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| Titel |
A new airborne tandem platform for collocated measurements of microphysical cloud and radiation properties |
| VerfasserIn |
W. Frey, H. Eichler, M. Reus, R. Maser, M. Wendisch, S. Borrmann |
| 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 ; 2, no. 1 ; Nr. 2, no. 1 (2009-05-06), S.147-158 |
| Datensatznummer |
250000434
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| Publikation (Nr.) |
 copernicus.org/amt-2-147-2009.pdf |
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| Zusammenfassung |
| A new airborne tandem measurement platform for cloud-radiation interaction
studies is introduced in this paper. It consists of a Learjet 35A research
aircraft and the AIRcraft TOwed Sensor Shuttle (AIRTOSS), which is an
instrumented drag-body towed by the Learjet. Currently, the AIRTOSS is
instrumented with a Cloud Imaging Probe (CIP) for measuring cloud
microphysical properties and an Inertial Navigation System (INS) for
measurements of flight attitudes. The cable dragging AIRTOSS can be as long
as four kilometres. Thus, truly collocated measurements in two altitudes
above, in, and below clouds can be obtained. Results from first test flights
with Learjet and AIRTOSS are reported here. The flights were performed from
Hohn Airport, Germany. Specific manoeuvres were flown to test the aerodynamic
behaviour of the drag-body and to investigate the suitability of AIRTOSS for
high-precision irradiance measurements which require a stable flight attitude
of AIRTOSS. The flight attitude data show that AIRTOSS is sensitive to
several flight manoeuvres such as turns, altitude and airspeed changes, and
also to changes of towing cable length. The effects of these manoeuvres on
the attitude angles of AIRTOSS have been quantified. Maximum roll angle
deviations were observed during turns. Even small changes in heading
can lead to high roll angles (one degree change in heading causes a change in
roll angle of about eight degrees). The pitch angle varies during climb or
dive periods, extending or retracting of towing cable, acceleration or
deceleration, and even when flying at too low or too high true airspeed
depending on altitude. Values of pitch angle between −5° (dive) and
8° (climb and retracting towing cable) have been observed. While
change in attitude is not problematic for cloud particle property
measurements it is for radiation measurements. Here, the deviation from the
horizontal should be no more than 3° to avoid large errors. When
keeping the above mentioned flight parameters constant, sufficiently stable
flight conditions can be maintained to perform high-quality irradiance
measurements with AIRTOSS in future experiments. During this test campaign
also observations of cloud microphysical data as for example droplet number
concentrations and size distributions with the AIRTOSS in stratocumulus
clouds were performed to prove the compliance with scientific needs.
Simultaneous spectral cloud radiation measurements have been made. The
measurements of internal operational data of AIRTOSS as well as the first
atmospheric data demonstrate the suitability of this tandem platform for
detailed cloud microphysics and radiation interaction studies. |
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