This dataset includes two cruises of data collected to investigate Arctic hydrate dissociation as a consequence of climate change and to determine vulnerable methane reservoir and gas escape mechanisms. Work during both JR269A and JR269B was focused on two separate geographical areas. The first of these was west of Prins Karls Forland, in water depths of between 150 and 1200 m. At its landward end, this survey area crosses a region at water depths up to 400 m where a dense concentration of methane escape bubble plumes occur. The second survey area straddles the summit of the Vestnesa Ridge, in water depths of 1180 to 1400 m, and is also the site of methane escape bubble plumes within the water column and of fluid escape chimneys and pockmarks previously imaged at and beneath the sea bed. This area lies approximately 100 km west of the mouth of Kongsfjorden. Data collection took place between August 2011 and July 2012. The research expedition used a deep-towed, very high resolution seismic system to image the small-scale structures that convey gas to the seabed and to detect the presence of gas in the sediments. This was done in conjunction with an electromagnetic exploration system that uses a deep-towed transmitter and receivers on the seabed to derive the variations in electrical resistivity in the sediments beneath the seabed. The observations carried out on the two cruises included; underway, meteorological observations and echo sounder data, multichannel seismic reflection profiling data, wide angle seismic survey data, and ocean bottom seismometer (OBS) data, ocean bottom electro-magnetometer data and controlled source electromagnetic surveys (CSEM). The overall objectives of the project were to determine the spatial distribution of gas and hydrate accumulations beneath the sea bed; to investigate and understand gas transport and escape mechanisms, their spatial distribution, and the controls on these; and to quantify gas and hydrate saturation values in situ within the pore spaces of the shallow sediment reservoirs. The research is focused on specific areas where significant accumulations of methane hydrate and active methane venting through the sea floor were observed and documented during the earlier JR211 cruise in 2008. This is a NERC funded project hosted by University of Southampton. The data held at BODC include multichannel seismic reflection, TOPAS sub-bottom profiler and 2D seismic reflection data in SEG-Y format. No further data are expected.

This dataset contains wave data collected by surface moorings across three sites (D1, D2 and D3) west of the Isle of Islay between February 2012 and August 2012. There was a Datawell Mk.III directional Waverider buoy moored at each of the three sites collecting the wave data every 30 minutes. The data were collected as part of the metocean survey of the proposed Islay Offshore Windfarm. Partrac Ltd were contracted to conduct the data collection by SSE Renewables and provided the data to The Crown Estate as the landowner of the UK seabed out to 12 nautical miles. The data and associated metadata reports are held at the British Oceanographic Data Centre, as a MEDIN Data Archiving Centre.

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.

A collection of raw water temperature-depth-time profiles were recorded from a selection of dive computers, underwater cameras and baseline Castaway microCTD devices. Data were collected at Oban recompression chamber (owned and managed by Tritonia Scientific), as well as during sea dives local to 56.42 N, 5.47W, over a two-week period between 08/01/2020 and 07/02/2020. A number of different devices and models were tested during the study. Chamber dives were undertaken to test and compare device response time (29 devices over 11 dives) and accuracy (6 replicate dives). This was followed by local sea dives to further compare device accuracy. During each pair of sea dives (6 total), half of the devices were mounted on a frame with the remainder worn by two divers. For the subsequent dives in each pair, each device was switched to the alternate mounting position. Dive profiles were exported from individual dive computers into Subsurface open source software, then exported in ssrf (XML) format for each week of data collection. Profiles from all dive computers were combined for analysis. Castaway microCTDs and Paralenz Dive Camera+ profiles were exported as individual CSV files per dive. Data were collected as part of Celia Marlowe’s PhD project at the University of East Anglia, which aimed to assess the precision, accuracy and uncertainty in water temperature profiles collected from devices commonly carried by Scuba divers. The PhD project is part of the Next Generation Unmanned Systems Science (NEXUSS) Centre for Doctoral Training, funded by the Natural Environment Research Council (NERC) and the Engineering and Physical Science Research Council (EPSRC) (NE/N012070/1), and is additionally supported by Cefas Seedcorn (DP901D). The diving and chamber tests were supported through a NERC National Facility for Scientific Diving grant (NFSD/17/02).

