Metadata Report for BODC Series Reference Number 938530

• 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

Sea-Bird SBE 37-SMP MicroCAT

The SBE 37-SMP MicroCAT is a high accuracy conductivity and temperature recorder (pressure optional) with Serial interface, internal battery, non-volatile FLASH Memory and integral Pump. The Integral Pump runs for 1 second each time the MicroCAT samples, improving the conductivity response and giving improved anti-foul protection.

Designed for moorings and other long-duration, fixed-site deployments, MicroCATs have non-corroding titanium housings rated for operation to 7000 meters or pressure sensor full scale-range. Communication with the MicroCAT is over an internal, 3-wire, RS-232C link. The MicroCAT's aged and pressure-protected thermistor has a long history of exceptional accuracy and stability (typical drift is less than 0.002°C per year). Electrical isolation of the conductivity electronics eliminates any possibility of ground-loop noise.

Specifications

Further information can be found via the following link: Sea-Bird SBE 37-SMP MicroCAT Datasheet

RAPID WAVE Calibration Coefficients: Series 938530

Calibration Coefficients

A linear calibration of the form:

Calibrated = A * (Raw) + B

was applied to the original conductivity, temperature and pressure data (based on the instrument CTD dip performed during D308).

The derived salinity was calibrated by multiplying values by 0.997423 and adding the offset of 0.092785. These coefficients were obtained by comparison of CTD salinity estimates to bottle salinities, as measured during the mooring deployment cruise, D308.

Anomalous salinity values in the series were identified using a threshold value of 0.004 / (30*60*60) ² (PSU/second ²).

RAPID WAVE Sea-Bird MicroCAT data processing document

This document outlines the procedures undertaken to process and quality assure the MicroCAT data collected under the RAPID WAVE project.

Originator's processing

The raw data are downloaded from the instrument and converted to ASCII format. All processing is performed in Matlab.

Calculating calibration coefficients

A CTD dip is performed, typically on the deployment or recovery cruise, with the MicroCATs strapped onto the CTD frame. This allows calibration of the instruments by comparing the MicroCAT data with the CTD data. As the MicroCATs adjust much slower than the CTD, data are only compared during five minute stops on the upcast, after the sensors have stabilised. The synchronisation between the CTD and MicroCAT data for calibration is performed by visual examination of the pressure data from each instrument.

Linear regression coefficients for temperature, conductivity and pressure (if present) are determined by minimising, by a least-square method, the differences between the MicroCAT measurements and the reference CTD measurements.

Application of calibrations and salinity computation

Linear regression coefficients, obtained by comparison of MicroCAT data with concurrent CTD upcast data, are applied to the relevant MicroCAT data series to obtain calibrated temperature, conductivity and pressure (where present).

Time series of salinity for each instrument are derived from temperature, conductivity and pressure using UNESCO 1983 algorithms as implemented by the CSIRO seawater Matlab package version 3.2. For instruments without pressure sensors, pressure is interpolated linearly from the instruments deployed above and below, where available. Finally, where required, an additional calibration of the moored salinity data is performed by comparison of on-board CTD salinity estimates to bottle salinity measurements obtained during the relevant cruise.

Quality control

All channels are visually inspected for anomalous values. Salinity values are regarded as spikes if the discrete second-derivative with respect to time is greater in magnitude than a threshold value. The threshold value is found by eye, subjectively, for each instrument. All erroneous values established in this way are flagged accordingly.

BODC processing

The data files are submitted in ASCII format as one file per instrument. Once the submitted data files are safely archived, the data undergo standard reformatting and banking procedures:

• The data files are reformatted into a common format, QXF, which is a NetCDF subset.

• Standard parameter codes are assigned that accurately describe the data.

• Unit conversions are applied, if necessary, so that units are standardised.

• The data are screened visually and any spikes or instrument malfunctions can be clearly labelled with quality control flags.

• Data files are trimmed to remove the pre deployment and post recovery data cycles that are null.

• Comprehensive documentation is prepared describing the collection, processing and quality of each data series.

• Detailed metadata and documents are loaded to the database and linked to each series so that the information is readily available to future users.

Parameter mapping

The following describes the parameters contained in the originator's files and their mapping to BODC parameter codes :

Project Information

Rapid Climate Change (RAPID) Programme

Rapid Climate Change (RAPID) is a £20 million, six-year (2001-2007) programme of the Natural Environment Research Council (NERC). The programme aims to improve our ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

Scientific Objectives

• To establish a pre-operational prototype system to continuously observe the strength and structure of the Atlantic Meridional Overturning Circulation (MOC).
• To support long-term direct observations of water, heat, salt, and ice transports at critical locations in the northern North Atlantic, to quantify the atmospheric and other (e.g. river run-off, ice sheet discharge) forcing of these transports, and to perform process studies of ocean mixing at northern high latitudes.
• To construct well-calibrated and time-resolved palaeo data records of past climate change, including error estimates, with a particular emphasis on the quantification of the timing and magnitude of rapid change at annual to centennial time-scales.
• To develop and use high-resolution physical models to synthesise observational data.
• To apply a hierarchy of modelling approaches to understand the processes that connect changes in ocean convection and its atmospheric forcing to the large-scale transports relevant to the modulation of climate.
• To understand, using model experimentation and data (palaeo and present day), the atmosphere's response to large changes in Atlantic northward heat transport, in particular changes in storm tracks, storm frequency, storm strengths, and energy and moisture transports.
• To use both instrumental and palaeo data for the quantitative testing of models' abilities to reproduce climate variability and rapid changes on annual to centennial time-scales. To explore the extent to which these data can provide direct information about the thermohaline circulation (THC) and other possible rapid changes in the climate system and their impact.
• To quantify the probability and magnitude of potential future rapid climate change, and the uncertainties in these estimates.

