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| Titel |
Radiation budget estimates over Africa and surrounding oceans: inter-annual comparisons |
| VerfasserIn |
A. Ben Rehouma, M. Viollier, M. Desbois |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2007-05-21), S.2617-2629 |
| Datensatznummer |
250004991
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| Publikation (Nr.) |
 copernicus.org/acp-7-2617-2007.pdf |
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| Zusammenfassung |
| Three independent datasets of Radiation Budget at the top of the atmosphere
(TOA) spanning two decades are compared: the Scanner Narrow Field of View
data (from ERBE, ScaRaB, and CERES instruments, 1985–2005), the ERBS
Nonscanner Wide Field of View data (1985–1998) and the simulated broadband
fluxes from the International Satellite Cloud Climatology Project (ISCCP-FD,
1983–2004). The analysis concerns the shortwave (SW) reflected flux, the
longwave (LW) emitted flux and the net flux at the Top Of the Atmosphere
(TOA) over Africa and the surrounding oceans (45° S–45° N/60° W–60° E),
a region particularly impacted by climate variability. For
each month, local anomalies are computed with reference to the average over
this large region, and their differences between the 2002–2005 and 1985–1989
periods are analysed. These anomalies are, for a large part, independent on
the general observed trends (about 2.5 W m−2 per decade), which may be
affected by possible calibration drifts. Although the regional flux
anomalies can be related to calibration through the scene identification and
the choice of the anisotropy correction, this effect is limited if the
calibration drifts remains reasonable. Large inter-annual variations are
observed locally. Over a part of the South East Atlantic (35°–10° S/10° W–10° E),
including the marine low cloud area off Angola, there
is a decrease of the yearly means of net flux estimated to 2.2, 3 and
6 W m−2 respectively for the Scanner, Nonscanner and ISCPP-FD data. Over a
narrow strip of the Sahel Zone, the net flux increases by about 5 W m−2.
We believe that these observations are real. They could be due to the impact
of calibration drift but only if the drifts were significant (>4%) and
correlated between the datasets, which is highly improbable. |
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