Methyl, ethyl, and propyl nitrates: global distribution and impacts on reactive nitrogen in remote marine environments

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2018jd029046.

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Authors

Jenny A. Fisher , Elliot L. Atlas, Barbara Barletta, Simone Meinardi, Don Blake, Chelsea R. Thompson, Thomas B. Ryerson, Jeff Peischl, Zitely A. Tzompa-Sosa, Lee T. Murray

Abstract

Alkyl nitrates (RONO2) are important components of tropospheric reactive nitrogen that serve as reservoirs for nitrogen oxides (NOx ≡ NO + NO2). Here we implement a new simulation of atmospheric methyl, ethyl, and propyl nitrate chemistry in a global chemical transport model (GEOS‐Chem). We show that the model can reproduce the spatial and seasonal variability seen in a 20‐year ensemble of airborne observations. Methyl nitrate accounts for 17 Gg N globally, with maxima over the tropical Pacific and Southern Ocean. Propyl nitrate is enhanced in continental boundary layers, but its global impact (6 Gg N) is limited by a short lifetime (8 days, versus 26 days for methyl nitrate and 14 days for ethyl nitrate) that inhibits long‐range transport. Ethyl nitrate has the smallest impact of the three species (4 Gg N). We find that methyl nitrate is the dominant form of reactive nitrogen (NOy) in the Southern Ocean marine boundary layer, where its addition to the model corrects a large NOy underestimate in austral winter relative to recent aircraft data. RONO2 serve as a small net NOx source to the marine troposphere, except in the northern mid‐latitudes where the continental outflow is enriched in precursors that promote NOx loss via RONO2 formation. Recent growth in NOx emissions from East Asia has enhanced the role of RONO2 as a source of NOx to the remote free troposphere. This relationship implies projected future NOx emissions growth across the southern hemisphere may further enhance the importance of RONO2 as a NOx reservoir.

DOI

https://doi.org/10.31223/osf.io/ny857

Subjects

Atmospheric Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Keywords

GEOS-Chem, air-sea exchange, alkyl nitrates, atmospheric chemistry, chemical transport model, methyl nitrate, nitrogen oxides, reactive nitrogen

Dates

Published: 2018-05-27 23:51

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License

GNU Lesser General Public License (LGPL) 2.1

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