GreenSeas was an EU FP7 programme funded to advance the quantitative knowledge of how planktonic marine ecosystems, including phytoplankton, bacterioplankton and zooplankton, will respond to environmental and climate changes. To achieve this GreenSeas employed a combination of observation data, numerical simulations and a cross-disciplinary synthesis to develop a high quality, harmonized and standardized plankton and plankton ecology long time-series, data inventory and information service. This contribution to the programme developed a number of indices to characterize quantitatively the seasonality of phytoplankton (Platt and Sathyendranath, 2008, Racault et al., 2014a). Specifically, indices that relate to the study of timing of periodic biological events as influenced by the environment are referred to as phytoplankton phenology. These indices include: timings of initiation, peak, and termination as well as the duration of the phytoplankton growing period. Changes in phytoplankton phenology (triggered by variations in climate) can profoundly alter: (1) the efficiency of the biological pump, with inevitable impact of the global carbon cycle; and (2) the interactions across trophic levels, which can engender trophic mismatch with major impacts on the survival of commercially important fish and crustacean larvae. Phenology indices were estimated using the R2010.0 reprocessing of Level 3 Mapped chlorophyll-a concentration from the Sea-viewing Wide Field-of-view (SeaWiFS) sensor. The chlorophyll-a data were retrieved from NASA Ocean Color Web http://oceancolor.gsfc.nasa.gov for the period 1997-2008 at 9 km spatial resolution and 8-day temporal resolution. Linear interpolation was applied to map the chlorophyll-a concentration onto a 1degreex1degree fixed grid. The phenology indices were estimated following the method described in Racault et al. (2012). Missing chlorophyll-a data were reduced from the time-series prior to estimating the timing of ecological events. Missing values were filled by interpolating spatially adjacent values (average of 3 × 3 pixels on the 9km grid), when these were available. Any remaining missing values were filled by interpolating temporally adjacent values (average of previous and following 8-day composites), when these were available. Otherwise the value was not filled. A 3-week running mean was applied to remove small peaks in chlorophyll-a. The timings of initiation and end of the phytoplankton growing period were detected as the weeks when the chlorophyll concentration in a particular year rose above the long-term median value plus 5% and later fell below this same threshold (Racault et al., 2012). The duration of the growing season is defined as the number of weeks between initiation and end.

This database, and the accompanying website called ‘SurgeWatch’ (http://surgewatch.stg.rlp.io), provides a systematic UK-wide record of high sea level and coastal flood events over the last 100 years (1915-2014). Derived using records from the National Tide Gauge Network, a dataset of exceedence probabilities from the Environment Agency and meteorological fields from the 20th Century Reanalysis, the database captures information of 96 storm events that generated the highest sea levels around the UK since 1915. For each event, the database contains information about: (1) the storm that generated that event; (2) the sea levels recorded around the UK during the event; and (3) the occurrence and severity of coastal flooding as consequence of the event. The data are presented to be easily assessable and understandable to a wide range of interested parties. The database contains 100 files; four CSV files and 96 PDF files. Two CSV files contain the meteorological and sea level data for each of the 96 events. A third file contains the list of the top 20 largest skew surges at each of the 40 study tide gauge site. In the file containing the sea level and skew surge data, the tide gauge sites are numbered 1 to 40. A fourth accompanying CSV file lists, for reference, the site name and location (longitude and latitude). A description of the parameters in each of the four CSV files is given in the table below. There are also 96 separate PDF files containing the event commentaries. For each event these contain a concise narrative of the meteorological and sea level conditions experienced during the event, and a succinct description of the evidence available in support of coastal flooding, with a brief account of the recorded consequences to people and property. In addition, these contain graphical representation of the storm track and mean sea level pressure and wind fields at the time of maximum high water, the return period and skew surge magnitudes at sites around the UK, and a table of the date and time, offset return period, water level, predicted tide and skew surge for each site where the 1 in 5 year threshold was reached or exceeded for each event. A detailed description of how the database was created is given in Haigh et al. (2015). Coastal flooding caused by extreme sea levels can be devastating, with long-lasting and diverse consequences. The UK has a long history of severe coastal flooding. The recent 2013-14 winter in particular, produced a sequence of some of the worst coastal flooding the UK has experienced in the last 100 years. At present 2.5 million properties and £150 billion of assets are potentially exposed to coastal flooding. Yet despite these concerns, there is no formal, national framework in the UK to record flood severity and consequences and thus benefit an understanding of coastal flooding mechanisms and consequences. Without a systematic record of flood events, assessment of coastal flooding around the UK coast is limited. The database was created at the School of Ocean and Earth Science, National Oceanography Centre, University of Southampton with help from the Faculty of Engineering and the Environment, University of Southampton, the National Oceanography Centre and the British Oceanographic Data Centre. Collation of the database and the development of the website was funded through a Natural Environment Research Council (NERC) impact acceleration grant. The database contributes to the objectives of UK Engineering and Physical Sciences Research Council (EPSRC) consortium project FLOOD Memory (EP/K013513/1).

