Metadata Report for BODC Series Reference Number 2027923

• 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

Nortek Aquadopp Open Water Current Meter

This instrument provides 3D acoustic doppler current measurements along with standard measurements of temperature, pressure, tilt and direction. It can be used in real time measurement situations or can log to an internal recorder powered by internal batteries. It can also be configured to measure surface wave height, period and direction concurrently. It has the unique feature of being run in 'diagnostic' mode when set to collect data at 1 Hz frequency in user specified intervals. This allows studies of mooring motion and the performance of other current meters to be conducted. It can be set in various configurations with titanium housings for deployment at greater depths.

Standard Measured Parameters

• 3D current velocity (East/North/Up, X/Y/Z or Beam 1/2/3)

• Acoustic signal strength (Beam 1/2/3)

• Compass

• Tilt

• Temperature

• Pressure

• Battery voltage

• Status code

• Error code

Surface wave monitoring

The standard Aquadopp is suitable for measuring surface wave height, period, and direction, which are calculated using the PUV method whereby spectra are estimated based on a combination of the pressure signal recorded by the instrument (P) and two horizontal components of the wave orbital velocity (U and V). More specifically, the pressure signal is used to provide an estimate of the wave frequency spectrum. The energy in this spectrum is then used to estimate wave height and period. The measurements of the wave orbital velocities are used to provide an estimate of the wave direction. Since these estimates are based on the distribution of wave energy and are not direct measurements of the free surface, they should be considered inferred estimates.

Both the dynamic pressure and the orbital velocities are driven by surface waves. The signals that are associated with these properties are complicated by the fact that they attenuate (that is the signals are weaker) with depth. The exact behaviour of the attenuation is determined by the water depth and the wavelength being observed. The greater the water depth the greater the attenuation; likewise, the shorter the wavelength (or higher the frequency of the wave) the greater the attenuation for a given water depth. This means that the estimation of wave parameters is limited by both water depth and wave frequency.

Specifications

Further details can be found in the manufacturer's specification sheets for the Aquadopp, Aquadopp 3000 and Aquadopp 6000.

Processing by BODC of Moored Current Meters: AR30-04

The Nortek Aquadopp current meter data were supplied to BODC as ASCII files representing the data collected from Aquadopp sensors deployed at the EB1, WB1, and WB2 sites as well as the IB3, IB4, and IB5 sites during cruise AR30-04.

During transfer to BODC internal format (QXF) the originator's variables were mapped to unique BODC parameter codes. The following table shows the paramater mapping:

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.

Processing by originator of Moored Current Meters: AR30-04

Sampling Strategy

During the RV Neil Armstrong cruise AR30-04, 6 Nortek Aquadopps were deployed at the UK-OSNAP EB1 site, 5 at the WB1 site, and 3 at the WB2 site. Additionally, 3 Nortek Aquadopps were deployed at the IB3 site, 3 at the IB4 site, and 2 at the IB5 site. These moorings were recovered during the RRS Discovery cruise DY120.

Data Acquisition and Initial Processing

The data were downloaded from the instruments with metadata recorded, and were corrected for water depth and the magnetic declination. The data were then converted to RODB format and merged with the metadata file, and the launch and recovery periods removed from the data.

The processed data were supplied to BODC for banking.

Project Information

Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)

Introduction

CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.

Scientific Rationale

The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.

Data Activity or Cruise Information

Data Activity

Ellett Array Moored Instruments WB1 2018-2020

This rig was deployed as part of the Rockall Trough Ellett Array.

The rig was held down by an 2100 kilogram anchor on the seabed at 1600 metres depth. It was kept erect by 40" syntactic float at 486 metres depth and a 31" syntactic float at 94 metres depth.

The instruments deployed on the rig were as follows:

Issues with sensors

The following sensors had data issues:

• SBE37 SMP MicroCAT S/N 14355 had a period of extremely unreliable conductivity data from day 400 to the end of deployment

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

UK-OSNAP/Ellett Array Mooring RTWB1 (OM55)

Mooring RTWB1 (called OM55 by the International OSNAP Community) forms part of the OSNAP-East Transect and, from 2018, the Ellett Array. It was first deployed on 17^th July 2014 by the UK-OSNAP Community.

It is located at 57.4707°N, 12.7050°W where there is a water depth of 1600m

Between 2014 and 2018 this mooring was funded by UK-OSNAP, from 2018 it was funded as part of the Ellett Array by CLASS (Climate Linked Atlantic Sector Science).

Related Fixed Station activities are detailed in Appendix 2

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: RTWB1_05_2018

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.

Appendix 2: UK-OSNAP/Ellett Array Mooring RTWB1 (OM55)

Related series for this Fixed Station 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.