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Metadata Report for BODC Series Reference Number 808705


Metadata Summary

Data Description

Data Category Surface temp/sal
Instrument Type
NameCategories
SeaTech transmissometer  transmissometers
WETLabs WETStar fluorometer  fluorometers
Falmouth Scientific Instruments OEM conductivity-temperature sensor  water temperature sensor; salinity sensor
Falmouth Scientific Instruments ocean temperature module  water temperature sensor
Ashtech ADU2 Global Positioning System receiver  NAVSTAR Global Positioning System receivers
Trimble 4000DL Global Positioning System receiver  Differential Global Positioning System receivers
Ashtech G12 Global Positioning System receiver  NAVSTAR Global Positioning System receivers; Differential Global Positioning System receivers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Stuart Cunningham
Originating Organization Southampton Oceanography Centre (now National Oceanography Centre, Southampton)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Rapid Climate Change Programme
 

Data Identifiers

Originator's Identifier D279_PRODQXF_SURF
BODC Series Reference 808705
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2004-04-04 16:43
End Time (yyyy-mm-dd hh:mm) 2004-05-08 23:59
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Start Latitude 26.49330 N ( 26° 29.6' N )
End Latitude 27.28080 N ( 27° 16.8' N )
Start Longitude 78.91810 W ( 78° 55.1' W )
End Longitude 15.42170 W ( 15° 25.3' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 5.0 m
Maximum Sensor or Sampling Depth 5.0 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor or Sampling Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ALATGP011DegreesLatitude north relative to WGS84 by unspecified GPS system
ALONGP011DegreesLongitude east relative to WGS84 by unspecified GPS system
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
FVLTWS011VoltsRaw signal (voltage) of instrument output by linear-response chlorophyll fluorometer
PSALSG011DimensionlessPractical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and calibration against independent measurements
TEMPHG011Degrees CelsiusTemperature of the water body by thermosalinograph hull sensor and verification against independent measurements

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

No Problem Report Found in the Database

RAPID Cruise D279 Underway Surface Hydrography Data Quality Report

Hydrography

Salinity and Temperature

The start of the series is flagged suspect on 04 April until 18:45 for temperature and 19:51 for salinity.

Beam attenuation

There is a steady increase in beam attenuation throughout the cruise, possibly indicating sensor fouling. There are numerous spikes throughout the series, which have been flagged suspect.

Fluorescence

There is a step in the data at 19:49 on the 04/04/2004 with values around 0.14 volts before and 0.08 volts afterwards. The higher values (at the start of the cruise) have been left unflagged, but should be used with caution.


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

Falmouth Scientific Inc. OEM CT sensor

The OEM CT sensor is designed to provide high accuracy conductivity and temperature measurements in a package that can be readily integrated into user systems. The CT sensor relies on an inductively coupled conductivity sensor, with a large inside diameter that eliminates the need for pumps. A high grade Platinum Resistance Thermometer is used to measure temperature.

Sensor specifications are given in the table below. Since 2009 this instrument has been manufactured by Teledyne RD Instruments as a Citadel CT-EK Sensor. More information about the instrument can be found on the Teledyne Citadel specification sheet.

Sensor Specifications

Instrument Parameter Small CT Cell Conductivity Large CT Cell Conductivity Temperature
Range 0 to 70 mS cm-1 0 to 70 mS cm-1 -2 to 35 degrees C
Accuracy ±0.020 mS cm-1 ±0.010 mS cm-1 ±0.050 degrees C
Stability ±0.005 mS cm-1 mo-1 ±0.003 mS cm-1 ±0.005 degrees C mo-1
Response 20 cm @ 1 m s-1 15 cm @ 1 m s-1 20 seconds internal, 1 second external

Power Input 50 mW @ 6 VDC, voltage range 6 - 14 VDC
Logic 2 0 - 5 VDC control lines
Output Impedance 500 ohms

WET Labs WETStar Fluorometers

WET Labs WETStar fluorometers are miniature flow-through fluorometers, designed to measure relative concentrations of chlorophyll, CDOM, uranine, rhodamineWT dye, or phycoerythrin pigment in a sample of water. The sample is pumped through a quartz tube, and excited by a light source tuned to the fluorescence characteristics of the object substance. A photodiode detector measures the portion of the excitation energy that is emitted as fluorescence.

