Metadata Report for BODC Series Reference Number 2058461
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
Throughout the cruise, the fluorometer primarily returned negative values (once a manufacturer's calibraiton had been applied). While peaks in fluorometry potentially correspond with when the ship was in regions of higher productivity, fluorometry values return to negative following cleaning events (BODC assessment during screening). The data should therefore be used with caution.
The attenuation channel was subject to a lot of noise between cleaning events, particularly following the ship docking in Luanda, Angola between 13th and 15th September 2019. This is likely due to trapped bubbles in the system when the ship's flowthrough system was turned back on (as indicated by the Scientific Ship Systems Cruise Report). It cannot be said with confidence which data are good, therefore they should be used with caution.
The transmittance channel was subject to a lot of noise between cleaning events, particularly following the ship docking in Luanda, Angola between 13th and 15th September 2019. This is likely due to trapped bubbles in the system when the ship's flowthrough system was turned back on (as indicated by the Scientific Ship Systems Cruise Report). It cannot be said with confidence which data are good, therefore they should be used with caution.
RRS James Cook cruise JC187 sea surface hydrography quality control report
Sea surface temperature
Throughout the cruise, the housing temperature readings (TMESSG01) are slightly (~0.2°C) warmer than the remote temperature readings (TEMPHU01). Additionally, there is a five minute delay between the two. These channels should therefore be treated 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
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 |
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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 James Cook cruise JC187 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 Fluorometer | WETStar | WS3S-246 | 13/06/2019 | |
WETLabs Transmissometer | C-Star | CST-112R | 14/06/2019 | 25 cm pathlength |
Sea-Bird Temperature sensor | SBE 38 | 0475 | 14/06/2019 | |
Sea-Bird Thermosalinograph | SBE 45 | 0229 | 02/08/2018 |
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 James Cook cruise JC187 surface hydrography data processing procedures
Originator's Data Processing
The data were logged by the TECHSAS (TECHnical and Scientific sensors Acquisition System) version 5.11 data logging system which is the main data logging system on NMF-SS operated research vessels. Data were processed using the National Oceanography Centre data processing routines into daily NetCDF files, and these TECHSAS (NetCDF) sea surface hydrography files provided to BODC were used for BODC processing. Please refer to the cruise report for more information.
File delivered to BODC
Filename | Content description | Format | Interval | Start date/time (UTC) | End date/time (UTC) | Comments |
*-*-SBE45-SBE45.TSG | Housing temperature, conductivity, salinity, and remote temperature | NetCDF | 1 hz | 29-Aug-2019 16:28:16 | 04-Oct-2019 14:37:37 | - |
*-*-Surf-SURFMETv3.SURFMETv3 | Fluorometry, transmissivity, flow rate | NetCDF | 1 hz | 29-Aug-2019 16:28:15 | 07-Oct-2019 09:41:18 | - |
BODC Data Processing
The files were reformatted to BODC internal format using standard data banking procedures. The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:
*-*-SBE45-SBE45.TSG
Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
temp_h | °C | Temperature (housing) | TMESSG01 | °C | N/A | - |
cond | s/m | Conductivity | CNDCSG01 | s/m | N/A | - |
salin | psu | Salinity | PSALSU01 | dimensionless | N/A | - |
temp_r | °C | Temperature (remote) | TEMPHU01 | °C | N/A | - |
*-*-Surf-SURFMETv3.SURFMETv3
Originator's variable | Originator's units | Description | BODC Code | BODC Units | Unit conversion | Comments |
trans | volts | Transmissometer raw output | TVLTZZ01 | volts | N/A | - |
fluo | volts | Fluorometer raw output | FVLTWS01 | volts | N/A | - |
flow | l/min | Flow meter | INFLTF01 | l/min | N/A | - |
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
No field calibrations have been applied to the data.
Manufacturers Calibrations
Transmissometer
The transmissometer voltage channel was converted to beam transmittance (beamtrans) and beam attenuation (atten) as follows:
beamtrans [%] = ([Volts - Vdark] / [Vref - Vdark])*100
atten [per m] = (-1/pathlength) * ln(beamtrans)
where Vdark = 0.057 V, Vref = 4.66 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 = 14.9 µg/L/V and CWO = 0.061 V.
