Metadata Report for BODC Series Reference Number 1803852

• 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

D381 LADCP Instrumentation

Sampling Strategy

LADCP deployments were carried out during both legs of RRS Discovery cruise D381 using the instrumentation detailed below.

The ADCP were attached to a SeaBird 9plus CTD frame during each deployment.

During cast 13 the CTD wire parted as the instrument was being lowered into the water resulting in the lost of ADCP unit (serial # 12919) and no data being supplied for cast 13.

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.

D381 LADCP Originator Processing

Sampling Strategy

Lowered Acoustic Doppler Current Profiler (LADCP) data were gathered during the RRS Discovery D381 cruise which was undertaken as part of the Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study (OSMOSIS), funded by NERC.

The cruise was split into two legs to encompass an initial mooring deployment cruise, D318A; and a process study cruise, D381B. Cruise D381A departed Southampton on 28 August 2012, returning to dock in Falmouth on 13 September 2012. Cruise D381B departed Falmouth on 14 September 2012, returning to dock in Southampton on 3 October 2012.

During the D381A cruise the LADCP was deployed 4 times and during the D381B cruise the LADCP was deployed 16 times in conjunction with a Seabird CTD at stations around the Porcupine Abyssal Plain Observatory in the Atlantic Ocean.

Data Processing

The data collected by the instrument were downloaded after each cast and stored as RDI binary files. The data were then processed following the cruise using the latest version of software provided Lamont- Doherty Earth Observatory (LDEO) which calculates velocities using an inverse method.

Field Calibrations

The real-time clock of the LADCP was checked prior to deployment and resynchronised with the ship's GPS clock if it was more than a few seconds in error and built-in pre-deployment tests (PA, PC2 and PT200) were run before each cast.

References

Thurnherr, A.M., (2014). How to Process LADCP Data with the LDEO Software (versions IX.7 - IX.10).

D381 LADCP Processing undertaken by BODC

The data arrived at BODC in single matlab file. The file contained u, v and z data collected from 20 LADCP deployments undertaken across both legs of the D381 cruise. The data were reformatted to BODC's internal NetCDF format and the following table shows the mapping of variables within the .mat file to the 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.

Additional data held at BODC

In addition to the above, BODC also hold the raw binary workhorse LADCP output files and the associated 1 Hz CTD files with calibrated salinity. These files can be used to reprocess the LADCP if desired.

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: