Metadata Report for BODC Series Reference Number 1207453

• 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

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

Trimble Applanix Position and Orientation Systems for Marine Vessels (POSMV)

The Position and Orientation Systems for Marine Vessels (POSMV) is a real time kinematic (RTK) and differential global positioning system (DGPS) receiver for marine navigation. It includes an inertial system that provides platform attitude information. The instrument provides accurate location, heading, velocity, attitude, heave, acceleration and angular rate measurements.

There are three models of Applanix POSMV, the POS MV 320, POS MV Elite and the POS MV WaveMaster. POS MV 320 and POS MV WaveMaster are designed for use with multibeam sonar systems, enabling adherence to IHO (International Hydrographic Survey) standards on sonar swath widths of greater than ± 75 degrees under all dynamic conditions. The POS MV Elite offers true heading accuracy without the need for dual GPS installation and has the highest degree of accuracy in motion measurement for marine applications.

Specifications

POS MV 320

POS MV WaveMaster

POS MV Elite

¹ One Sigma, depending on quality of differential corrections
² Whichever is greater, for periods of 20 seconds or less

Further details can be found in the manufacturer's specification sheet.

JC090 Vessel Mounted ADCP Data Document

Originator's Protocol for Data Acquisition and Analysis

The RRS James Cook JC090 funded by NERC was the concluding phase of the fieldwork for the Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS) project. OSMOSIS set out to explore the processes responsible for the deepening and shallowing of the oceanic mixed layer.

JC090 was a 18 day cruise sailing from the port of Vigo, Spain on the 30 August 2013 to the Porcupine Abyssal Plain before returning to the port of Santander, Spain on 17 September 2013.

Sample collection

During cruise JC090, a 75 kHz vessel mounted ADCP (VMADCP) Ocean Surveyor was operating. The VMADCP was run in narrowband single-ping mode with the keel retracted throughout the cruise. To obtain the highest vertical resolution the instrument was configured to fifty-five bins with intervals of 8 m.

A consequence of running with the keel retracted was the data quality was uniformly poor when wind speeds were in excess of a couple of knots and this was the case for most of the cruise. Reasonable data quality was achieved while stationary.

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 movescript2 - creates a new directory called rawdata<<nnn>>and moves the relevant data to this new location.
• adcptree.py jc090<<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

From a previous cruise, it was known that the Ocean Surveyor 75KHz is approximately 9° out of alignment. To allow real time monitoring of the currents and for internal VmDas processing, this was corrected for in a command setting in the control file.

To provide a best calibration for the velocity data, the seabed is used as a reference. During this cruise, there was insufficient good quality data obtained while the water depth was within the ADCP profiling range. The Originator therefore used calibration coefficients from cruise JC068. The final calibration was: rotation angle = -0.25 °, amplitude = 1.004 meters. When combined with the rotation angle set in the control file, there was a net rotation angle of 8.75 °.

References

Forryan, A. et al. (2013). 'Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS)'. Cruise Report No. 25 National Oceanography Centre, Southampton.

Processing by BODC of RRS James Cook Vessel Mounted ADCP data

The data arrived at BODC in one MStar file representing the data collected from the vessel mounted ADCP during cruise JC090. 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.

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

• Irregularities such as unfeasible values
• Inconsistencies between related information, for example:
  • Times for instrument deployment and for start/end of data series
  • Length of record and the number of data cycles/cycle interval
  • Parameters expected and the parameters actually present in the data cycles
• Originator's comments on meter/mooring performance and data quality

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

• Spurious data at the start or end of the record.
• Obvious spikes occurring in periods free from meteorological disturbance.
• A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

• Maximum and minimum values of parameters (spikes excluded).
• The occurrence of meteorological events.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.

Project Information

Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS)

Background

The Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS) consortium was funded to deliver NERC's Ocean Surface Boundary Layer (OSBL) programme. Commencing in 2011, this multiple year study will combine traditional observational techniques, such as moorings and CTDs, with the latest autonomous sampling technologies (including ocean gliders), capable of delivering near real-time scientific measurements through the water column.

The OSMOSIS consortium aims to improve understanding of the OSBL, the interface between the atmosphere and the deeper ocean. This layer of the water column is thought to play a pivotal role in global climate and the productivity of our oceans.

OSMOSIS involves collaborations between scientists at various universities (Reading, Oxford, Bangor, Southampton and East Anglia) together with researchers at the National Oceanography Centre (NOC), Scottish Association for Marine Science (SAMS) and Plymouth Marine Laboratory (PML). In addition, there are a number of project partners linked to the consortium.

Scientific Objectives

• The primary goal of the fieldwork component of OSMOSIS is to obtain a year-long time series of the properties of the OSBL and its controlling 3D physical processes. This is achieved with an array of moorings (two nested clusters of 4 moorings, each centred around a central mooring) and gliders deployed near the Porcupine Abyssal Plain (PAP) observatory. Data obtained from this campaign will help with the understanding of these processes and subsequent development of associated parameterisations.
• OSMOSIS will attempt to create parameterisations for the processes which determine the evolving stratification and potential vorticity budgets of the OSBL.
• The overall legacy of OSMOSIS will be to develop new (physically based and observationally supported) parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions.

Fieldwork

Three cruises are directly associated with the OSMOSIS consortium. Preliminary exploratory work in the Clyde Sea (September 2011) to hone techniques and strategies, followed by a mooring deployment and recovery cruise in the vicinity of the Porcupine Abyssal Plain (PAP) observatory (in late Summer 2012 and 2013 respectively). Additional opportunist ship time being factored in to support the ambitious glider operations associated with OSMOSIS.

Instrumentation

Types of instrumentation and measurements associated with the OSMOSIS observational campaign:

• Ocean gliders
• Wave rider buoys
• Towed SeaSoar surveys
• Microshear measurements
• Moored current meters, conductivity-temperature sensors and ADCPs
• Traditional shipboard measurements (including CTD, underway, discrete nutrients, LADCP, ADCP).

Contacts

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: