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Vertical velocity of the water column (currents)

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  • This dataset consists of model outputs from ensemble simulations of an idealised Southern Ocean using a quasi-geotrophic model called Q-GCM. As such, there are no calendar dates associated with it. Two models were generated: Initial Condition Perturbation Ensemble (ICPE) experiments model output covers years 162-168 of the simulation; Boundary Condition Perturbation Ensemble (BCPE) experiments model output covers years 150-180 of the simulation. The models created form the practical element of the NERC project ‘The structure and stability of transport and fixing barriers within the Antarctic Circumpolar Current’. The project aims to quantify the relationship between Southern Ocean winds, the eddy saturation mechanism and the branch-like structure of the Antarctic Circumpolar Current. The work was funded by means of a Natural Environment Research Council (NERC) Discovery Science New Investigators Grant ‘NE/I001794/1’. The grant ran from 02 August 2010 to 21 September 2012 and was led by Dr. Chris Wilson at the UK’s National Oceanography Centre (NOC). The model simulation data were submitted to the British Oceanographic Data Centre (BODC) for archive and are stored in the originator format.

  • This dataset consists of current velocity measurements of the water column from an upward-looking Acoustic Doppler Current Profiler (ADCP) deployed on the seabed and also includes CTD casts from an SBE 911+ CTD taken a long the Wyville Thompson Ridge. The mooring is situated in the region of the Wyville Thomson Ridge – a notable bathymetric feature running north-west from the Scottish shelf towards the Faroe Bank. The gully present between the Ridge and the parallel Ymir Ridge is the study site chosen for mooring work that began in 2003 and ended in 2013. Mooring deployment durations have typically ranged from between five and twelve months. Successive deployments have enabled a multi-year time series to develop. There have, however, been periods of instrumentation loss, which account for some gaps in the overall record (most noticeably during 2008/2009). Servicing of the mooring has been achieved using various research vessels and has often been incorporated into the schedule of the annual cruises occupying the Extended Ellett Line. The mooring consists of an anchored buoy housing an RDI Long Ranger ADCP, designed to rest on the seabed, with the instrument facing upwards. Current velocity measurements from the mooring help to provide valuable insight into regional ocean circulation. A small, poorly quantified, component of the southward-flowing deep water from the Arctic cascades over the Wyville Thomson Ridge from the Faroe Bank Channel into the northern Rockall Trough. Maintaining this time series will afford a better understanding of this outflow. The Wyville Thomson mooring work is led by Toby Sherwin at the Scottish Association for Marine Science (SAMS).

  • This dataset consists of measurements of horizontal and vertical current velocity and of vertical profiles of temperature and salinity collected during cruise PE372 in the Bosphorus Strait and South West Black Sea, June and July 2013 . Pelagia cruise PE372 formed part of the field collection of project "Flow dynamics and sedimentation in an active submarine channel: a process-product approach" which was composed of NERC Discovery Science lead grant NE/F020511/1 and 2 child grants: NE/F020120/1 and NE/F020279/1

  • This multi-decadal time series initially contains water current and temperature data from a single, near bottom instrument. A second, shallower instrument recording the same parameters was subsequently added after several years of successful operation. Conductivity data are similarly integrated into the time series after a further period of operation. The data are typically at hourly resolution. The mooring is situated in the Tiree Passage, between the Isles of Mull and Coll, off the west coast of Scotland. The specific site chosen was where the passage is at its narrowest (10 km), mid-way between the coasts of the two Isles. The mooring site is in water depths of approximately 45 m. Mooring activity began in June 1981 and consisted of a single RCM current meter placed 11 m above the seabed. The mooring design was modified to incorporate a second RCM current meter at 22 m above the seabed from November 1987. Aanderaa conductivity sensors were added at the two depths in 1993, with MicroCAT conductivity sensors being incorporated in 2002. There are some gaps in the record, most noticeably between January 2000 and May 2002, a period when the observations were temporarily suspended. Fishing damage has generated smaller gaps in the data set over the years. This region was chosen as a site for long term monitoring after radiocaesium studies showed that the major part of the water carried northwards from the North Channel in the Scottish coastal current passes between Mull and Coll. The mooring provides data for comparison with tracer studies and for an examination of the roles of wind forcing and buoyancy contributions to the coastal current. Tiree Passage mooring work is led by Colin Griffiths at the Scottish Association for Marine Science (SAMS).

