Metadata Report for BODC Series Reference Number 679974

• 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

Maximum Instrument Depth Greater Than Sea Floor Depth

CTD/XBT Data

It is possible for the maximum depth of a CTD/XBT cast to exceed the estimated sea floor depth at a given location.

The depth of a CTD unit is calculated from its measurements of pressure using an algorithm which makes assumptions about the density profile of the water column and XBT depth is often estimated from an assumed descent rate. Similarly, total water depth is calculated from the two-way travel time of sound waves through the water column making assumptions about the velocity of the sound waves. All of these calculations may contain errors, and the depth of a CTD/XBT unit may therefore appear to be below the sea floor.

Other Instrument Types

It is possible that instrument depths are taken from instantaneous measurements whereas water depth is read from a chart or corrected to a datum, such as mean sea level. If this occurs and the instrument depth has been read at high tide it is possible that an instrument mounted on the sea floor will have a depth half of the tidal range below the sea floor depth.

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Teledyne RDI's Workhorse Monitor ADCP

The Workhorse Monitor acoustic doppler current profler (Teledyne RD Instruments) is a long-range and long-term self contained ADCP. It has a patented four beam signal (300, 600 or 1200 kHz) and a standard depth rating of 200m or 600m. It operates effectively between temperatures of -5°C and 45°C and has a velocity accuracy of ±1% ±5mm/s.

OC401 LADCP data processing

Data Originator's processing

The software used to process the data is a descendent of the Visbeck software (Visbeck, 2002). In most cases, corresponding CTD time series data and shipboard adcp data are incorporated into the processing.

BODC post-processing and screening

• Reformatting

  The data were converted from ASCII format into BODC internal format (a netCDF subset) to allow use of in-house visualisation tools.

• Screening

  Reformatted data were visually checked using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

• Banking

  Once quality control screening was complete, the data were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.

References

Visbeck, M (2002): Deep Velocity Profiling Using Lowered Acoustic Doppler Current Profilers: Bottom Track and Inverse Solutions. Journal of Atmospheric and Oceanic Technology Volume 19, Issue 5.

Project Information

Line W Project

Introduction

Line W is a U.S-led initiative to monitor the North Atlantic Ocean's deep western boundary current. The programme is funded through the U.S National Science Foundation and has been active since October 2001. It brings together scientists from Woods Hole Oceanographic Institution (WHOI) and Lamont-Doherty Earth Observatory (LDEO). Between 2004 and 2010, scientists from the RAPID WAVE project (a component of the U.K's RAPID Climate Change Programme) also collaborated with Line W. This U.K element was funded by the Natural Environment Research Council (NERC) and brought additional instrumentation (predominantly bottom pressure landers) to the mooring array. The contact details of the principal collaborators involved with Line W are noted below.

Users of these data are referred to the Line W Project Website for more information. The following text has been taken from the website.

Scientific Rationale

Located on the continental slope south of New England (near 40°N, 70°W) Line W is one component of a long-term climate observing system that is positioned to quantify variability in the deep limb of the Atlantic meridional overturning circulation (MOC). Combining an array of moored instruments with shipboard observations, Line W is designed to directly measure the time dependence of volume transport, advection of property anomalies, and propagation of topographic Rossby waves and boundary waves in the equatorward flowing deep western boundary current (DWBC). These measurements are key to clarifying the deep ocean response to variability in high-latitude air-sea exchanges and, ultimately, the ocean's role in global climate variability through changes in its transport of heat and freshwater.

Instrumentation

Types of instruments and measurements:

• Moored Profilers (temperature, salinity, velocity)
• Current meters (VACMs) with Temperature/Conductivity sensors and upward-looking ADCP
• Shipboard measurements: CTD, CFCs, salinity, dissolved oxygen, I129, LADCP, ADCP

The full array of instruments was installed April 2004 with servicing as follows:

• Annual spring turnaround for profilers
• 2-year turnaround for VACMs
• Twice yearly shipboard measurements

Contacts

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: