Observing Air Quality from Space Randall Martin, Aaron van Donkelaar, Lok Lamsal, Chulkyu Lee, Carolyn Verduzco Undergraduate Science Conference 25 September 2010 Dalhousie University With contributions from Mike Brauer: University of British Columbia Ralph Kahn, Rob Levy: NASA Goddard Paul Villeneuve: UofT, Health Canada

A Group Effort

Major Air Pollutants and Health Effects Key Pollutants that Contribute to Respiratory and Cardiovascular Illness Fine Aerosol (PM 2.5 ), Ozone (O 3 ), Nitrogen Dioxide (NO 2 ) (AQHI) Health Canada, Health Effects of Air Pollution AQHI = f(NO 2, O 3, PM 2.5 ) Smog Alert, Toronto

Sources of Major Air Pollutants FiresBiosphereHuman activity Nitric oxide (NO) Carbon monoxide (CO), Volatile organics (VOCs) Ozone (O 3 ) Hydroxyl (OH) sunlight H 2 O, sunlight Ammonia (NH 3 ), Sulfur dioxide (SO 2 ), NO, VOCs oxidation NH 3, H 2 SO 4, HNO 3 Semivolatile Organics Nucleation, Condensation, Coagulation Mineral Dust Aerosol NO 2 Sea Salt

Large Regions Have Insufficient In Situ Measurements for Air Quality Assessment Canada Wide Standard (CWS): 3-year average of annual 98 th percentile of the daily 24-hour average PM 2.5 < 30 ug m -3 WHO standard 10 ug m -3 in annual mean

Sun-synchronous Polar Orbiting Geometry Sun-synchronous Polar Orbit ~14 orbits / day

VisibleUltraviolet Photographs in the

Satellite Observations of Tropospheric NO 2 SCIAMACHY Tropospheric NO 2 (10 15 molecules cm -2 ) Martin et al., JGR, 2006 Method: Solar backscatter Scattering by Earth surface and atmosphere   Idealized NO 2 absorption spectrum  

Visibility Impeded by Aerosol Loading Waterton Lakes/Glacier National Park 7.6 ug m ug m ug m ug m -3 Malm, 1999

Aerosol Remote Sensing Pollution haze over East Coast Dust off West Africa Aerosol Reflectance for specific wavelength and geometry For dark scenes measured molecular surface Aerosol optical thickness For small  a single scattering albedo P( Θ) phase function

Aerosol Optical Thickness ( τ) from Satellite Using MODIS and MISR Instruments over van Donkelaar et al., EHP, τ [unitless]

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

Ground-level PM 2.5 = η τ Ground-level PM 2.5 = η · τ η affected by vertical structure, aerosol properties, relative humidity Obtain η from aerosol-oxidant model (GEOS-Chem) sampled coincidently with satellite obs GEOS-Chem Simulation of η for van Donkelaar et al., EHP, 2010

Significant Agreement with Coincident In situ Measurements Satellite Derived In-situ Satellite-Derived [ μ g/m3] In-situ PM 2.5 [μg/m 3 ] Annual Mean PM 2.5 [ μ g/m 3 ] ( ) r MODIS τ 0.40 MISR τ 0.54 Combined τ 0.63 Combined PM van Donkelaar et al., EHP, 2010

Evaluation with measurements outside Canada/US Global Climatology ( ) of PM 2.5 Better than in situ vs model (GEOS-Chem): r= , slope = 0.63 – 0.71 Number sitesCorrelationSlopeBias (ug/m 3 ) Including Europe Excluding Europe van Donkelaar et al., EHP, 2010

30% of Asia exposed to >50 μg/m 3 in annual mean 0.61±0.20 years lost per 10 μg/m 3 [Pope et al., 2009] Estimate decreased life expectancy due to PM 2.5 exposure PM 2.5 Exposure [μg/m 3 ] Population [%] Data Valuable to Assess Health Effects of PM 2.5 van Donkelaar et al., EHP, 2010

Simulated (GEOS-Chem) Sulphate Transport Aaron van Donkelaar

Challenges 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 Sensing of Air Quality Acknowledgements: Health Canada NSERC NASA