Metadata Report for BODC Series Reference Number 1762389


Metadata Summary

Data Description

Data Category Surface temp/sal
Instrument Type
NameCategories
WETLabs C-Star transmissometer  transmissometers
Sea-Bird SBE 45 MicroTSG thermosalinograph  thermosalinographs; water temperature sensor; salinity sensor
Sea-Bird SBE 38 thermometer  water temperature sensor
Turner 10-AU chlorophyll field fluorometer  fluorometers
Litre Meter flow meter  flow meters
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Miss Arwen Bargery
Originating Organization British Oceanographic Data Centre, Liverpool
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier JR15001_PRODQXF_SURF
BODC Series Reference 1762389
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2015-09-15 18:26
End Time (yyyy-mm-dd hh:mm) 2015-11-03 17:11
Nominal Cycle Interval 30.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 51.66967 S ( 51° 40.2' S )
Northernmost Latitude 53.63483 N ( 53° 38.1' N )
Westernmost Longitude 57.79783 W ( 57° 47.9' W )
Easternmost Longitude 1.93567 E ( 1° 56.1' E )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 6.5 m
Maximum Sensor Depth 6.5 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
CNDCSG01 1 Siemens per metre TSG_Cond Electrical conductivity of the water body by thermosalinograph
CPHLUMTF 1 Milligrams per cubic metre chl-a_water_NTTFfluor_manufctrcal Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by through-flow fluorometer plumbed into non-toxic supply and manufacturer's calibration applied
INFLTF01 1 Litres per minute TSG+Fl_Flow Flow rate through instrument
POPTDR01 1 Percent Trans_Red_25cm Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer
PSALSU01 1 Dimensionless P_sal_TSG_uncalib Practical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
SVELSG01 1 Metres per second TSG_Sound_Vel Sound velocity in the water body by thermosalinograph and computation from temperature and salinity by unspecified algorithm
TEMPHG01 1 Degrees Celsius CalTSGHullTmp Temperature of the water body by thermosalinograph hull sensor and verification against independent measurements
TMESSG01 1 Degrees Celsius TSG_Meas_Temp Temperature of conductivity measurement by thermosalinograph
 

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

Fluorescence

The underway fluorometer may be operating close to the lower limits of detection for the instrument along much of the transect. The bench fluorometric measurements made on discrete samples collected for the extraction of chlorophyll-a recorded marked difference between different regions of the cruise track whereas the underway fluorometer shows continuously similar values from around 24/10/2015. Data from this point onwards have been flagged. The fluorometer readings show jumps in values throughout the cruise. There is no record of the fluorometer being cleaned before or during the cruise and the observed pattern may be due to bio-fouling of the sensor further reducing the limits of detection. For this reason the discrete underway chlorophyll-a measurement data sets should be used in preference to the ship's fluorometer.

RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Surface Hydrography Data Quality Report

Salinity, Temperature, Conductivity and Sound velocity

Unrealistic values in the PSALSU01, TEMPHU02, TEMPHU01, SVELSG01 and CNDCSG01 channels were flagged as suspect.


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

SeaBird Digital Oceanographic Thermometer SBE38

The SBE38 is an ultra-stable thermistor that can be integrated as a remote temperature sensor with an SBE21 Thermosalinograph or an SBE 45 Micro TSG, or as a secondary temperature sensor with an SBE 16 plus, 16plus-IM, 16plus V2, 16plus-IM V2 or 19plus V2 SEACAT CTD.

Temperature is determined by applying an AC excitation to reference resistances and an ultra-stable aged thermistor. The reference resistor is a hermetically sealed VISHAY. AC excitation and ratiometric comparison using a common processing channel removes measurement errors due to parasitic thermocouples, offset voltages, leakage currents and gain errors.

The SBE38 can operate in polled sampling, where it takes one sample and transmits the data, or in continuous sampling.

Specifications

Depth rating up to 10500 m
Temperature range -5 to 35°C
Initial accuracy ± 0.001°C
Resolution 0.00025°C
Stability 0.001°C in 6 months
Response time 500 ms
Self-heating error < 200 µK

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

Turner Designs 10AU Field Fluorometer

The Turner Designs 10AU is designed for continuous-flow monitoring or discrete sample analyses of fluorescent species. A variety of optical kits with appropriate filters and lamps are available for a wide range of applications. Individual filters and lamps are also available for customised applications.

Standard optical kits include those for chlorophyll- a (extracted and/or in vivo ), phycocyanin, phycoerythrin, CDOM, ammonium, rhodamine and fluorescein dye tracing, crude oil, refined oil, histamine and optical brighteners.

The instrument's light source is a 4 watt lamp and the detector is a photomultiplier tube with a standard detection range of 300-650 nm. A red-sensitive version with a detetion range of 185-970 nm is also available.

Specifications

Operating temperature 0 to 55°C
Detector PhotoMultiplier Tube

300 to 650 nm (standard)

185 to 870 nm (Red)

Detection Limits:
Extracted Chlorophyll- a
Rhodamine WT Dye
Fluorescein Dye

0.025 µg L -1
0.01 ppb (in potable water)
0.01 ppb (in potable water)
Linear range:
Extracted Chlorophyll- a
Rhodamine WT Dye
Fluorescein Dye

0 to 250µg L -1
0 to 250 ppb
0 to 250 ppb

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

WETLabs C-Star transmissometer

This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.

Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.

This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.

Specifications

Pathlength 10 or 25 cm
Wavelength 370, 470, 530 or 660 nm
Bandwidth

~ 20 nm for wavelengths of 470, 530 and 660 nm

~ 10 to 12 nm for a wavelength of 370 nm

Temperature error 0.02 % full scale °C -1
Temperature range 0 to 30°C
Rated depth

600 m (plastic housing)

6000 m (aluminum housing)

Further details are available in the manufacturer's specification sheet or user guide .

Litre Meter flow meter

A flow meter used to monitor water flow rates for pumped systems such as ships' continuous seawater supplies.

RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Surface Hydrography Instrument Description Document

The following instruments were used during the cruise.

Instrumentation

Manufacturer Model Main Function Serial number Last calibration date
Sea Bird Electronics SBE45 Thermosalinograph 0016 14/05/2014
Sea Bird Electronics SBE38 Temperature x2 sensors 0601 and 0599 11/06/2015
Chelsea Technologies 10 AU-005 Fluorometer 1100243 -
Wet Labs C-Star Transmissometer CST-396DR 06/08/2015
Litremeter 05SPFA40CE Flow meter 05/811950 09/06/2011

SeaBird MicroTSG Thermosalinograph SBE 45

The SBE45 MicroTSG is an externally powered instrument designed for shipboard measurement of temperature and conductivity of pumped near-surface water samples. The instrument can also compute salinity and sound velocity internally.

The MicroTSG comprises a platinum-electrode glass conductivity cell and a stable, pressure-protected thermistor temperature sensor. It also contains an RS-232 port for appending the output of a remote temperature sensor, allowing for direct measurement of sea surface temperature.

The instrument can operate in Polled, Autonomous and Serial Line Sync sampling modes:

Specifications

  Conductivity Temperature Salinity
Range 0 to 7 Sm -1 -5 to 35°C  
Initial accuracy 0.0003 Sm -1 0.002°C 0.005 (typical)
Resolution 0.00001 Sm -1 0.0001°C 0.0002 (typical)
Typical stability (per month) 0.0003 Sm -1 0.0002°C 0.003 (typical)

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

RRS James Clark Ross Cruise JR15001 (AMT25, JR864) Surface Hydrography Processing Document

Originator's Data Processing

The sea surface hydrography measurements were performed by a Sea Bird electronics thermosalinograph in the ship's flow through system and by a temperature sensor located near the flow through intake, at the hull. The depth of the flow through intake was 5.5 m. The data streams were logged every second to the SCS system and merged into a comma separated file format, and the header information was stored in .TPL files.

The surface hydrography data were also logged to the Oceanlogger.ACO file. This file exhibits four initial columns: Year (yyyy), Julian day.day fraction (days), Julian day (days), day fraction (days). The file structure then contains 10 columns with meteorological data as outlined above followed by the hydrography channels in the order: tstemp (Celsius), conductivity (S m -1 ), salinity (psu), sound_velocity (m s -1 ) chlorophyll (µg l -1 ), sampletemp (Celsius), flowrate (l min -1 ), sstemp (Celsius).

Filename Content Description Format Interval Start date Start Time End date End Time
oceanlogger.ACO
  • Temperature (housing)
  • Temperature (remote x2)
  • Transmissometer
  • Conductivity
  • Salinity
  • Fluorometer
  • Sound velocity
  • Fluorometer flow meter
ASCII (.ACO) ~1-2 minutes 15/9/2015 14:18:00 04/11/2015 14:50:40

BODC Data Processing

Sea surface hydrography parameters were transferred to internal BODC format and matched against BODC parameter codes, as presented in the table below. No unit conversions were applied, as the originators units were equivalent to the units of the respective BODC parameter code units assigned. BODC processing procedures included loading of data and reduction through averaging, unit conversions, visual screening and flagging of anomalous values.

