Publication Date:
2023-11-15
Description:
〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Chemical processing of reactive nitrogen species, especially of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 (= NO + NO〈sub〉2〈/sub〉) and nitrous acid (HONO), determines the photochemical ozone production and oxidation capacity in the troposphere. However, sources of HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 in the remote marine atmosphere are still poorly understood. In this work, the multiphase chemistry mechanism CAPRAM in the model framework SPACCIM was used to study HONO formation at Cape Verde (CVAO) in October 2017, adopted with the input of current parameterizations for various HONO sources. Three simulations were performed that adequately reproduced ambient HONO levels and its diurnal pattern. The model performance for NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 and O〈sub〉3〈/sub〉 improves significantly when considering dust‐surface‐photocatalytic conversions of reactive nitrogen compounds with high correlation coefficients up to 0.93, 0.56, and 0.89 for NO, NO〈sub〉2〈/sub〉, and O〈sub〉3〈/sub〉, respectively. Photocatalytic conversion of the adsorbed HNO〈sub〉3〈/sub〉 on dust is modeled to be the predominant contributor for daytime HONO at CVAO, that is, accounting for about 62% of the chemical formation rate at noontime. In contrast, the ocean‐surface‐mediated conversion of NO〈sub〉2〈/sub〉 to HONO and other discussed pathways are less important. The average OH levels at midday (9:00–16:00) modeled for cluster trajectory 1, 2, and 3 are 5.2, 5.1, and 5.2 × 10〈sup〉6〈/sup〉 molecules cm〈sup〉−3〈/sup〉, respectively. Main OH formation is driven by O〈sub〉3〈/sub〉 photolysis with a contribution of 74.6% to the total source rate, while HONO photolysis is negligible (∼1.8%). In summary, this study highlights the key role of dust aerosols for HONO formation and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 cycling at CVAO and possibly in other dust‐affected regions, urgently calling for further investigations using field and model studies.〈/p〉
Description:
Plain Language Summary: Chemical processing of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 (= NO + NO〈sub〉2〈/sub〉) and nitrous acid (HONO) is important for the tropospheric O〈sub〉3〈/sub〉 budget and oxidation capacity. However, the sources of HONO and cycling of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 in the remote marine atmosphere are still poorly explored. A detailed multiphase chemistry model simulation showed a better performance of HONO, NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 and O〈sub〉3〈/sub〉 when considering dust‐surface‐photocatalytic conversions of reactive nitrogen compounds, especially the photocatalytic conversion of the adsorbed HNO〈sub〉3〈/sub〉 on dust. The simulations demonstrated that OH formation is mainly driven by the O〈sub〉3〈/sub〉 photolysis, while HONO photolysis is a negligible OH radical source due to its low concentration levels at Cape Verde. The study highlights the key role of dust aerosols for HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 chemistry in the remote marine boundary layer.〈/p〉
Description:
Key Points:
〈list list-type="bullet"〉
〈list-item〉
〈p xml:lang="en"〉The sources of HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 at Cape Verde are well modeled with CAPRAM〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Photocatalytic conversion of adsorbed HNO〈sub〉3〈/sub〉 on dust is the predominant contributor for daytime HONO〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Photolysis of O〈sub〉3〈/sub〉 is the prevailing source of OH radical at Cape Verde, while HONO photolysis is a negligible OH radical source〈/p〉〈/list-item〉
〈/list〉
〈/p〉
Description:
Leibniz Association SAW
Description:
Horizon 2020 Framework Programme
http://dx.doi.org/10.13039/100010661
Description:
National Key Research and Development Program of China
http://dx.doi.org/10.13039/501100012166
Description:
National Natural Science Foundation of China
http://dx.doi.org/10.13039/501100001809
Description:
https://doi.org/10.5281/zenodo.8070265
Description:
http://mcm.york.ac.uk/
Description:
https://capram.tropos.de/
Description:
https://ebas.nilu.no/
Description:
https://www.ready.noaa.gov/HYSPLIT_traj.php
Keywords:
ddc:551
;
HONO
;
NOx
;
CAPRAM
;
heterogenous chemistry
;
mineral dust
;
OH radical
;
marine boundary layer
Language:
English
Type:
doc-type:article
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