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Volumes of water masses penetrating during major Baltic inflows and their characteristic properties

100%

Franck H., Matthaus W.

Acta Ichthyologica et Piscatoria. Supplementum

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1991

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tom 21

2

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

80%

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

Oceanologia

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2003

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tom 45

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nr 4

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

Hydrographic and hydrochemical conditions in the Gotland Deep area between 1992 and 2003

80%

Nausch G., Matthaus W., Feistel R.

Oceanologia

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2003

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tom 45

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nr 4

The paper describes the hydrographic-hydrochemical development in the eastern Gotland Basin between the major saltwater inflows into the Baltic Sea in 1993 and 2003. This period is characterised by only low inflow activity. The most important hydrographic events were the effects of the very strong inflow in 1993 and the weak inflows in 1993/1994 and 1997. The 1993/1994 inflows led to deep-water renewal, a steep fall in deep-water temperatures, and increasing salinity. The effects of the inflow of very warm, saline and oxygen-rich water in autumn 1997 were observed in the deep water in 1998, resulting in temperatures rising to 7◦C. The recent renewal in spring 2003 is reflected in the decreasing temperature, higher salinity and improved ventilation of the bottom water. Changes in the redox conditions exert a considerable influence on the nutrient distribution. During stagnation periods, there is enrichment of phosphate and ammonium, while nitrate is absent. Thus, around 31 μmol l−1 ammonium and 7 μmol l−1 phosphate were measured prior to the water renewal in 2003. Deepwater ventilation results in lower phosphate concentrations of around 2 μmol l−1, the nitrification of ammonium and the occurrence of nitrate. For the observation period, an estimate of nutrients stored in the deep water was done for the eastern Gotland Basin. During the recent stagnation period, there was an increase of up to 150% in the phosphate pool below the halocline, whereas the pool of inorganic nitrogen compounds decreased to 80% compared with 1992 when the previous stagnation period had ended. Under specific circumstances, these unbalanced nutrients can be made available to the upper water layers and can induce large-scale blooms of algae, especially of cyanobacteria.

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Warm waters of summer 2002 in the deep Baltic Proper

51%

Feistel R., Nausch G., Mohrholz V., Lysiak-Pastuszak E., Seifert T., Matthaus W., Kruger S., Hansen I. S.

Oceanologia

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2003

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tom 45

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nr 4

From October 2002 until March 2003 surprisingly warm, oxygenated waters were frequently encountered in the Baltic Sea in the area between the Bornholm and Fårö Deeps from the halocline down to the bottom. Owing to their ventilation effect in the stagnating deep waters, their occasional observations have partly been incorrectly attributed to the inflow events of October 2002 or January 2003. The emergence of some of these waters can be traced back to the exceptional summer weather conditions in August and September 2002 in central Europe. The warm waters played a remarkable renewal pacemaker role for the subsequent important winter inflow of January 2003. The evolution of this summer inflow is described and possible causes are discussed.

Ograniczanie wyników

3 Oceanologia

1 Acta Ichthyologica et Piscatoria. Supplementum

4 Matthaus W.

3 Feistel R.

3 Nausch G.

1 Franck H.

1 Hagen E.

1 Hansen I. S.

1 Kruger S.

1 Lysiak-Pastuszak E.

1 Mohrholz V.

1 Seifert T.

3 2003

1 1991

Volumes of water masses penetrating during major Baltic inflows and their characteristic properties

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

Hydrographic and hydrochemical conditions in the Gotland Deep area between 1992 and 2003

Warm waters of summer 2002 in the deep Baltic Proper