Metadata Report for BODC Series Reference Number 1017746


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
Chelsea Technologies Group Aquatracka fluorometer  fluorometers
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Chelsea Technologies Group Alphatracka transmissometer  transmissometers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Brian King
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Project(s) Rapid Climate Change Programme
RAPIDMOC
Oceans 2025
RAPID-WATCH
Oceans 2025 Theme 1 WP1.2
Oceans 2025 Theme 10 SO3: MOC
 

Data Identifiers

Originator's Identifier CTD_DI346_083_2DB
BODC Series Reference 1017746
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-01-30 15:19
End Time (yyyy-mm-dd hh:mm) 2010-01-30 17:12
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 23.87390 N ( 23° 52.4' N )
Longitude 46.33370 W ( 46° 20.0' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 4.97 m
Maximum Sensor Depth 5065.16 m
Minimum Sensor Height -6.1 m
Maximum Sensor Height 5054.08 m
Sea Floor Depth 5059.05 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
ACYCAA01 1 Dimensionless Record_No Sequence number
CNDCST01 1 Siemens per metre CTDCond Electrical conductivity of the water body by CTD
CNDCST02 1 Siemens per metre CTDCond2 Electrical conductivity of the water body by CTD (sensor 2)
CPHLPM01 1 Milligrams per cubic metre chl-a_water_ISfluor_manufctrcal_sensor1 Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer and manufacturer's calibration applied
DOXYSC01 1 Micromoles per litre WC_dissO2_calib Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by Sea-Bird SBE 43 sensor and calibration against sample data
POPTDR01 1 Percent Trans_Red_25cm Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer
PRESPR01 1 Decibars Pres_Z Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALCC01 1 Dimensionless P_sal_CTD_calib Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements
PSALCU02 1 Dimensionless P_sal_CTD_uncalib2 Practical salinity of the water body by CTD (second sensor) and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
TEMPCU01 1 Degrees Celsius Uncal_CTD_Temp Temperature of the water body by CTD and NO verification against independent measurements
TEMPCU02 1 Degrees Celsius Uncal_CTD_Temp2 Temperature of the water body by CTD (second sensor) and NO verification against independent measurements
TOKGPR01 1 Litres per kilogram Vol2MassCTD Conversion factor (volume to mass) for the water body by CTD and computation of density (in-situ potential temperature surface pressure) reciprocal from pressure, temperature and salinity
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

During station 50 the secondary conductivity sensor on the CTD package failed at the start of the upcast and was not replaced. This sensor did continue to record data until it was replaced prior to cast 96 so for these casts the data from the secondary conductivity sensor, along with the salinity data derived from the conductivity channel, should be viewed as unreliable.

Maximum Instrument Depth Greater Than Sea Floor Depth

CTD/XBT Data

It is possible for the maximum depth of a CTD/XBT cast to exceed the estimated sea floor depth at a given location.

The depth of a CTD unit is calculated from its measurements of pressure using an algorithm which makes assumptions about the density profile of the water column and XBT depth is often estimated from an assumed descent rate. Similarly, total water depth is calculated from the two-way travel time of sound waves through the water column making assumptions about the velocity of the sound waves. All of these calculations may contain errors, and the depth of a CTD/XBT unit may therefore appear to be below the sea floor.

Other Instrument Types

It is possible that instrument depths are taken from instantaneous measurements whereas water depth is read from a chart or corrected to a datum, such as mean sea level. If this occurs and the instrument depth has been read at high tide it is possible that an instrument mounted on the sea floor will have a depth half of the tidal range below the sea floor depth.


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 Dissolved Oxygen Sensor SBE 43 and SBE 43F

The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.

Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.

Specifications

Housing Plastic or titanium
Membrane

0.5 mil- fast response, typical for profile applications

1 mil- slower response, typical for moored applications

Depth rating

600 m (plastic) or 7000 m (titanium)

10500 m titanium housing available on request

Measurement range 120% of surface saturation
Initial accuracy 2% of saturation
Typical stability 0.5% per 1000 h

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

Oceans 2025 Cruise D346 CTD instrument description

CTD unit and auxiliary sensors

The CTD system used on cruise D346 was a NOC 24-way stainless steel frame system consisting of a Sea-Bird 911 plus , with a Sea-Bird 32 carousel. The CTD frame was equipped with 20L Niskin bottles. In addition the CTD was fitted with a number of scientific sensors as detailed in the table below. During the cruise various problems with sensors required them to be replaced on the CTD frame (see Section 1 of the D346 cruise report). The table below shows which sensors were attached to the CTD frame and on which casts.

Sensor Serial Number Casts Last calibration date
SBE 911+ deck unit - 1-135,200,202 -
SBE 32 carousel - 1-135,200,202 -
Primary Temperature SBE-03P 4872 1-135,200,202 6 October 2009
Secondary Temperature SBE-03P 4381 1-67,69-135,200,202 25 August 2009
Secondary Temperature SBE-03P 2674 68 08 May 2009
Primary Conductivity SBE-04C 3258 1-41 5 October 2009
Primary Conductivity SBE-04C 3054 42-77,200 25 June 2009
Primary Conductivity SBE-04C 2231 78-135,202 8 May 2009
Secondary Conductivity SBE-04C 3052 1-95,200 10 September 2009
Secondary Conductivity SBE-04C 3258 96-135,200,202 05 October 2009
Dissolved oxygen sensor SBE-43 1624 1-36 22 April 2009
Dissolved oxygen sensor SBE-43 0621 37-135,200,202 17 October 2008
Pressure-Digiquartz 90573 1-135,200,202 20 October 2008
Benthos PSA-916T Altimeter 47597 1-135 -
Chelsea Aquatracka Fluorometer 088095 1-63,70-135,202 28 May 2009
Chelsea Alphatracka Transmissometer 161048 1-63,70-135,202 28 May 2008
RDI 300kHz Workhorse LADCP (aluminium cased) 9191 1-63,114-135 26 May 2009
RDI 300kHz Workhorse LADCP (titanium cased) 13399 70-72 19 November 2009
RDI 300kHz Workhorse LADCP (titanium cased) 13400 73-113,202 19 November 2009

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus ) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus , that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus ) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus ) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus .

Specifications

Specifications for the SBE 9 plus underwater unit are listed below:

Parameter Range Initial accuracy Resolution at 24 Hz Response time
Temperature -5 to 35°C 0.001°C 0.0002°C 0.065 sec
Conductivity 0 to 7 S m -1 0.0003 S m -1 0.00004 S m -1 0.065 sec (pumped)
Pressure 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) 0.015% of full scale 0.001% of full scale 0.015 sec

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

Aquatracka fluorometer

The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.

The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.

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

Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers

The Chelsea Technologies Group ALPHA tracka (the Mark I) and its successor, the ALPHA tracka II (the Mark II), are both accurate (< 0.3 % fullscale) transmissometers that measure the beam attenuation coefficient at 660 nm. Green (565 nm), yellow (590 nm) and blue (470 nm) wavelength variants are available on special order.

The instrument consists of a Transmitter/Reference Assembly and a Detector Assembly aligned and spaced apart by an open support frame. The housing and frame are both manufactured in titanium and are pressure rated to 6000 m depth.

The Transmitter/Reference housing is sealed by an end cap. Inside the housing an LED light source emits a collimated beam through a sealed window. The Detector housing is also sealed by an end cap. A signal photodiode is placed behind a sealed window to receive the collimated beam from the Transmitter.

The primary difference between the ALPHA tracka and ALPHA tracka II is that the Alphatracka II is implemented with surface-mount technology; this has enabled a much smaller diameter pressure housing to be used while retaining exactly the same optical train as in the Mark I. Data from the Mark II version are thus fully compatible with that already obtained with the Mark I. The performance of the Mark II is further enhanced by two electronic developments from Chelsea Technologies Group - firstly, all items are locked in a signal nulling loop of near infinite gain and, secondly, the signal output linearity is inherently defined by digital circuitry only.

Among other advantages noted above, these features ensure that the optical intensity of the Mark II, indicated by the output voltage, is accurately represented by a straight line interpolation between a reading near full-scale under known conditions and a zero reading when blanked off.

For optimum measurements in a wide range of environmental conditions, the Mark I and Mark II are available in 5 cm, 10 cm and 25 cm path length versions. Output is default factory set to 2.5 volts but can be adjusted to 5 volts on request.

Further details about the Mark II instrument are available from the Chelsea Technologies Group ALPHA tracka II specification sheet .

Oceans 2025 Cruise D346 BODC CTD data processing

The data arrived at BODC in 137 MSTAR format files representing the CTD casts conducted during cruise D346. The data contained in the files are the downcast data averaged to a 2db pressure grid. The casts were reformatted to BODC's internal netCDF format. The following table shows the mapping of variables within the MSTAR files to appropriate BODC parameter codes:

Originator's variable Units Originator's description BODC parameter code Units Comments
press dbar Pressure exerted by the water column PRESPR01 dbar Manufacturer's calibration applied.
temp °C Temperature of the water column by CTD TEMPCU01 °C ITS-90
This parameter represents the first choice sensor data, which was collected from the secondary temperature sensor for casts 1-49 and the primary temperature sensor for casts 50-135, 200 and 202.
temp1 °C Temperature of the water column by CTD (primary sensor) TEMPCU02 °C ITS-90
Data not transferred for casts 50-135, 200 and 202 as these data were deemed to be the first choice sensor data and have been duplicated in the temp channel.
temp2 °C Temperature of the water column by CTD (secondary sensor) TEMPCU02 °C ITS-90
Data not transferred for casts 1-49 as these data were deemed to be the first choice sensor data and have been duplicated in the temp channel.
cond mS/cm Electrical conductivity of the water column CNDCST01 S/m /10
Calibrated by data originator with discrete salinity samples.This parameter represents the first choice sensor data, which was collected from the secondary conductivity sensor for casts 1-49 and the primary conductivity sensor for casts 50-135, 200 and 202.
cond1 mS/cm Electrical conductivity of the water column (Primary sensor) CNDCST02 S/m /10
Data not transferred for casts 50-135, 200 and 202 as these data were deemed to be the first choice sensor data and have been duplicated in the cond channel
cond2 mS/cm Electrical conductivity of the water column (Secondary sensor) CNDCST02 S/m /10
Data not transferred for casts 1-49 as these data were deemed to be the first choice sensor data and have been duplicated in the cond channel.
psal - Practical salinity of the water column PSALCC01 - Calculated by data originator using calibrated conductivity.
This parameter represents the first choice sensor data, which was derived from data collected from the secondary conductivity sensor for casts 1-49 and the primary conductivity sensor for casts 50-135, 200 and 202.
psal1 - Practical salinity of the water column (Primary sensor data) PSALCU02 - Calculated by data originator using uncalibrated conductivity.
Data not transferred for casts 50-135, 200 and 202 as these data were deemed to be the first choice data and have been duplicated in the psal channel
psal2 - Practical salinity of the water column (Secondary sensor data) PSALCU02 - Calculated by data originator using uncalibrated conductivity.
Data not transferred for casts 1-49 as these data were deemed to be the first choice data and have been duplicated in the psal channel
oxygen µmol/kg Concentration of oxygen per unit volume of the water body. DOXYSC01 µmol/l Unit conversion applied during transfer.
Calibrated by data originator using discrete oxygen samples.
fluor µg/l Concentration of chlorophyll-a per unit volume of the water body CPHLPM01 mg/m 3 No unit conversion is necessary as µg/l are equivalent to mg/m 3
transmittance % Transmittance per length of water body POPTDR01 % -
potemp °C Potential temperature of the water column POTMCV01 °C Not transferred
potemp1 °C Potential temperature of the water column (Primary sensor) POTMCV02 °C Not transferred
potemp2 °C Potential temperature of the water column (Secondary sensor) POTMCV02 °C Not transferred
depth metres Depth below surface converted from pressure using UNESCO algorithm DEPHPR01 metres Not transferred
altimeter metres Depth below surface by altimeter - - Not transferred
time seconds Time in seconds since the origin defined in the metadata field data_time_origin - - Not transferred

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data marked by setting both the data to an appropriate value and setting the quality control flag. In addition any data outside of the allocated range for each parameter have been flagged as null and values set to absent data value for that parameter.

