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| Titel |
Comparison of cloud statistics from spaceborne lidar systems |
| VerfasserIn |
S. Berthier, P. Chazette, J. Pelon, B. Baum |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 23 ; Nr. 8, no. 23 (2008-12-03), S.6965-6977 |
| Datensatznummer |
250006475
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| Publikation (Nr.) |
 copernicus.org/acp-8-6965-2008.pdf |
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| Zusammenfassung |
| The distribution of clouds in a vertical column is assessed on the global
scale through analysis of lidar measurements obtained from three spaceborne
lidar systems: LITE (Lidar In-space Technology Experiment, NASA), GLAS
(Geoscience Laser Altimeter System, NASA), and CALIOP (Cloud-Aerosol LIdar
with Orthogonal Polarization). Cloud top height (CTH) is obtained from the
LITE profiles based on a simple algorithm that accounts for multilayer cloud
structures. The resulting CTH results are compared to those obtained by the
operational algorithms of the GLAS and CALIOP instruments. Based on our
method, spaceborne lidar data are analyzed to establish statistics on the
cloud top height. The resulting columnar results are used to investigate the
inter-annual variability in the lidar cloud top heights. Statistical analyses
are performed for a range of CTH (high, middle, low) and latitudes (polar,
middle latitude and tropical). Probability density functions of CTH are
developed. Comparisons of CTH developed from LITE, for 2 weeks of data
in 1994, with ISCCP (International Satellite Cloud Climatology Project) cloud
products show that the cloud fraction observed from spaceborne lidar is much
higher than that from ISCCP. Another key result is that ISCCP products tend
to underestimate the CTH of optically thin cirrus clouds. Significant
differences are observed between LITE-derived cirrus CTH and both GLAS and
CALIOP-derived cirrus CTH. Such a difference is due primarily to the lidar
signal-to-noise ratio that is approximately a factor of 3 larger for the LITE
system than for the other lidars. A statistical analysis for a full year of
data highlights the influence of both the Inter-Tropical Convergence Zone and
polar stratospheric clouds. |
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