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| Titel |
High-resolution measurement of cloud microphysics and turbulence at a mountaintop station |
| VerfasserIn |
H. Siebert, R. A. Shaw, J. Ditas, T. Schmeissner, S. P. Malinowski, E. Bodenschatz, H. Xu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 8 ; Nr. 8, no. 8 (2015-08-13), S.3219-3228 |
| Datensatznummer |
250116526
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| Publikation (Nr.) |
 copernicus.org/amt-8-3219-2015.pdf |
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| Zusammenfassung |
| Mountain research stations are advantageous not only for long-term sampling
of cloud properties but also for measurements that are
prohibitively difficult
to perform on airborne platforms due to the large true air speed or adverse
factors such as weight and complexity of the equipment necessary. Some
cloud–turbulence measurements, especially Lagrangian in nature, fall into
this category. We report results from simultaneous, high-resolution and
collocated measurements of cloud microphysical and turbulence properties
during several warm cloud events at the Umweltforschungsstation
Schneefernerhaus (UFS) on Zugspitze in the German Alps. The data gathered
were found to be representative of observations made with similar instrumentation
in free clouds. The observed turbulence shared all features known for
high-Reynolds-number flows: it exhibited approximately Gaussian fluctuations for
all three velocity components, a clearly defined inertial subrange following
Kolmogorov scaling (power spectrum, and second- and third-order Eulerian
structure functions), and highly intermittent velocity gradients, as well as
approximately lognormal kinetic energy dissipation rates. The clouds were
observed to have liquid water contents on the order of 1 g m−3 and size
distributions typical of continental clouds, sometimes exhibiting long
positive tails indicative of large drop production through turbulent mixing
or coalescence growth. Dimensionless parameters relevant to cloud–turbulence
interactions, the Stokes number and settling parameter are in the range
typically observed in atmospheric clouds. Observed fluctuations in droplet
number concentration and diameter suggest a preference for inhomogeneous
mixing. Finally, enhanced variance in liquid water content fluctuations is
observed at high frequencies, and the scale break occurs at a value
consistent with the independently estimated phase relaxation time from
microphysical measurements. |
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