Detailed metadata and documentation were compiled and linked to the data.

Oceans 2025 Cruise D346 Originator's CTD data processing

Sampling Strategy

A total of 137 CTD casts were performed during the cruise which aimed to attempt to calculate the transport of water and its constituents along a latitude of 24°N, completing a section across the Atlantic from North America to Africa, beginning and ending at the edge of the continental shelf. Of the 137 CTD stations occupied, 2 (Casts 200 and 202) were bottle blank stations run for the CFC team, so the principle data collected along the 24°N section comprised of 135 stations. In addition a number of instruments were mounted onto the CTD frame including an LADCP, fluorometer, transmissometer and a dissolved oxygen sensor. Instruments not pressure rated below 6000m were removed for the duration of the deeper casts (Casts 64-69 and 200). Some data for certain parameters are, therefore, unavailable for deeper casts. The chronological order of the casts were as follows: 1-64, 200, 65-100, 202, 101-135.

Data Processing

Raw CTD data were transferred from the Sea-Bird deck unit to a LINUX machine via Sea-Bird software. The binary files are converted using Sea-Bird processing software (SBE Data Processing v7.19). ALIGNCTD was run to advance the oxygen measurements by 5 seconds, ensuring the calculations of dissolved oxygen concentration are made using measurements from the same parcel of water. CELLTM was run to minimise salinity spiking in steep vertical gradients applying two constants; the thermal anomaly amplitude alpha=0.03 and thermal anomaly time constant 1/ß=7. The ASCII files were converted to MSTAR format, averaging 24Hz data to 1Hz data, and calculating salinity and potential temperature in addition to recording the first choice conductivity-temperature sensor pair for each station.

A correction for downcast-upcast sensor hysteresis was made during the MSTAR processing, applying an algorithm provided by Sea-Bird for oxygen concentration values measured by the SBE 43 sensor.

The algorithm used was as follows:

Oxnew conc = {( Oxygen conc ( i ) + ( Oxnew conc ( i -1) x C x D ))-( Oxygen conc ( i -1) x C )}/ D

where D = 1 + H 1 x ( exponential ( P ( i )/ H 2)-1) and C = exponential (-1 x ( Time ( i )- Time ( i -1))/ H 3)

and i = indexing variable, P = pressure (db), Time = time (seconds), H 1 = amplitude of hysteresis correction function (-0.028 for the first oxygen sensor and 0.037 for the second), H 2 = function constant (5000 for both oxygen sensors), H 3 = time constant for hysteresis (2500 for the first and 1450 for the second oxygen sensor).

In addition a number of minor spurious features were identified in the oxygen and conductivity channels, including spikes associated with CTD telemetry failures and spikes at the beginning and end of a cast where bad start and end scan numbers were chosen. Such problems were resolved during processing by adjusting the start and end scan numbers of files to omit bad data or by removing spikes using a median de-spiking routine.

Further details of this processing routine can be found in the D346 cruise report.

Field Calibrations

Upcast conductivity from the first choice sensor was calibrated against conductivity derived from bottle samples. The final calibration ratios applied to the secondary, second primary and third primary conductivity sensors were 0.9999719, 1.0000574 and 1.0000285, respectively. In addition bottle-CTD conductivity residuals showed some structure against pressure believed to be related to sensor performance. Calibrations were, therefore, applied by correcting conductivity values using an additive factor decided by a pressure lookup table. This table was created for each sensor by calculating median offset in pressure bins. Application of the calibration ratios and pressure corrections reduced rms offset of salinity offset from 0.00128, 0.00238 and 0.00202 to 0.00073, 0.00119 and 0.00064 for the secondary, second primary and third primary conductivity sensors, respectively.

