| 1. |
- Arneborg, Lars, 1969, et al.
(författare)
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Spatial variability of diapycnal mixing and turbulent dissipation rates in a stagnant fjord basin
- 2004
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Ingår i: Journal of Physical Oceanography. - 0022-3670. ; 34:7, s. 1679-1691
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Tidskriftsartikel (refereegranskat)abstract
- Two microstructure profilers, two ships, and four moorings with acoustic Doppler current profilers and conductivity-temperature loggers were used in an intensive effort to map the spatial and temporal variations of vertical mixing in the stagnant deep basin of Gullmar Fjord, Sweden. During three days in the beginning of August 2001 a continuous time series of turbulent kinetic energy dissipation profiles was obtained with one microstructure profiler at a fixed position near the deepest part of the fjord. During the same period the other microstructure profiler was used to obtain six sections of dissipation through the length of the basin. Two moorings were deployed in the fjord basin for one month from the end of July to the end of August. The mapping of dissipation rates reveals that the dissipation in the deep basin is confined to areas just inside the sill. More than 77% of the dissipation in the fjord basin happens above the sloping bottoms closest to the sill.
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| 2. |
- Arneborg, Lars, 1969, et al.
(författare)
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The rate of inflow and mixing during deep-water renewal in a sill fjord
- 2004
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Ingår i: Limnology and Oceanography. - 0024-3590. ; 49:3, s. 768-777
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Tidskriftsartikel (refereegranskat)abstract
- We obtained high-resolution data on a deep-water renewal in the basin of Gullmar Fjord, Sweden, using an autonomous profiling platform. In the middle of the fjord, where the platform is anchored, renewal starts with the passage of a gravity current front and continues with a steady thickening of the new, oxygen-rich, low-nitrate bottom layer and an associated lifting of the old, oxygen-depleted, high-nitrate bottom water. The basin continuously fills to sill level during a period of 10 d. At the mouth of the fjord, a three-layer structure develops. Renewal is driven by the density difference between the intermediate water inside and the new deep water outside the fjord. The volume flux is well predicted by a hydraulic exchange model in which the upper layer plays a passive role. Local upwelling and downwelling of the upper halocline cause fluctuating baroclinic currents during renewal, but these seem to have little influence on the average volume flux of new deep water. Entrainment rates are small, and the associated volume flux increase seems to be balanced by detrainment.
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| 3. |
- Arneborg, Lars, 1969
(författare)
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Turnover times for the water above sill level in Gullmar Fjord
- 2004
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Ingår i: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 24:4-5, s. 443-460
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Tidskriftsartikel (refereegranskat)abstract
- Daily hydrographic measurements between 1954 and 1986, monthly environmental monitoring data from the last decades, and high-resolution data from 2001 are combined to obtain statistics on the exchange of the water above sill level in Gullmar Fjord, Sweden. The analyses show: (i) that the average turnover time is 16-26 days for the water above the halocline (S < 28), and 40 days for the intermediate water below the halocline, (ii) that the exchange is dominated by baroclinic currents caused by vertical fluctuations of the halocline outside the fjord, and (iii) that the statistics for the turnover times are relatively independent of year and season. One implication of these results is that a coupling between climate variations and water quality in Gullmar Fjord, cannot be explained in terms of variations in the water exchange. (C) 2004 Elsevier Ltd. All rights reserved.
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