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| Titel |
Can one detect small-scale turbulence from standard meteorological radiosondes? |
| VerfasserIn |
R. Wilson, F. Dalaudier, H. Luce |
| 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. 5 ; Nr. 4, no. 5 (2011-05-04), S.795-804 |
| Datensatznummer |
250001974
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| Publikation (Nr.) |
 copernicus.org/amt-4-795-2011.pdf |
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| Zusammenfassung |
It has been recently proposed by Clayson and
Kantha (2008) to evaluate
the climatology of atmospheric turbulence through the
detection of overturns in the free atmosphere
by applying a Thorpe analysis on
relatively low vertical resolution (LR) profiles
collected from standard radiosoundings.
Since then, several studies based on this idea
have been published.
However, the impact of instrumental noise on the detection
of turbulent layers was completely ignored in these works.
The present study aims to evaluate the feasibility of overturns
detection from radiosoundings.
For this purpose, we analyzed data of two field campaigns
during which high-resolution (HR) soundings
(10–20 cm) were performed simultaneously
with standard LR soundings.
We used the raw data of standard meteorological radiosondes,
the vertical resolution ranging from 5 to 9 m.
A Thorpe analysis was applied to both LR and HR
potential temperature profiles.
A denoising procedure was first applied
in order to reduce the probability of occurrence
of artificial overturns,
i.e. potential temperature inversions due to instrumental noise only.
We then compared the empirical probability density functions
(pdf) of the sizes of the selected overturns from LR and HR profiles.
From HR profiles measured in the troposphere,
the sizes of the detected overturns range from
4 to ~1000 m.
The shape of the size pdf of overturns
is found to sharply decrease with increasing scales.
From LR profiles,
the smallest size of detected overturns is ~32 m,
a similar decrease in the shape
of the pdf of sizes being observed.
These results suggest that overturns,
resulting either from small-scale turbulence
or from instabilities,
can indeed be detected from meteorological radiosonde measurements
in the troposphere and in the stratosphere as well.
However they are rather rare as they belong
to the tail of the size distribution of overturns:
they only represent the 7 % largest events in the troposphere,
and 4 % in the stratosphere. |
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