Compilation of Summaries 
30 
System Nordsee 
was cut by the mean SST of the span July 2006 through June 2007, which at 11.6 °C 
was 3.7 standard deviations above the base period mean of 9.9 °C for 1971 - 1993. 
This extreme warm phase well-nigh coincides with the warmest 12-month period in 
the Northern Hemisphere for at least 130 years. The seasonal SST cycle proceeded 
on an almost constantly elevated level of 1.7 K - in the German Bight even 2.7 K - 
above normal. Excited was the warm anomaly by the pan-European heatwave of July 
2006. Its longevity resulted from consolidating and reinforcing atmospheric conditions 
of which had most notable impact a strong S-ly flow component from September, an 
exceedingly high gale frequency from October through March, an excessively high 
radiative surplus in April in steady high pressure weather, and summery weak winds 
in spring 2007. 
After spring had been somewhat on the cold side, particularly in eastern parts, an 
exceedingly warm isothermal surface layer was encountered during the North Sea 
Survey in August 2006. This layer had such low a thickness, however, that heat con 
tent (1.520 x 10 21 J) and volume temperature (10.4 °C) turned out about as small as 
observed in August 2002 for the last time. By contrast, a mighty surface layer and next 
to normal surface temperatures were found in August 2007. Referring to mean condi 
tions of stratification during the past decade, temperatures above 20 m depth were 
too cold by 1 - 2 K, while those between 20 - 40 m were too warm by this amount. In 
comparison to conditions in August 2006, this contrast becomes as stark as 2 - 3 K. 
The vertical temperature distribution in the German Bight was documented by refer 
ence to continuous data acquired at MARNET stations >NSB lll< and >EMS<. Located 
a touch beyond perennially mixed shallow coastal water, at >EMS< alternate phases of 
stratification and erosion were observed in spring, in particular, which were associated 
with spells of weak winds and intense insolation on the one hand, and episodes or 
events of high winds and low radiation on the other. These conditions went along with 
decoupled and interlocked turbulence regimes of the top and bottom layer due to wind 
stirring and tidal friction, respectively. By contrast, an incessant stratification together 
with a sharp thermocline in the 15 - 20 m depth range could evolve since early June 
2006 at >NSB Ills under virtually identical meteorological forcing but weaker tidal cur 
rents and larger water depth. Here, stratification was eroded only gradually through an 
abundance of low pressure disturbances in the course of August. 
In spite of an inherently favorable weak zonal circulation, sea ice started to form not 
until the end of January 2006 and almost exclusively along the Northfrisian coast 
line. At thicknesses ranging within 5-20 cm, the ice season 2005/06 lasted barely a 
week and, hence, was classified >weak<. Throughout the winter 2006/07 the German 
waters remained clear of ice. The heat content of German Bight sea water was again 
excessive at the onset of winter. All the more insufficient as to exhaust this heat much 
prior to crossing the seasonal minimum in February were reduced cooling rates under 
intensified zonal flow. 
Salinity (p. 156 sqs.) 
Throughout 2006, inflowing Atlantic water of S > 35 from the north spread south as 
far as 55.5° N, both in the bottom and surface layers. At the bottom, Atlantic water 
spread as far as the Norwegian coast and intruded into the Skagerrak. At the sur 
face, lower-salinity Baltic outflow through the Norwegian channel blocked its westward 
progress. Total salinity, with 0.7 standard deviations, was below the long-term mean 
of 2000 - 2009.