Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species
Item
Title (Dublin Core)
Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species
Description (Dublin Core)
The isotope anomaly (Δ<sup>17</sup>O) of secondary atmospheric species such as nitrate (NO<sub>3</sub><sup>−</sup>) or hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) has potential to provide useful constrains on their formation pathways. Indeed, the Δ<sup>17</sup>O of their precursors (NO<sub>x</sub>, HO<sub>x</sub> etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ<sup>17</sup>O in the atmosphere. Interpreting variations of Δ<sup>17</sup>O in secondary species requires an in-depth understanding of the Δ<sup>17</sup>O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. <br><br> This article reviews and illustrates a series of basic concepts relevant to the propagation of the Δ<sup>17</sup>O of ozone to other reactive or secondary atmospheric species within a photochemical box model. We present results from numerical simulations carried out using the atmospheric chemistry box model CAABA/MECCA to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NO<sub>x</sub> and HO<sub>x</sub>. Using a simplified but realistic tropospheric gas-phase chemistry mechanism, Δ<sup>17</sup>O was propagated from ozone to other species (NO, NO<sub>2</sub>, OH, HO<sub>2</sub>, RO<sub>2</sub>, NO<sub>3</sub>, N<sub>2</sub>O<sub>5</sub>, HONO, HNO<sub>3</sub>, HNO<sub>4</sub>, H<sub>2</sub>O<sub>2</sub>) according to the mass-balance equations, through the implementation of various sets of hypotheses pertaining to the transfer of Δ<sup>17</sup>O during chemical reactions. <br><br> The model results confirm that diurnal variations in Δ<sup>17</sup>O of NO<sub>x</sub> predicted by the photochemical steady-state relationship during the day match those from the explicit treatment, but not at night. Indeed, the Δ<sup>17</sup>O of NO<sub>x</sub> is "frozen" at night as soon as the photolytical lifetime of NO<sub>x</sub> drops below ca. 10 min. We introduce and quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H<sub>2</sub>O<sub>2</sub>, which is of particular relevance to larger-scale simulations of Δ<sup>17</sup>O where high computational costs cannot be afforded.
Creator (Dublin Core)
Morin, S.
Sander, R.
Savarino, J.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-11-3653-2011
https://acp.copernicus.org/articles/11/3653/2011/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
