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| Titel |
HelioFTH: combining cloud index principles and aggregated rating for cloud masking using infrared observations from geostationary satellites |
| VerfasserIn |
B. Dürr, M. Schröder, R. Stöckli, R. Posselt |
| 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 ; 6, no. 8 ; Nr. 6, no. 8 (2013-08-06), S.1883-1901 |
| Datensatznummer |
250085029
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| Publikation (Nr.) |
 copernicus.org/amt-6-1883-2013.pdf |
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| Zusammenfassung |
In this paper a cloud mask and cloud fractional coverage (CFC) retrieval scheme
called HelioFTH is presented. The algorithm is self-calibrating and
relies on infrared (IR) window-channel observations only. It needs
no input from numerical weather prediction (NWP) or radiative
transfer models, nor from other satellite platforms. The scheme is
applicable to the full temporal and spatial resolution of the
Meteosat Visible and InfraRed Imager (MVIRI) and the Spinning
Enhanced Visible and InfraRed Imager (SEVIRI) sensors. The main
focus is laid on the separation of middle- and high-level cloud
coverage (HCC) from low-level clouds based on an internal cloud-top
pressure (CTP) product.
CFC retrieval employs a IR-only cloud mask based on an aggregated
rating scheme. CTP retrieval is based on a Heliosat-like cloud index
for the MVIRI IR channel. CFC from HelioFTH, the International
Satellite Cloud Climatology Project (ISCCP) DX and the Satellite
Application Facility on Climate Monitoring (CM SAF) were validated
with CFC from the Baseline Surface Radiation Network (BSRN) and
the Alpine Surface Radiation Budget (ASRB) network. HelioFTH CFC
differs by not more than 5–10% from CM SAF CFC but it is higher
than ISCCP-DX CFC. In particular the conditional probability to
detect cloud-free pixels with HelioFTH is raised by about 35%
compared to ISCCP-DX. The HelioFTH CFC is able to reproduce the
day-to-day variability observed at the surface.
Also, the HelioFTH HCC was inter-compared to CM SAF and ISCCP-DX
over different regions and stations. The probability of false
detection of cloud-free HCC pixels is in the same order as
ISCCP-DX compared to the CM SAF HCC product over the full-disk
area. HelioFTH could be used for generating an independent climate
data record of cloud physical properties once its consistency and
homogeneity is validated for the full Meteosat time series. |
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