This dataset has been extracted as part of an exercise to assemble "all" Cefas
Temperature Data and publish it in a Data paper. It is one of 17 Cefas data
sources assembled. Sampling of plankton has been carried out by Cefas since
the 1940’s. In recent decades sampling has mainly been concentrated on fish
eggs and larvae, and other zooplankton. Samples were collected using
‘high–speed towed nets’ that capture plankton from the surface to near–seabed.
At each sampling position the sampler was deployed in an oblique tow from the
surface to within approximately 2 m of the seabed. Veering and hauling speeds
were manually adjusted with the aim of sampling each depth band equally. Since
the early 1980’s CTD sensor packages were fitted to the plankton samplers to
continuously monitor temperature and salinity throughout each deployment. From
1982 until 2003 the Guildline CTD system was used. Subsequently the ESM2
Profiler/mini CTD Logger (see 3.17) has been used.
For each sampler deployment a raw data file was created from the logged
values. Data were logged at intervals varying from 2 to 5 seconds. Raw files
were subsequently post–processed using custom–written software (two different
packages over the time period covered here) to produce calibrated profiles of
the environmental values measured. Depending on the software used and level of
post–processing undertaken by the operator either the whole profile (i.e. both
dive and haul portions of the deployment) or just the dive part of the
profile, were derived. Pressure averaged profiles may also have been created
where mean values were ‘binned’ into depth bands of 1 m width.
Pressure (Depth), Temperature and Conductivity (CTD) profiles collected on
Cefas (or DFR) plankton research cruises. The data in this archive broadly
cover the European Shelf. Original output files are varied in data format
according to the collection system used and the level of post-processing
carried out.