  • The World Ocean Isopycnal-Level Velocity (WOIL-V) climatology was derived from the United States Navy's Generalised Digital Environmental Model (GDEM) temperature and salinity profiles, using the P-Vector Method. The absolute velocity data have the same horizontal resolution and temporal variation (annual, monthly) as GDEM (T, S) fields. These data have an horizontal resolution of 0.5 degrees ×0.5 degrees, and 222 isopycnal-levels (sigma theta levels) from sigma theta = 22.200 to 27.725 (kg m-3) with the increment delta sigma theta = 0.025 (kg m-3), however in the equatorial zone (5 degrees S – 5 degrees N) they are questionable due to the geostrophic balance being the theoretical base for the P-vector inverse method. The GDEM model, which served as the base for the calculations includes data from 1920s onwards and the WOIL-V will be updated with the same frequency as the GDEM. The climatological velocity field on isopycnal surface is dynamically compatible to the GDEM (T, S) fields and provides background ocean currents for oceanographic and climatic studies, especially in ocean isopycnal modeling. The climatology was prepared by the Department of Oceanography, Naval Postgraduate School.

  • The dataset comprises current profiles and temperature data from 9 half-day survey cruises in the Pentland Firth during April, June, July and October 2009. The data were collected using an acoustic Doppler current profiler (ADCP) mounted on the Aurora, the Environmental Research Institute (ERI) survey vessel, and have been fully processed and calibrated by Dr Lonneke Goddijn-Murphy from the Environmental Research Institute, University of the Highlands and Islands prior to submission to the British Oceanographic Data Centre (BODC). The circulation patterns of the inner sound, Pentland Firth were studied. The purpose of the study was to improve knowledge and capabilities for understanding wave and tidal renewable energy devices and predicting environmental impacts of renewable energy development. The data are available on request from BODC.

  • 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 data set comprises measurements of water temperature, salinity, current velocities and sound velocity, and sediment characteristics. The data were collected in the Clyde Sea in July and August 1997. The bulk of the measurements were made at the acoustic transmission point Tx1 (55 31.6N, 4 49.7W), and at receiving points SW of Tx1 up to 20 km away. In addition a SW-NE section (55 13.5N, 5 9.4W to 55 35.0N, 4 46.3W) was sampled at the beginning and end of the experiment, and a W-E section (5 3.0W to 4 52.7W at 55 31.6N) was run three times during the experiment. The data were collected by the research vessels Prince Madog and Calanus. Throughout the experiment the Prince Madog was used to deploy the acoustic transmission equipment, and as the main oceanographic vessel. The Calanus acted as the receiving ship, and also collected conductivity-temperature-depth (CTD) profiles. Overall, 199 CTD casts, 71 hours of temperature time series data, 150 hours of acoustic Doppler current profiler (ADCP) data, 70 hours of RoxAnn (sidescan sonar), position and water depth data, and three sediment sound speed profiles were collected. Two CTDs were used onboard the Prince Madog: a Seabird SBE-19 and a Neil Brown Mk. III. A Neil Brown SmartCTD was used on the Calanus. Several casts were made onboard the Madog with both CTDs attached to the same frame for intercalibration purposes. At the bottom of each cast with the Neil Brown Mk. III CTD two SIS digital reversing thermometers were triggered and a seawater sample collected, which was later analysed in the laboratory for salinity. Temperature and salinity data from the Madog CTDs were calibrated using these values. No seawater samples were collected by the Calanus. Data from all CTDs were despiked and spurious density inversions were removed. The majority of the CTD casts were repeat casts at either the acoustic transmission or reception point, the object being to monitor the high frequency variability of the water column, and allow model predictions of the acoustic signal characteristics to be tested against observed signal variations. Whilst the Prince Madog was on station at Tx1 four internally recording temperature sensors were deployed at fixed depths. During some overnight runs a single temperature/depth sensor was also deployed; during transmission experiments this sensor was attached to the acoustic source. The ADCP onboard the Madog was used to record vertical current profiles for most of the experiment. A RoxAnn system onboard the Prince Madog was used during part of the experiment to log ship position, water depth, and the bottom roughness and hardness indices E1 and E2. Three bottom sediment cores were collected on 5/8/97 with a hydroplastic (gravity) corer. Two metre core barrels with an internal diameter of about 8cm were used. The cores each contained between 1m and 1.5m of sediment, and were analysed for sound speed at the University of Wales, Bangor after the cruise. The cores were taken at Tx1 (55.527N, 4.832W), 10 km (55.441N, 4.843W), and 20 km (55.371N, 4.880W) along the primary acoustic track. The precision of the sound speed measurements is +/- 10 m/s. The PROSIM Clyde Sea experiment was primarily an acoustic transmission experiment designed to study shallow water acoustic propagation. The oceanographic data were collected to provide information on the mean and time-varying characteristics of the water column for use in acoustic modelling. PROSIM was undertaken by the Unit for Coastal and Estuarine Studies, a self-funded research unit attached to the School of Ocean Sciences, University of Wales, Bangor. The unit specialises in physical oceanography and ocean modelling. The data are stored at the British Oceanographic Data Centre (BODC).

