Metadata Report for BODC Series Reference Number 1971672

• 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

JR16006 CAO 75kHz VMADCP Data Quality Report

Data Quality Information

The originators file 10 had no start or end positions. Latitude and longitude were interpolated from the underway for the first and last cycle of this file (series 1971659), these data points have been flagged 'i'.

Cycles with null dates were removed. Constant null bins were also removed.

There were no other issues.

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

JR16006 CAO 75 kHz VMADCP Data: Processing by BODC

The Teledyne RDI 75kHz VMADCP data were supplied to BODC as Matlab files and were converted to BODC internal format (QXF).

During transfer the originator's variables were mapped to unique BODC parameter codes. The following table shows the parameter mapping:

Quality Control and Screening

Following transfer the data were screened using BODC in-house visualisation software. Suspect data values were assigned the appropriate BODC data quality flag. Missing data values, where present, were changed to the missing data value and assigned a BODC data quality flag.

JR16006 CAO Originator's 75kHz VMADCP Data Processing

This document contains extracts from the JR16006 cruise report.

Configuration

A 75 kHz RD Ocean Surveyor ADCP was fitted to the hull of the RRS James Clark Ross for cruise JR16006. The transducer head was mounted 6.3m below the waterline and beam 3 was rotated 60.08° relative to the ships centreline. A nominal rotation of 60.08° (misalignment angle) is therefore necessary to remove the ships velocity from the data. With the exception of file 5, which recorded in deep water off the shelf edge, the following settings were used:

• Narrow band (low res.)
• 65 x 8m bins
• Ambiguity velocity 390 cm/s
• 8m blanking distance
• 1 second ensembles
• 0.5 seconds between bottom track and water pings
• Bottom track on (500m)

The following settings were used for file 5:

• Narrow band (low res.)
• water track mode
• 50 x 16m bins
• Ambiguity velocity 390 cm/s
• 8m blanking distance
• ping as fast as possible
• Bottom track off

Data Originator's Processing

Data acquisition

The ADCP was controlled using the proprietary VmDas software, version 1.42.

The software creates a series of ram files needed for processing:

• .ENR binary file
• .N1R ascii file with the NMEA telegram and ADCP time stamp
• .VMO ascii file with VmDas configuration

Additional files output are:

• .ENS binary file of beam coordinate single ping data and NMEA data
• .NMS binary file of navigation and attitude
• .ENX binary file of earth coordinate, single ping data
• .STA binary file of earth coordinate, short time average
• .LTA binary file of earth coordinate, long time average data
• .LOG ascii file with record of ADCP communication and VmDas errors

.ENX, .STA and .LTA files can be read by the WinADCP software

NMEA strings were fed to the VMDas software from the Navigation Repeater and output in the .N1R files.

A suite of matlab routines was used to perform data screening and transformation into absolute velocities in Earth coordinates. The routines were obtained from IfM Kiel and adapted for use on the RRS James Clark Ross by Deb Shoosmith in 2005. Numerous bug fixes and refinements have since been added by various users.

The following processing steps take place:

1. ENX RDI binary file and .N1R ascii files are read into the Matlab environment. NB: The N1R file consists of ADCP single ping time stamps and pitch, roll and heading information from the Seapath.
2. Ensembles with no ADCP data are removed.
3. Ensembles with bad or missing heading data identified and adjusted GYRO heading substituted.
4. Attitude information time merged with single ping ADCP velocities.
5. Heading data used to rotate single ping ADCP velocities from vessel centreline reference to True North reference.
6. Transducer mis-alignment error corrected for (derived from the mis-alignment determination).
7. Ship velocity derived from SeaTex positional information.
8. Further data screening performed to remove data where:
   • the correlation in any bin is below 128 (i.e. more noise than signal)
   • there is more than 1 bad beam in the bin
   • the percentage good 4 beam solution=0
   • Max heading change between pings > 10 degrees per ping
   • Max ship velocity change between pings > 0.5514 ms^-1ping rate^-1
   • Error velocity greater than twice STD of error velocities of single ping profile
9. All data averaged into 300 second super-ensembles.
10. Determine absolute water velocities from either bottom track derived ship velocity or SeaTex GPS derived ship velocity, dependent on depth.

Calibration

Angle and amplitude were calibrated using the following values for files 1-5 (with Seapath):

• Misalignment= -0.9226
• Amplitude = 1.006743

The values used for corrections during the final processing for files 15-20 were:

• Misalignment = 1.5225
• Amplitude = 1.007944

Intermittent loss of the Seapath navigation data (see problem report) meant that .N1R and .ENX files between 6 and 7 could not be read by the Matlab processing software. As a workaround, the .LTA files created by VmDas (10 minute averages) were exported using the RDI WinRiver software. A 10 minute average for file 10 (no navigation stream) was also extracted using WinRiver.

Problem Report

Seapath failure:

From 14/07/2017 onwards the Seapath intermittently lost its heading. The heading information in files 6 and 7 is therefore periodically missing.

On 23/07/2017 at ~10:53 the Seapath completely failed and stopped providing position, heading, pitch and roll to the ADCP (while file 8 was running).

