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| Titel |
Aerosol specification in single-column Community Atmosphere Model version 5 |
| VerfasserIn |
B. Lebassi-Habtezion, P. M. Caldwell |
| 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 ; 8, no. 3 ; Nr. 8, no. 3 (2015-03-27), S.817-828 |
| Datensatznummer |
250116189
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| Publikation (Nr.) |
 copernicus.org/gmd-8-817-2015.pdf |
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| Zusammenfassung |
| Single-column model (SCM) capability is an important tool for general
circulation model development. In this study, the SCM mode of version 5 of
the Community Atmosphere Model (CAM5) is shown to handle aerosol
initialization and advection improperly, resulting in aerosol, cloud-droplet,
and ice crystal concentrations which are typically much lower than observed
or simulated by CAM5 in global mode. This deficiency has a major impact on
stratiform cloud simulations but has little impact on convective case studies
because aerosol is currently not used by CAM5 convective schemes and
convective cases are typically longer in duration (so initialization is less
important). By imposing fixed aerosol or cloud-droplet and crystal number
concentrations, the aerosol issues described above can be avoided.
Sensitivity studies using these idealizations suggest that the Meyers et
al. (1992) ice nucleation scheme prevents mixed-phase cloud from existing by
producing too many ice crystals. Microphysics is shown to strongly deplete
cloud water in stratiform cases, indicating problems with sequential
splitting in CAM5 and the need for careful interpretation of output from
sequentially split climate models. Droplet concentration in the general circulation model (GCM) version
of CAM5 is also shown to be far too low (~ 25 cm−3) at the
southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site. |
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