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Electrical conductivity of the water column

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  • For around a decade, southern elephant seals (mirounga leonina) have been used to collect hydrographic (temperature & salinity) profiles in the Southern Ocean. CTD-SRDLs (Conductivity Temperature Depth –Satellite Relayed Data Loggers) attached to seals' heads in Antarctic and sub-Antarctic locations measure water property profiles during dives and transmit data using the ARGOS (Advanced Research & Global Observation Satellite) network (Fedak 2013). CTD-SRDLs are built by the Sea Mammal Research Unit (SMRU, University of St Andrews, UK); they include miniaturised CTD units made by Valeport Ltd. When seals are foraging at sea 2.5 profiles can be obtained daily, on average. Profiles average 500m depth, but can be 2000m in extreme cases (Boehme et al. 2009, Roquet et al. 2011). Deployment efforts have been very intensive in the Southern Indian Ocean, with biannual campaigns in the Kerguelen Islands since 2004 and many deployments in Davis and Casey Antarctic stations (Roquet et al., 2013) more recently. 207 CTD-SRDL tags have been deployed there, giving about 75,000 hydrographic profiles in the Kerguelen Plateau area. About two thirds of the dataset was obtained between 2011 & 2013 as a consequence of intensive Australian Antarctic station deployments. There is also regular data since 2004 from French and Franco-Australian Kerguelen Island deployments. Although not included here, many CTD-SRDL tags deployed in the Kerguelen Islands included a fluorimeter. Fluorescence profiles can be used as a proxy for chlorophyll content (Guinet et al. 2013, Blain et al. 2013). Seal-derived hydrographic data have been used successfully to improve understanding of elephant seal foraging strategies and their success (Biuw et al., 2007, Bailleul, 2007). They provide detailed hydrographic observations in places and seasons with virtually no other data sources (Roquet et al. 2009, Ohshima et al. 2013, Roquet et al. 2013). Hydrographic data available in this dataset were edited using an Argo-inspired procedure and then visually. Each CTD-SRDL dataset was adjusted using several delayed-mode techniques, including a temperature offset correction and a linear-in-pressure salinity correction - described in Roquet et al. (2011). Adjusted hydrographic data have estimated accuracies of about +/-0.03oC and +/-0.05 psu (practical salinity unit). The salinity accuracy depends largely on the distribution of CTD data for any given CTD-SRDL, which decides the quality of adjustment parameters. Adjustments are best when hydrographic profiles are available in the region between the Southern Antarctic Circumpolar Current Front and the Antarctic divergence (55oS-62oS latitude range in the Southern Indian Ocean). Several institutes provided funding for the associated programs and the logistics necessary for the fieldwork. The observatory MEMO (Mammifères Echantillonneurs du Milieu Marin), funded by CNRS institutes (INSU and INEE), carried out the French contribution to the study. The project received financial and logistical support from CNES (TOSCA program), the Institut Paul-Emile Victor (IPEV), the Total Foundation and ANR. MEMO is associated with the Coriolis centre, part of the SOERE consortium CTD02 (Coriolis-temps différé Observations Océaniques, PI: G. Reverdin), which distributes real-time and delayed-mode products. The Australian contribution came from the Australian Animal Tracking and Monitoring System, an Integrated Marine Observing System (IMOS) facility. The work was also supported by the Australian Government's Cooperative Research Centres Programme via the Antarctic Climate & Ecosystem Cooperative Research Centre. The University of Tasmania and Macquarie University's Animal Ethics Committees approved the animal handling. Both tagging programs are part of the MEOP (Marine Mammals Exploring the Oceans Pole to Pole) international consortium - an International Polar Year (IPY) project.

  • The dataset comprises 36 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the Irish Sea and St. George's Channel, and the North East Atlantic Ocean (limit 40W) areas specifically from around the Rosemary Bank and George Bligh Bank areas. The data were collected during August and September 1978. 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 Oceanographic Sciences Wormley Laboratory.

