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| Titel |
A surface radiation climatology across two Meteosat satellite generations |
| VerfasserIn |
Rebekka Posselt, Richard Müller, Jörg Trentmann, Reto Stöckli, Mark A. Liniger |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078305
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| Zusammenfassung |
| Long term observations of the surface radiation budget are essential for climate monitoring,
for climate model evaluation and for applications such as in the solar energy or agriculture
sector. The Satellite Application Facility on Climate Monitoring (CM SAF) released a
Climate Data Record (CDR) of global and direct surface irradiance as well as effective cloud
albedo derived from observations of the Meteosat First Generation satellites (MFG,
1983-2005).
We will present an extension of this CDR using measurements from the Meteosat Second
Generation satellites (MSG, 2004-present). The differences in the spectral properties of the
radiometers aboard the MFG and MSG satellites requires a modification of the original
MagicSol algorithm. In order to guarantee a climatologically homogeneous continuation of
MFG-based CDR, the two narrowband visible channels of the MSG satellites are combined
to simulate the MFG broadband visible channel.
The combination of the MFG and MSG based datasets is tested for homogeneity and no
significant breaks are detected during the overlap period of 2004-2005. Validation of the
extended global radiation dataset against ground based observations from the Baseline
Surface Radiation Network yields a mean monthly absolute bias of 8.15 Wm-2. This
complies to the target accuracy threshold of 15 Wm-2 (including a measurement uncertainty
of the surface observations of 5 Wm-2) required for satellite-derived CDR’s of global
radiation by the Global Climate Observing System.
Climatological analysis of the extended surface radiation dataset shows an overall positive
trend of the global radiation for the Meteosat disc (with variable extents and significances for
different regions) which can be attributed to a negative trend in the effective cloud albedo,
i.e., a decrease in cloudiness. Trends due to changes in the clear sky radiation are small and
only induced by trends in the water vapour fields. Trends caused by changes in the direct
effects of atmospheric aerosol are not represented because an aerosol climatology is used. |
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