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| Titel |
Downscale cascades in tracer transport test cases: an intercomparison of the dynamical cores in the Community Atmosphere Model CAM5 |
| VerfasserIn |
J. Kent, C. Jablonowski, J. P. Whitehead, R. B. Rood |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 6 ; Nr. 5, no. 6 (2012-12-06), S.1517-1530 |
| Datensatznummer |
250002955
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| Publikation (Nr.) |
 copernicus.org/gmd-5-1517-2012.pdf |
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| Zusammenfassung |
The accurate modeling of cascades to unresolved scales is an important part
of the tracer transport component of dynamical cores of weather and climate
models. This paper aims to investigate the ability of the advection schemes
in the National Center for Atmospheric Research's Community Atmosphere Model
version 5 (CAM5) to model this cascade. In order to quantify the effects of
the different advection schemes in CAM5, four two-dimensional tracer
transport test cases are presented. Three of the tests stretch the tracer
below the scale of coarse resolution grids to ensure the downscale cascade of
tracer variance. These results are compared with a high resolution reference
solution, which is simulated on a resolution fine enough to resolve the
tracer during the test. The fourth test has two separate flow cells, and is
designed so that any tracer in the western hemisphere should not pass into
the eastern hemisphere. This is to test whether the diffusion in transport
schemes, often in the form of explicit hyper-diffusion terms or implicit
through monotonic limiters, contains unphysical mixing.
An intercomparison of three of the dynamical cores of the National Center for
Atmospheric Research's Community Atmosphere Model version 5 is performed. The
results show that the finite-volume (CAM-FV) and spectral element (CAM-SE)
dynamical cores model the downscale cascade of tracer variance better than
the semi-Lagrangian transport scheme of the Eulerian spectral transform core
(CAM-EUL). Each scheme tested produces unphysical mass in the eastern
hemisphere of the separate cells test. |
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