Metadata Report for BODC Series Reference Number 1196091

• 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

BAS Marine Geophysics cruise D172 Data Quality Report

Data from CTD 18 and CTD 24 are upcast data which have been flipped to be represented as downcast.

The originator's data required binning. Before this was done, the channels were flagged based on negative pressure values and pressure reversals. Temperature and salinity spikes were also flagged.

The following table contains information per CTD cast on: the total number of data points included in the binning process, how many negative pressures (-3 dbar) were present and flagged, how many pressure values were flagged as pressure reversals (not including the negative values), and how many temperature and salinity data points were flagged (not related to pressure values).

After binning, empty pressure bins get populated with interpolated values. The result for all CTD casts is that between 2 and 10 % of values are interpolated.

There are 6 empty pressure bins for CTD 18 and 5 for CTD 21.

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

BAS Marine Geophysics cruise D172 BODC data processing

The files were processed and calibrated at the British Antarctic Survey and were sent to BODC in excel format. Originator's variables include: press, temp, pottemp, sal, sigmat, trans and for some files, press/5, ptemp/5 and trans/5. Not all variables were transferred as there was no information on how they were obtained or their units.

The files were converted to BODC internal format (QXF) using established procedures, and included matching the originator's variables to the appropriate BODC parameter codes.

The following table shows how the variables within the originator's files were mapped to :

Processing of the BODC QXF files

The data received had not been binned and some files included up and down cast data or were just up cast data. A series of steps were carried out at BODC to remedy these issues:

BAS Marine Geophysics cruise D172 CTD originator's data processing

Sampling Strategy

A total of 16 CTD profiles were performed during the cruise. Data from each cast were logged independently on the BBC micro and ABC computer system. The problems with negative temperatures and pressures were solved by modifying the programs whilst on board.

The water bottles were removed from the CTD as soon as it was on deck and stored in the lab where sampling was performed. Samples were collected for suspended particulate matter studies, salinity calibration and oxygen isotope measurements.

The comparison between the reversing thermometer and the CTD sensor on casts 9 and 20 showed an agreement within 0.02°C for bottom temperatures.

The CTD unit was attached to a carousel with 12 bottles. The CTD sensors were pressure, conductivity, temperature and transmissivity. There was a reversing thermometer attached on the rosette, on casts 9 and 20, which provided independent measurements.

Project Information

Marine Geophysics- Scotia and Bellingshausen

Introduction

Marine geoscience in the Scotia and Bellingshausen Seas was one of the main research interests for British Antarctic Survey (BAS). The investigations were carried out by a group of scientists based at the University of Birmingham, which was absorbed by BAS in the mid- 1980's.

The different survey methods included, amongt others, multichannel and single channel seismic reflection, deeptow boomers, GLORIA (Geological Long Range Inclined Asdic) side-scan sonar and HAWAII-MR1 (HIGP Acoustic Wide_Angle Imaging Instrument) swath bathymetry and side-scan sonar.

This project was funded by BAS and most of the surveys were also carried out by this institution.

Scientific Objectives

This project was carried out in order to gain a better understanding of the Southern Ocean's:

• Tectonic history
• Active tectonic processes
• Paleoceanography
• Stratigraphy
• Ice dynamics during glacial intervals

Data Availability

Data sets collected during this project are available to the academic community.

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: