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Titel |
Effective resolution concepts for lidar observations |
VerfasserIn |
M. Iarlori, F. Madonna, V. Rizi, T. Trickl, A. Amodeo |
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 ; 8, no. 12 ; Nr. 8, no. 12 (2015-12-10), S.5157-5176 |
Datensatznummer |
250116719
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Publikation (Nr.) |
copernicus.org/amt-8-5157-2015.pdf |
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Zusammenfassung |
Since its establishment in 2000, EARLINET (European Aerosol Research Lidar
NETwork) has provided, through its database, quantitative aerosol
properties, such as aerosol backscatter and aerosol extinction coefficients,
the latter only for stations able to retrieve it independently (from Raman
or high-spectral-resolution lidars). These coefficients are stored in terms
of vertical profiles, and the EARLINET database also includes the details of
the range resolution of the vertical profiles. In fact, the algorithms used
in the lidar data analysis often alter the spectral content of the data,
mainly acting as low-pass filters to reduce the high-frequency noise. Data
filtering is described by the digital signal processing (DSP) theory as a
convolution sum: each filtered signal output at a given range is the result
of a linear combination of several signal input data samples (relative to
different ranges from the lidar receiver), and this could be seen as a loss
of range resolution of the output signal. Low-pass filtering always
introduces distortions in the lidar profile shape. Thus, both the removal of
high frequency, i.e., the removal of details up to a certain spatial
extension, and the spatial distortion produce a reduction of the range
resolution.
This paper discusses the determination of the effective resolution (ERes) of
the vertical profiles of aerosol properties retrieved from lidar data. Large
attention has been dedicated to providing an assessment of the impact of
low-pass filtering on the effective range resolution in the retrieval
procedure. |
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