Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 5467-5479, 2016
http://www.atmos-chem-phys.net/16/5467/2016/
doi:10.5194/acp-16-5467-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
02 May 2016
The global tropospheric ammonia distribution as seen in the 13-year AIRS measurement record
Juying X. Warner1, Zigang Wei1, L. Larrabee Strow2, Russell R. Dickerson1, and John B. Nowak3 1Department of Atmospheric and Oceanic Science, University of Maryland College Park, College Park, MD 20742, USA
2Department of Physics and Joint Center for Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21250, USA
3Aerodyne Research, Inc., Billerica, MA 01821, USA
Abstract. Ammonia (NH3) plays an increasingly important role in the global biogeochemical cycle of reactive nitrogen as well as in aerosol formation and climate. We present extensive and nearly continuous global ammonia measurements made by the Atmospheric Infrared Sounder (AIRS) from the Aqua satellite to identify and quantify major persistent and episodic sources as well as to characterize seasonality. We examine the 13-year period from September 2002 through August 2015 with a retrieval algorithm using an optimal estimation technique with a set of three, spatially and temporally uniform a priori profiles. Vertical profiles show good agreement (∼  5–15 %) between AIRS NH3 and the in situ profiles from the winter 2013 DISCOVER-AQ (DISCOVER-Air Quality) field campaign in central California, despite the likely biases due to spatial resolution differences between the two instruments. The AIRS instrument captures the strongest consistent NH3 concentrations due to emissions from the anthropogenic (agricultural) source regions, such as South Asia (India/Pakistan), China, the United States (US), parts of Europe, Southeast (SE) Asia (Thailand/Myanmar/Laos), the central portion of South America, as well as Western and Northern Africa. These correspond primarily to irrigated croplands, as well as regions with heavy precipitation, with extensive animal feeding operations and fertilizer applications where a summer maximum and a secondary spring maximum are reliably observable. In the Southern Hemisphere (SH) regular agricultural fires contribute to a spring maximum. Regions of strong episodic emissions include Russia and Alaska as well as parts of South America, Africa, and Indonesia. Biomass burning, especially wildfires, dominate these episodic NH3 high concentrations.

Citation: Warner, J. X., Wei, Z., Strow, L. L., Dickerson, R. R., and Nowak, J. B.: The global tropospheric ammonia distribution as seen in the 13-year AIRS measurement record, Atmos. Chem. Phys., 16, 5467-5479, doi:10.5194/acp-16-5467-2016, 2016.
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Short summary
We present the global distributions of tropospheric ammonia observed by the satellite sensor AIRS from September 2002 through August 2015. The AIRS instrument captures the ammonia concentrations emitted from the anthropogenic (agricultural) source regions where a summer maximum and secondary spring maximum are observable, and the high ammonia concentrations from episodic biomass burning events.
We present the global distributions of tropospheric ammonia observed by the satellite sensor...
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