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Titel |
An analysis of cloud overlap at a midlatitude atmospheric observation facility |
VerfasserIn |
L. Oreopoulos, P. M. Norris |
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 ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-16), S.5557-5567 |
Datensatznummer |
250009845
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Publikation (Nr.) |
copernicus.org/acp-11-5557-2011.pdf |
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Zusammenfassung |
An analysis of cloud overlap based on high temporal and vertical resolution
retrievals of cloud condensate from a suite of ground instruments is
performed at a mid-latitude atmospheric observation facility. Two facets of
overlap are investigated: cloud fraction overlap, expressed in terms of a
parameter "α" indicating the relative contributions of maximum and
random overlap, and overlap of horizontal distributions of condensate,
expressed in terms of the correlation coefficient of condensate ranks. The
degree of proximity to the random and maximum overlap assumptions is also
expressed in terms of a decorrelation length, a convenient scalar parameter
for overlap parameters assumed to decay exponentially with separation
distance. Both cloud fraction overlap and condensate overlap show
significant seasonal variations with a clear tendency for more maximum
overlap in the summer months. More maximum overlap is also generally
observed when the domain size used to define cloud fractions increases.
These tendencies also exist for rank correlations, but are significantly
weaker. Hitherto unexplored overlap parameter dependencies are investigated
by analyzing mean parameter differences at fixed separation distance within
different layers of the atmospheric column, and by searching for possible
systematic relationships between alpha and rank correlation. We find that
for the same separation distance the overlap parameters are significantly
distinct in different atmospheric layers, and that random cloud fraction
overlap is usually associated with more randomly overlapped condensate
ranks. |
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