Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 9081-9102, 2017
https://doi.org/10.5194/acp-17-9081-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Jul 2017
Global atmospheric chemistry – which air matters
Michael J. Prather1, Xin Zhu1, Clare M. Flynn1, Sarah A. Strode2,3, Jose M. Rodriguez2, Stephen D. Steenrod2,3, Junhua Liu2,3, Jean-Francois Lamarque4, Arlene M. Fiore5, Larry W. Horowitz6, Jingqiu Mao7, Lee T. Murray8, Drew T. Shindell9, and Steven C. Wofsy10 1Department of Earth System Science, University of California, Irvine, CA 92697-3100, USA
2NASA Goddard Space Flight Center, Greenbelt, MD, USA
3Universities Space Research Association (USRA), GESTAR, Columbia, MD, USA
4Atmospheric Chemistry, Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80301, USA
5Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA
6Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, NJ, USA
7Geophysical Institute and Department of Chemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
8Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627-0221, USA
9Nicholas School of the Environment, Duke University, Durham, NC, USA
10School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
Abstract. An approach for analysis and modeling of global atmospheric chemistry is developed for application to measurements that provide a tropospheric climatology of those heterogeneously distributed, reactive species that control the loss of methane and the production and loss of ozone. We identify key species (e.g., O3, NOx, HNO3, HNO4, C2H3NO5, H2O, HOOH, CH3OOH, HCHO, CO, CH4, C2H6, acetaldehyde, acetone) and presume that they can be measured simultaneously in air parcels on the scale of a few km horizontally and a few tenths of a km vertically. As a first step, six global models have prepared such climatologies sampled at the modeled resolution for August with emphasis on the vast central Pacific Ocean basin. Objectives of this paper are to identify and characterize differences in model-generated reactivities as well as species covariances that could readily be discriminated with an unbiased climatology. A primary tool is comparison of multidimensional probability densities of key species weighted by the mass of such parcels or frequency of occurrence as well as by the reactivity of the parcels with respect to methane and ozone. The reactivity-weighted probabilities tell us which parcels matter in this case, and this method shows skill in differentiating among the models' chemistry. Testing 100 km scale models with 2 km measurements using these tools also addresses a core question about model resolution and whether fine-scale atmospheric structures matter to the overall ozone and methane budget. A new method enabling these six global chemistry–climate models to ingest an externally sourced climatology and then compute air parcel reactivity is demonstrated. Such an objective climatology containing these key species is anticipated from the NASA Atmospheric Tomography (ATom) aircraft mission (2015–2020), executing profiles over the Pacific and Atlantic Ocean basins. This modeling study addresses a core part of the design of ATom.

Citation: Prather, M. J., Zhu, X., Flynn, C. M., Strode, S. A., Rodriguez, J. M., Steenrod, S. D., Liu, J., Lamarque, J.-F., Fiore, A. M., Horowitz, L. W., Mao, J., Murray, L. T., Shindell, D. T., and Wofsy, S. C.: Global atmospheric chemistry – which air matters, Atmos. Chem. Phys., 17, 9081-9102, https://doi.org/10.5194/acp-17-9081-2017, 2017.
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Short summary
We present a new approach for comparing atmospheric chemistry models with measurements based on what these models are used to do, i.e., calculate changes in ozone and methane, prime greenhouse gases. This method anticipates a new type of measurements from the NASA Atmospheric Tomography (ATom) mission. In comparing the mixture of species within air parcels, we focus on those responsible for key chemical changes and weight these parcels by their chemical reactivity.
We present a new approach for comparing atmospheric chemistry models with measurements based on...
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