The fundamental dataset consists of full water column temperature and salinity profiles, with discrete inorganic nutrient data added later on. Between 1975 and January 1996 there were usually multiple occupations, in a single year, of a section between the Scottish shelf and the Rockall Channel. Many of these occupations targeted only a selection of the 35 stations collectively recognised as the Ellett Line. Over the years various names were used to describe the hydrographic section (or components of it): The Rockall Section, The Anton Dohrn Seamount Section, The Shelf-Edge-Sound of Mull Section. These are collectively termed the Ellett Line, after the scientist David Ellett, who coordinated much of this early work. The Extended Ellett Line consisted of 58 identified stations between the North West coast of Scotland and Iceland, crossing the Scottish shelf, Rockall Channel and Iceland Basin. The Extended Ellett Line was occupied at least annually from 1996 to 2018. The water column profiles were collected using STDs/CTDs at recognised fixed stations along the section. The discrete inorganic nutrient data were obtained from water bottles fired at multiple depths on each profile, although these data are absent (or more limited) in the earlier stages of the time series. In 2018, the Extended Ellett Line became the Ellett Array. The Ellett Array consists of moorings, gliders and CTD sections in the Rockall Trough and Hatton-Rockall Basin. The overall Ellett Line/Extended Ellett Line/Ellett Array dataset is recognised as a key oceanographic time series. Several important water masses are captured within it – water masses that help drive ocean thermohaline circulation and consequently regulate climate on a global scale. The multi-decadal nature of the dataset provides a rare opportunity for scientists to monitor changing ocean circulation patterns. Ellett Line occupations were first carried out by the Scottish Marine Biological Association (SMBA), now the Scottish Association for Marine Science (SAMS). From 1996 there was a move to joint maintenance, with Southampton Oceanography Centre (SOC), now the National Oceanography Centre (NOC), sharing the responsibility with SAMS. Data collection as part of the Ellett Array is an ongoing activity. Some of the data are subject to a two-year embargo upon generation, after which they become available as part of this growing unrestricted data collection.

Seawater samples were collected from a series of ships of opportunity transiting between the UK and the Caribbean. Crossings occured almost monthly between May 2002 and October 2017. Roughly 90-100 samples were collected for each return journey from the ships' underway system and were frozen immediately for subsequent laboratory analysis. Nitrate, silicate, and phosphate levels were measured from these seawater samples. This work was funded by 5 different projects over the years - The Carbon variability studies by ships of opportunity (2000-2003), CARBOOCEAN FP6 (2001-2009), Carbochange (2011-2015), FixO3 (2013-2016), and NERC Greenhouse Gas most recently.

The data set comprises measurements of temperature, salinity, oxygen, chlorophyll and nutrients from two locations near Port Erin, Isle of Man. Sea surface temperature has been measured at Port Erin breakwater (54 05.113N, 04 46.083W) on a twice-daily basis from 1904 to the present day, accompanied by twice-daily sea surface salinity measurements since 1965. Since 1954, further measurements have been taken at the Cypris station in Port Erin Bay, 5km west of Port Erin (54 05.5N, 004 50.0W). The Cypris data have been collected at frequencies ranging from weekly to monthly depending on season, boat availability and weather, and comprise measurements of temperature at 0, 5, 10, 20 and 37m since 1954; salinity, dissolved oxygen and phosphate at 0 and 37m since 1954; silicate at 0 and 37m since 1958; nitrate and nitrite and 0 and 37 m since 1960; chlorophyll a at 0 m since 1966; ammonia at 0 and 37m since 1992; total dissolved nitrogen at 0 and 37m from 1996-2005; and total dissolved phosphorus at 0 and 37m from 1996-June 2002. At Port Erin temperatures were recorded using a Meteorological Office issue thermometer from the mid-1900s to October 2006. Since then Vemco temperature autologgers and Star-Oddi DST CTD loggers have been deployed from the Port Erin lifeboat slip and are exchanged on an approximately monthly basis. Until November 1961 temperature was recorded in degrees Fahrenheit; these data have since been converted to degrees Celsius. At the Cypris station water samples were collected with either a Nansen-Pettersen or an NIO bottle from 1954-2005. The Nansen-Pettersen bottle was used in conjunction with an insulated thermometer, while the NIO bottle was used in conjunction with a mercury reversing thermometer. From 2006 onwards an RTM 4002 X digital deep sea reversing thermometer has been used with an NIO bottle. Salinity was determined by titration against silver nitrate until 1965, thereafter using inductively coupled salinometers (Plessey 6230N until June 1998; Guildline Portasal from July 1998). Nutrients are estimated colorimetrically and dissolved oxygen is determined by the Winkler technique. Until 2006 chlorophyll-a was estimated using the trichromatic methods recommended by SCOR-UNESCO Working Group 17. Since that year the spectroscopic methods of Aminot & Rey (2000) have been used. Dissolved nitrogen and phosphorus were measured using the persulphate digestion method adapted from Valderama (1981). The Cypris station data are frequently split into the Cypris I (D. John Slinn) data set comprising data from 1954-1992 and the Cypris II data set from 1992-present. Data from the Port Erin and Cypris stations are sometimes known collectively as the ‘Port Erin Bay’ data set. Data from Port Erin Bay form part of the Isle of Man GAL Coastal Monitoring Sites network, which is described in a separate EDMED entry. The data were collected by the Port Erin Marine Laboratory (part of the University of Liverpool) until its closure in 2006. Sampling has since been taken over by the Isle of Man Government Laboratory. The data are managed by the British Oceanographic Data Centre.

