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| Titel |
In-situ turbulence observations in the stratospheric wind and temperature field with LITOS |
| VerfasserIn |
A. Schneider, A. Theuerkauf, M. Gerding, F.-J. Lübken |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063021
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| Zusammenfassung |
| Although stably stratified, turbulence occurs in the stratosphere due to breaking gravity
waves. This leads to energy dissipation which modifies the energy transfer from the
troposphere to the mesosphere. Stratospheric turbulence is also important for vertical mixing
of trace species. In order to derive turbulent parameters accurately very small scales on the
order of centimeters and below have to be resolved. This can only be performed applying
in-situ techniques. Our balloon-borne in-situ measurement system LITOS (Leibniz Institute
Turbulence Observations in the Stratosphere) utilizes constant temperature anemometer
(CTA) and constant current anemometer (CCA) for simultaneous observation of small scale
fluctuations of wind and temperature with high vertical resolution (~1 mm). The CTA
consists of a small, thin (5 µm) wire kept at constant temperature; its principle of
operation is based on the cooling effect of the air flow around the wire. The CCA
is a thin (3.8 µm) wire which is basically operated as a resistance thermometer.
Three flights in different configurations have been carried out at Kiruna, Sweden
(67°N, 21°E) within the BEXUS programme in 2008, 2009 and 2011. The balloons
reached altitudes of typically 27 km. To our knowledge, during the flights in 2009 and
2011 the first simultaneous turbulence measurements of winds and temperatures
in the stratosphere were performed. Turbulent layers with a vertical thickness in
the order of several 10 m have been observed. Results for energy dissipation rates
computed directly from the spectrum of wind or temperature fluctuations will be
presented. We will compare measurements from different flights for both wind and
temperature fluctuations and consider a potential dependence on background conditions. |
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