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1

Synoptic changes in the deep rim current during stagnant hydrographic conditions in the Eastern Gotland Basin, Baltic Sea

100%

Hagen E. , Feistel R.

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tom No. 49 (2)

185-208

EN

Hydrographic and current measurements are analysed for stagnant deep-water conditions over the south-eastern topographic flank of the Eastern Gotland Basin (EGB) in April 2000. Results suggest a prevailing barotropic motion mode on a synoptic scale of several days. Deep along-slope volume transports derived from subsurface current meter moorings are compared with those of the baroclinic fraction of geostrophic motions crossing the plane of a hydrographic section. This was aligned perpendicular to deep isobaths and was repeated 40 times with a time step of six hours. Changes in regional winds produced a quasi-ten day cycle in the filling level of the Baltic Proper. Associated wave-like fluctuations of the mass field propagated cyclonically with a velocity of about 0.04 m s-1 around the deep basin's rim. It is concluded that associated changes in deep volume transports result mainly from barotropically governed advection processes and that those of the baroclinic component of geostrophic currents provide a qualitatively and quantitatively quite inaccurate description of related transport fluctuations on a daily scale.

2

Temporal and spatial evolution of the Baltic deep water renewal in spring 2003

80%

Feistel R. , Nausch G. , Matthäus W. , Hagen E.

Oceanologia

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2003

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tom No. 45 (4)

623-642

EN

In January 2003, a deep-water renewal process in the Baltic Sea commenced with an inflow of about 200 km3 of cold and well oxygenated water from the Kattegat, half of which was of salinity >17 PSU; it is considered to be the most important inflow since 1993. Related front propagation and the ventilation of anoxic waters between the western and the central Baltic were recorded by the Darss Sill measuring mast, the Arkona Basin buoy, a subsurface mooring in the Eastern Gotland Basin, and hydrographic research cruises conducted in January, February, March, May and August 2003. Already in May, the central Gotland Basin was reached by water with near-bottom oxygen concentrations among the highest ever recorded there. A comprehensive review of the observed spatial and temporal structures together with additional background data is presented. Estimates of the intensity of the present inflow are discussed.

3

Unusual Baltic inflow activity in 2002-2003 and varying deep-water properties

80%

Feistel R. , Nausch G. , Hagen E.

Oceanologia

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2006

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tom No. 48 (S)

21-35

EN

The unusual sequence of inflow events into the Baltic Sea that occurred in 2002 and 2003 includes the first ever important baroclinic inflow to be described (August 2002), the Major Baltic Inflow (January 2003), which gave rise to the highest oxygen levels in the Gotland Deep since the 1930s, and the baroclinic inflow (August 2003) that elevated the Gotland Basin deep water salinity to values last observed in 1977, and caused the surface salinity to rise again. From these trend changes, salt residence times were estimated at about 20 years in the deep waters and 30 years above the pycnocline. Ventilation of the remote Karlsö Deep took until 2005, two years after the inflow event responsible, at a time when the Bornholm and Eastern Gotland Basins were already returning to stagnation.

4

Temporal and spatial evolution of the Baltic deep water renewal in spring 2003

80%

Feistel R. , Nausch G. , Matthaus W. , Hagen E.

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nr 4

EN

In January 2003, a deep-water renewal process in the Baltic Sea commenced with an inflow of about 200 km3 of cold and well oxygenated water from the Kattegat, half of which was of salinity >17 PSU; it is considered to be the most important inflow since 1993. Related front propagation and the ventilation of anoxic waters between the western and the central Baltic were recorded by the Darss Sill measuring mast, the Arkona Basin buoy, a subsurface mooring in the Eastern Gotland Basin, and hydrographic research cruises conducted in January, February, March, May and August 2003. Already in May, the central Gotland Basin was reached by water with near-bottom oxygen concentrations among the highest ever recorded there. A comprehensive review of the observed spatial and temporal structures together with additional background data is presented. Estimates of the intensity of the present inflow are discussed.

5

Evidence for a warm water inflow into the Baltic Proper in summer 2003

71%

Feistel R. , Nausch G. , Heene T. , Piechura J. , Hagen E.

Oceanologia

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2004

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tom No. 46 (4)

581-598

EN

The exceptional warm water inflow into the Baltic Sea in summer 2002, which preceded the major Baltic inflow of January 2003, was surprisingly repeated in modified form in summer 2003. Its warm waters even replaced the renewed, cold inflow waters in the eastern Gotland Basin and commenced another warm period in its deep layers, where the previous one had lasted from 1997 to 2003. Details of the temporal and spatial behaviour of this new baroclinic inflow are presented from various measurements carried out from the Kiel Bight up to Gotland, covering the Darss Sill, the Arkona, Bornholm, Gdańsk Basins and the Słupsk Channel, focused mainly on the time period between July 2003 and July 2004. Hypothetically, the repetition of these exceptional warm inflow events could be regarded as a possible regional indicator for global climatic change.

6

Evidence for a warm water inflow into the Baltic Proper in summer 2003

70%

Feistel R. , Nausch G. , Heene T. , Piechura J. , Hagen E.

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2004

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tom 46

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nr 4

EN

The exceptional warm water inflow into the Baltic Sea in summer 2002, which preceded the major Baltic inflow of January 2003, was surprisingly repeated in modified form in summer 2003. Its warm waters even replaced the renewed, cold inflow waters in the eastern Gotland Basin and commenced another warm period in its deep layers, where the previous one had lasted from 1997 to 2003. Details of the temporal and spatial behaviour of this new baroclinic inflow are presented from various measurements carried out from the Kiel Bight up to Gotland, covering the Darss Sill, the Arkona, Bornholm, Gdańsk Basins and the Słupsk Channel, focused mainly on the time period between July 2003 and July 2004. Hypothetically, the repetition of these exceptional warm inflow events could be regarded as a possible regional indicator for global climatic change.