  • The North Atlantic Norwegian Sea Exchange (NANSEN) data set comprises hydrographic profiles (temperature and salinity) and time series of current velocity, temperature and occasionally conductivity from the North Atlantic Ocean. The measurements were collected between 1986 and 1988 using conductivity-temperature-depth (CTD) profilers, moored current meters and thermistor chains. Data collection was undertaken by six laboratories in four countries (Faroes, Germany, Norway and the UK). The NANSEN project was conceived by the International Council for the Exploration of the Sea (ICES) Oceanic Hydrography Working Group. It aimed to study the hydrography and circulation of the Iceland Basin and the temporal and spatial variability of the inflows and outflows across the Greenland-Scotland Ridge. Current meter data from a number of laboratories involved in NANSEN and CTD data collected by UK participants are managed by the British Oceanographic Data Centre (BODC). A further 50 current meter series have been collected, but have not yet been acquired by BODC. The data will be subjected to the usual BODC quality control procedures for current meter series. The hydrographic data set collected during the NANSEN experiment has been compiled by the ICES Secretariat.

  • The data set comprises more than 7000 time series of ocean currents from moored instruments. The records contain horizontal current speed and direction and often concurrent temperature data. They may also contain vertical velocities, pressure and conductivity data. The majority of data originate from the continental shelf seas around the British Isles (for example, the North Sea, Irish Sea, Celtic Sea) and the North Atlantic. Measurements are also available for the South Atlantic, Indian, Arctic and Southern Oceans and the Mediterranean Sea. Data collection commenced in 1967 and is currently ongoing. Sampling intervals normally vary between 5 and 60 minutes. Current meter deployments are typically 2-8 weeks duration in shelf areas but up to 6-12 months in the open ocean. About 25 per cent of the data come from water depths of greater than 200m. The data are processed and stored by the British Oceanographic Data Centre (BODC) and a computerised inventory is available online. Data are quality controlled prior to loading to the databank. Data cycles are visually inspected by means of a sophisticated screening software package. Data from current meters on the same mooring or adjacent moorings can be overplotted and the data can also be displayed as time series or scatter plots. Series header information accompanying the data is checked and documentation compiled detailing data collection and processing methods.

  • The dataset comprises 37 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the North Sea and the North East Atlantic Ocean (limit 40W) areas specifically the Fair Isle-Munken, Nolso-Flugga, along the shelf edge to the north and west of Shetland, the standard JONSIS, East Shetland (ES), and northern North Sea (EC) sections. The data were collected during November of 1994. 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 Proudman Oceanographic Laboratory.

