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Titel |
Correcting orbital drift signal in the time series of AVHRR derived convective cloud fraction using rotated empirical orthogonal function |
VerfasserIn |
A. Devasthale, K.-G. Karlsson, J. Quaas, H. Grassl |
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 ; 5, no. 2 ; Nr. 5, no. 2 (2012-02-01), S.267-273 |
Datensatznummer |
250002457
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Publikation (Nr.) |
copernicus.org/amt-5-267-2012.pdf |
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Zusammenfassung |
The Advanced Very High Resolution Radiometer (AVHRR) instruments onboard the
series of National Oceanic and Atmospheric Administration (NOAA) satellites
offer the longest available meteorological data records from space. These
satellites have drifted in orbit resulting in shifts in the local time
sampling during the life span of the sensors onboard. Depending upon the
amplitude of the diurnal cycle of the geophysical parameters derived,
orbital drift may cause spurious trends in their time series. We investigate
tropical deep convective clouds, which show pronounced diurnal cycle
amplitude, to estimate an upper bound of the impact of orbital drift on
their time series. We carry out a rotated empirical orthogonal function
analysis (REOF) and show that the REOFs are useful in delineating orbital
drift signal and, more importantly, in subtracting this signal in the time
series of convective cloud amount. These results will help facilitate the
derivation of homogenized data series of cloud amount from NOAA satellite
sensors and ultimately analyzing trends from them. However, we suggest
detailed comparison of various methods and rigorous testing thereof applying
final orbital drift corrections. |
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