Specifications

By model:

  Chlorophyll WETStar CDOM WETStar Uranine WETStar Rhodamine WETStar Phycoerythrin WETStar
Excitation wavelength 460 nm 370 nm 485 nm 470 nm 525 nm
Emission wavelength 695 nm 460 nm 530 nm 590 nm 575 nm
Sensitivity 0.03 µg l-1 0.100 ppb QSD 1 µg l-1 - -
Range 0.03-75 µg l-1 0-100 ppb; 0-250 ppb 0-4000 µg l-1 - -

All models:

Temperature range 0-30°C
Depth rating 600 m
Response time 0.17 s analogue; 0.125 s digital
Output 0-5 VDC analogue; 0-4095 counts digital

Further details can be found in the manufacturer's specification sheet, and in the instrument manual.

Ashtech G12 Global Positioning System Receiver

The Ashtech G12 Global Positioning System (GPS) uses all-in-view tracking and 12 channels to provide real time three-dimensional positional measurements. It is Differential GPS (DGPS) ready, offering an accuracy of better than 40 cm, position latency better than 50 ms, and exact position latency to millisecond accuracy.

Specifications

Parameter Values
Operating Temperature -30°C to 70°C
Sampling frequency up to 10 Hz
Receiver channels 12
Real-Time Position Accuracy Horizontal, DGPS: 40 cm Horizontal 95%: 90 cm Vertical 95%: 1.6 m

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

Ashtech Global Positioning System receivers (ADU series)

The ADU series of Global Positioning System (GPS) receivers are designed to give real-time three-dimensional position and attitude measurements. Attitude determination is based on differential carrier phase measurements between four antennas connected to a receiver, providing heading, pitch and roll, along with three-dimensional position and velocity.

The ADU2 model receives information from 48 channels, while the upgraded model (ADU5) uses 56 channels. The ADU5 also features a unique Kalman filter with user selectable dynamic modes to match operating conditions. It also incorporates signals from Satellite Based Augmentation Systems (SBAS) and features an embedded 2-channel 300 kHz beacon receiver for easy differential GPS (DGPS) operations.

Specifications

Parameter ADU2 ADU5

Operational Temperature range:
Antenna
Receiver


-40°C to 65°C
-20°C to 55°C


-40°C to 65°C
-20°C to 55°C

Sampling frequency 5 Hz 5 Hz
Receiver channels 48 56

Accuracy:
Heading
Pitch/Roll


0.2° rms (dynamic) - 0.4° rms (static)
0.4° rms (dynamic) - 0.8° rms (static)


0.02° to 0.2° rms
0.04° to 0.4° rms

Circular Error Probability:
Autonomous
Differential


5.0 m
1.0 m


3.0 m
0.4 to 1.0 m

Further details can be found in the manufacturer's specification sheets for the ADU2 andADU5.

SeaTech Transmissometer

Introduction

The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.

Specifications

  • Water path length: 5 cm (for use in turbid waters) to 1 m (for use in clear ocean waters).
  • Beam diameter: 15 mm
  • Transmitted beam collimation: <3 milliradians
  • Receiver acceptance angle (in water): <18 milliradians
  • Light source wavelength: usually (but not exclusively) 660 nm (red light)

Notes

The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

Further details can be found in the manufacturer's Manual.

Falmouth Scientific Inc. Ocean Sensor Modules

FSI's individual sensor modules include an Ocean Conductivity Module (OCM), Ocean Temperature Module (OTM) and Ocean Pressure Module (OPM). All three use a low power micro-controller to collect, scale and transmit real-time data via RS-232 or RS-485.

Parameter OCM Conductivity OTM Temperature OPM Pressure
Range 0 - 7.0 S/m(0 - 70 mS/cm) -2 to 32 °C User Specified:0-200 dBar0-1000 dBar0-2000 dBar0-3000 dBar0-7000 dBar
Accuracy -0.0003* S/m(-0.003 mS/cm) -0.003 °C* -0.03% full scale*
Stability /month -0.00005 S/m(-0.0005 mS/cm) -0.0005 °C -0.002% full scale
Resolution 0.00001 S/m(-0.0001 mS/cm) 0.0001 °C 0.0004% full scale
Response at 1 m/s flow 50 msec 150 msec 25 msec
Sensor Type Inductive cell Platinum thermometer Strain gauge

* Higher accuracy available

For further details, see the manufacturer's specification sheet.

RAPID Cruise D279 Underway Surface Hydrography Instrumentation

Seawater was continually pumped from the hull of the ship at an approximate depth of 5m through the UKORS Surfmet system (known as the ship's non-toxic supply). The details of these sensors are shown in the table below.

Sensor Serial number Last calibration date
FSI OCM housing conductivity sensor 1376 Calibration stored internally
FSI OTM housing temperature sensor 1340 25/06/2002
FSI OTM remote temperature sensor 1348 June 2003
WetLabs fluorometer WS3S-248 26/02/2003
SeaTech Transmissometer CST-113R -

RAPID Cruise D279 Underway Meteorology, Surface Hydrography and Navigation Series

Cruise details

Dates 4 April 2004 - 10 May 2004
Principal Scientific Officer Dr Stuart Cunningham (SOC)
Cruise Report Cunningham, S. A., 2005. RRS Discovery Cruise D279 04 APR - 10 MAY 2004. A Transatlantic hydrography section at 24.5°N. Southampton, UK, National Oceanoraphy Centre Southampton.(National Oceanography Centre Southampton Cruise Report No. 54).

D279 travelled from Freeport in the Bahamas across the Atlantic to Tenerife in Spain. After initially focussing on the collection of chemical data from the Florida Current at 27°N, the main focus of the cruise was the collection of hydrographic data across the Atlantic Ocean between approximately 24 and 27.5°N.

It should be noted that the data series supplied by the originator covers 04 April to 08 May 2004, which is less that the duration of the cruise.

Data Processing Procedures

Two minute averaged sea surface hydrographic and meteorological data, together with navigation and bathymetric files, were transferred from PSTAR format into BODC internal format (QXF), using time (UTC) as the primary linking key, to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed in the individual instrument sections. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect. The capabilities of the workstation screening software allows comparative screening checks between channels.

The qxf file then underwent a further step. This involved using Matlab to split the qxf file into three separate qxf files. One contained data for hydrography, one for meterological data and the final qxf file held the navigation data.

RAPID Cruise D279 Underway Surface Hydrography Processing

Originator's Processing

Sea surface meteorology and thermosalinograph measurements were made by the UKORS Surfmet system. The depth of the ship's flow through intake is approximately 5 m and sent to the ship's central logging system. Onboard processing was carried out on a daily basis and involved running a sequence of executable programs. The initial stage transferred the underway surfmet data into PSTAR from RVS format. Subsequent processing included the calculation of salinity. Finally, Julian Day time variable data were calculated and the resulting data examined by plotting on a daily and weekly basis.

Salinity

The underway salinity channel was calibrated by the originator using independent bottle salinity samples drawn from the ship's contaminated water supply at 2-8 hour intervals. The uncontaminated water supply wasn't available for sampling during this cruise due to low water pressure.

Calibration was achieved with a combination of PSTAR and Matlab routines. Bottle salinity data (.csv files) were transferred to the ship's Unix system and appended into one file. Salinities were converted back to conductivities and merged with 5 minute binned underway conductivity data. A 6 point running mean of conductivity offset was calculated in Matlab, and the calibration curve (with end point outliers excluded) applied to the original 2 minute averaged underway data. The mean offset applied (calibrated - uncalibrated salinity) was -0.11361 with a standard deviation of 0.009. Comparisons were also made between gridded 10 m CTD station and underway salinities (mean difference 0.002 with a standard deviation of 0.012).

BODC processing

Temperature

The hull temperature data were calibrated against CTD temperature averaged over the top 5 m. Several outliers were identified and discarded on the basis that they had high standard deviations associated with them. In the remaining dataset, the offset (CTD temperature - underway temperature) was stable and did not show a relationship with time or temperature. The data were calibrated using a mean offset correction (N = 108, standard deviation = 0.03) as follows:

Calibrated temperature = temperature - 0.013.

Beam attenuation

Raw output voltages from the transmissometer were converted to beam attenuation after correction with readings taken at the time of sensor calibration. The equation used was:

Attenuation = -1/PL * ln((Transmissometer output * (1/Vref-Vd)) + (-Vd/Vref-Vd))

where PL = path length = 0.25 m; Vref = Voltage out in particle-free water = 4.826; Vd = Blocked path voltage = 0.057.

Fluorescence

There were no samples against which to calibrate the fluorometer, so the fluorescence data remain as raw voltages and no further processing was possible.


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.


Data Activity or Cruise Information

Cruise

Cruise Name D279
Departure Date 2004-04-04
Arrival Date 2004-05-10
Principal Scientist(s)Stuart A Cunningham (Southampton Oceanography Centre)
Ship RRS Discovery

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:

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
Q value below limit of quantification