Originator's File Originator's Parameter Originator's Units Description BODC code BODC Units Comments and unit conversions
oceanlogger.ACO salinity psu Practical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and NO calibration against independent measurements PSALSU01 Dimensionless -
oceanlogger.ACO sstemp °C Temperature of the water body by thermosalinograph hull sensor and NO verification against independent measurements TEMPHU01 °C -
oceanlogger.ACO sstemp2 °C Temperature of the water body by thermosalinograph hull sensor and NO verification against independent measurements sensor 2 TEMPHU02 °C -
oceanlogger.ACO tstemp °C Temperature of conductivity measurement by thermosalinograph TMESSG01 °C -
oceanlogger.ACO conductivity S m -1 Electrical conductivity of the water body by thermosalinograph CNDCSG01 S m -1 -
oceanlogger.ACO sound_velocity m s -1 Sound velocity in the water body by thermosalinograph and computation from temperature and salinity by unspecified algorithm SVELSG01 m s -1 -
oceanlogger.ACO chlorophyll µg l -1 Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate phase] by through-flow fluorometer plumbed into non-toxic supply and manufacturer's calibration applied CPHLUMTF mg m -3 -
oceanlogger.ACO flowrate l min -1 Flow rate through instrument INFLTF01 l min -1 -
oceanlogger.ACO trans % Transmittance POPTDR01 % x 100 %

Sample Calibrations

Temperature

The hull temperature sensor data were calibrated against the CTD temperature sensors during the cruise. The data from the hull sensor were compared with the temperature from the average of two externally mounted CTD temperature sensors at 6 decibars at corresponding measurement times. The temperature offsets (CTD - Hull) were plotted against cruise day and CTD sensor temperature to identify and remove outliers. A regression analysis was run on the remaining data points and revealed a weak and insignificant relationship between the offset and CTD sensor data (R 2 = 0.0458; n = 58; p = 0.1066) and between the offset and cruise time (R 2 = 0.047; n = 58; p = 0.099). The mean offset was therefore applied to the uncalibrated hull temperature data.

The mean offset was applied to the hull mounted temperature sensor as shown in the equation below to generate the calibrated hull temperature channel.

Salinity

Bench salinometer discrete surface samples collected from the non-toxic underway system during the cruise were used to create a calibration dataset for the calibration of the SBE45 TSG salinity data. The offset between the bench salinity and TSG salinity was calculated and plotted against bench salinity to identify outliers. The relationship between the offset and time was also assessed to check for any drift in the sensor over the course of the cruise and to remove further outliers. Two phases over the duration of the cruise were identified and required two separate analyses. The first phase was from the start of the cruise to the port dock at Cape Verde at 07/10/2015 20:59, and the second phase was from 07/10/2015 21:00 to the end of the cruise. The relationship between the offset and bench salinity and between offset and cruise day were then analysed using a linear regression for each phase.

In the first phase, the relationship between offset and cruise time, although not strong, was significant (R 2 = 0.191; n = 37; p = 0.0068), indicating a possible sensor drift over time. However, the quality of the bench salinity measurements were in question for the first half of the cruise and therefore applying a calibration was not deemed appropriate.

For the second phase of the cruise, the sensor drift over time was not strong or significant (R 2 = 0.018; n = 56; p = 0.325). As the relationship between offset and bench salinity (R 2 = 0.00005; n = 56; p = 0.957) for this phase was also weak and insignificant a regression was not applied. The TSG salinity is only reported to 2 decimal places and the mean offset in the second half of the cruise was less than +/-0.01 so that applying a mean offset did not move the TSG values closer to the bench salinity, so therefore a calibration was not necessary to improve the dataset.

Chlorophyll

Discrete samples of seawater were collected during the cruise from the non-toxic supply and analysed for extracted chlorophyll-a following Welschmeyer (1994). These samples were obtained to create a calibration dataset for the underway fluorometer sensor. Each discrete sample of 250 ml was filtered through a 47 mm 0.2 µm polycarbonate filter. The filters were then placed in a vial with 10 ml 90% acetone and left in a freezer for 24 hours. The samples were analysed on a pre-calibrated Turner Designs Trilogy fluorometer with a non-acidified chl module (CHL NA #046) fitted.

The underway fluorometer readings appear to be unrealistic, displaying values that flat-line from around the 24/10/2015 onwards. As a result of this, no calibration has been applied to the fluorometer channel.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name JR15001 (AMT25, JR864)
Departure Date 2015-09-15
Arrival Date 2015-11-04
Principal Scientist(s)David Barnes (British Antarctic Survey), Jonathan Sharples (University of Liverpool Department of Earth, Ocean and Ecological Sciences), Tim Smyth (Plymouth Marine Laboratory)
Ship RRS James Clark Ross

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