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| Titel |
Cloud base vertical velocity statistics: a comparison between an atmospheric mesoscale model and remote sensing observations |
| VerfasserIn |
J. Tonttila, E. J. O'Connor, S. Niemelä, P. Räisänen, H. Järvinen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 17 ; Nr. 11, no. 17 (2011-09-07), S.9207-9218 |
| Datensatznummer |
250010058
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| Publikation (Nr.) |
 copernicus.org/acp-11-9207-2011.pdf |
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| Zusammenfassung |
| The statistics of cloud base vertical velocity simulated by the
non-hydrostatic mesoscale model AROME are compared with Cloudnet remote
sensing observations at two locations: the ARM SGP site in central Oklahoma,
and the DWD observatory at Lindenberg, Germany. The results show that AROME
significantly underestimates the variability of vertical velocity at cloud
base compared to observations at their nominal resolution; the standard
deviation of vertical velocity in the model is typically 4–8 times smaller
than observed, and even more during the winter at Lindenberg. Averaging the
observations to the horizontal scale corresponding to the physical grid
spacing of AROME (2.5 km) explains 70–80 % of the underestimation by
the model. Further averaging of the observations in the horizontal is
required to match the model values for the standard deviation in vertical
velocity. This indicates an effective horizontal resolution for the AROME
model of at least 10 km in the presented case. Adding a TKE-term on the
resolved grid-point vertical velocity can compensate for the underestimation,
but only for altitudes below approximately the boundary layer top height. The
results illustrate the need for a careful consideration of the scales the
model is able to accurately resolve, as well as for a special treatment of
sub-grid scale variability of vertical velocities in kilometer-scale
atmospheric models, if processes such as aerosol-cloud interactions are to be
included in the future. |
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