Metadata Report for BODC Series Reference Number 1817085
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
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Problem Reports
Very spiky throughout the cruise with exhibited decrease trend. Looks to be evidence of trapped bubbles. All values have been flagged. (BODC assessment)
Transmissometer channel very spiky throughout the cruise with exhibited decrease trend. Looks to be evidence of trapped bubbles. All calibrated channels have been flagged as well. (BODC assessment)
Transmissometer channel very spiky throughout the cruise with exhibited decrease trend. Looks to be evidence of trapped bubbles. All calibrated channels have been flagged as well. (BODC assessment)
RRS Discovery cruise DY078 surface hydrography quality control report
General comments
The non-toxic, pumped seawater supply was not switched on until 13:30 on 06/05/2017.
All channels were flagged when the pump for the non-toxic supply was temporarily switched off between 14:00 to 14:15 on 15/05/2017.
Flags were also added a few minutes after the non-toxic supply was turned on. (BODC assessment)
RRS Discovery Surface Hydrography Quality Control Report
Sea Surface Temperature
The remote underway sea surface temperature data readings have been found to display a consistent variable offset when compared to CTD temperature readings at the same depth. As this is a general occurance, the remote underway temperature data should be used with caution if they have not been calibrated against in situ CTD temperature values.
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.
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.
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.
RRS Discovery DY078 Surface Hydrography Instrumentation
Instrumentation
The sea surface hydrographical suite of sensors was fed by the pumped-seawater, non-toxic supply. The depth of the seawater intake was at 5.5 m.
The following surface hydrology sensors were fitted:
| Manufacturer | Model | Serial number | Last manufacturer's calibration date | Comments |
| WETLabs Fluorimeter | WETStar | WS3S-247 | 14/04/2017 | |
| WETLabs Transmissometer | C-Star | CST-1131PR | 12/04/2016 | 25 cm pathlength |
| Sea-Bird Temperature sensor | SBE38 | 3854115-0489 | 28/08/2016 | |
| Sea-Bird | SBE45 TSG | 4548881-0233 | 28/07/2016 |
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:
- Polled sampling: the instrument takes one sample on command
- Autonomous sampling: the instrument samples at preprogrammed intervals and does not enter quiescence (sleep) state between samples
- Serial Line Sync: a pulse on the serial line causes the instrument to wake up, sample and re-enter quiescent state automatically
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 Discovery DY078 Surface Hydrography processing procedures
Originator's Data Processing
Thermosalinograph (TSG, SurfTSG)
The daily processing creates two sets of raw files and two concatenated cruise master files related to the underway thermosalinograph (TSG) stream. The surftsg steam doe not log the actual temperatures (temp_h and temp_m) or conductivity (cond). These data streams are logged as constant values.
The TSG stream contains the logged temperatures, conductivity, and derived salinity from the TSG. The salinity values were recalculated from the housing temperature and conductivity (using mtsg_make_sal.m) to confirm that the salinity values stored in the files was reliable and the conductivity units (S/m) as reported in the netCDF attributes.
Calibration of TSG salinity:
1) Edit mtsg_cleanup.m to hardcode the times when the pumps were switched of, such as the stat and end of the cruise, and any periods of the maintenance. This routine will be run later as part of mtsg_medav_clean_sal.m.
2) Run mcd('M_TSG') to move to the TSG directory within Matlab.
3) Run mtsg_findbad_dy078.m to interactively remove spikes and bad data from the temp_h, cond and salin variables. The commands to select periods to be marked as bad are explained on running the routine. Note the use of 'n' to store the start and end of the bad data and move on to the next segment. The output file with bad times is appended every time this routine is run, so can be done throughout the cruise.
Input: data/tsg/tsg_dy078_01.nc Output: data/tsg/bad_time_limits.mat
4) Run mtsg_medav_clean_cal_dy078.m to create 1-minute median-binned data and remove known bad data identified in the previous step (the times stored in bad_time_limits.mat).
Input: data/tsg/tsg_dy078_01.nc Output: data/tsg/tsg_dy078_01_medav_clean.nc
5) Check for updates to the TSG salinity bottle samples, in data/ctd/BOTTLE_SAL/.
6) Run mtsg_01_dy078.m to convert TSG salinity bottle samples from ASCII to NetCDF. First the routine had to be updated with a cruise specific bath temperature. For DY078, the same settings were used as had been agreed for the CTD salt sample processing. This step can be run as each TSG crate has been processed.
Input: data/ctd/BOTTLE_SAL/tsg_dy078_nnn.csv_linux Output: data/ctd/tsg_dy078_nnn.nc Output: data/ctd/tsg_dy078_all.nc
7) Run mtsg_bottle_compare_dy078.m to merge the clean 1-minute data onto bottle samples. This should first be run with the switch at the top of the script set to uncalibrated. Individual bottle residuals are plotted, as well as a smoothed time series of the residuals.
Input: data/ctd/tsg_dy078_01_medav_clean_cal.nc Output: data/tsg/tsg_dy078_01_medav_clean_cal_botcompare.nc
8) Run mtsg_apply_salcal_dy078.m to smooth the differences in botcompare, interpolates and adds them to the uncalibrated salinity data.
