Metadata Report for BODC Series Reference Number 1762316


Metadata Summary

Data Description

Data Category Surface temp/sal
Instrument Type
NameCategories
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 JR20131005_PRODQXF_SURF
BODC Series Reference 1762316
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2013-10-07 07:51
End Time (yyyy-mm-dd hh:mm) 2013-11-08 13:04
Nominal Cycle Interval 60.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 51.24900 S ( 51° 14.9' S )
Northernmost Latitude 50.80017 N ( 50° 48.0' N )
Westernmost Longitude 57.11533 W ( 57° 6.9' W )
Easternmost Longitude 0.97200 W ( 0° 58.3' W )
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
CPHLUT01 1 Milligrams per cubic metre chl-a_water_NTTFfluor_sampcal 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 calibration against sample data
INFLTF01 1 Litres per minute TSG+Fl_Flow Flow rate through instrument
PSALSG01 1 Dimensionless P_sal_TSG_calib Practical salinity of the water body by thermosalinograph and computation using UNESCO 1983 algorithm and 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
TEMPSU01 1 Degrees Celsius UncalTSGTmp Temperature of the water body by thermosalinograph and NO 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

Fluorometer

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 the gyres and the region 7°N, whereas the underway fluorometer did not detect this pattern. The ship's fluorometer appears to show a slight decline in signal throughout the cruise until moving out of the southern Atlantic gyre towards the end of the cruise. There is no record of the fluorometer being cleaned before or during the cruise and the observed pattern may be due to biofouling of the sensor further reducing the limits of detection. For this reason the discrete underway chlorophyll-a measurement datasets should be used in preference to the ship's fluorometer, even with a post cruise calibration applied.

RRS James Clark Ross Cruise AMT23 JR300 JR20131005 Surface Hydrography Data Quality Document

Unrealistic values in the PSALSU01, TEMPSU01, 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 .

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 AMT23 JR300 JR20131005 Surface Hydrography Instrument Description Document

Manufacturer Model Sensor Serial number Last calibration date
Sea Bird Electronics SBE45 Thermosalinograph 0018 15/08/2012
Chelsea Technologies 10 AU-005 Fluorometer - -

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 AMT23 JR300 JR20131005 Surface Hydrography Processing Procedures 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 6 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).

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 parameter Units Description BODC code Units Comments
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, tstemp °C Temperature of the water body by thermosalinograph and NO verification against independent measurements TEMPSU01 °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 -

Sample Calibrations

Temperature

The hull temperature sensor data were calibrated against the CTD temperature sensors during the cruise. The data from the hull sensor at the CTD start time were compared with the temperature from the externally mounted CTD temperature at 6 decibars. The temperature offsets (CTD - Hull) were plotted against date/time and CTD sensor temperature and no outliers were identified. The relationships in the offset between sensors were then compared to the date/time and the CTD sensor temperature in separate linear regressions. There was a reasonably significant relationship between the offset and the CTD temperature (R 2 = 0.4824; n = 48; F = 42.8786; p = 0.91682 (intercept close to zero) and p < 0.00001 (slope not close to zero)). ).

Applying the regression between the externally mounted CTD temperature sensor and the hull mounted temperature sensor, the calibrated temperature channel data were generated.

Salinity

The SBE45 salinity data were calibrated against bench salinometer data from samples collected from the underway system during the cruise. The data from the SBE45 TSG at the discrete sampling times were compared with the bench salinometer measurements. The salinity offsets (bench - TSG) were plotted against date/time and bench salinity then outliers were identified. The relationships in the offset between TSG and bench salinometer were then compared to bench salinity using a linear regression. The regression of offset against bench salinity was not significant (R 2 = 0.03847; n = 83; F = 3.2407; p = 0.1342 (intercept) and p =0.07555 (slope). The mean of the calculated offsets was then applied as the correction to the TSG salinity channel (offset mean = 0.011; offset SD = 0.008; n = 83).

Applying the mean offset from the bench salinometer - TSG salinity comparison, the calibrated salinity channel data were generated.

Chlorophyll

The fluorometer voltage data were calibrated against extracted chlorophyll-a data from samples collected from the underway system during the cruise. Samples of seawater were collected and extracted chlorophyll-a measurements were made following Welschmeyer (1994). Each 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 then analysed on a pre-calibrated Turner Designs Trilogy fluorometer with a non-acidified chl module (CHL NA #046) fitted.

The raw voltage data from the fluorometer at the discrete sampling times were compared with the extracted chlorophyll-a measurements. The offsets (extracted chl-a - voltage) were plotted against date/time and extracted chlorophyll-a with no outliers identified. There was a significant relationship between the offset and extracted chl-a concentration (R 2 = 0.992; n = 129; F = 15806.76 and p < 0.0001 for both the slope and intercept).

Applying the equation from the extracted chlorophyll-a regression, the calibrated fluorescence channel data were generated.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name JR20131005 (AMT23, JR300)
Departure Date 2013-10-01
Arrival Date 2013-11-11
Principal Scientist(s)Mikhail V Zubkov (National Oceanography Centre, Southampton)
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