Metadata Report for BODC Series Reference Number 1806259

• 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

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): Data Quality Report

The LADCP was used in all CTD stations, except for cast 51 due to the high depth reached in this station. No file was generated.

The orignator noted there was no evident issue during the processing of most of the stations, with the data looking reasonably good. On stations 14 and 58 the ADCP did not detect the bottom correctly; this problem was overcome by forcing the software to use its own bottom track/ranges. On station 14 the bottom detection still did not work as intended, and the bottom depth needed to be set manually in Matlab. All other casts ran as intended,without any need for manual intervention by the originator.

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

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.

RRS James Clark Ross JR20150309 (JR272D, JR310) CTD Instrumentation

A Sea-Bird 911 plus CTD system was used on cruise JR20150309 (JR272D, JR310). This was mounted on a SBE-32 carousel water sampler holding 24 12-litre Niskin bottles. The CTD was fitted with the following scientific sensors:

A single Teledyne RDI 300kHz Workhorse Monitor direct-reading ADCP was also fitted to the CTD frame.

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): BODC Processing

LADCP processed matlab files were converted into a BODC internal NetCDF format. The following table shows how the variables were mapped to appropriate BODC parameter codes:

All reformatted data were visualised using the in-house Edserplo software and screened for suspect and missing data.

RRS James Clark Ross JR20150309 (JR272D, JR310) Lowered Acoustic Doppler Current Profiler (LADCP): Originator's processing

Sampling strategy

A single RDI 300-kHz Workhorse Monitor LADCP was mounted on the CTD frame in a downward-facing orientation and was deployed on all 74 CTD casts, however was switched off for CTD cast 51 due to the deep depth of the station. The instrument was configured to record 16 depth bins in a 10m bin length, in a narrow bandwidth with 5m blanking distance. Before each cast was deployed, a pre-deployment test script was run to verify that the internal electronics were performing correctly. Both the test script and deployment script are outlined in detail in the cruise report.

Data processing

The binary files recorded by the instrument, together with the log files, were downloaded to the local computer and copied to the server after each cast. The data were processed using a package fully written in Matlab code, originally developed at Lamont-Doherty Earth Observatory (LDEO) by Martin Visbeck and updated by Andreas Thurnherr (version LDEO IX_10). This package calculates velocity based both on the velocity inversion and shear methods.

Modifications to the set_cast_params.m script were made by Marina Azaneu and Povl Abrahamsen to load CTD, GPS, and SADCP data from the JCR. This created files containing CTD time series and CTD profile data from the mstar-processed CTD data with resolution of 1 Hz and averaged into 2 dbar, respectively. GPS time series were also generated during the processing (based on the 1-Hz CTD data), in addition to SADCP time series. These auxiliary data are not required for the LADCP processing, but are essential for acquiring better quality results.

Two main modifications were applied to the original scripts. Firstly, it was noticed that if the same station were processed twice, there was a conflict when the software overwrites the created auxiliary data, CTD time series, CTD profile data, navigation datam, SADP time series, leading to unreasonable results. Thus, the script was modified to verify the existence of these files and delete them before creating the new files. The second modification regards the SADCP data, which were considered too noisy in some stations. After testing different thresholds, it was defined that only SADCP data with percent good higher than 25% would be used for the LADCP processing. Both modifications are included on the set_cast_params.m file.

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

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: