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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 - PowerPoint PPT Presentation
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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 (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
1
3
4 eQrM
115.2,
3
5.2 3
4zrQ
r
rPM ed
zd
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
InstrumentationMODIS• 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
MISR• Multiangle Imaging
Spectroradiometer• 4 spectral bands at 9 different
viewing angles• 6-9 days for global coverage• No assumption regarding
surface reflectivity
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
MODIS MISR
standard 0.68 0.54
constant vertical structure (τz/τ) 0.29 0.29
constant AOD 0.54 0.38
constant aerosol properties (Qe, r, rd, ρd)
0.73 0.52
115.2,
3
5.2 3
4zrQ
r
rPM ed
zd
Scatter Plot Comparison/Table Holding Constants
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