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www.atmos-meas-tech-discuss.net/2/3183/2009/
doi:10.5194/amtd-2-3183-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Ground-based observations for the validation of contrails and cirrus detection in satellite imagery
1Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
2UBIMET GmbH, 1200 Wien, Austria
Abstract. 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 can be derived from satellite observations, but considerable local and global uncertainties remain, as detection limits and efficiency are still unknown. A 6 months time series of the occurrence of high-level clouds and contrails was analysed visually from an all-sky camera situated at Oberpfaffenhofen (Southern Germany). It shows a contrail occurrence (fraction of time with visible contrails during one hour) of 21% being 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, convection. 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 highly on their width. Of the contrails observed with the all-sky camera being 1–5 km wide, 60–65% are visually detectable in AVHRR data, while only 17% are identified by an automated contrail detection algorithm (CDA). However, the CDA detects approx. 28% of the visually detected contrails. As far as SEVIRI is concerned, visual inspection yields 48% of the contrails of 1–5 km width, the CDA 19%. This value rises to 40% when comparing to the visually detected contrails. As far as cirrus detection with SEVIRI is concerned, an automated algorithm tends to overestimate cirrus occurrence but correctly appraises cirrus changes during the day.
Discussion Paper (PDF, 2582 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (AMT)
Notice on Discussion StatusCitation: Mannstein, H., Brömser, A., and Bugliaro, L.: Ground-based observations for the validation of contrails and cirrus detection in satellite imagery, Atmos. Meas. Tech. Discuss., 2, 3183-3220, doi:10.5194/amtd-2-3183-2009, 2009. Bibtex EndNote Reference Manager XML