  • This collection comprises physical measurements of the water column and surface waters, together with supporting discrete chemical and biological datasets. The data were obtained from the Irish Sea and in the sea off western Scotland over 4 periods: 17 and 23 August 2011 and 06 - 07 March 2012, all collected on Seiont IV cruises and 15 - 22 June 2012 obtained using the RV Prince Madog. These datasets and their collection methods are as follows: 1) LISST particle size data - A LISST 100X type C laser diffraction instrument was lowered in a frame from the ship and the depth-averaged volumes of particles in 32 size classes in a water column from the surface to a depth of 10 m (or the bottom, where shallower) were measured. 2) CTD profiles of conductivity, temperature, sigma-theta and salinity. At each station, a CTD with attached rosette was lowered, with data measurements taken. 3) SPM, mineral SPM, chlorophyll and CDOM water sample data. At each station a surface water sample was collected either in a bucket or in a rosette sampler on the CTD and triplicate sub-samples were filtered and subsequently dried and weighed, baked (at 500°C for 3 hours to remove organic material) and weighed again. 4) CDOM discrete samples taken from CTD and underway. Surface water samples collected at each station were filtered through 0.2 μm filters and the spectral variation of the absorption coefficient of the dissolved material in the filtrate was measured in a 10 cm cell in a Shimadzu 1600 dual-beam spectrophotometer, using distilled water as a reference.. 5) Water column inherent optical property profiles. Measurements of beam attenuation were made using a Sea Tech T1000 transmissometer (20cm pathlength) fixed to the CTD on the RV Prince Madog. At some stations, vertical profiles of downwelling irradiance and upwelling radiance were made with a PRR radiometer. These cruises formed the fieldwork component of the NERC-funded project “Measurement of the abundance and optical significance of sub-micron sized particles in the ocean”. The project aimed to use different magnifications and commercially available in-situ particle sizing instruments to create a package of instruments for measuring the undisturbed particle size distributions from 0.2 μm to 1 mm. This package will first be used in a turbulence tank to 'film' the flocculation process. The insight this gives will be used to construct new theoretical models of the particle size distribution. Because the camera also measures the shape of the particles, differences between observed and calculated optical properties can be compared, for the first time, to particle shape. Finally, the complete dataset will be collated to determine what size particles, under what conditions, are primarily responsible for the signals seen in visible band satellite images of the oceans. The NERC-funded project was held under lead grant reference NE/H022090/1 with child grants NE/H020853/1 and NE/H021493/1. The lead grant was held at Bangor University, School of Ocean Sciences by Professor David Bowers and ran from 01 April 2011 to 31 March 2014. Grant NE/H020853/1 was held at the University of Plymouth, School of Marine Science and Engineering by Dr. William Alexander Nimmo Smith and ran from 01 October 2010 to 30 September 2013. Finally, grant NE/H021493/1 was held at the University of Strathclyde Physics Department by Dr. David McKee and ran from 01 April 2011 to 31 March 2014. All data have been received by BODC as raw files from the RV Prince Madog and Seiont IV, processed and quality controlled using in-house BODC procedures.

  • The dataset comprises hydrographic measurements including current velocity, temperature, salinity and sea level data. Results of one iodine experiment are also included. The data were collected in the area of the Faroe Islands, Shetland, the Norwegian Sea and the Barents Sea between May 2000 and November 2001 over a series of 31 cruises using the research vessels Scotia (UK), Magnus Heinason (Faroes), Johan Hjort and G.O.Sars (Norway). Measurements included five repeated conductivity-temperature-depth (CTD) sections in the Faroe Shetland Channel, North of Faroes, Gimsøy and Svinøy and Fugløya - Bear Island. Fifty one moorings containing current meters, acoustic Doppler current profilers (ADCPs), bottom pressure recorders and inverted echosounders were deployed along the sections. Ten RAFOS floats were also deployed in the Lofoten Basin to measure Lagrangian currents. During the Johan Hjort cruise in May 2000 about 300 water samples were collected in order to measure 129Iodine concentration (relative to 127I). Analysis was carried out by the Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, France. Observational data from the standard tidal stations at Tórshavn, Lerwick, Bodø and Ny-Ålesund were also used in the analysis. The main objective of MAIA was the development of an inexpensive, reliable system for monitoring the inflow of Atlantic water to the northern seas, based on coastal sea-level data. The project involved contributions from a number of international institutions. The resulting data set was collated at BODC and published on CD-ROM in March 2003.

  • The dataset comprises 23 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the Inner Seas off the west coast of Scotland area specifically of Loch Fyne, during November of 1994. 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 Scottish Office Agriculture Environment and Fisheries Department Aberdeen Marine Laboratory.

  • The dataset comprises 25 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the North Sea area specifically in the Scottish coastal zone between Arbroath and Fife Ness, during March and April of 1994. 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 Scottish Office Agriculture Environment and Fisheries Department Aberdeen Marine Laboratory.

  • The dataset comprises 17 hydrographic data profiles, collected by a conductivity-temperature-depth (CTD) sensor package, from across the North Sea area specifically along the east coast of Scotland from the Moray Firth to the Firth of Forth, during September of 1993. 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 Scottish Office Agriculture and Fisheries Department Aberdeen Marine Laboratory.