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Aerosol Simulation Over North America

Aaron Van Donkelaar

April 2005

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Remote Sensing of Surface Particulate Matter

M –mass loading
ρ – particle mass density
r – effective radius (AERONET)
τ – aerosol optical depth (MODIS/GEOS-CHEM)
Q_ext – extinction factor (AERONET)
Z – air mass height (GEOS-CHEM)

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GEOS-CHEM Underestimates AOD

MODIS, July 2002

GEOS-CHEM v7-02-01, July 2002

Optical Depth at 550nm [unitless]

AERONET, July 2002

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GEOS-CHEM Organic Carbon Too Low

GEOS-CHEM v7-02-01 Mass Concentrations [ug/m³]

July 2002

IMPROVE

Mass Concentrations [ug/m³]

July 2002

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Summer Organic Carbon Bias

GEOS-CHEM – IMPROVE [ug/m³]

May, 2002

June, 2002

September, 2002

April, 2002

July, 2002

August, 2002

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Low OC Yield from Isoprene

Matsunaga, S. N. et al. Isoprene oxidation products are a significant atmospheric aerosol component. in prep.
Claeys, M. et al. Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide. Atmospheric Environment.
Claeys, M. et al. Formation of Secondary Organic Aerosols Through Photooxidation of Isoprene. Science.

Recent literature has proposed OC yield from isoprene

Guenther has suggested specific pathways

Assume 1% to 3% Yield

Matsunaga, S. N., Wiedinmyer, C., Guenther, A. B., Orlando, J. J., Thomas, K., Greenberg, J. P., Kajii Y. Isoprene oxidation products are a significant atmospheric aerosol component. in prep.

Claeys, M., Wang, W., Ion, A. C., Kourtchev, I., Gelencser, A., Maenhaut, W. Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide. Atmospheric Environment, 38 (2004) 4093-4098

Claeys, M., Graham, B., Vas, G., Wang, W., Vermeylen, R., Pashynska, V., Cafmeyer, J., Guyon, P., Andreae, M. O., Artaxo, P., Maenhaut, W. Formation of Secondary Organic Aerosols Through Photooxidation of Isoprene. Science, 308 (2004), 1173-1176

Recent literature has proposed pathways:

YGA = 8.49×10-2[NOx]0.15 + 2.64×10-3[Isoprene] – 1.70×10-4[O3] - 9.20×10-3

YHA = 8.26×10-2[NOx]0.2 - 4.38×10-3[Isoprene] – 1.30×10-4[O3] + 2.37×10-2

YMG = 5.68×10-2[NOx]0.1 + 1.07×10-2[Isoprene] + 3.60×10-4[O3] – 3.54×10-2

High Uncertainties: Assume 1% to 3% Yield

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OC from Isoprene Corrected Bias�-remaining bias from biomass burning regions

GEOS-CHEM – IMPROVE [ug/m³]

April, 2002

May, 2002

June, 2002

July, 2002

August, 2002

September, 2002

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OC Does Not Correct AOD Bias

MODIS, July 2002

GEOS-CHEM w Isoprene Yield, July 2002

Optical Depth at 550nm [unitless]

AERONET, July 2002

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Preliminary Vertical Structure Evaluation - ICARTT

NH₄

NO₃

OC

SO₄

GEOS-CHEM

PILS

AMS

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Summary

Low yield OC production from isoprene corrects seasonal bias
Biomass burning inventories for 2002 are needed
Continue to evaluate model vertical structure using ICARTT data

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Acknowledgements

Randall Martin
Alex Guenther
Rokjin Park
Solene Turquety
Easan Drury