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| Titel |
Ceilometer lidar comparison: backscatter coefficient retrieval and signal-to-noise ratio determination |
| VerfasserIn |
B. Heese, H. Flentje, D. Althausen, A. Ansmann, S. Frey |
| 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 ; 3, no. 6 ; Nr. 3, no. 6 (2010-12-20), S.1763-1770 |
| Datensatznummer |
250001373
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| Publikation (Nr.) |
 copernicus.org/amt-3-1763-2010.pdf |
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| Zusammenfassung |
| The potential of a new generation of ceilometer
instruments for aerosol monitoring has been studied in the
Ceilometer Lidar Comparison (CLIC) study. The used ceilometer was
developed by Jenoptik, Germany, and is designed to find both thin
cirrus clouds at tropopause level and aerosol layers at close ranges
during day and night-time. The comparison study was performed to
determine up to which altitude the ceilometers are capable to
deliver particle backscatter coefficient profiles. For this, the
derived ceilometer profiles are compared to simultaneously measured
lidar profiles at the same wavelength. The lidar used for the
comparison was the multi-wavelengths Raman lidar PollyXT. To
demonstrate the capabilities and limits of ceilometers for the
derivation of particle backscatter coefficient profiles from their
measurements two examples of the comparison results are shown. Two
cases, a daytime case with high background noise and a less noisy
night-time case, are chosen. In both cases the ceilometer profiles
compare well with the lidar profiles in atmospheric structures like
aerosol layers or the boundary layer top height. However, the
determination of the correct magnitude of the particle backscatter
coefficient needs a calibration of the ceilometer data with an
independent measurement of the aerosol optical depth by a sun
photometer. To characterizes the ceilometers signal performance with
increasing altitude a comprehensive signal-to-noise ratio study was
performed. During daytime the signal-to-noise ratio is higher than 1
up to 4–5 km depending on the aerosol content. In our night-time
case the SNR is higher than 1 even up to 8.5 km, so that also
aerosol layers in the upper troposphere had been detected by the
ceilometer. |
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