Metadata Report for BODC Series Reference Number 1765062

• 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 Discovery Cruise DY052 Vessel Mounted ADCP Data Quality Report

The data were visually inspected and found to be noisy, particularly in the shallowest 2 bins. Obvious spikes were flagged, but some noisiness remains. Further quality control has been left to the discretion of the end user.

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

RD Instruments- Ocean Surveyor 75kHz Vessel mounted ADCP.

¹ Ranges at 1 to 5 knots ship speed are typical and vary with situation.
² Single-ping standard deviation.
³ User's choice of depth cell size is not limited to the typical values specified.

Profile Parameters

• Velocity long-term accuracy (typical): ±1.0%, ±0.5cm/s
• Velocity range: -5 to 9m/s
• # of depth cells: 1 - 128
• Max ping rate: 0.7

Bottom Track

Maximum altitude (precision <2cm/s): 950m

Echo Intensity Profile

Dynamic range: 80dB
Precision: ±1.5dB

Transducer and Hardware

Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W

Standard Sensors

Temperature (mounted on transducer)

• Range: -5° to 45°C
• Precision: ±0.1°C
• Resolution: 0.03°

Environmental

Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*

*later instruments have greater range.

Web Page

Further details can be found on the manufacturer's website or in the specification sheet

RRS Discovery DY052 Originator's Vessel Mounted ADCP data processing

Originator's Protocol for Data Acquisition and Analysis

The RRS Discovery DY052 occupied the Extended Ellett Line.

The cruise departed on the 7th June 2016 from the port of Glasgow and returned on the 24th June 2016 to Glasgow.

Sample collection

During cruise DY052, a 75 kHz and a 150 kHz vessel mounted ADCP (VMADCP) Ocean Surveyor was operating. The 75 kHz instrument was configured to 64 bins with intervals of 16 m and the 150 kHz instrument was configured to 64 bins with intervals of 8 m.

The data from the VMADCP was collected in real-time using the RD Instrument VMDas software package which controlled the instrument. The VMDas software allowed data acquisition in a number of configurable formats and performed preliminary screening and transformation of the data from beam to Earth coordinates.

Data Processing

The final processing of the data was done using the CODAS (Common Ocean Data Access System) software provided by the University of Hawaii. CODAS is a suite of Unix and Matlab programs which allows manual inspection and editing of bad profiles and provides best estimates of the required rotation of the data, either from water profiling or bottom tracking.

A summary of these steps are:

• vmadcp_linkcript150 and vmadcp_linkscript76 - creates a new directory called rawdata<<nnn>>and moves the relevant data to this new location.
• adcptree.py dy052<<nnn>> nbenx --datatype enx - sets up a directory tree for the CODAS dataset and an extensive collection of configuration files, text files and m files.
• quick adcp.py --cntfile q py.cnt - loads the data into the directory tree, performs routine editing and processing and makes estimates of both water track and (if available) bottom track calibrations. The raw ping files are also averaged into 5-minute periods. The calibration values are stored in the adcpcal.out and btcaluv.out files found in the cal/watertrk and cal/botmtrk directory respectively and are appended each time quick adcp.py is run.
• Manual editing - data checked in Gautoedit to flag any data that is deemed to be bad.
• quick adcp.py - cntfile q pyedit.cnt - flags from Gautoedit are passed forward and using this command, the discarded data was removed.
• Once the editing and rotations were completed, the final velocities were collated into Mstar files (*.nc) using the Matlab mcod 01 and mcod 02. Files were then appended using mcod_mapend.

Field Calibrations

To provide the best calibration for the velocity data, the mean was taken from BT (bottom track) medians. The final calibration was: rotation angle = 0.2245 °, amplitude = 0.9984 meters.

References

Gary, S.F. et al. (2016). Cruise DY052 Extended Ellett Line. Cruise Report Scottish Association for Marine Science

RRS Discovery DY052 Vessel Mounted ADCP: Processing undertaken by BODC

The data arrived at BODC in two MStar files representing the data collected from the two vessel mounted ADCPs (75 kHz and 150 kHz) during cruise DY052. The data were reformatted to BODC's internal NetCDF format. The following table shows the mapping of variables within the MStar file to appropriate BODC parameter codes:

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.

Project Information

No Project Information held for the Series

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: