The dataset contains hydrographic, biogeochemical and biological measurements of ocean and seabed sediment properties. Hydrographic profiles provided measurements of temperature, salinity, dissolved oxygen and fluorescence to accompany biogeochemical and biological samples, including concentrations of nutrients, particulate organic carbon (POC) and particulate organic nitrogen (PON). Emphasis was placed on the collection of benthic data, with numerous core samples being collected and analysed for pigments, biomarkers, lipids and other organic compounds. Samples were also collected and analysed for Holothurian species, while a large volume in situ filtration system was used to measure biogeochemical variables including POC and PON, and particulate iron. Station data were supplemented by continuous underway measurements of bathymetry, current velocities, sea surface salinity, temperature, fluorescence and beam attenuation across the survey area. These were accompanied by underway measurements of surface meteorological parameters including irradiance, air temperature, humidity, sea level pressure and wind velocities. The data were collected across the Crozet Plateau in the Southern Indian Ocean between 1st December 2005 and 14th January 2006 on RRS Discovery cruise D300. Data collection focused on four sites, with repeated hydrographic profiles, water and sediment samples collected at each location. In total, 89 instrumentation deployments were carried out at the four stations, including a conductivity-temperature-depth (CTD) package and a Megacorer (for sediment sampling). The underway system utilised a hull-mounted acoustic Doppler current profiler (ADCP) as well as a thermosalinograph and other standard surface hydrographic and meteorological instruments. Further data were collected using a variety of equipment including an otter trawl (net) and submersible cameras but these data are currently held by the data originators and are undergoing processing so are not included in the parameter and instrument lists above. The principal objective of Benthic CROZEX was to assess the manner in which biogeochemical composition and flux of organic matter to the deep-sea floor drives benthic community structure, dynamics and diversity at sites with contrasting primary production regimes. Investigators from British Antarctic Survey (BAS), Natural History Museum (NHM), National Oceanographic Centre (NOC) and the National University of Ireland, Galway (NUIG) were involved. Data management is being undertaken by the British Oceanographic Data Centre (BODC) but data processing is ongoing and various data are yet to be submitted to BODC.

The dataset contains physical, biogeochemical and biological data, including measurements of water temperature, salinity, fluorescence, dissolved gases and current velocities; plankton samples from nets and plankton recorders; water samples for analysis of nutrients, phytoplankton, radioactivity and biogeochemical parameters; benthic cores; meteorological time series (pressure, temperature, humidity, wind velocities); atmospheric samples and ocean-atmosphere fluxes; and results from incubation experiments. The data were collected north of the Crozet Plateau in the Southern Ocean/Southwest Indian Ocean on RRS Discovery cruises D285 (3rd November - 10th December 2004) and D286 (13th December 2004 - 21st January 2005). Much of the data collection focussed on a series of Major Stations (called M1 to M10), with measurements being collected at these stations every two or three days. Conductivity-temperature-depth (CTD) casts were undertaken at each station, providing both hydrographic data and water samples from a range of depths. Other work at each Major Station included zooplankton nets, Longhurst-Hardy Plankton Recorder (LHPR) tows, sediment coring and Argo float deployment. In between Major Stations some additional CTD casts were undertaken. The SeaSoar oceanographic undulator provided further hydrographic data, while hull-mounted acoustic Doppler current profilers (ADCPs) provided current velocity data across the survey area. In addition, continuous underway measurements of hydrographic and meteorological parameters and surface water samples were collected along the cruise track. Five moorings were deployed, one of which was recovered at the end of D286. The other four, including sediment traps, current profilers and CTDs were deployed for one year. CROZEX (CROZet circulation, iron fertilization and Export production experiment) is a complex, multidisciplinary project to examine, from surface to sediment, the structure, causes and consequences of a naturally occurring annual phytoplankton bloom that forms. This collaborative project involved researchers in Ireland and the UK, and was administered by the National Oceanography Centre (NOC), Southampton. Data are managed by the British Oceanographic Data Centre. Much of the CROZEX data processing is ongoing and a number of datasets have yet to be submitted to BODC. The data described here are those presently held by BODC, with the exception of the Argo floats (these data are not expected by BODC and should be accessible via the Argo website) and the four year-long mooring deployments (data from these will be submitted to BODC in the future).

The dataset includes a wide range of physical, chemical and biological oceanographic parameters. Physical hydrographic measurements include temperature, salinity, optical backscatter, current velocities and turbulence, while biogeochemical measurements in the water column include dissolved oxygen, organic carbon and nitrogen, and nutrients. Biogeochemical parameters were also measured in sediment cores, while phytoplankton and zooplankton data were also collected. The marine data were supplemented by meteorological measurements including temperature, pressure, irradiance and wind. The experimental phase of the project was undertaken in the North Sea between 1998 and 1999, and data were collected at two contrasting sites: Northern North Sea (NNS, 59deg 20.0E, 1deg 00.0E) and Southern North Sea (SNS, 52deg 15.0N, 4deg 17.0E). At both locations measurements were concentrated at a central position with additional measurements being made to estimate horizontal gradients. Moored instruments were deployed at NNS from September - November 1998 and at SNS from March - May 1999. Each experiment was supported by intensive measurement series made from oceanographic ships and involving turbulence dissipation profiler, conductivity-temperature-depth (CTD) profilers, particle size profilers, optical profilers, benthic sampling and water bottle sampling. PROVESS is an interdisciplinary study of the vertical fluxes of properties through the water column and the surface and bottom boundary layers with the aim of improving understanding and quantification of vertical exchange processes in the water column. Scientists from 18 institutions distributed in 8 European countries participated in the fieldwork and modelling parts of the programme and was co-ordinated by John Howarth of the Proudman Oceanographic Laboratory. The British Oceanographic Data Centre (BODC) is responsible for assembling the data collected during the project into a comprehensive data set. The data has been organised onto a CD-ROM product available through BODC.