As a workaround, new NMEA strings for the navigation feed into the ADCP were created using alternative navigation sources (Ashtech, Gyro and Furuno) which were redirected from the data server via a pre-existing NMEA splitter PC. This rebuilt the required NMEA strings that the VMDas software could recognise (high latency, low frequency (1Hz) data). Under the normal configuration the Seapath feeds the VMADCP computer with navigation information directly (low latency, high frequency (10Hz) data).

Project Information

Changing Arctic Ocean: Implications for marine biology and biogeochemistry

Changing Arctic Ocean (CAO) is a £16 million, five year (2017-2022) research programme initially funded by the Natural Environment Research Council (NERC). The aim of the CAO programme is to understand how change in the physical environment (ice and ocean) will affect the large-scale ecosystem structure and biogeochemical functioning of the Arctic Ocean, the potential major impacts and provide projections for future ecosystem services. In July 2018, additional projects were added to the programme that were jointly funded by NERC and the German Federal Ministry of Education and Research.

Background

The Arctic Ocean is responding to global climate change in ways that are not yet fully understood and in some cases, not yet identified. The impacts of change in the Arctic are global in range and international in importance. To achieve the aim, the programme has two key research challenges:

• To develop quantified understanding of the structure and functioning of Arctic ecosystems.
• To understand the sensitivity of Arctic ecosystem structure, functioning and services to multiple stressors and the development of projections of the impacts of change.

The decision to fund the CAO project was both scientific and political and is the second largest research programme funded by NERC.

The programme involves 33 organisations, the majority of which are research institutions in the UK and Germany, and over 170 scientists. The programme consists of four large projects with an additional 12 research projects added in July 2018.

Further information can be found on the Changing Arctic Ocean website.

Participants

There are 33 organisations involved in the Changing Arctic Ocean project, these are:

• Alfred Wegener Institut (AWI)
• Bangor University
• British Antarctic Survey (BAS)
• Centre for Environment, Fisheries and Aquaculture Science (CEFAS)
• Durham University
• GEOMAR
• Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research
• Lancaster University
• Marine Biological Association (MBA)
• Max Planck Institute for the Science of Human History
• National Oceanography Centre (NOC)
• Newcastle University
• Northumbria University
• Ocean Atmosphere Systems GmbH
• Plymouth Marine Laboratory (PML)
• Scottish Association for Marine Science (SAMS)
• Scottish Universities Environmental Research Centre (SUERC)
• Université Libre de Bruxelles
• University College London (UCL)
• University of Bristol
• University of East Anglia (UEA)
• University of Edinburgh
• University of Glasgow
• University of Huddersfield
• University of Leeds
• University of Liverpool
• University of Manchester
• University of Oldenburg
• University of Oxford
• University of Southampton
• University of St Andrews
• University of Stirling
• University of Strathclyde

In addition to the core organisation, there are a number of international collaborators.

Research Details

The four large projects funded by NERC are:

• Arctic Productivity in the seasonal Ice Zone (Arctic PRIZE)
• Can we detect changes in Arctic ecosystems? (ARISE)
• The Changing Arctic Ocean Seafloor (ChAOS) - How changing sea ice conditions impact biological communities, biogeochemical processes and ecosystems
• Mechanistic understanding of the role of diatoms in the success of the Arctic Calanus complex and implications for a warmer Arctic (DIAPOD)

The additional 12 projects added in July 2018 funded jointly by NERC and the German Federal Ministry of Education and Research are:

• Advective Pathways of nutrients and key Ecological substances in the Arctic (APEAR)
• How will changing freshwater export and terrestrial permafrost thaw influence the Arctic Ocean? (CACOON)
• Chronobiology of changing Arctic Sea Ecosystems (CHASE)
• Potential benefits and risks of borealisation for fish stocks and ecosystems in a changing Arctic Ocean (Coldfish)
• Diatom Autecological Responses with Changes To Ice Cover (Diatom-ARCTIC)
• Ecosystem functions controlled by sea ice and light in a changing Arctic (Eco-Light)
• Effects of ice stressors and pollutants on the Arctic marine cryosphere (EISPAC)
• Linking Oceanography and Multi-specific, spatially-Variable Interactions of seabirds and their prey in the Arctic (LOMVIA)
• Understanding the links between pelagic microbial ecosystems and organic matter cycling in the changing Arctic (Micro-ARC)
• Microbes to Megafauna Modelling of Arctic Seas (MiMeMo)
• Primary productivity driven by escalating Arctic nutrient fluxes? (PEANUTS)
• Pathways and emissions of climate-relevant trace gases in a changing Arctic Ocean (PETRA)

Fieldwork and Data Collection

The programme consists of seven core cruises that survey areas in the Barents Sea and the Fram Strait on board the NERC research vessel RRS James Clark Ross. Measurements will include temperature, salinity, dissolved oxygen, dissolved inorganic carbon, total alkalinity, inorganic nutrients, oxygen and carbon isotopes and underway meteorological and surface ocean observations. In addition to ship based cruise datasets gliders, moorings and animal tags are part of the fieldwork. Further data are collected from model runs.

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: