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| Titel |
The ceilometer inter-comparison campaign CeiLinEx2015 |
| VerfasserIn |
Ina Mattis, Robert Begbie, Neda Boyouk, Juan Antonio Bravo-Aranda, Mike Brettle, Jan Cermak, Marc-Antoine Drouin, Alexander Geiß, Ulrich Görsdorf, Alexander Haefele, Martial Haeffelin, Maxime Hervo, Kateřina Komínková, Ronny Leinweber, Gerhard Müller, Christoph Münkel, Margit Pattantyús-Ábrahám, Kornelia Pönitz, Frank Wagner, Matthias Wiegner |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129557
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| Publikation (Nr.) |
 EGU/EGU2016-9687.pdf |
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| Zusammenfassung |
| Ceilometers are well established instruments for the detection of cloud base heights. Since
about 2000, modern ceilometer types (mainly CHM15k, CL51, and CL31) are used also for
investigations of the top height of the planetary boundary layer and for quantitative retrievals
of vertical profiles of backscatter coefficients. In the framework of the European projects
E-PROFILE and TOPROF, tools for the exchange of ceilometer data among European
meteorological services, as well as calibration and visualization procedures are developed and
established. Unfortunately, the national networks are equipped with instruments of
different generations and different manufacturers. In order to quantify and reduce those
inhomogeneities, the ceilometer inter-comparison experiment CeiLinEx2015 was performed
between June and September 2015 at the Meteorological Observatory Lindenberg,
Germany.
We tested six different instrument types: LD40, CL31, CL51, CHM15k, CHM15kx, and
CS135. Each instrument type was represented by two instruments to estimate the
instrument-to-instrument variability and the influence of different firmware versions.
Two Raman lidars (RAMSES and RALPH), operated by German Meteorological
Service (DWD) are used as reference instruments. Further ancillary data are available,
e.g., hourly eye observations, four radio soundings per day, and AERONET sun
photometer observations. Beside the typical vertically pointing measurement scheme, we
performed special measurements with horizontal pointing direction or blocked receiver
telescope.
During the experiment, we could collect measurements under very different
meteorological situations: Several clear nights allow for Rayleigh-Calibration (see Hervo and
CeiLinEx2015 team [EGU2016-4785]), a strong event of Sahara dust intrusion can be used to
study the behaviour of the instruments in presence of large, non-spherical particles (like
volcanic ash). Further investigations focus, e.g., on the detection of very low cloud
base heights, on the retrieval of boundary layer heights, on the performance of the
individual instruments in the overlap region, on the characterization of signal artefacts
in the clean free troposphere, on daytime performance, and on the estimation of
measurement range. All those investigations need calibrated ceilometer profiles as input
data. Therefore, quantitative calibration of all instruments is a very important first
step of data analysis. [Hervo and CeiLinEx2015 team EGU2016-4785] present the
procedure and results of calibration of all individual instruments in a companion
contribution.
In this contribution, we will provide a general overview on the CeiLinEx2015 experiment
together with first results. We present preliminary results concerning signal artefacts in the
free troposphere and correlation studies in more detail. |
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