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The influence of mixing on the stratospheric age of air changes in the 21st century

Eichinger, Roland and Dietmüller, Simone and Garny, Hella and Sacha, Petr and Birner, Thomas and Bönisch, Harald and Pitari, Giovanni and Visioni, Daniele and Stenke, Andrea and Rozanov, Eugene and Revell, Laura and Plummer, David and Jöckel, Patrick and Oman, Luke and Deushi, Makoto and Kinnison, Douglas and Garcia, Rolando and Morgenstern, Olaf and Zeng, Guang and Stone, Kane and Schofield, Robyn (2019) The influence of mixing on the stratospheric age of air changes in the 21st century. Atmospheric Chemistry and Physics, 19, pp. 921-940. Copernicus Publications. doi: 10.5194/acp-19-921-2019. ISSN 1680-7316.

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Official URL: https://www.atmos-chem-phys.net/19/921/2019/


Climate models consistently predict an acceleration of the Brewer-Dobson circulation (BDC) due to climate change in the 21st century. However, the strength of this acceleration varies considerably among individual models, which constitutes a notable source of uncertainty for future climate projections. To shed more light upon the magnitude of this uncertainty and on its causes, we analyse the stratospheric mean age of air (AoA) of 10 climate projection simulations from the Chemistry-Climate Model Initiative phase 1 (CCMI-I), covering the period between 1960 and 2100. In agreement with previous multi-model studies, we find a large model spread in the magnitude of the AoA trend over the simulation period. Differences between future and past AoA are found to be predominantly due to differences in mixing (reduced aging by mixing and recirculation) rather than differences in residual mean transport. We furthermore analyse the mixing efficiency, a measure of the relative strength of mixing for given residual mean transport, which was previously hypothesised to be a model constant. Here, the mixing efficiency is found to vary not only across models, but also over time in all models. Changes in mixing efficiency are shown to be closely related to changes in AoA and quantified to roughly contribute 10 % to the long-term AoA decrease over the 21st century. Additionally, mixing efficiency variations are shown to considerably enhance model spread in AoA changes. To understand these mixing efficiency variations, we also present a consistent dynamical framework based on diffusive closure, which highlights the role of basic state potential vorticity gradients in controlling mixing efficiency and therefore aging by mixing.

Item URL in elib:https://elib.dlr.de/126503/
Document Type:Article
Title:The influence of mixing on the stratospheric age of air changes in the 21st century
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Eichinger, RolandDLR, IPA und MIM, Univ. MünchenUNSPECIFIED
Garny, HellaDLR, IPA und MIM, Univ. MünchenUNSPECIFIED
Sacha, PetrUniv. Prag, Tschechische RepublikUNSPECIFIED
Birner, ThomasMIM, Univ. MünchenUNSPECIFIED
Bönisch, HaraldKIT KarlsruheUNSPECIFIED
Pitari, GiovanniUniv. Acquila, ItalienUNSPECIFIED
Visioni, DanieleUniv. Acquila, ItalienUNSPECIFIED
Stenke, AndreaETH Zürich, SchweizUNSPECIFIED
Rozanov, EugeneETH Zürich und PMOD, Davos, SchweizUNSPECIFIED
Revell, LauraUniv. Canterbury, NeuseelandUNSPECIFIED
Plummer, DavidECCC, Montréal, KanadaUNSPECIFIED
Oman, LukeECCC, Montréal, KanadaUNSPECIFIED
Deushi, MakotoMRI, Tsukuba, JapanUNSPECIFIED
Kinnison, DouglasNCAR, Boulder, CO, USAUNSPECIFIED
Garcia, RolandoNCAR, Boulder, CO, USAUNSPECIFIED
Morgenstern, OlafNIWA, Wellington, NeuseelandUNSPECIFIED
Zeng, GuangNIWA, Wellington, NeuseelandUNSPECIFIED
Stone, KaneUniv. Melbourne, AustraliaUNSPECIFIED
Schofield, RobynUniv. Melbourne, AustraliaUNSPECIFIED
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 921-940
Publisher:Copernicus Publications
Keywords:Stratosphere, Age of air, mixing, CCMI, climate projection, simulation, model
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Middle Atmosphere, R - Atmospheric and climate research
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Eichinger, Roland
Deposited On:15 Feb 2019 17:53
Last Modified:02 May 2019 14:05

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