Decadal variability on the northwest European shelf
Sündermann, J.; Becker, G.; Damm, P.; Van den Eynde, D.; Laane, R.W.P.M.; van Leussen, W.; Pohlmann, T.; Van Raaphorst, W.; Radach, G.; Schultz, H.; Visser, M. (1996). Decadal variability on the northwest European shelf, in: NOWESP: 2. Compilation of scientific reports. pp. 8 [1-23] In: (1996). NOWESP: 2. Compilation of scientific reports. North-West European Shelf Programme (NOWESP): Hamburg. 324 pp., more |
| Authors | | Top | - Sündermann, J.
- Becker, G.
- Damm, P.
- Van den Eynde, D., more
| - Laane, R.W.P.M., more
- van Leussen, W.
- Pohlmann, T.
- Van Raaphorst, W.
| - Radach, G., more
- Schultz, H.
- Visser, M.
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| Abstract | The seasonal cycles of sea surface temperature and other parameters at eight sites on the Northwest European shelf show an inter-annual variability in the range of years to decades for the years 1960-1995. Statistical methods like spectral analysis or phase diagrams prove that only a few frequency peaks beyond the annual cycle are of real significance. Most prominent signals for temperature and salinity on the shelf are the periods around 8 and 17 years. In general the time series are too short to identify definitely long-term trends or transitions between different states of equilibrium. However, there is an indication of a shift in the thermohaline regime along the Belgian-Dutch coast from the eighties to the nineties. Explanations for the decadal variability can be given by the intrinsic time scales of the internal shelf dynamics as well as by external periods. A spectral analysis of calculated mass fluxes at sections across the Northern and the Channel entrances of the North Sea show significant periods beyond the seasonal cycle. This suggests an advective influence form the Atlantic Ocean. Another external source of decadal variability on the Northwest European shelf is the atmosphere. Here no phase shift can be expected between corresponding signals of time series at different North Sea sites as it is indeed observed. |
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