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

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 methyl, ethyl, and propyl nitrates in a global chemical transport model (GEOS-Chem). We show that the model can repro...

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Bibliographic Details
Main Authors: Fisher, Jenny, Atlas, Elliot, Barletta, Barbara, Meinardi, Simone, Blake, Don, Thompson, Chelsea, Ryerson, Thomas, Peischl, Jeff, Tzompa-Sosa, Zitely, Murray, Lee
Format: Report
Language:unknown
Published: EarthArXiv 2018
Subjects:
Physical Sciences and Mathematics
Oceanography and Atmospheric Sciences and Meteorology
Atmospheric Sciences
FOS Earth and related environmental sciences
Austral
Pacific
Southern Ocean
Online Access:https://dx.doi.org/10.17605/osf.io/ny857
https://eartharxiv.org/ny857/
Description
Summary: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 methyl, ethyl, and propyl nitrates 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. Combined, 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 in situ 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 emissions growth across the southern hemisphere may further enhance the importance of RONO2 as a NOx reservoir.

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