Input: data/met/surftsg/met_tsg_dy078_01_medav_clean.nc Input: data/met/surftsg/met_tsg_dy078_01_medav_clean_botcompare.nc Output: data/met/surftsg/met_tsg_dy078_medav_clean_cal.nc
9) Rerun mtsg_bottle_compare_dy078.m to merge the clean 1-minute data onto bottle samples. This should now be run with the switch at the top of the script set to calibrated.
10) Run met_tsg_av_addnav_dy078.m to merge with navigation data (lat and long) on variable time. Run mbest_all.m prior to this to update the best navigation file bst_dy078_01.nc.
Input: data/tsg/tsg_dy078_01_medav_clean_cal.nc Input: data/nav/posmvpos/bst_dy078_01.nc Output: data/tsg/tsg_dy078_medav_clean_cal_nav.nc (final file)
The daily Mstar Thermosalinograph files provided to BODC were used for BODC processing. Data were additionally logged into the RVS Level-C format files and TECHSAS which have been archived at BODC.
For more detailed information on the Originator's underway data processing, please see the cruise report, p64-73.
Files delivered to BODC
| Filename | Content description | Format | Interval | Start date/time (UTC) | End date/time (UTC) | Comments |
| met_tsg_dy078_01.nc | Fluorescence and transmittance | Mstar | 1 sec. | 06/05/2017 00:00:00 | 26/05/2017 23:59:58 | |
| tsg_dy078_01_medav_clean_cal_nav.nc | Housing Temperature, remote temperature, salinity and conductivity | Mstar | 60 seconds. | 06/05/2017 00:00:00 | 27/05/2017 00:00:00 |
BODC Data Processing
The files were reformatted to BODC internal format using standard data banking procedures. All files were averaged to 60 second intervals. The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:
met_tsg_dy078_01.nc
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| trans | volts | Raw voltage measured by transmissometer | TVLTDR01 | volts | none | |
| temp_h | degrees celcius | Housing water temperature | Not transferred | |||
| fluo | volt | Raw voltage measured by fluorometer | FVLTWS01 | volt | none | |
| temp_m | degrees celcius | Remote temperature | Not transferred | |||
| cond | s/m | Conductivity | Not transferred | |||
| time | seconds since 01/01/2017 | Measure timestamp | Not transferred |
tsg_dy078_01_medav_clean_cal_nav.nc
| Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
| salin | dimensionless | TSG salinity | Not transferred | |||
| salin_cal | pss-78 | TSG salinity calibrated | PSALSG01 | dimensionless | none | Not transferred |
| temp_h | degrees celcius | Housing water temperature | TMESSG01 | degrees celcius | none | |
| sndspeed | m/s | TSG sound velocity | Not transferred | |||
| cond | s/m | Conductivity | CNDCSG01 | s/m | none | |
| temp_r | degrees celcius | Remote water temperature | TEMPHU01 | degrees celcius | none | |
| time | seconds since 01/01/2017 | Measure timestamp | Not transferred |
Screening
All the reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag.
Calibration
Field Calibrations
Salinity was calibrated as described in the originators processing section above.
Manufacturers Calibrations
Transmissometer
The transmissometer voltage channel was converted to beam transmission ( beamtrans ) and beam attenuation ( atten ) as follows:
beamtrans [%] = ([ volts - Vdark ] / [ Vref - Vdark ])100
atten [per m] = (-1/ pathlength ) ln( beamtrans /100)
where Vdark = 0.058 V, Vref = 4.668 V and pathlength = 0.25 m.
Fluorometer
The fluorescence voltage channel was converted to engineering units ( chla ) using the following calibration:
chla [µg/L]= SF ( volts - CWO )
where SF = 6 µg/L/V and CWO = 0.049 V.
Project Information
UK - Overturning in the Subpolar North Atlantic Programme (UK-OSNAP) Programme
UK-OSNAP is part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic. The aim is to quantify and understand the Subpolar Gyre's response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the Atlantic Meridional Overturning Circulation (AMOC).
UK-OSNAP is developing a new observing system to provide a continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes. Combining these sustained measurements with innovative modelling techniques will enable the project to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre.
UK-OSNAP is funded by the Natural Environment Research Council (NERC). The project is led by the National Oceanography Centre (NOC) with partners in the University of Liverpool, the University of Oxford and the Scottish Association for Marine Science (SAMS). It is a part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project involves fieldwork at sea and model studies.
The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.
NERC have added an extension to UK-OSNAP, until October 2024. This will result in the UK-OSNAP-Decade: 10 years of observing and understanding the overturning circulation in the subpolar North Atlantic (2014-2024).
Data Activity or Cruise Information
Cruise
| Cruise Name | DY078 (DY079) |
| Departure Date | 2017-05-06 |
| Arrival Date | 2017-05-28 |
| Principal Scientist(s) | N Penny Holliday (National Oceanography Centre, Southampton) |
| 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 |
| B | nominal value |
| Q | value below limit of quantification |