Following the hysteresis correction applied to the oxygen data, upcast oxygen concentrations for each sensor were calibrated against oxygen concentrations derived from bottle samples. For the first oxygen sensor, bottle and CTD oxygen showed a clear linear relationship. Subsequently a multiplicative correction factor, calculated as the median ratio between bottle and CTD oxygen, was applied. This was calculated and applied in bulk for stations 1-22. For stations 23-36 the correction was calculated and applied on a station by station basis to account for the gradual degradation in sensor performance over this period. For the second oxygen sensor, bottle oxygen and CTD oxygen concentration offset was typically > 10µmol/kg, however, a linear relationship was less obvious. Bottle-CTD offset was reduced to ±2µmol/kg by applying a combined second order pressure and first order temperature dependent offset to all data with a potential temperature <7.5°C with the pressure-temperature offset function calculated using a least-squares approach. For data with potential temperature >7.5°C, a simple offset of 7µmol/kg was added.


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

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.


Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)

Scientific Rationale

There is a northward transport of heat throughout the Atlantic, reaching a maximum of 1.3PW (25% of the global heat flux) around 24.5°N. The heat transport is a balance of the northward flux of a warm Gulf Stream, and a southward flux of cooler thermocline and cold North Atlantic Deep Water that is known as the meridional overturning circulation (MOC). As a consequence of the MOC northwest Europe enjoys a mild climate for its latitude: however abrupt rearrangement of the Atlantic Circulation has been shown in climate models and in palaeoclimate records to be responsible for a cooling of European climate of between 5-10°C. A principal objective of the RAPID programme is the development of a pre-operational prototype system that will continuously observe the strength and structure of the MOC. An initiative has been formed to fulfill this objective and consists of three interlinked projects:

The entire monitoring array system created by the three projects will be recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2014 the array will continue to be serviced annually under RAPID-WATCH funding.

The array will be focussed on three regions, the Eastern Boundary (EB), the Mid Atlantic Ridge (MAR) and the Western Boundary (WB). The geographical extent of these regions are as follows:

References

Baehr, J., Hirschi, J., Beismann, J.O. and Marotzke, J. (2004) Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. Journal of Marine Research, Volume 62, No 3, pp 283-312.

Baringer, M.O'N. and Larsen, J.C. (2001) Sixteen years of Florida Current transport at 27N Geophysical Research Letters, Volume 28, No 16, pp3179-3182

Bryden, H.L., Johns, W.E. and Saunders, P.M. (2005) Deep Western Boundary Current East of Abaco: Mean structure and transport. Journal of Marine Research, Volume 63, No 1, pp 35-57.

Hirschi, J., Baehr, J., Marotzke J., Stark J., Cunningham S.A. and Beismann J.O. (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophysical Research Letters, Volume 30, No 7, article number 1413 (DOI 10.1029/2002GL016776)


Oceans 2025 - The NERC Marine Centres' Strategic Research Programme 2007-2012

Who funds the programme?

The Natural Environment Research Council (NERC) funds the Oceans 2025 programme, which was originally planned in the context of NERC's 2002-2007 strategy and later realigned to NERC's subsequent strategy (Next Generation Science for Planet Earth; NERC 2007).

Who is involved in the programme?

The Oceans 2025 programme was designed by and is to be implemented through seven leading UK marine centres. The marine centres work together in coordination and are also supported by cooperation and input from government bodies, universities and other partners. The seven marine centres are:

Oceans2025 provides funding to three national marine facilities, which provide services to the wider UK marine community, in addition to the Oceans 2025 community. These facilities are:

The NERC-run Strategic Ocean Funding Initiative (SOFI) provides additional support to the programme by funding additional research projects and studentships that closely complement the Oceans 2025 programme, primarily through universities.

What is the programme about?