  • Rothera Oceanographic and Biological Time Series (RaTS) in Antarctica began in 1997 and involves regular sampling of the water column undertaken by CTD (conductivity, temperature and depth) casts with associated collection of discrete water samples and the deployment of three moorings. The RaTS site is located in Marguerite Bay, approximately 4 km from shore and over a water depth of approximately 520 m. Marguerite Bay is enclosed by Adelaide Island to the north, Alexander Island to the south and the Antarctic Peninsula to the east. When optimal conditions are not available a secondary site is occupied. In times when fast ice prevents sampling at both the primary and secondary site, a third site is utilised close to the Rothera Research Station. However, only a water sample is collected during this time as the water is too shallow to allow for a cast to be conducted. An upper ocean CTD cast is made every five days in the summer and every seven days in the winter, except when weather, ice or logistic constraints intervene. A CTD unit is lowered from an inflatable boat by use of a hand-cranked winch during summer months and through a hole in the ice during the winter. As well as conductivity, temperature and depth other variables measured from the CTD cast include fluorescence and down-welling irradiance. Measurements are typically binned to 1 metre increments with a varying maximum depth typically ranging between 200 and 500 metres. Subsequent data processing involves the calculation of salinity from the conductivity channel (applying the UNESCO 1983 algorithm), calculation of chlorophyll from raw fluorescence and calibration, plus calculating depth from the pressure output. Discrete water samples are taken from a depth of 15 m using a Niskin bottle closed with a brass messenger. Water samples collected are measured for macronutrients (nitrate, nitrite, phosphate, ammonia and silicate), chlorophyll (both whole and size fractionated), dissolved oxygen isotopes, dissolved organic carbon and microbial community analysis. There are two extended periods during which no data could be collected. August to December, in both 2000 and 2001. In 2000, there was an unusually extended period of unfavourable ice conditions which were too heavy for boat operations and unsafe for sledge operations. Then in the period during 2001 a fire occurred which resulted in loss of use of the laboratory at Rothera. It was not possible to restart observations until replacement equipment arrived with the relief of the Rothera Research Station the following December. The mooring deployments took place in January 2005 (13 months), February 2006 (10 months) and December 2006 (4 months). All three moorings included current meters, acoustic Doppler current profilers (ADCP), temperature and depth recorders, a CTD and a sediment trap. These sensors were strung out from the surface down to approximately 390 m (sediment trap). Data was collected in 15 minute intervals from the ADCP and once every hour from all the other sensors. Data processing included calibration of the pressure, conductivity and pressure channels and calculation of salinity (from conductivity channel) and depth (from pressure channel). This time series is continuously monitored by the British Antarctic Survey in an attempt to gain a suite of oceanographic data which provide an environmental background to aid interpretation of the near-shore marine ecology and to test a series of broad hypothesis concerned with pelagic-benthic coupling and environmental forcing of the near-shore oceanographic environment. Until the summer of 2008 the project was managed by Prof. Andrew Clarke. At present (June 2010), the project and dataset is directed and managed by Dr. Mike Meredith of the British Antarctic Survey and data are available on request from the British Oceanographic Data Centre.

  • This dataset comprises hydrographic sections, together with measurements collected by ocean gliders and moored instrumentation deployed during the UK Overturning In the Subpolar North Atlantic Programme (UK-OSNAP). UK-OSNAP is the UK contribution to the International OSNAP Programme. The dataset also includes modelling output informed by the observations. OSNAP observations are focused on two lines: i) OSNAP West, extending from south Labrador to southwest Greenland and ii) OSNAP East from southeast Greenland to Scotland. Data collection commenced June 2014 and is ongoing. UK_OSNAP consists of cruises JR302, PE399, DY053, DY054, two alternating glider deployments, current meter moorings (five at Cape Farewell and three in the Rockall trough) and ADCPs in the Rockall Trough Shelf Edge Current. The model data addresses the Subpolar Gyre circulation and fluxes using data assimilation and theoretical analysis. The datasets assembled as part of UK-OSNAP provide a continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes in the North Atlantic Subpolar Gyre. These, coupled with the associated modelling exercises help improve the understanding of the circulation and fluxes of the North Atlantic Subpolar Gyre. UK-OSNAP, funded by the Natural Environment Research Council (NERC) is led by the National Oceanography Centre (NOC). UK-OSNAP is a partnership between NOC, Scottish Association for Marine Science (SAMS), University of Oxford and the University of Liverpool. It is part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. Investigators: National Oceanography Centre (NOC): Dr Penny Holliday, Dr Sheldon Bacon, Dr Chris Wilson, Neill Mackay. Scottish Association for Marine Science (SAMS): Dr Stuart Cunningham, Prof Mark Inall, Loic Houpert. University of Oxford: Prof David Marshall, Dr Helen Johnson. University of Liverpool: Prof Ric Williams, Dr Vassil Roussenov. The full dataset is still being assembled and currently consists of near real time glider measurements made (to date) on the project, the mooring dataset and cruise data. NERC have added a 2-year extension to UK-OSNAP, until October 2020. This covers a 2-year deployment of 3 moorings in the Iceland Basin as partof the international OSNAP programme. The moorings will be recovered in 2020.