Participants 
Science Crew Working Group 
Holger Klein Marine Physics, Chief Scientist 
ı Andreas Pfeiffer Tarine Physics 
Sören Joswig Marine Physics a 
Dr. Jan Reißmann : Marine Physics — 
Peter Löwe | Marine Physics 
‚ Jens Gerull ' Marine Physics 
Dr. Christian Senet !' Marine Physics 
Wiebke Brandt Marine Chemistry, Nutrients 
Roswitha Velten Marine Chemistry, Nutrients 
| Christina Wehner ' Marine Chemistry, Radioactivity 
| Anke Gottschalk ' Marine Chemistry, Radioactivity 
Andreas Jacobsen & Marine Chemistry, Metals 
Ship Crew Rank 
ı Antony Hobin I Master 
Damien McCalling I Chief Engineer 
Kenny Downing | Chief Officer 
Barry Hooper | 2"7 Officer 
David Stack | 2" Engineer 
Dave Steward ıETO 
Gerry Carty ! Bosun 
Tony Reck Cook I 
Ken O’Neill Bosun’s Mate 
Martin Goggin | AB Deckhand GP1 
Paddy Kenny | AB Deckhand GP1 
Michael Doogan ı Assistant Cook 
Brian Sharkey _ Technician 
Declan Horan | AB Deckhand GP1 
Noel O’Driscoll | AB Deckhand GP1 
Daniel Rose ! Eng. Cadet 
Objectives and scientific background 
The North Sea is a shallow shelf sea with a deep trough along the Norwegian coast with 
depth exceeding 700 m locally. Its physical status, primarily characterised by temperature 
and salinity, is to a large extent determined by the exchange of water masses with the 
Atlantic at its open northern boundary. There is also a link to Atlantic via the English Channel 
which is important for the shallow southern North Sea. The Baltic Sea is linked to the North 
Sea via Skagerrak, Kattegat, Great and Little Belt, and The Sound. The Baltic outflow with its 
low saline water influences significantly the oceanographic conditions of the Skagerrak and 
Norwegian Coastal Current. Other drivers are inter alia continental river run-offs, the ocean- 
atmosphere heat exchange, and the rate of precipitation to evaporation. 
All parameters exhibit a strong seasonal and/or inter-annual variability. Seasonal heating 
leads to the establishment of a seasonal thermocline between spring and end of 
August/midst of September with vertical gradients exceeding 3 K/m in most of the years. 
Strength and depth of the thermocline vary locally and from year to year. Near-bottom tidal 
mixing and wind induced mixing at the surface suppress stratification in areas shallower than 
25 to 30 m. Stratified and vertically mixed areas are separated by so-called tidal mixing 
fronts. 
In order to assess the summer state of the North Sea the BSH started its North Sea Summer 
Surveys (NSSS) in 1998. They cover the entire North Sea with seven coast to coast east- 
west sections between 54° and 60°N and additional stations between 54°N and the entrance 
of the English Channel. The surveys were realised at a time when thermal stratification is 
expected to be at its maximum and phytoplankton production has passed its maximum. With 
Ihe exception of the first survey in 1998 all surveys served a fixed grid of vertical CTD casts 
(see red dots in Fig. 1). Between these fixed stations a towed CTD-system (1998-2008 the