Oceans 2025 sets out to address some key challenges that face the UK as a result of a changing marine environment. The research funded through the programme sets out to increase understanding of the size, nature and impacts of these changes, with the aim to:

In order to address these aims there are nine science themes supported by the Oceans 2025 programme:

In the original programme proposal there was a theme on health and human impacts (Theme 7). The elements of this Theme have subsequently been included in Themes 3 and 9.

When is the programme active?

The programme started in April 2007 with funding for 5 years.

Brief summary of the programme fieldwork/data

Programme fieldwork and data collection are to be achieved through:

The data is to be fed into models for validation and future projections. Greater detail can be found in the Theme documents.


RAPID- Will the Atlantic Thermohaline Circulation Halt? (RAPID-WATCH)

RAPID-WATCH (2007-2014) is a continuation programme of the Natural Environment Research Council's (NERC) Rapid Climate Change (RAPID) programme. It aims to deliver a robust and scientifically credible assessment of the risk to the climate of UK and Europe arising from a rapid change in the Atlantic Meridional Overturning Circulation (MOC). The programme will also assess the need for a long-term observing system that could detect major MOC changes, narrow uncertainty in projections of future change, and possibly be the start of an 'early warning' prediction system.

The effort to design a system to continuously monitor the strength and structure of the North Atlantic MOC is being matched by comparative funding from the US National Science Foundation (NSF) for the existing collaborations started during RAPID for the observational arrays.

Scientific Objectives

This work will be carried out in collaboration with the Hadley Centre in the UK and through international partnerships.

Mooring Arrays

The RAPID-WATCH arrays are the existing 26°N MOC observing system array (RAPIDMOC) and the WAVE array that monitors the Deep Western Boundary Current. The data from these arrays will work towards meeting the first scientific objective.

The RAPIDMOC array consists of moorings focused in three geographical regions (sub-arrays) along 26.5° N: Eastern Boundary, Mid-Atlantic Ridge and Western Boundary. The Western Boundary sub-array has moorings managed by both the UK and US scientists. The other sub-arrays are solely led by the UK scientists. The lead PI is Dr Stuart Cunningham of the National Oceanography Centre, Southampton, UK.

The WAVE array consists of one line of moorings off Halifax, Nova Scotia. The line will be serviced in partnership with the Bedford Institute of Oceanography (BIO), Halifax, Canada. The lead PI is Dr Chris Hughes of the Proudman Oceanographic Laboratory, Liverpool, UK.

All arrays will be serviced (recovered and redeployed) either on an annual or biennial basis using Research Vessels from the UK, US and Canada.

Modelling Projects

The second scientific objective will be addressed through numerical modelling studies designed to answer four questions:


Oceans 2025 Theme 1, Work Package 1.2: Atlantic Circulation and Transports

This Work Package is run by the National Oceanography Centre, Southampton (NOCS) and aims to establish whether the Atlantic Meridional Overturning Circulation (MOC) is slowing down, and to relate this to changes in regional storage of heat, freshwater and carbon.

More detailed information on this Work Package is available at pages 8 - 10 of the official Oceans 2025 Theme 1 document: Oceans 2025 Theme 1

Weblink: http://www.oceans2025.org/


Oceans 2025 Theme 10, Sustained Observation Activity 3: Monitoring the Atlantic Meridional Overturning Circulation

The Meridional Overturning Circulation (MOC) is the key component of ocean circulation in the Atlantic responding to climate change. Under the NERC directed programme Rapid Climate Change (RAPID) two arrays of instruments have been positioned in the ocean to monitor the MOC, one at 26.5 °N to capture the southward flow at depth, and the Western Atlantic Variability Experiment (WAVE) array across the Canadian-US continental slope, closer to the presumed source variations. Sustained Observation Activity (SO) 3 will continue these measurements to observe the strength and structure of the MOC, working closely with Oceans 2025 Theme 1 and the RAPID-WATCH directed programme.

There are two elements to this SO activity. SO 3.1. relates to the E-W mooring array in the mid-North Atlantic at 26.5 °N while SO 3.2. is concerned with the Western Atlantic array between Cape Cod and the Grand Banks.

Aims and Purpose of SO 3.1.