The 'End of the Pier' Menai Strait data set is a collection of biogeochemical and physical parameters (including temperature, salinity, transmittance and attenuation of the water column) measured in the Menai Strait since 1955.The aim is to concatenate data both historical and current, preventing the loss of valuable information and creating a time series for a variety of parameters in a unique environment. Data have been extracted from Ph.D. and M.Sc. theses undertaken at the School of Ocean Sciences (SOS) at Bangor University, in addition to published sources. In all cases data has undergone a very thorough quality audit and sufficient detail is provided so that the original source may be located. Data collection is ongoing but the British Oceanographic Data Centre (BODC) only holds data up to 2003.

The data set includes the classical oceanographic parameters of temperature, salinity, nutrients, oxygen, pH, alkalinity, and chlorophyll-a. This data set comprises more than 100,000 profiles collected by UK research and naval vessels in the shelf seas around the UK, the North Atlantic, the Norwegian Sea, the Barents Sea, the Mediterranean Sea, the South Atlantic, the Southern Oceans, the Indian Ocean, the Arabian Sea, the East Indian Archipelago (Indonesia) and the Pacific Ocean since the beginning of the twentieth century. In recent years, conductivity-temperature-depth (CTD) data have been collected in a higher resolution form than water bottle data; these have been included in this data set in a reduced resolution/water bottle form and merged with any available chemical parameters. This data set is one of the most complete of its kind in the world; the majority of the data known to have been collected prior to 1970 have been 'rescued' and work will continue to rescue the remainder. All of the profiles in this data set have been quality checked, cross-checked against original documentation, and all duplications removed. This data set has been compiled by the International Council for the Exploration of the Sea (ICES) Oceanographic Data Centre and is available from the ICES website.

The COMICS (Controls over Ocean Mesopelagic Interior Carbon Storage) project consists of observations, at sea, of particle flux and stable isotopes. It applies organic geochemical and molecular biological techniques to samples collected using nets and traps. The study areas are the tropical Atlantic and Southern Oceans. The results will be combined with models to quantify the flow of carbon in the ocean’s ‘twilight’ zone in order to accurately model global climate change. This ‘twilight’ zone is the part of the ocean between 100m and 1000m below the sea surface, where only a small amount of light from the sun can still penetrate. By investigating carbon dynamics in the ocean interior, COMICS will help to improve predictions of future global climate change. The COMICS project is led by the National Oceanography Centre and is a collaboration between the British Antarctic Survey and the universities of Queen Mary London, Liverpool, Oxford and Southampton. The project received funding from the Natural Environmental Research Council and runs between 2017 and 2022.

An Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas (AlterEco) will utilise a small fleet of submarine and surface autonomous vehicles combined with ongoing observational programmes to capture a seasonal cycle of physical, chemical and biological measurements on repeat transects over ~150km in the North Sea between November 2017 and January 2019. This dataset contains near real-time hydrographic measurements through the water column obtained from submarine Slocum gliders and Seagliders. The submarine vehicles have also been equipped with auxiliary sensors such as turbulence probes, nutrient sensors and acoustic sensors. Data from these platforms will be converted into the international 'Everyone's Gliding Observatories (EGO)' exchange format. This dataset will also contain measurements taken from CTDs deployed on eight cruises to provide calibration data for the autonomous vehicles. AlterEco involves collaboration between scientists at a number of organisations (National Oceanography Centre (NOC, lead), University of East Anglia (UEA), University of Liverpool (UoL), Plymouth Marine Laboratory (PML), Scottish Association for Marine Science (SAMS) and the Centre for Environment, Fisheries and Aquaculture Science (Cefas). In addition, there are a number of UK and international project partners.

The data set comprises measurements of temperature, salinity, oxygen, chlorophyll and nutrients from six locations near Port Erin, Isle of Man. The data collected at Port Erin breakwater (54 05.113N, 04 46.083W) and the Cypris station in Port Erin Bay (54 05.5N, 004 50.0W) are described separately in the "Port Erin (Isle of Man, Irish Sea) Temperature, Salinity and Nutrient Data Set (1904-)". The remaining four stations are described here. Data have been collected at the Resa (also known as Bayrnagh), approximately 5km east of Santon Head, Isle of Man (54 05.00N, 04 30.00W) at least once per month since 1994, with a hiatus from 2003-2006. The data comprise measurements of temperature at 0, 5, 10, 20 and 37m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 37m; and chlorophyll-a at the surface. Total dissolved nitrogen was also measured at 0 and 37m between 1996 and 2003, while total dissolved phosphorus was measured at 0 and 37m between 1996 and June 2002. Corresponding data have been collected at Laxey Bay (54 12.00N, 04 23.00W), Ramsey Bay (54 20.47N, 04 17.47W) and Jurby Head Targets area (54 21.50N, 04 38.00W) at least once a month since 2006. Laxey Bay data comprise temperature at 0, 5, 10, 20 and 24m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 24m; and chlorophyll-a at the surface. Ramsey Bay data comprise temperature at 0, 5, 10 and 19m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 19m; and chlorophyll-a at the surface. Targets data comprise temperature at 0, 5, 10, 20 and 43m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 24m; and chlorophyll-a at the surface. Prior to 2006 water samples and temperature measurements were collected using either a Nansen-Pettersen bottle with an insulated thermometer or an NIO bottle with a mercury reversing thermometer. Since 2006 an NIO bottle and a Sensoren Instrumente Systeme (SIS) RTM 4002 X digital deep sea reversing thermometer have been used. Salinity was determined by titration against silver nitrate until 1965, thereafter using inductively coupled salinometers (Plessey 6230N until June 1998; Guildline Portasal from July 1998). Nutrients are estimated colorimetrically and dissolved oxygen is determined by the Winkler technique, as outlined in Jacobsen et al. (1950). Until 2006, chlorophyll-a was estimated using the trichromatic methods recommended by SCOR-UNESCO Working Group 17. Since that year the spectroscopic methods of Aminot & Rey (2000) have been used. Dissolved nitrogen and dissolved phosphorus were measured using the persulphate digestion method adapted from Valderama (1981). The data were collected by the Port Erin Marine Laboratory (part of the University of Liverpool) until its closure in 2006. Sampling has since been taken over by the Isle of Man Government Laboratory (GAL). The data are managed by the British Oceanographic Data Centre.

This dataset comprises 4 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, in July 1995 from stations in the Ria de Vigo between 42 - 43 N, 8.5 - 9.5 W. A complete list of all data parameters are described by the SeaDataNet Parameter Discovery Vocabulary (PDV) keywords assigned in this metadata record. The data were collected by the Institute of Marine Research, Vigo as part of the Ocean Margin Exchange (OMEX) I project.

This dataset comprises 4 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, in September 1995 from stations in the Ria de Vigo between 42 - 43 N, 8.5 - 9.5 W. A complete list of all data parameters are described by the SeaDataNet Parameter Discovery Vocabulary (PDV) keywords assigned in this metadata record. The data were collected by the Institute of Marine Research, Vigo as part of the Ocean Margin Exchange (OMEX) I project.