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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
16 Jan 2017
Review status
A revision of this discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Global Atmospheric Chemistry – Which Air Matters
Michael J. Prather1, Xin Zhu1, Clare M. Flynn1, Sarah A. Strode2,3, Jose M. Rodriguez3, 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 & Modelling 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, New York, USA
6Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, NJ, USA
7Geophysical Institute and Department of Chemistry, University of Alaska Fairbanks, Fairbanks, Alaska, 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, Massachusetts, 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 vertically. Six global models have prepared such climatologies (at model resolution) for August with emphasis on the vast central Pacific and Atlantic Ocean basins. We show clear 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 multi-dimensional probability densities of key species weighted by 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. 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 observed climatology is anticipated from the NASA Atmospheric Tomography (ATom) aircraft mission (2015–2020), measuring the key species, executing profiles over the Pacific and Atlantic Ocean basins. This work is 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. Discuss.,, in review, 2017.
Michael J. Prather et al.
Michael J. Prather et al.
Michael J. Prather et al.


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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 (calculate changes in ozone and methane, prime greenhouse gases) that 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...