Metadata Report for BODC Series Reference Number 2108999

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

Non-toxic (underway) sea water supply

A source of uncontaminated near-surface (commonly 3 to 7 m) seawater pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the non-toxic supply. The system is also referred to as the underway supply.

AMT20 (JC053) CTD bottle and surface underway sampled Particulate Inorganic Carbon (PIC), Particulate Organic Carbon (POC), Particulate Organic Nitrogen (PON) and Biogenic Silica (BSi)

Data Acquisition and Analysis

The data originates from analyses on samples collected from CTD rosette bottle and underway samples collected from the ship's non-toxic supply during the cruise JC039 (AMT19). Discrete underway samples were collected from the ship's Surf-Met (underway surface and meteorological data collection) flow system in the CTD hanger lab 3 times per day (every 3-4 hours, spaced around stations). Samples for POC, PIC, BSi, and coccolith enumeration were obtained along with chlorophyll samples taken for fluorometer calibration.

During the pre-dawn CTD (second cast of the day) six light depths (1%, 7%, 14%, 33%, 55%, 97%) and at least one below the mixed layer deeper (down to 200m) depths were analysed. Seven depths (DMC and several depths above and below) were analysed from the local noon CTD each day.

PIC samples were collected on 0.4 µm polycarbonate filters, rinsed with potassium tetraborate buffer and stored in metal free centrifuge tubes. These will be analyzed by ICPOES for particulate calcium. Coccolith and cell counts are collected on Millipore HA (nitrocellulose) filters, rinsed with potassium tetraborate buffer, frozen at 20°C, dried, then mounted onto slides using Norland Optical Adhesive. They will later be enumerated by birefringence microscopy.

Biogenic silica (BSi) samples were filtered onto 0.4 µm polycarbonate filters, dried in clean centrifuge tubes, and will be analysed following the protocol of Brzezinski and Nelson (1989).

POC and PON samples were filtered onto pre-combusted (450°C for 5 hours) glass fiber filters. Filters were rinsed with filtered seawater (FSW) and then stored in individual petri-plates and dried (60°C) for storage. Prior to analysis, the plates are opened and placed overnight in a sealed container like a dessicator with saturated HCL fumes to remove any PIC. The filters were packed into pre-combusted nickel sleeves and analysed on a Perkin Elmer 2400 Series II CHNS/O for C, N, and H.

References

Brzezinski, M.A., Nelson, D.M., (1989). Seasonal changes in the silicon cycle within a Gulf Stream warm-core ring. Deep-Sea Research 36, 1009-1030.

Instrumentation Description

Perkin Elmer 2400 Series II CHNS/O

BODC Data Processing

Data were submitted in a tab delimited text format and accessioned under BODC archive BGL120224. Sample metadata (Date, time, latitude, longitude, sampling event ID and depth) for the CTD samples were checked against information held in the database - there were no discrepancies found.

Parameter codes defined in the BODC parameter dictionary were assigned to the variables. The data for PIC and POC were converted from mg m^-3 to µmol L^-1, this was acheived by dividing by 12 (atomic mass of carbon). The same was done for PON though the conversion was made by dividing by 14 (atomic mass of Nitrogen) and the BSi data were provided in units (mmol m^-3), which were consistent with those used in the BODC database for the parameter codes (µmol L^-1).

Data were loaded to BODC's database with only a unit conversion applied.

A parameter mapping table is provided below:

Data Quality Report

BODC were not advised of specific quality checks carried out by the data originators. There were no standout values in the sample data provided to BODC.

Problem Report

Not relevant for this dataset

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

• give early warning of any fundamental change in Atlantic ecosystem functionng
• improve forecasts of the future ocean state and associated socio-economic impacts
• provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.

The specific objectives are:

• To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
• To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
• To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: