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. See
https://www.cefas.co.uk/cefas-data-hub/sea-temperature-and-salinity-trends/_
for a full description of the originating system which has sea-surface
temperature (and sometimes salinity) data collected at a number of coastal
sites around England and Wales, some operated by volunteers, some operated by
local councils and some associated with power stations. 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.
.. _https://www.cefas.co.uk/cefas-data-hub/sea-temperature-and-salinity-trends/:
https://www.cefas.co.uk/cefas-data-hub/sea-temperature-and-salinity-trends/