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Quantitative Interpretation of Satellite and Surface Measurements of Aerosols over North America. Aaron van Donkelaar M.Sc. Defense December, 2005. Aerosols – Why do we care?. Climate Change Direct Effect Indirect Effect Health Effects (PM 2.5 ) Lung cancers Pulmonary Inflammation
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Quantitative Interpretation of Satellite and Surface Measurements of Aerosols over North America Aaron van Donkelaar M.Sc. Defense December, 2005
Aerosols – Why do we care? • ClimateChange • Direct Effect • Indirect Effect • Health Effects (PM2.5) • Lung cancers • Pulmonary Inflammation • Visibility Image from http://cariari.ucr.ac.cr/~faccienc/temas2/planeta.htm
Part I – Remote Sensing of Ground-Level PM2.5 Column Mass Loading: Ground-Level PM2.5: • ρ – particle mass density • r – effective radius • τ – aerosol optical depth • Qe – Mie extinction efficiency • z – Height of regional air mass subscript d denotes dry conditions
Instrumentation MISR • Multiangle Imaging Spectroradiometer • 4 spectral bands at 9 different viewing angles • 6-9 days for global coverage • No assumption regarding surface reflectivity MODIS • Moderate Resolution Imaging Spectroradiometer • 32 channels (7 used for Aerosol Retrieval): 0.47, 0.55, 0.67, 0.87, 1.24, 1.64 um • Approx. daily global coverage • Requires dark surface for AOD retrieval
GEOS-CHEM • 50 Tracers • 1º x 1º resolution • 30 vertical levels (lowest at ~10, 50, 100, 200, 300 m) • GMAO fields: temperature, winds, cloud properties, heat flux and precipitation • sulphate, nitrate, mineral dust, fine/coarse seasalt, organic and black carbon • Aerosol and oxidant simulations coupled through • formation of sulphate and nitrate • heterogeneous chemistry • aerosol effect of photolysis rates • Seasonal average biomass burning
Part II –Organic Aerosol Sources • Primary Sources: • combustion (biomass/biofuel) • Secondary Sources: • condensation of gaseous species • not well understood • GEOS-CHEM OA Simulation • Seasonally varying biomass burning inventories • Inversion removed • SOA based upon Chung and Seinfeld [2002] • Biogenic emissions from MEGAN inventory • HxCy + (O3, OH, NO3) → semi-volatile products
Conclusions • Remote PM2.5 • significant correlation (MODIS: R=0.68, MISR:0.54) • dominant factors include AOD and vertical structure • reveals global regions of high PM2.5 • Sources of Organic Aerosol • isoprene conversion reduces model bias • non-OA condensation unclear