Screening
All reformatted data were visualised using the in-house EDSERPLO software. Where calibrations had been applied, only the calibrated versions of those parameters were screened. Suspect data were marked by adding an appropriate quality control flag.
Project Information
How do deep-ocean turbidity currents behave that form the largest sediment accumulations on Earth?
Background
Seafloor flows called turbidity currents form the largest sediment accumulations on Earth (submarine fans). They flush globally significant amounts of sediment, organic carbon, nutrients and fresher-water into the deep ocean, and affect its oxygen levels. Only rivers transport comparable volumes of sediment across such large expanses of our planet, although a single turbidity current can transport more sediment than the combined annual flux from all of the World's rivers combined. This project aimed to improve understanding of turbidity currents, and their wider impacts, by making the first detailed measurements of turbidity currents that runout into the deep (2-5 km) ocean. This project followed recent successful tests of new methods and technology for measuring turbidity currents in shallower (less than 2 km) water, which can now be applied to deep-water, large-scale submarine fan settings. Such measurements at 2 km water depth are the deepest yet for turbidity currents. Surprisingly, they showed that individual turbidity currents lasted for almost a week, and occupied 20% of the time. This was surprising because all previously measured oceanic turbidity currents lasted for just a few hours or minutes, and occurred for <0.1% of the total time. It suggests that turbidity currents that runout into the deep ocean to form major submarine fans may differ from their shallow water cousins in key regards. Preliminary measurements from 2010 and 2013 showed how monitoring is feasible for the study area here, the Congo Canyon off West Africa. The overall aim was to show how deep-sea turbidity current behave using the first direct measurements, and understand causes and wider implications of this behaviour.
This project set out to answer the following key questions about flow behaviour:
- What controls flow duration, and does flow stretching cause near-continuous canyon flushing? We will test a new hypothesis that predicts flows will stretch dramatically as a 'hot spot' of faster moving fluid runs away from the rest of the event, thereby producing near-continuous flushing of submarine canyons.
- What controls runout and whether flows become more powerful? We will test whether turbidity currents tend towards one of two distinct modes of behaviour, in which they erode and accelerate (a process termed ignition), or deposit sediment and dissipate.
- How is flow behaviour and character recorded by deposits? This is important because deposits are the only record of most turbidity currents.
- How does flow behaviour affect the transfer and burial of terrestrial organic carbon in the deep-sea? It was proposed recently that burial of terrestrial organic carbon in the deep sea is very efficient, and an important control on long-term atmospheric CO2 levels. This hypothesis implies little fractionation of terrestrial organic carbon occurs during submarine transport. Composition of organic carbon buried by the offshore flows is similar to that supplied by the river. We will test this hypothesis by analysing amounts and types of organic carbon along the offshore pathway in both flows and deposits.
Fieldwork
Data were collected on James Cook cruise JC187 between August and October 2019. Eight moorings were deployed along the Congo Canyon at warer depths of 2 to 5 km to measure frequency, duration, and run-out distance of multiple flows; together with their velocity, turbulence and sediment concentration structures; as well as changes in water, sediment and organic carbon discharge.
Participants
- Professor Peter Talling (Principal Investigator - Parent Grant) Durham University
- Dr Mattieu Cartigny (Co-Investigator) Durham University
- Professor Robert Hilton (Co-Investigator) Durham University
- Professor Jim McElwaine (Co-Investigator) Durham University
- Professor Daniel Parsons (Principal Investigator - Child Grant) University of Hull
Funding
This project was funded by Natural Environment Research Council parent and child grants NE/R001952/1 and NE/R001960/1, entitled 'How do deep-ocean turbidity currents behave that form the largest sediment accumulations on Earth?', with the former, parent grant led by Professor Peter Talling, Durham University, and the latter child grant led by Professor Daniel Parsons, University of Hull.
Data Activity or Cruise Information
Cruise
Cruise Name | JC187 |
Departure Date | 2019-08-31 |
Arrival Date | 2019-10-07 |
Principal Scientist(s) | Peter J Talling (University of Durham Department of Geography) |
Ship | RRS James Cook |
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 |