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| Titel |
Modeling the ascent of sounding balloons: derivation of the vertical air motion |
| VerfasserIn |
A. Gallice, F. G. Wienhold, C. R. Hoyle, F. Immler, T. Peter |
| 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 ; 4, no. 10 ; Nr. 4, no. 10 (2011-10-20), S.2235-2253 |
| Datensatznummer |
250002121
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| Publikation (Nr.) |
 copernicus.org/amt-4-2235-2011.pdf |
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| Zusammenfassung |
| A new model to describe the ascent of sounding balloons in the
troposphere and lower stratosphere (up to ∼30–35 km
altitude) is presented. Contrary to previous models, detailed account
is taken of both the variation of the drag coefficient with altitude
and the heat imbalance between the balloon and the atmosphere. To
compensate for the lack of data on the drag coefficient of sounding
balloons, a reference curve for the relationship between drag
coefficient and Reynolds number is derived from a dataset of flights
launched during the Lindenberg Upper Air Methods Intercomparisons
(LUAMI) campaign. The transfer of heat from the surrounding air into
the balloon is accounted for by solving the radial heat diffusion
equation inside the balloon. In its present state, the model does not
account for solar radiation, i.e. it is only able to describe the
ascent of balloons during the night. It could however be adapted to
also represent daytime soundings, with solar radiation modeled as a
diffusive process. The potential applications of the model
include the forecast of the trajectory of sounding balloons, which can
be used to increase the accuracy of the match technique, and the
derivation of the air vertical velocity. The latter is obtained by
subtracting the ascent rate of the balloon in still air calculated by
the model from the actual ascent rate. This technique is shown to
provide an approximation for the vertical air motion with an
uncertainty error of 0.5 m s−1 in the troposphere and
0.2 m s−1 in the stratosphere. An example of extraction of
the air vertical velocity is provided in this paper. We show that the
air vertical velocities derived from the balloon soundings in this
paper are in general agreement with small-scale atmospheric velocity
fluctuations related to gravity waves, mechanical turbulence, or other
small-scale air motions measured during the SUCCESS campaign (Subsonic
Aircraft: Contrail and Cloud Effects Special Study) in the
orographically unperturbed mid-latitude middle troposphere. |
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