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Description and Evaluation of the Specified-Dynamics Experiment in the Chemistry-Climate Model Initiative We provide an overview of the REF-C1SD specified-dynamics experiment that was conducted as part of phase 1 of the Chemistry-Climate Model Initiative (CCMI). The REF-C1SD experiment, which consisted of mainly nudged general circulation models (GCMs) constrained with (re)analysis fields, was designed to examine the influence of the large-scale circulation on past trends in atmospheric composition. The REF-C1SD simulations were produced across various model frameworks and are evaluated in terms of how well they represent different measures of the dynamical and transport circulations. In the troposphere there are large (~40 %) differences in the climatological mean distributions, seasonal cycle amplitude, and trends of the meridional and vertical winds. In the stratosphere there are similarly large (~50 %) differences in the magnitude, trends and seasonal cycle amplitude of the transformed Eulerian mean circulation and among various chemical and idealized tracers. At the same time, interannual variations in nearly all quantities are very well represented, compared to the underlying reanalyses. We show that the differences in magnitude, trends and seasonal cycle are not related to the use of different reanalysis products; rather, we show they are associated with how the simulations were implemented, by which we refer both to how the large-scale flow was prescribed and to biases in the underlying free-running models. In most cases these differences are shown to be as large or even larger than the differences exhibited by free-running simulations produced using the exact same models, which are also shown to be more dynamically consistent. Overall, our results suggest that care must be taken when using specified-dynamics simulations to examine the influence of large-scale dynamics on composition.
Document ID
20205000259
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Clara Orbe
(Goddard Institute for Space Studies)
David A. Plummer
(Environment and Climate Change Canada)
Darryn Warwick Waugh
(Johns Hopkins University Baltimore, Maryland, United States)
Huang Yang
(Johns Hopkins University Baltimore, Maryland, United States)
Patrick Jockel
(German Aerospace Center Cologne, Germany)
Douglas E. Kinnison
(National Center for Atmospheric Research Boulder, Colorado, United States)
Beatrice Josse
(Centre National de Recherches Météorologiques Toulouse, France)
Virginie Marecal
(Centre National de Recherches Météorologiques Toulouse, France)
Makoto Deushi
(Meteorological Research Institute (MRI))
Nathan Luke Abraham
(University of Cambridge Cambridge, United Kingdom)
Alexander T. Archibald
(University of Cambridge Cambridge, United Kingdom)
Martyn P. Chipperfield
(University of Leeds Leeds, United Kingdom)
Sandip Dhomse
(University of Leeds Leeds, United Kingdom)
Wuhu Feng
(National Centre for Atmospheric Science Leeds, England, United Kingdom)
Slimane Bekki
(Laboratoire de Météorologie Dynamique Palaiseau, France)
Date Acquired
March 31, 2020
Publication Date
March 31, 2020
Publication Information
Publication: Atmospheric Chemistry and Physics
Publisher: European Geosciences Union
Volume: 20
Issue: 6
Issue Publication Date: January 1, 2020
ISSN: 1680-7316
e-ISSN: 1680-7324
Subject Category
Meteorology And Climatology
Funding Number(s)
WBS: 281945.02.31.04.14
CONTRACT_GRANT: AGS-1403676
CONTRACT_GRANT: NNX14AP58G
Distribution Limits
Public
Copyright
Use by or on behalf of the US Gov. Permitted.
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