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| Titel |
Ground-based observations for the validation of contrails and cirrus detection in satellite imagery |
| VerfasserIn |
H. Mannstein, A. Brömser, L. Bugliaro |
| 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. 3 ; Nr. 3, no. 3 (2010-06-07), S.655-669 |
| Datensatznummer |
250001112
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| Publikation (Nr.) |
 copernicus.org/amt-3-655-2010.pdf |
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| Zusammenfassung |
| Contrails and additional cirrus clouds caused by air traffic have a
potential warming effect due to their optical properties and their
location in the upper troposphere. The effect of contrails is
directly related to their coverage and optical properties, which
both can be derived from satellite observations. However,
considerable local and global uncertainties remain, as detection
limits and efficiency are still unknown. A six months time series of
the occurrence of high-level clouds and contrails was analysed
visually using an all-sky camera situated at Oberpfaffenhofen
(Southern Germany). It shows a contrail occurrence of 21% (fraction
of time with visible contrails during one hour) which is nearly
constant over daytime and a cirrus occurrence that increases from
27% in the morning to 48% in the evening, suggesting a possible
influence of air traffic or, more probably, convective cloud
formation. Furthermore, we compared selected all-sky camera images
with data of the satellite instruments NOAA/AVHRR and MSG/SEVIRI. As
expected, the fraction of contrails visible and detectable in
satellite images depends strongly on their width. Of the contrails
observed with the all-sky camera of 1–5 km width 60–65% are
visually detectable in AVHRR data while only 17% are identified by
an automated contrail detection algorithm (CDA). This means that
the automated CDA detects approx. 28% of the contrails which are
identified by visual inspection in AVHRR data alone. As far as
SEVIRI is concerned, visual inspection yields 48% of the contrails
of 1–5 km width, the CDA 19%. That means 40% of all contrails
visually identifiable in SEVIRI data are found by the automated
algorithm. As far as cirrus detection using SEVIRI data is
concerned, an automated algorithm tends to overestimate cirrus
occurrence but correctly measures cirrus changes during the day
compared to visual inspection. |
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