mike Brauer: University of British Columbia

Ralph Kahn, Rob Levy: NASA GoddardPaul Villeneuve: UofT, Health Canada

A Group EffortA Group Effort

Major Air Pollutants and Health EffectsMajor Air Pollutants and Health Effects

Key Pollutants that Contribute to Respiratory and Cardiovascular Illness

Fine Aerosol (PM2.5), Ozone (O3), Nitrogen Dioxide (NO2)

(AQHI)

Health Canada, Health Effects of Air Pollution

AQHI = f(NO2, O3, PM2.5)

Smog Alert, Toronto

Sources of Major Air PollutantsSources of Major Air Pollutants

Fires Biosphere Humanactivity

Nitric oxide (NO)Carbon monoxide (CO), Volatile organics (VOCs)

Ozone (O3) Hydroxyl (OH)sunlight

H2O, sunlight

Ammonia (NH3), Sulfur dioxide (SO2), NO, VOCs

oxidation

NH3, H2SO4, HNO3

Semivolatile Organics

Nucleation, Condensation,Coagulation

Mineral Dust

Aerosol

NO2

Sea Salt

Large Regions Have Insufficient In Situ Measurements Large Regions Have Insufficient In Situ Measurements for Air Quality Assessmentfor Air Quality Assessment

Canada Wide Standard (CWS): 3-year average of annual 98th percentile of the daily 24-hour average PM2.5 < 30 ug m-3

WHO standard 10 ug m-3 in annual mean

Sun-synchronous Polar Orbiting GeometrySun-synchronous Polar Orbiting Geometry

Sun-synchronous Polar Orbit

~14 orbits / day

VisibleVisible UltravioletUltraviolet

Photographs in thePhotographs in the

Satellite Observations of Tropospheric NOSatellite Observations of Tropospheric NO22

SCIAMACHY 2003-2005

Tropospheric NO2 (1015 molecules cm-2)

Martin et al., JGR, 2006

Method: Solar backscatter

Scattering by Earth surface and atmosphere

IdealizedNO2

absorptionspectrum

Visibility Impeded by Aerosol LoadingVisibility Impeded by Aerosol LoadingWaterton Lakes/Glacier National ParkWaterton Lakes/Glacier National Park

7.6 ug m-3 12 ug m-3

22 ug m-365 ug m-3

Malm, 1999

Aerosol Remote Sensing Aerosol Remote Sensing

Pollution haze over East Coast Dust off West Africa

a m sR R R R Aerosol Reflectance for specific wavelength and geometry

For dark scenes

measuredmolecular

surface

Aerosol optical thickness

aa

R

P

For small a single scattering albedo P(Θ) phase function

Aerosol Optical Thickness (Aerosol Optical Thickness (ττ)) from Satellite from SatelliteUsing MODIS and MISR Instruments over 2001-2006Using MODIS and MISR Instruments over 2001-2006

van Donkelaar et al., EHP, 2010

0.3

0.25

0.2

0.15

0.1

0.05

0

τ [u

nitle

ss]

Chemical Transport Model (GEOS-Chem) Chemical Transport Model (GEOS-Chem) Simulation of Aerosol Optical Depth Simulation of Aerosol Optical Depth

Aaron van Donkelaar

Ground-level PMGround-level PM2.52.5 = = ηη · ττ

η affected by vertical structure, aerosol properties, relative humidityObtain η from aerosol-oxidant model (GEOS-Chem) sampled coincidently with satellite obs

GEOS-Chem Simulation of η for 2001-2006

van Donkelaar et al., EHP, 2010

Significant Agreement with Coincident In situ MeasurementsSignificant Agreement with Coincident In situ Measurements

SatelliteDerived

In-situ

Sat

ellit

e-D

eriv

ed

[μg/

m3]

In-situ PM2.5 [μg/m3]

Ann

ual M

ean

PM

2.5 [

μg/

m3]

(200

1-20

06)

r

MODIS τ 0.40

MISR τ 0.54

Combined τ 0.63

Combined PM2.5 0.78

van Donkelaar et al., EHP, 2010

Evaluation with measurements outside Canada/US

Global Climatology (2001-2006) of PMGlobal Climatology (2001-2006) of PM2.52.5

Better than in situ vs model (GEOS-Chem): r=0.52-0.62, slope = 0.63 – 0.71

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

van Donkelaar et al., EHP, 2010

van Donkelaar et al., EHP, 2010

van Donkelaar et al., EHP, 2010

• 30% of Asia exposed to >50 μg/m3 in annual mean

• 0.61±0.20 years lost per 10 μg/m3 [Pope et al., 2009]

• Estimate decreased life expectancy due to PM2.5 exposure

PM2.5 Exposure [μg/m3]

Pop

ulat

ion

[%]

Data Valuable to Assess Health Effects of PMData Valuable to Assess Health Effects of PM2.52.5

van Donkelaar et al., EHP, 2010

Simulated (GEOS-Chem) Sulphate TransportSimulated (GEOS-Chem) Sulphate Transport

Aaron van Donkelaar

ChallengesChallenges

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

Encouraging Prospects for Satellite Remote Encouraging Prospects for Satellite Remote Sensing of Air QualitySensing of Air Quality

Acknowledgements:Acknowledgements: Health Canada Health Canada NSERC NSERC NASA NASA