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Aaron van Donkelaar 1 , Randall Martin 1,2 , Ralph Kahn 3 and Robert Levy 3 AGU Fall Meeting

Global Climatology of Fine Particulate Matter Concentrations Estimated from Remote-Sensed Aerosol Optical Depth. Aaron van Donkelaar 1 , Randall Martin 1,2 , Ralph Kahn 3 and Robert Levy 3 AGU Fall Meeting December 13-18, 2009 1 Dalhousie University 2 Harvard-Smithsonian 3 NASA Goddard.

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Aaron van Donkelaar 1 , Randall Martin 1,2 , Ralph Kahn 3 and Robert Levy 3 AGU Fall Meeting

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  1. Global Climatology of Fine Particulate Matter Concentrations Estimated from Remote-Sensed Aerosol Optical Depth Aaron van Donkelaar1, Randall Martin1,2, Ralph Kahn3 and Robert Levy3 AGU Fall Meeting December 13-18, 2009 1Dalhousie University 2Harvard-Smithsonian 3NASA Goddard

  2. vertical structure • aerosol type • meteorological effects • meteorology • diurnal effects η Approach We relate satellite-based measurements of aerosol optical depth to PM2.5 using a global chemical transport model Following Liu et al., 2004: Estimated PM2.5 = η· τ Combined MODIS/MISR Aerosol Optical Depth GEOS-Chem

  3. MODIS and MISR τ Mean τ2001-2006 at 0.1º x 0.1º MODIS τ • 1-2 days for global coverage • Requires assumptions about surface reflectivity MODIS r = 0.40 vs. in-situ PM2.5 MISR τ • 6-9 days for global coverage • Simultaneous surface reflectance and aerosol retrieval MISR r = 0.54 vs. in-situ PM2.5 0 0.1 0.2 0.3 τ [unitless]

  4. Agreement varies with surface type July MODIS MISR 9 surface types, defined by monthly mean surface albedo ratios, evaluation against AERONET AOD

  5. Combining MODIS and MISR improves agreement 0.3 0.25 0.2 0.15 0.1 0.05 0 τ[unitless] Combined MODIS/MISR r = 0.63 (vs. in-situ PM2.5) MODIS r = 0.40 (vs. in-situ PM2.5) MISR r = 0.54 (vs. in-situ PM2.5)

  6. Global CTMs can directly relate PM2.5 to τ GEOS-Chem • Detailed aerosol-oxidant model • 2º x 2.5º • 54 tracers, 100’s reactions • Assimilated meteorology • Year-specific emissions • Dust, sea salt, sulfate-ammonium-nitrate system, organic carbon, black carbon, SOA η [ug/m]

  7. Significant agreement with coincident ground measurements over NA Annual Mean PM2.5 [μg/m3] (2001-2006) Satellite Derived Satellite-Derived [μg/m3] In-situ In-situ PM2.5 [μg/m3]

  8. Method is globally applicable • Annual mean measurements • Outside Canada/US • 244 sites (84 non-EU) • r = 0.83 (0.91) • slope = 0.86 (0.84) • bias = 1.15 (-2.52) μg/m3

  9. High global PM2.5 exposure WHO Guideline AQG IT-3 IT-2 IT-1 100 90 80 70 60 50 40 30 20 10 0 • Satellite-PM2.5 + population map → exposure • 80% of world population exceeds WHO guideline of 10 μg/m3 • 49% of eastern Asia exceeds 35 μg/m3 Population [%] 5 10 15 25 35 50 100 PM2.5 Exposure [μg/m3]

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