Preliminary findings 
With the exception of statements concerning the sea surface temperature (SST), all 
assessments are basing on raw data collected during the cruise. All temperature and salinity 
data will be processed and — if necessary — re-calibrated after the cruise. 
In the month before the cruise the monthly means of the area averaged North Sea SSTs 
exceeded the climatological means by about 2 K. July 2014 was the warmest July since 
1969 with an anomaly of +2.1 K. The weekly mean July 23“ — 29" directly before the cruise 
amounted to 18.1 °C, this is only 0.3 K below the records of the extremely warm years 2003 
and 2006. During the week August 13" to 19" the area averaged North Sea SST dropped by 
1.6 K! 
The SST is a good representative for the temperature of the seasonal upper warm layer. Due 
to increasing solar radiation the North Sea established a seasonal stratification during spring 
over wide areas of the North Sea which last normally until end of August or beginning of 
September. Then the water column will be vertically mixed again by the first fall storms. The 
upper layer is separated from the colder bottom layer by a sharp thermocline with vertical 
gradients of the order of 3 K/m. While the oceanographic conditions in the upper layer are 
mainly determined by local radiation, the conditions in the bottom layer are influenced by the 
inflow of Atlantic Water (AW) with salinities >35 psu via the northern open boundary to the 
Atlantic and to a lesser degree via the English Channel. Only the knowledge of the 
hydrographic condition in both layers, determined by the spatial distribution of temperature 
and salinity, allows the calculation of heat and salt budgets. 
The spatial structure of temperature distribution corresponds largely to that of the reference 
veriod (RP) 2000-2010 with upper layer depths between 20 and 30 m and the shallow south- 
gastern part of the North Sea vertically mixed. However, in 2014 the temperatures in the 
south-eastern North Sea exceed the RP by about 2 K. Reliable data about the strength of the 
vertical gradient can be provided not before the re-processing of the raw data. Also the 
temperature distribution of the bottom layer corresponds largely to that of the RP with the 
exception of the eastern part of the 58 °N section. Here the passage of ex-hurricane “Bertha” 
orobably caused a vertical mixing inside the upper and bottom layer in the central and 
eastern part of the section. 
Atlantic Water intruding from the northern boundary is traceable as a massive structure down 
to 57 °N and shaped as small lenses at 56 °N. Generally, the volume of AW is smaller as that 
of the RP. It is concentrated to the bottom layer and shows a reduced vertical extension. The 
inflow paths via the Fair-Isle-Channel and the East Shetland Shelf can be distinguished 
clearly along the 58 °N section. 
Concerning SST the summer 2014 was significantly warmer as the climatological mean, this 
holds also for the volume of the south-eastern North Sea. The total salt content is expected 
to be below the long-term mean. However, quantitative assessments concerning the North 
Sea summer state 2014 will be possible not before the re-processing of the data at BSH. 
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