Metadata Report for BODC Series Reference Number 1807496

• 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

• There is clear evidence of 'knock-down' on mooring B1, from 08 November 2003 05:47:29 hours to 24 November 2003 05:47:58 hours. All current parameters for Series 1807460 were flagged M during this period.
• The conductivity channel on all instruments is of poor quality thus, following the originator's recommendations, it was flagged for the entire deployment period.

GIANTS/RISOC Data Quality Report

• All Conductivity data were flagged L as per originator's comments. According to the originator, the conductivity cells used in these instruments are quite old and of poor quality. One cell, series 1807460, had no calibrations performed.
• All current parameters for series 1807484 were flagged L as per originator's comments. the rotor shield was damaged by an iceberg at an unknown time, so all measurements should be considered suspect.
• From 08 November 2003 05:47:29 hours to 24 november 2003 05:47:58 hours, series 1807460 exhibits anomalous pressure data which can be related to the instrument being knocked down by an iceberg. M flags were applied to all current parameters as there was evidence of anomalous data.
• From 27 January 2004 21:49:57 hours to 06 March 2004 22:51:45 hours, the temperature data for series 1807460 and 1807484 exhibits warmer tempereratures, as well as bigger amplitudes. The data were not flagged but caution is advised when using these data.
• From 27 April 2004 20:39:06 hours to 01 May 2004 15:39:06 hours, the durrent parameters for series 1807472 exhibit fairly constant data. M flags were applied to all instances as these were considered to be anomalous.

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

Aanderaa Recording Current Meter Model 7/8

Manufacturer's specifications: recording unit height 49.5cm (RCM8 52.0cm), diameter 12.8cm, vane size 48.5x50.0cm. Meter is designed for depths down to 2000m (RCM8 6000m). It incorporates a spindle which is shackled to the mooring line. The meter is attached to the spindle through a gimbal mounting which permits a maximum 27° deviation of the spindle from the vertical, the meter still remaining horizontal.

Meter comprises :

1. Paddle wheel rotor magnetically coupled to an electronic counter

2. Vane, which aligns instrument with current flow, has a balance weight ensuring static balance and tail fins to ensure dynamic balance in flows up to 250cm/s.

3. Magnetic compass (needle is clamped to potentiometer ring) - direction recorded with 0.35° resolution, 5° accuracy for speeds 5 to 100cm/s, 7.5° accuracy for remaining speeds within 2.5 to 200cm/s range.

4. Quartz clock, accuracy better than 2 sec/day within temperature range 0 to 20°C.

5. Thermistor (temperature sensor), standard range -2.46 to 21.48°C (max on high range 36.04°C), accuracy 0.05°C, resolution 0.1 per cent of range, 63 per cent response time 12sec.

6. Inductive cell conductivity sensor (optional), range 0 to 70mmho/cm standard resolution 0.1 per cent of range.

7. Silicon piezoresistive bridge, standard range 0 to 3000 psi (RCM8 to 9000 psi), resolution 0.1% of range.

8. Self balancing potentiometer which converts the output from each sensor into a 10 bit binary number for storage on magnetic tape.

9. Associated electronics.

A built-in clock triggers the instrument at preset intervals and up to six channels are sampled in sequence. Channel 1 is a fixed reference reading for control purposes and data identification. Channels 2, 3 and 4 represent measurement of temperature, conductivity and pressure. Channels 5 and 6 represent the VECTOR AVERAGED current speed and direction since the previous triggering of the instrument. The number of rotor revolutions and the direction is sampled every 12 seconds and broken into North and East components. Successive components are added and recorded as speed and direction. For recording intervals longer than 10 minutes, speed and direction are sampled 1/50th of recording interval.

It has become common practice in some laboratories to deploy these meters as temperature and conductivity loggers without current measuring capabilities.

The following link will provide the manufacturer specifications:

BODC Data Processing Brunt Ice Shelf moorings

One file in Matlab format was received at BODC. The file contained data for all current meters attached to the mooring. All parameters were transferred to BODC format and originator's variables were mapped to BODC codes according to the table below:

The originator sent two temperature variables,, although both were transferred, only one remains in the final file as a generic calibration was applied to the other data. These data are available upon request.

Data were visualised in EDSERPLO and M flags applied to anomalous data. L flags were applied to instances where the originator had made comments on the data quality.

Originator's Processing of the Brunt Ice Shelf moorings

Data Aquisition and analysis

Three moorings were deployed as part of the GIANTS/RISOC project. The moorings were deployed on cruise ES006 and recovered on cruise JR20050203 (JR97). Data were read using Aanderaa's "5059" data conversion software data were processed at the British Antarctic Survey.

Current speed is integrated over the sampling interval. Current direction and, where measured, temperature, conductivity or pressure are taken as spot measurements at the end of the sampling interval. Direction was not corrected for magnetic variation and pressure was not corrected for atmospheric variations. All parameter values are given at times incremented by the nominal sample interval. The time assigned to each parameter is that of the end of the sampling period. Sea floor depths were obtained through the ship's echosounder.

Data from two moorings was submitted to BODC, the remaining mooring, B2, was not recovered and it is supected that it was released by an iceberg and got stuck under the ice.

Calibration

The instruments were calibrated and checked by the UK Ocean Research Services (UKORS). Laboratory calibration formulae were used for all parameters. A cardinal point compass check was conducted before deployment.

Project Information

Global Interactions of the Antarctic Ice Sheets- GIANTS

Introduction

GIANTS was created to describe and understand the interactions and internal processes controlling the Antarctic ice sheet, to explore its history and to predict its future evolution and how this might drive global changes. The research draws together a multi-disciplinary team which will study large-scale and local processes linking ice with environment.

The research will be conducted through different methods, from observations from ships, to holes drilled through the ice shelves, seismic techniques, radar data collection, aerial magnetic and gravity surveys and satellite data. All these data will be fed to computer simulations to obtain a clearer understanding of the history of the ice sheet and its future evolution.

This project encompasses 5 components:

• response of the ice-shelf ocean system to climate
• Late-Cenozoic history of the Antarctic ice sheet
• Targeting ice stream onset regions and under-ice systems
• Data and dynamics (Optical estimation of the state of the Antarctic Ice Sheet)
• Basin balance assessment and synthesis

Scientific Objectives

The main objectives are:

• To describe how interactions between the ice sheet and the oceans modify globally important water masses sucha as the Antarctic Bottom Water
• To understand geological and glaciological controls on ice-stream flow
• To study the history of the ice sheet over the last 10 million years using volcanic evidence
• To understand the coupling between ice sheets and the Earth's uppermost layers during deglaciations
• To integrate real ice-sheet histories into ice-sheet simulation models
• To use the models to produce policy-relevant predictions of the future effect of the West Antarctic Ice Sheet on global sea level

Data Availability

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

Data Activity or Cruise Information

Data Activity

GIANTS-RISOC B3 mooring

Deployment

This rig was deployed as part of the British Antarctic Survey Global Interactions of the Antarctic Ice Sheet Project (GIANTS), sub-component Response of the Ice-Shelf Ocean System to Climate (RISOC), at Site B3.

Rig Description

This mooring consisted of three Aanderaa RCM7, one Aanderaa RCM8 current meter and one Sediment Trap. A ground line attached a 500 kg anchor to a sub-surface buoy (32 inch steel). All instruments were attached to this line.

Related Data Activity activities are detailed in Appendix 1

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:

Appendix 1: B3

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.