Statistical analysis of the interdecadal variability over the North Atlantic
The climate variability over the North Atlantic region is described in the 10-50 year band, using a 500-year integration of the Hamburg ECHAMl/LSG coupled general circulation model. In order to isolate nearly periodic components of the atmosphere and the ocean, the multichannel version of the singul...
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
1996
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| Online Access: | https://nbn-resolving.org/urn:nbn:de:bsz:15-qucosa-213076 https://ul.qucosa.de/id/qucosa%3A15063 https://ul.qucosa.de/api/qucosa%3A15063/attachment/ATT-0/ |
| Summary: | The climate variability over the North Atlantic region is described in the 10-50 year band, using a 500-year integration of the Hamburg ECHAMl/LSG coupled general circulation model. In order to isolate nearly periodic components of the atmosphere and the ocean, the multichannel version of the singular spectrum analysis (MSSA) is applied to 11 components of the climate system. In doing so the main focus is on the turbulent exchange between the two subsystems. One interdecadal oscillation of the system ocean and atmosphere is detected with a period of about 18 years. The associated anomalies of sea level pressure (SLP) are situated east of Newfoundland while these of the geopotential height at 500 hPa are slightly shifted to the East. Both the fields undergo a primarily standing oscillation. The sea surface temperature (SST) and the sub surface temperature anomalies have a large extension along the 40° N latitude circle with most of their variability south of Newfoundland. lt is found that the SST anomaly is primarily generated by the temperature advection in the upper ocean layer which is coupled to the Subpolar Gyre strength and Ekman pumping vertical velocity. Both the processes are forced by the atmosphere. In a further analysis applied only to the SST and the Geopotential height at 500 hPa over the whole Northern Hemisphere this 18 year mode was also isolated. The modes obtained by the local and hemispheric analyses are well correlated both in time and space, suggesting a more active role of atmosphere than of the ocean, in addition a strong modulation of the amplitude of the oscillation due to local processes over the North Atlantic was detected. Die Klimavariabilität über dem Nordatlantik wird anhand einer 500 Jahre Integration des Hamburger gekoppelten Klimamodels ECHAMl/LSG untersucht. Um periodische Komponenten in Ozean und Atmosphäre zu isolieren, wird die MSSA ('multichannel singular spectrum analysis') auf 11 Komponenten des Klimasystems angewandt. Bei den Analysen wird besonderes Augenmerk auf den ... |
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