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| Titel |
Upper mixed layer temperature anomalies at the North Atlantic storm-track zone |
| VerfasserIn |
S. N. Moshonkin, N. A. Diansky |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 13, no. 10 ; Nr. 13, no. 10, S.1015-1026 |
| Datensatznummer |
250012004
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| Publikation (Nr.) |
 copernicus.org/angeo-13-1015-1995.pdf |
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| Zusammenfassung |
| Synoptic sea surface temperature anomalies (SSTAs)
were determined as a result of separation of time scales smaller than 183 days.
The SSTAs were investigated using daily data of ocean weather station
"C" (52.75°N; 35.5°W) from 1 January 1976 to 31 December 1980 (1827
days). There were 47 positive and 50 negative significant SSTAs (lifetime longer
than 3 days, absolute value greater than 0.10 °C) with four main intervals of
the lifetime repetitions: 1. 4–7 days (45% of all cases), 2. 9–13 days (20–25%),
3. 14–18 days (10–15%), and 4. 21–30 days (10–15%) and with a magnitude 1.5–2.0
°C. An upper layer balance model based on equations for temperature, salinity,
mechanical energy (with advanced parametrization), state (density), and drift
currents was used to simulate SSTA. The original method of modelling taking into
account the mean observed temperature profiles proved to be very stable. The
model SSTAs are in a good agreement with the observed amplitudes and phases of
synoptic SSTAs during all 5 years. Surface heat flux anomalies are the main
source of SSTAs. The influence of anomalous drift heat advection is about 30–50%
of the SSTA, and the influence of salinity anomalies is about 10–25% and less.
The influence of a large-scale ocean front was isolated only once in
February-April 1978 during all 5 years. Synoptic SSTAs develop just in the upper
half of the homogeneous layer at each winter. We suggest that there are two main
causes of such active sublayer formation: 1. surface heat flux in the warm
sectors of cyclones and 2. predominant heat transport by ocean currents from the
south. All frequency functions of the ocean temperature synoptic response to
heat and momentum surface fluxes are of integral character (red noise), though
there is strong resonance with 20-days period of wind-driven horizontal heat
advection with mixed layer temperature; there are some other peculiarities on
the time scales from 5.5 to 13 days. Observed and modelled frequency functions
seem to be in good agreement. |
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