Aims and Purpose of SO 3.2.

More detailed information on this Work Package is available at pages 11 - 14 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/


Data Activity or Cruise Information

Cruise

Cruise Name D346
Departure Date 2010-01-05
Arrival Date 2010-02-19
Principal Scientist(s)Brian A King (National Oceanography Centre, Southampton)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameMid-Atlantic Ridge Array
CategoryOffshore area
Latitude24° 45.00' N
Longitude45° 30.00' W
Water depth below MSL

RAPIDMOC Mid-Atlantic Ridge (MAR) Array

The Mid-Atlantic Ridge Array defines a box in which moorings are deployed either side of the Mid-Atlantic Ridge in the North Atlantic as part of the RAPIDMOC project. The box region has latitudinal limits of 23° N to 26.5° N and longitudinal limits of 40° W to 52.1° W. Moorings have occupied this region since 2004 and are typically deployed for 12 to 18 months.

Moored data summary

A description of the data types can be found at the bottom of this document

Year Cruise ID Number of moorings Data types (number of instruments)
2004 D277 4 BPR (4), CM (5), MCTD (20), MMP (1)
2005 CD170 6 BPR (4), CM (6), MCTD (24)
2006 D304 5 BPR (3), CM (3), MCTD (32)
2007 D324 6 BPR (4), CM (3), MCTD (33)
2008 D334 6 BPR (4), CM (3), MCTD (39)
2009 D344 6 BPR (6), CM (3), MCTD (40)
2010 D359 6 BPR (6), CM (5), MCTD (40)
2011 JC064 6 BPR (6), CM (5), MCTD (40)
2012 D382 6 BPR (6), CM (5), MCTD (34)
2014 JC103 6 BPR (6), CM (1), MCTD (34)

Cruise data summary

During the cruises to service the moored array, a variety of data types are collected. The table below is a summary of these data. The number of CTD profiles performed on these cruises within the box region defined above is also included. Trans-Atlantic hydrographic CTD sections have also been performed since 2004 and are included in the table.

Cruise ID Cruise description Data types Number of CTD profiles performed within the box region
D277 Initial array deployment DIS, MET, NAV, SADCP, SURF -
D279 Hydrographic section CTD, DIS, LADCP, MET, NAV, SADCP, SURF 19
CD170 Array service CTD, DIS, MET, NAV, SADCP, SURF 5
D304 Array service CTD, DIS, MET, NAV, SADCP, SURF 1
D324 Array service CTD, DIS, MET, NAV, SADCP, SURF 3
D334 Array service CTD, DIS, MET, NAV, SADCP, SURF 5
D344 Array service CTD, DIS, MET, NAV, SADCP, SURF 5
D346 Hydrographic section CTD, DIS, LADCP, MET, NAV, SADCP, SURF 21
D359 Array service CTD, DIS, MET, NAV, SADCP, SURF 5
JC064 Array service CTD, DIS, MET, NAV, SADCP, SURF 6
D382 Array service CTD, DIS, MET, NAV, SADCP, SURF 3
JC103 Array service CTD, DIS, MET, NAV, SADCP, SURF 4

Data type ID and description

Data type ID Description
ADCP Acoustic Doppler Current Profiler
BATH Bathymetry
BPR Bottom Pressure Recorder
CM Current Meter
CTD Conductivity-Temperature-Depth profiler
DIS Discrete water bottle samples
IES Inverted Echo Sounder
LADCP Lowered Acoustic Doppler Current Profiler
MET Meteorology
MCTD Moored Conductivity-Temperature-Depth sensor
MMP McLane Moored Profiler - profiling CTD and current meter
NAV Navigation
SADCP Shipborne Acoustic Doppler Current Profiler
SURF Sea surface data

Other Series linked to this Fixed Station for this cruise - 1017630 1017642 1017654 1017666 1017678 1017691 1017709 1017710 1017722 1017734 1017758 1017771 1017783 1017795 1017802 1017814 1017826 1017838 1017851 1017863

Other Cruises linked to this Fixed Station (with the number of series) - CD170 (33) D277 (24) D304 (31) D324 (40) D334 (32) D344 (42) D359 (49) D382 (32) JC064 (45) JC103 (4)

Fixed Station Information

Station Name25 N Hydrographic Transatlantic section
CategoryOffshore route/traverse

25° N Hydrographic Transatlantic section

The hydrographic transatlantic section at 25° has been occupied 6 times, namely in 1957, 1981, 1992, 1998, 2004 and 2010. The section is an attempt to calculate the transports of water and its constituents (heat, salinity, nutrients, biological productivity) along this latitude, and to compare the data so that the degree of change in the North Atlantic transports can be revealed.

Map of stations

BODC image

The station positions for all the occupied sections are shown in the above figures. Sections occupied in 1957, 1981, 1992, 1998 and 2004 are shown in the upper figure. The section occupied in 2010 is shown in the lower figure.

The 1957 and 1992 sections each went zonally along 24.5° N from the African coast to the Bahama Islands. Because of diplomatic clearance issues, the 1981, 1998, 2004 and 2010 sections angled southwestward from the African coast at about 28° N to join the 24.5° N section at about 23° W. The 1998, 2004 and 2010 sections angled northwestward at about 73° W to finish the section along 26.5° N. The 2010 section deviated from the previous sections across the Mid-Atlantic Ridge (MAR) in order to sample the deepest channel and capture the passage of the deep water across the MAR.

Table 1: Occupations of the section

Year Cruise Reference
1957 - Fuglister (1960)
1981 - Roemmich and Wunsch (1985)
1992 HE06 Parilla et al. (1994)
1998 - Baringer and Molinari (1999)
2004 D279 Bryden et al. (2005b)
2010 D346 -

References

Baringer, M. O. N. and R. L. Molinari, 1999. Atlantic Ocean baroclinic heat flux at 24 to 26°N. Geophysical Research Letters, 26, 353-356.

Bryden, H. L., H. R. Longworth, and S. Cunningham, 2005b. Slowing of the Atlantic meridional overturning circulation at 25°N. Nature, 438, 655-657.

Fuglister, F. C., 1960. Atlantic Ocean Atlas of Temperature and Salinity Profiles and Data from the International Geophysical Year of 1957-1958. Vol. 1, Woods Hole Oceanographic Institution Atlas Series, WHOI, Woods Hole, Massachusetts.

Parilla, G., A.Lavin, H. Bryden, M. Garcia, and R. Millard, 1994. Rising temperatures in the subtropical North Atlantic Ocean over the past 35 years. Nature, 369, 48-51.

Roemmich, D. and C. Wunsch, 1985. Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean. Deep Sea Research, 32, 619-664.

Other Series linked to this Fixed Station for this cruise - 1016988 1017003 1017015 1017027 1017039 1017040 1017052 1017064 1017076 1017088 1017107 1017119 1017120 1017132 1017144 1017156 1017168 1017181 1017193 1017200 1017212 1017224 1017236 1017248 1017261 1017273 1017285 1017297 1017304 1017316 1017328 1017341 1017353 1017365 1017377 1017389 1017390 1017408 1017421 1017433 1017445 1017457 1017469 1017470 1017482 1017494 1017501 1017513 1017525 1017537 1017549 1017550 1017562 1017574 1017586 1017598 1017605 1017617 1017629 1017630 1017642 1017654 1017666 1017678 1017691 1017709 1017710 1017722 1017734 1017758 1017771 1017783 1017795 1017802 1017814 1017826 1017838 1017851 1017863 1017875 1017887 1017899 1017906 1017918 1017931 1017943 1017955 1017967 1017979 1017980 1017992 1018006 1018018 1018031 1018043 1018055 1018067 1018079 1018080 1018092 1018111 1018123 1018135 1018147 1018159 1018160 1018172 1018184 1018196 1018203 1018215 1018227 1018239 1018240 1018252 1018264 1018276 1018288 1018307 1018319 1018320 1018332 1018344


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain