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Transport patterns of global aviation NOx and their short-term O3 radiative forcing - a machine learning approach

Maruhashi, Jin and Grewe, Volker and Frömming, Christine and Jöckel, Patrick and Dedoussi, Irene C. (2022) Transport patterns of global aviation NOx and their short-term O3 radiative forcing - a machine learning approach. Atmospheric Chemistry and Physics (ACP), 22 (21), pp. 14253-14282. Copernicus Publications. doi: 10.5194/acp-22-14253-2022. ISSN 1680-7316.

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Official URL: https://acp.copernicus.org/articles/22/14253/2022/

Abstract

Aviation produces a net climate warming contribution that comprises multiple forcing terms of mixed sign. Aircraft NOx emissions are associated with both warming and cooling terms, with the short-term increase in O3 induced by NOx emissions being the dominant warming effect. The uncertainty associated with the magnitude of this climate forcer is amongst the highest out of all contributors from aviation and is owed to the nonlinearity of the NOx–O3 chemistry and the large dependency of the response on space and time, i.e., on the meteorological condition and background atmospheric composition. This study addresses how transport patterns of emitted NOx and their climate effects vary with respect to regions (North America, South America, Africa, Eurasia and Australasia) and seasons (January–March and July–September in 2014) by employing global-scale simulations. We quantify the climate effects from NOx emissions released at a representative aircraft cruise altitude of 250 hPa (∼10 400 m) in terms of radiative forcing resulting from their induced short-term contributions to O3. The emitted NOx is transported with Lagrangian air parcels within the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. To identify the main global transport patterns and associated climate impacts of the 14 000 simulated air parcel trajectories, the unsupervised QuickBundles clustering algorithm is adapted and applied. Results reveal a strong seasonal dependence of the contribution of NOx emissions to O3. For most regions, an inverse relationship is found between an air parcel's downward transport and its mean contribution to O3. NOx emitted in the northern regions (North America and Eurasia) experience the longest residence times in the upper midlatitudes (40 %–45 % of their lifetime), while those beginning in the south (South America, Africa and Australasia) remain mostly in the Tropics (45 %–50 % of their lifetime). Due to elevated O3 sensitivities, emissions in Australasia induce the highest overall radiative forcing, attaining values that are larger by factors of 2.7 and 1.2 relative to Eurasia during January and July, respectively. The location of the emissions does not necessarily correspond to the region that will be most affected – for instance, NOx over North America in July will induce the largest radiative forcing in Europe. Overall, this study highlights the spatially and temporally heterogeneous nature of the NOx–O3 chemistry from a global perspective, which needs to be accounted for in efforts to minimize aviation's climate impact, given the sector's resilient growth.

Item URL in elib:https://elib.dlr.de/189814/
Document Type:Article
Title:Transport patterns of global aviation NOx and their short-term O3 radiative forcing - a machine learning approach
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Maruhashi, JinTU DelftUNSPECIFIED
Grewe, VolkerDLR, IPAhttps://orcid.org/0000-0002-8012-6783
Frömming, ChristineDLR, IPAhttps://orcid.org/0000-0001-5516-7180
Jöckel, PatrickDLR, IPAhttps://orcid.org/0000-0002-8964-1394
Dedoussi, Irene C.TU DelftUNSPECIFIED
Date:8 November 2022
Journal or Publication Title:Atmospheric Chemistry and Physics (ACP)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:22
DOI:10.5194/acp-22-14253-2022
Page Range:pp. 14253-14282
Publisher:Copernicus Publications
ISSN:1680-7316
Status:Published
Keywords:Transport pathways Aviation NOx ozone
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Air Transportation and Impact
DLR - Research area:Aeronautics
DLR - Program:L AI - Air Transportation and Impact
DLR - Research theme (Project):L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Grewe, Prof. Dr. Volker
Deposited On:08 Nov 2022 15:14
Last Modified:30 Nov 2022 14:02

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