Projects

Overall 38 projects have been funded by the RAPID programme. These include 4 which focus on Monitoring the Meridional Overturning Circulation (MOC), and 5 international projects jointly funded by the Netherlands Organisation for Scientific Research, the Research Council of Norway and NERC.

The RAPID effort to design a system to continuously monitor the strength and structure of the North Atlantic Meridional Overturning Circulation is being matched by comparative funding from the US National Science Foundation (NSF) for collaborative projects reviewed jointly with the NERC proposals. Three projects were funded by NSF.

A proportion of RAPID funding as been made available for Small and Medium Sized Enterprises (SMEs) as part of NERC's Small Business Research Initiative (SBRI). The SBRI aims to stimulate innovation in the economy by encouraging more high-tech small firms to start up or to develop new research capacities. As a result 4 projects have been funded.

RAPID Western Atlantic Variability Experiment (WAVE)

Introduction

The RAPID WAVE project began in 2004 as an observational component of the U.K Natural Environment Research Council's RAPID Climate Change Programme in the western North Atlantic Ocean. In 2008, funding to continue RAPID WAVE was secured through the continuation programme, RAPID-WATCH, which is due to end in 2014.

The RAPID WAVE team brings together scientists at the National Oceanography Centre in Liverpool. Between 2004 and 2010, the RAPID WAVE team also contributed to the Line W mooring array, joining colleagues from the U.S. Line W is a U.S-led initiative used to monitor the North Atlantic Ocean's deep western boundary current whilst being funded through the U.S National Science Foundation and has been active since October 2001. It brings together scientists from Woods Hole Oceanographic Institution (WHOI) and Lamont-Doherty Earth Observatory (LDEO). Users of these data are referred to the Line W Project Website for more information.

In 2007, further collaboration was established with scientists at the Bedford Institute of Oceanography (BIO). This arrangement was formalised and continues under RAPID-WATCH. Smaller scale collaboration with scientists at the Instituto Espanol de Oceanografia (IEO) during RAPID-WATCH saw additional RAPID WAVE observational work in the eastern North Atlantic Ocean. This work commenced in 2009 as part of the RAPID WAVE RAPIDO campaign.

Scientific Rationale

The primary aim of the RAPID WAVE project is to develop an observing system that will identify the propagation of overturning signals, from high to low latitudes, along the western margin of the North Atlantic. It specifically aims to monitor temporal changes in the Deep Western Boundary Current and reveal how coherent the changes are along the slope. Ultimately it is envisaged that this will enable scientists to develop a better understanding of larger-scale overturning circulation in the Atlantic, and its wider impacts on climate.

Fieldwork

The fieldwork aspect of the project was to deploy arrays of Bottom Pressure Recorders (BPRs) and CTD moorings along specified satellite altimeter groundtracks off the eastern continental slope of Canada and the United States. In 2004, fieldwork focused on three array lines. Line A was established heading south west from the Grand Banks, whilst the Line B array ran south east on the continental slope of Nova Scotia. The third line, Line W, was an established hydrographic array on the continental slope of New England, serviced by Woods Hole Oceanographic Institute (WHOI), to which RAPID WAVE contributed BPR instrumentation.

The original intention was that each array would be serviced by a cruise every two years. However, following a very poor return rate of instrumentation during the first servicing cruise of Lines A and B in 2006, this plan was modified significantly, and the decision made to abandon work on Line A. In 2007, additional logistical support from Canada's Bedford Institute of Oceanography (BIO) enabled Line B to be serviced again after just one year of deployment, with a much improved recovery record.

The transition from RAPID to RAPID-WATCH funding marked significant changes to the RAPID WAVE observational system. Line B was abandoned and a joint array with BIO, known as the RAPID Scotia Line, to the south west was developed. This line receives annual servicing by BIO, with cruise participation from the RAPID WAVE team.

The servicing of RAPID WAVE BPRs on Line W remained a biennial activity during the RAPID and RAPID-WATCH programmes.

A small number of BPR deployments have also taken place off the coast of Spain as part of the RAPIDO element of RAPID WAVE.

Instrumentation

Types of instruments and measurements:

• Moored BPRs
• Moored CTD/CT loggers
• Moored current meters (RAPID-WATCH)
• Moored ADCPs (RAPID-WATCH)
• Shipboard measurements: CTD, underway, salinity, LADCP, ADCP

Contacts

Data Activity or Cruise Information

Data Activity

RAPID Moored Instrument Rig B5LM#2

This rig was deployed as part of the Line B array of the RAPID WAVE project.

The rig was anchored by a cast iron sinker and kept erect by groups of buoyancy spheres attached regularly along the mooring.

Instruments deployed on the rig

MicroCAT instruments with serial numbers #3675, #3676 and #3680 were not equipped with pressure sensors.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

RAPID Mooring Site B5

This fixed station forms part of the Line B mooring array located to the east of Halifax, Nova Scotia, deployed as part of the RAPID WAVE project.

Site occupations

* Mooring lost

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: B5LM#2

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: RAPID WAVE Site B5

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.