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Metadata Report for BODC Series Reference Number 792191


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
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Prof Mike Meredith
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
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 CD160_PRODQXF_SURF
BODC Series Reference 792191
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2004-08-04 19:56
End Time (yyyy-mm-dd hh:mm) 2004-08-24 10:58
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 42.19400 N ( 42° 11.6' N )
Northernmost Latitude 47.47590 N ( 47° 28.6' N )
Westernmost Longitude 63.61570 W ( 63° 36.9' W )
Easternmost Longitude 52.17050 W ( 52° 10.2' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 2.5 m
Maximum Sensor or Sampling Depth 2.5 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution -
Sensor or Sampling Depth Datum -
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
TEMPHU011Degrees CelsiusTemperature of the water body by thermosalinograph hull sensor and NO verification against independent measurements
TVLTCR011VoltsRaw signal (voltage) of instrument output by 20cm path length red light transmissometer

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


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.

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 CD160 hydrography instrument details

Underway hydrography was recorded by a suite of instruments in the ship's flow through system and a temperature sensor located near the flow through intake, at the hull. The depth of the flow through intake was approximately 2.5 m. Instrument details are given in the table below.

Sensor Serial number Last calibration date
FSI OCM housing conductivity sensor 1358 23/03/2004
FSI OTM housing temperature sensor 1361 18/02/2004
FSI OTM remote temperature sensor 1370 18/02/2004
WetLabs fluorometer WS3S-134 24/01/2003

RAPID Cruise CD160 Sea Surface Hydrography Series Processing

  • Thermosalinograph

    Salinity was back calibrated at BODC with 22 discrete TSG samples collected during the cruise. 2 additional discrete samples could not be used as their corresponding underway values were null. The offset (discrete sample - underway salinity) was examined to see if it varied with time or underway salinity. A significant correlation was established between offset and discrete salinity, but not between offset and time. The data were corrected for the trend with discrete salinity using the following equation:

    Calibrated underway salinity = (underway salinity * 1.5015) -17.2673.

    The calibration residuals ranged between -0.0038 and 0.4225. The root mean square of the calibration residuals was 0.4035.

    No calibrations were applied to temperature by BODC.

  • Beam transmissometer

    Raw voltages were converted to beam attenuation after correction with air readings obtained during the cruise (05/08/2004). The equation used was:

    Attenuation = -1/PL*ln((Va/Vb)*k*20*(Vx-Vz)/100)

    where PL = path length = 0.2 m; Va = transmission voltage in air (recorded at water calibration time) = 4.684; Vb = transmission voltage in air (current value) = 4.405; k = water calibration constant = 1.002; Vx = transmissometer output voltage; Vz = blocked path voltage = 0.001.

  • Fluorescence

    Fluorescence data were logged as raw voltages, and no calibrations were applied by BODC.

RAPID Cruise CD160 Sea Surface Hydrography, Meteorology and Navigation

Cruise details

Dates 5 - 24 August 2004
Principal Scientific Officer Mike Meredith (POL)

A full copy of the Metadata report can be found here: CD160

Data Aquisition and Onboard Processing

Meterological data were collected with a Vaisala QLI50 sensor collector (s/n: R381006) and sent, along with TSG system measurements, to the ship's central logging system. ASCII files were generated for each 24 hour period of the cruise and loaded into Matlab for further processing. Large spikes in conductivity and temperature were removed, and surface salinity calculated from conductivity and housing temperature data. An additional routine was run to determine the true wind speed and direction, taking account of the ship's motion. The data were subsequently averaged (2 minute resolution) with latitude and longitude interpolated to the SurfMet timestamps. Finally, one file was produced, containing the averaged data for the whole cruise.

BODC underway data processing

All underway sea surface hydrography, meteorology and ship's navigation data were merged into a common QXF file using time (GMT) as the primary linking key. Navigation was checked for improbable speeds and gaps, wind speed and direction were corrected for ship's motion and heading and any additional data calibrations were applied as appropriate.

The QXF file then underwent a further step. This involved using Matlab transfer 378 to split the underway QXF file into three separate QXF files. One contained data for sea surface hydrography, one for meteorological data and the final QXF file held the navigation data.

Each data channel was visually inspected on a graphics workstation and any spikes or periods of dubious data were flagged as suspect. The capabilities of the workstation screening software allows all possible comparative screening checks between channels (e.g. to ensure corrected wind data have not been influenced by changes in ship's heading). The system also has the facility of simultaneously displaying the data and the ship's position on a map to enable data screening to take oceanographic climatology into account.

RAPID Cruise CD160 Underway Hydrography - Data Quality Report

It should be noted that data logging was suspended between 13/08/2004 and 18/08/2004 whilst the ship was in port for engine repairs.

Beam transmissometer

At the start of the cruise, as well as some spikes, the values are around 1.2 m-1. After 11:10 on 05/08/2004 there is a sudden decrease in beam attenuation to approx 0.45 m-1. Beam attenuation stays at this lower value for the remainder of the dataset. The data at the higher value has not been flagged but should be treated with caution.

The shape of the small spike at 11:52 on 07/08/2004 is indicative of bubbles having affected the sensor. As a consequence, this spike is also flagged suspect.


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 CD160
Departure Date 2004-08-04
Arrival Date 2004-08-24
Principal Scientist(s)Mike Meredith (Proudman Oceanographic Laboratory)
Ship RRS Charles Darwin

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