Document Type
Article
Publication Date
8-13-2015
Department
Department of Physics
Abstract
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 < sup> -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.
Publication Title
Atmospheric Measurement Techniques
Recommended Citation
Siebert, H.,
Shaw, R. A.,
Ditas, J.,
Schmeissner, T.,
Malinowski, S.,
Bodenschatz, E.,
&
Xu, H.
(2015).
High-resolution measurement of cloud microphysics and turbulence at a mountaintop station.
Atmospheric Measurement Techniques,
8(8), 3219-3228.
http://doi.org/10.5194/amt-8-3219-2015
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/3182
Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.
Version
Publisher's PDF
Publisher's Statement
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License. Publisher’s version of record: https://doi.org/10.5194/amt-8-3219-2015