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Sensitivity to grid resolution in the ability of a chemical transport model to simulate observed oxidant chemistry under high-isoprene conditions

Yu, Karen and Jacob, Daniel J. and Fisher, Jenny A. and Kim, Patrick S. and Marais, Eloise A. and Miller, Christopher C. and Travis, Katherine R. and Zhu, Lei and Yantosca, Robert M. and Sulprizio, Melissa P. and Cohen, Ron C. and Dibb, Jack E. and Fried, Alan and Mikoviny, Tomas and Ryerson, Thomas B. and Wennberg, Paul O. and Wisthaler, Armin (2016) Sensitivity to grid resolution in the ability of a chemical transport model to simulate observed oxidant chemistry under high-isoprene conditions. Atmospheric Chemistry and Physics Discussions, 16 (7). pp. 4369-4378. ISSN 1680-7367.

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Formation of ozone and organic aerosol in continental atmospheres depends on whether isoprene emitted by vegetation is oxidized by the high-NO_x pathway (where peroxy radicals react with NO) or by low-NO_x pathways (where peroxy radicals react by alternate channels, mostly with HO_2). We used mixed layer observations from the SEAC^4RS aircraft campaign over the Southeast US to test the ability of the GEOS-Chem chemical transport model at different grid resolutions (0.25°  ×  0.3125°, 2°  ×  2.5°, 4°  ×  5°) to simulate this chemistry under high-isoprene, variable-NO_x conditions. Observations of isoprene and NO_x over the Southeast US show a negative correlation, reflecting the spatial segregation of emissions; this negative correlation is captured in the model at 0.25°  ×  0.3125° resolution but not at coarser resolutions. As a result, less isoprene oxidation takes place by the high-NO_x pathway in the model at 0.25°  ×  0.3125° resolution (54 %) than at coarser resolution (59 %). The cumulative probability distribution functions (CDFs) of NO_x, isoprene, and ozone concentrations show little difference across model resolutions and good agreement with observations, while formaldehyde is overestimated at coarse resolution because excessive isoprene oxidation takes place by the high-NO_x pathway with high formaldehyde yield. The good agreement of simulated and observed concentration variances implies that smaller-scale non-linearities (urban and power plant plumes) are not important on the regional scale. Correlations of simulated vs. observed concentrations do not improve with grid resolution because finer modes of variability are intrinsically more difficult to capture. Higher model resolution leads to decreased conversion of NO_x to organic nitrates and increased conversion to nitric acid, with total reactive nitrogen oxides (NO_y) changing little across model resolutions. Model concentrations in the lower free troposphere are also insensitive to grid resolution. The overall low sensitivity of modeled concentrations to grid resolution implies that coarse resolution is adequate when modeling continental boundary layer chemistry for global applications.

Item Type:Article
Related URLs:
URLURL TypeDescription
Jacob, Daniel J.0000-0002-6373-3100
Marais, Eloise A.0000-0001-5477-8051
Travis, Katherine R.0000-0003-1628-0353
Sulprizio, Melissa P.0000-0003-4641-5546
Cohen, Ron C.0000-0001-6617-7691
Dibb, Jack E.0000-0003-3096-7709
Ryerson, Thomas B.0000-0003-2800-7581
Wennberg, Paul O.0000-0002-6126-3854
Additional Information:© Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 05 Dec 2015. Published in Atmos. Chem. Phys. Discuss.: 18 Jan 2016. Revised: 26 Mar 2016. Accepted: 29 Mar 2016. Published: 07 Apr 2016. Edited by: M. C. Facchini. We are grateful to the entire NASA SEAC^4RS team for their help in the field. This work was funded by the NASA Atmospheric Composition Modeling and Analysis Program and by the NASA Tropospheric Chemistry Program. Jenny A. Fisher acknowledges financial support from a University of Wollongong Vice Chancellor’s Postdoctoral Fellowship. Isoprene measurements during SEAC^4RS were supported by the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) through the Austrian Space Applications Programme (ASAP) of the Austrian Research Promotion Agency (FFG). Armin Wisthaler and Tomas Mikoviny received support from the Visiting Scientist Program at the National Institute of Aerospace (NIA).
Funding AgencyGrant Number
Austrian Space Applications Programme (ASAP)UNSPECIFIED
Österreichische Forschungsförderungsgesellschaft (FFG)UNSPECIFIED
National Institute of Aerospace (NIA)UNSPECIFIED
Issue or Number:7
Record Number:CaltechAUTHORS:20160519-143211547
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Official Citation:Yu, K., Jacob, D. J., Fisher, J. A., Kim, P. S., Marais, E. A., Miller, C. C., Travis, K. R., Zhu, L., Yantosca, R. M., Sulprizio, M. P., Cohen, R. C., Dibb, J. E., Fried, A., Mikoviny, T., Ryerson, T. B., Wennberg, P. O., and Wisthaler, A.: Sensitivity to grid resolution in the ability of a chemical transport model to simulate observed oxidant chemistry under high-isoprene conditions, Atmos. Chem. Phys., 16, 4369-4378, doi:10.5194/acp-16-4369-2016, 2016.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67193
Deposited By: Ruth Sustaita
Deposited On:19 May 2016 22:07
Last Modified:09 Mar 2020 13:19

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