Seawater temperature records for the UK Shelf - 01 - Cefas Coastal Temperature Network

The Coastal Temperature Network consists of Cefas (and predecessor) originated 
data and data from external suppliers, who have agreed their data can be 
published as part of the network (Jones, 1981). The earliest data are from 
1875 (Owers Light vessel) and have been supplied by the Met Office. The 
longest continuous record provided here is from Eastbourne (1892–2014). 
Sampling is from piers and breakwaters 50-200m from the shore where possible 
(Jones, 1981). The present network covers the temperature condition of coastal 
waters around the coast of England and Wales and was operationally combined 
with the salinity and temperature conditions across the Southern Bight of the 
North Sea. Individuals on behalf of Cefas, councils, companies and other 
organisations have obtained records of coastal sea surface temperature, for 
some stations, of more than 100-year duration. Approximately half of the 
stations started recording coastal temperatures in the mid–1960s. There are 41 
stations in England and Wales where 20 out of 41 are still in operation. Cefas 
observers record coastal sea surface temperature using calibrated thermometers 
approximately 6 – 14 times per month, usually close to the time of high water. 
Other organisations record sea surface temperature ranging from daily values 
to monthly means. Since 2012, the data from Dover Council is recorded every 
minute. Data are published as monthly means (Joyce, 2006); the extracted data 
are the measurements used to calculate the means. The Cefas instruments are 
calibrated at Lowestoft to an accuracy of ±0.1°C. The accuracy of other 
instruments is not known, but is thought to be at least to an accuracy of 
±0.2°C. The ferry route observers record offshore sea surface temperature from 
the ships main seawater pipe using a calibrated thermometer 4 times a month. 
The temperatures are recorded to at least an accuracy of ±0.2°C. The seawater 
samples are taken from the sea water main pipe to the harbour pump about 1.5 
metres inboard. Quality assurance checks are applied to the data for each 
station by comparing the current dataset with either a 5 or 10 year running 
mean for each month. The data is first tested to see whether it is normally 
distributed i.e. whether all the data are close to average. The standard 
deviation is calculated to see how tightly the data are clustered around the 
mean; three standard deviations are then calculated to account for 99% of the 
data. If the data are outside this range (3 std dev) then the value is flagged 
and removed from subsequent analysis. See Joyce (2006) for details of the 
duration and history of individual datasets. Inevitably, there are changes in 
the number and location of monitoring stations over such a long period. At its 
peak the network reported on about 100 locations. This has reduced to around 
30 in the late 20th century. Jones & Jeffs (1991) show the locations of early 
coastal stations. In addition, operating sites are moved and data recording 
upgraded, e.g. Eastbourne from a manual coastal site (see Joyce, 2006) to, in 
2013, an electronic logging system mounted on an offshore buoy. These changes 
are reflected in the positions associated with the extracted data. The longest 
time-series include those from Eastbourne (1892 - present), Dover (1926 - 
present) and Port Erin, Isle of Man (1903 - present) although most time series 
began in the 1960s or 1970s.

Organization: Marine Environmental Data & Information Network