Metadata Report for BODC Series Reference Number 2047149

• 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

Problem Reports

Attenuation

The attenuation (ATTNDR01) channel is of poor quality and the entire series has been flagged. There are numerous spikes within the series and the signal arbitrarily tails off between periods where the non-toxic supply has been switched off for cleaning. Algal growth was an issue affecting the transmissometer during JC112 and is likely the reason why the signal arbitrarily declined after each sensor cleaning and it is not clear which are the good data (BODC assessment).

Transmittance

The transmittance (POPTDR01) channel is of poor quality and the entire series has been flagged. There are numerous spikes within the series and the signal arbitrarily tails off between periods where the non-toxic supply has been switched off for cleaning. Algal growth was an issue affecting the transmissometer during JC112 and is likely the reason why the signal arbitrarily declined after each sensor cleaning and it is not clear which are the good data (BODC assessment).

JC112 Surface Hydrography Quality Control Report

Each of the surface hydrography channels had flags applied to the four occasions where the thermo-salinograph logging system had crashed and to the periods where the system was being cleaned.

Fluorescence

The fluorescence (CPHLUMTF) data are of moderate quality. There is an extended period where algal growth was affecting the sensor between 14/12/2014 and 22/12/2014. In addition, some anomalous spikes were observed. These were all flagged accordingly.

SST and housing temperature, conductivity and salinity

The housing temperature (TMESSG01) readings are slightly (~0.15°C) warmer than the remote temperature (TEMPHU01) values and features a ~4 minute delay. Both channels are quite consistent overall. However, there is some short periods of discontinuity that looks like saturation peaks in the TMESSG01 channel. M flags were applied to these. The conductivity (CNDCSG01) and (PSALSU01) also look to be of good quality and no additional flags have been applied to these.

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

JC112 Underway Document

Cruise Details

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

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:

All models:

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

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

JC112 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:

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

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

JC112 Surface Hydrography Data Processing Procedures

Originator's Data Processing

The data were logged by the TECHSAS (TECHnical and Scientific sensors Acquisition System) data logging system into daily NetCDF files which were provided to BODC for processing. Data was additionally logged into the RVS Level-C format which have been archived at BODC.

Files delivered to BODC

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:

yyyymmdd-000000-Surf-JC-SM_JC1.SURFMETv2

yyyymmdd-000000-SBE45-SBE45_JC1.TSG

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 = 0.060 V, Vref = 4.625 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 = 6.2 µg/L/V and CWO = 0.070 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

Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR)

Background

The cooling of young oceanic crust is the main physical process responsible for removing heat from the solid Earth to the hydrosphere. Close to the mid-ocean ridge rapid cooling is dominated by hydrothermal circulation of seawater through the porous and fractured basalt crust. This hydrothermal fluid is then discharged into the ocean mainly along the ridge. Once in the ocean, released heated seawater mixes with the ambient cold water to form a plume, which provides a mechanism to lift the densest waters away from the bottom boundary layer. These waters are then more readily available for further mixing and heating as part of the global thermohaline circulation system.

The data collected as part of the interdisciplinary OSCAR project will be used to investigate the effects of heat loss and hydrothermal circulation in both the solid Earth and the ocean.

The aim is to:

1. Characterise how heat from the interior of the Earth is transported across the crust into the ocean by hydrothermal flows
2. Determine the impact the hydrothermal and geothermal fluxes have on the circulation of the abyssal ocean and on the evolution of the oceanic crust.

With this aim, the data will be used to derive a new integrated model of the ocean and hydrothermal circulations at active ocean ridges and ridge flanks. The model will be constrained by geophysical, geological, and physical oceanography data and include fluxes through a permeable seabed. These data and resultant models will set a new benchmark for integrated multi-physics experiments. They will result in a new understanding of the fluid and heat fluxes at ocean ridges and a better understanding of what geophysical and oceanographic data actually resolve in the context of an oceanic axial ridge setting. The result is also a predictive model that can be applied to similar ocean ridge systems world-wide.

Fieldwork

Data collection took place in the Panama Basin, bounded in the north-west by the Cocos Ridge, by the Carnegie Ridge in the south and by South and Central America in the east and north, respectively. Measurements were collected during RRS James Cook cruises JC112 and JC113 (05/12/2014 to 16/01/2015), RRS James Cook cruise JC114 (22/01/2015 to 08/03/2015) and RV Sonne cruise SO328 (06/02/2015 to 06/03/2015). Data were collected using Bottom Pressure Recorder, Acoustic Doppler Current Profiler (ADCP), Magnetotelluric Lander, CTD, Vertical Microstructure Profiler, Synthetic Aperture Radar, Ocean-bottom seismograph and Multibeam echosounder. Measurement of salinity, oxygen and helium were also made and zooplankton samples collected with vertical net casts.

Participants

• Professor Richard W Hobbs (Principal Investigator - Parent Grant) Durham University
• Professor Christine Peirce (Co-Investigator) Durham University
• Professor Christopher J Ballentine (Co-Investigator) University of Oxford
• Professor Joanna V Morgan (Co-Investigator) Imperial College London
• Dr Miguel Morales Maqueda (Principal Investigator - Child Grant) Newcastle University
• Dr David A Smeed (Co-Investigator - Child Grant) National Oceanography Centre
• Dr Vincent CH Tong (Principal Investigator - Child Grant) Birkbeck College

Funding

This project was funded by Natural Environment Research Council parent grant NE/I027010/1 and child grants NE/I022868/1, NE/I022868/2, NE/I022957/1, and NE/I022957/2, entitled 'OSCAR - Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge', with the former, parent grant led by Professor Richard W Hobbs, Durham University, and the latter child grants led by Dr Miguel Morales Maqueda, Newcastle University and Dr Vincent CH Tong, Birkbeck College.

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: