| Report: | Gunni Ærtebjerg |
| Cruise leader: | Gunni Ærtebjerg/Kjeld Sauerberg |
| Participants: | 5-15/2: Kjeld Sauerberg, Dorete Jensen, Jan Damgaard; 5-12/2: Gunni Ærtebjerg, Peter Kofoed, Lars Renvald, Martin Larsen; 12-15/2: Hanne Ferdinand; 5/2: Ole Lund Jensen; 5-6/2: Bo Nielsen, Danish Fishery Research Institute |
This report is based on preliminary data, which might later be corrected. Citation permitted only when quoting is evident. This file contains the summary only. To get the full report, click here. This file is in Adobe Acrobat ™ format. If you do not have a a Adobe Acrobat ™ Reader, click here, to download
Summary
The hydrographic situation was rather unusual compared to previous February cruises. As usual, the Jutland Coastal Current (JCC) with lower salinity and temperature was evident but relatively narrow along the Danish North Sea coast up to the entrance to Skagerrak. However, west of the JCC and in the central Skagerrak the surface salinity was unusually high, 34.5-34.9, probably due to an unusually large inflow of Atlantic water from the Biscay in late 2000 (Jan Aure, pers.com.). The Kattegat and Belt Sea area was characterised by out flowing low saline Baltic water at the surface, high saline bottom water, strong stratification and for the season relatively low oxygen concentrations in the bottom water. This is probably due to the prevailing relatively weak southerly wind in the months prior to the cruise.
In the North Sea the nutrient concentrations as usual varied inversely to the salinity. Due to the relation to the salinity the nutrient concentrations were generally highest in the south-eastern German Bight, decreasing to the north and west. However, the estimated nitrate concentration at salinities above 34 is higher than at earlier February cruises, which is in agreement with a higher dominance of Atlantic water. The estimated nitrate concentration in river water (0 psu) was lower than usual. The reason for this is yet unknown. The nitrate concentrations in the Kattegat and Belt Sea were relatively low compared to the 1980s, especially in the eastern Kattegat and the Arkona Sea.
The mean chlorophyll concentration in the uppermost 10 m varied from 0.2 (g/l in the central Skagerrak to 2.4 (g/l in the German Bight, 2.5 (g/l in Kiel Bight and 3.1 (g/l at Hanstholm. Generally, the phytoplankton spring bloom was not yet developed, but seemed just about to start in the southern Belt Sea, Arkona Sea and western Kattegat, and may be at Hanstholm. The lowest oxygen concentration of 4.3-4.8 ml/l (63-73% saturation) was observed in the Sound the 5 February in 20 to 50 m depth, but had 10 days later increased to 5.2 ml/l (78%). Otherwise, the minimum saturation was 80-100%. Compared to February last year and to mean for February in the 1980s the minimum oxygen concentrations were generally lower in the Kattegat-Belt Sea this year.