Metadata Report for BODC Series Reference Number 1368817

• 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

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 Processing

Data Processing

The data arrived at BODC in Matlab format representing data collected from moorings CI1, CI2, OP1, OP2, OP3, OP5 and OP6. Data were obtained from a total of five different types of instruments, RCM8, RCM11, SBE37, SBE39 and Aquadopps.

Reformatting

The RCM 8 files were reformatted to an internal format using BODC established procedures. The parameters which were not reformatted include botdepth, date, latitude, longitude, mooring name, nomdepth (m), serial_no and type as these constitute metadata and not environmental data, however, these variables are available upon request.

The table below illustrates how the originator's variables within the .MAT files were mapped to the appropriate BODC parameter codes:

None of the parameters required a unit conversion and no derived parameters were created during reformatting.

Note that PREXPR01 is only present in series reference: 1368805, 1368830, 1368842 and 1368878.

Screening

The data were visualised using in house software and quality flags were applied to any improbable data.

Originators Data Processing

Sampling Strategy:

Sampling was carried out as part of the BAS LTMS (British Antarctic Survey Long Term Monitoring and Survey). The project involved the deployment of moorings CI1, CI2, OP1, OP2, OP3, OP4, OP5 and OP6 in the Southern Ocean, situated north of Coronation Island and the Orkney Passage in the Weddell and Scotia Sea.

Moorings CI1 and CI2 were deployed from 2005 to 2007 and moorings OP1, OP2, OP3, OP4, OP5 and OP6 have been continuously maintained since 2007.

RCM8 data are being collected on a 60 minute interval.

Gaps in the data series may be due to measurements not being obtained, instrument malfunction and/or the instruments not being recovered.

Data Processing:

Little information is known with regards to the exact details of calibrations carried out on the mooring data. Originators data processing, visualisation and calibration were completed using Matlab version R2014b using a script created by the originator. The calibration, which was applied to the raw data, corrected, plot overview figures and thus exported a final Matlab data version which was transferred by BODC.

The originator reported that the current velocity and direction components for the data from 2005 to 2013 have not been corrected for magnetic variation. This is due to the variation in this region being less than one degree, which is less than the accuracy of the current direction measurements of the instrument.

An offset value has been applied to the corrected/calibrated temperature variables, the offset values applied can be found below:

Project Information

BAS Long Term Monitoring and Survey

Introduction

The Long Term Monitoring and Survey project (LTMS) has been running since the British Antarctic Survey (BAS) was created. This project is one of the BAS core projects, with several groups of scientists collecting various types of data e.g biological, geological, atmospheric, among others.

Data collection is achievable through a wide scope of instruments and platforms, e.g. the Antarctic research stations, autonomous instrument platforms deployed on or from BAS research ships, BAS aircrafts, satellite remote sensing and others.

Scientific Objectives

This project was implemented in order to measure change and variability in the Earth system. Its long term duration allows for the monitoring of processes that could be missed in shorter term studies and experiments. The data collected is also used to check and improve the reliability of models used to stimulate and predict the behavior of the Earth system.

The main objectives are:

• Topographic survey
• Geosciences survey
• Biological survey and monitoring
• Atmospheric and oceanographic monitoring

Data Availability

The data sets obtained through this project are available to the academic community.

Data Activity or Cruise Information

Data Activity

Coronation Island mooring 2

The mooring was deployed at the following positions:

The mooring was deployed off Coronation Island on cruise JR20051226 (JR151) on 26 December 2005 and recovery was done on cruise ES20070116 (ES031, ES038, ES048) on 24 February 2007.

The table below lists the instruments deployed on this mooring:

Data issues found at recovery

Upon recovery it was found that RCM 11 sn521 presented some data corruption. Aanderaa conductivity sensors also exhibited large jumps in two records and a rapid initial drift which the originator estimates is due to distortion/creeping to accomodate the water pressure.

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: CI2

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.