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 data set comprises time series of sea level data from coastal tide gauges. The data holdings include over 1000 site years of data from about 200 sites comprising about 10 million records. About 75 per cent of the data are from some 100 sites around the British Isles - the remaining data are from coastal sites and islands scattered across the globe. Data are primarily hourly values. Recording periods vary from one month at some sites to over several years.There are three short series from around the Irish coast which were collected in 1842.

The GEBCO_2021 Grid is a global continuous terrain model for ocean and land with a spatial resolution of 15 arc seconds. In regions outside of the Arctic Ocean area, the grid uses as a base, Version 2.2 of the SRTM15+ data set between latitudes of 50 degrees South and 60 degrees North. This data set is a fusion of land topography with measured and estimated seafloor topography. This version of SRTM15+ is similar to version 2.1 [Tozer et al., 2020] with minor updates. Version 2.2 uses predicted depths based on the V29 gravity model [Sandwell et al., 2019] and approximately 400 small areas containing suspect data were visually identified and removed from the grid. Included on top of this base grid are gridded bathymetric data sets developed by the four Regional Centers of The Nippon Foundation-GEBCO Seabed 2030 Project. The GEBCO_2021 Grid represents all data within the 2021 compilation. The compilation of the GEBCO_2021 Grid was carried out at the Seabed 2030 Global Center, hosted at the National Oceanography Centre, UK, with the aim of producing a seamless global terrain model. Outside of Polar regions, the gridded bathymetric data sets are supplied by the Regional Centers as sparse grids, i.e. only grid cells that contain data were populated, were included on to the base grid without any blending. The data sets supplied in the form of complete grids (primarily areas north of 60N and south of 50S) were included using feather blending techniques from GlobalMapper software. The primary GEBCO_2021 grid contains land and ice surface elevation information - as provided for previous GEBCO grid releases. In addition, for the 2021 release a version with under-ice topography/bathymetry information for Greenland and Antarctica is also available. The GEBCO_2021 Grid has been developed through the Nippon Foundation-GEBCO Seabed 2030 Project. This is a collaborative project between the Nippon Foundation of Japan and the General Bathymetric Chart of the Oceans (GEBCO). It aims to bring together all available bathymetric data to produce the definitive map of the world ocean floor by 2030 and make it available to all. Funded by the Nippon Foundation, the four Seabed 2030 Regional Centers include the Southern Ocean - hosted at the Alfred Wegener Institute, Germany; South and West Pacific Ocean - hosted at the National Institute of Water and Atmospheric Research, New Zealand; Atlantic and Indian Oceans - hosted at the Lamont Doherty Earth Observatory, Columbia University, USA; Arctic and North Pacific Oceans - hosted at Stockholm University, Sweden and the Center for Coastal and Ocean Mapping at the University of New Hampshire, USA.

The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 4.0 is a gridded continuous terrain model covering ocean and land of the Arctic region. The grid has been compiled from data covering approximately 14.2 percent of the Arctic seafloor with multibeam bathymetry and about 5.5 percent with other sources, excluding digitized depth contours. The grid-cell size (resolution) is 200x200 m on a Polar Stereographic projection, with the true scale set at a latitude of 75 deg N and a central meridian of 0 deg. The horizontal datum is WGS 84 and the vertical datum is assumed Mean Sea Level. IBCAO Version 4.0 has been compiled with support from the Nippon Foundation-GEBCO-Seabed 2030 Project, an international effort whose goal it is to see the entire world ocean mapped by 2030. A geographic version of the Polar Stereographic grid serves as input to the General Bathymetric Chart of Oceans (GEBCO) global gridded terrain model.