Metadata Report for BODC Series Reference Number 1988180

• 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

No Problem Report Found in the Database

Data Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

Scripps Institution of Oceanography ODF (automated) oxygen titrator

A bench-top, oxygen titrator system designed by the Ocean Data Facility (ODF) at the Scripps Institution of Oceanography that is based on the Winkler titration method. It measures dissolved oxygen using photometric end-point detection based on the absorption of 365nm wavelength ultra-violet light. Theosulphate is typically dispensed from a Dosimat burette. The titration and data logging are controlled by ODF PC software compiled in LabView.

Currently no specifications sheet available.

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles and Lever Action bottles have a capacity between 1.7 and 30 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

JR15003 CTD Bottle Oxygen Samples

Originator's Protocol for Data Acquisition and Analysis

Oxygen samples were collected during cruise JR15003 between 6^th and 11^th January 2016. Samples were obtained at 15 stations along the repeat hydrographic section SR1b, over a range of depths. An SBE 911plus CTD unit was used, with 24 Niskin bottles fitted to the rosette sampler.

Samples were collected for dissolved oxygen analyses as the first sample after the rosette was brought on board. Using a Tygon drawing tube, nominal 125 ml volume-calibrated iodine flasks were rinsed three times then filled and allowed to overflow for approximately three flask volumes. The sample draw temperature was measured with a small thermometer embedded in the drawing tube. Reagents (MnCl₂ and NaOH/NaI) were added to fix the oxygen before stoppering. The flasks were shaken twice to assure thorough dispersion of the precipitate, once immediately after drawing, and then again after about 20 minutes. The samples were usually analysed within several hours of collection. Thiosulfate normalities were calculated from each standardisation and corrected to 20°C. The 20°C normalities and the blanks were plotted versus time and were reviewed for possible problems. Oxygens were converted from millilitres per litre to micromoles per kilogram using the sampling draw temperature and the samples salinity.

Dissolved oxygen analyses were performed with a Scripps Oceanographic Data Facility (ODF) designed automated oxygen titrator using photometric end-point detection based on the absorption of 365 nm wavelength ultra-violet light. The titration of the samples and the data logging were controlled by LabView software. Thiosulfate was dispensed by a Dosimat 665 buret driver fitted with a 1.0 ml buret. The ODF method used a wholebottle modified-Winkler titration following the technique of Carpenter (1965) with modifications by Culberson et al. (1991), but with higher concentrations of potassium iodate standard (approximately 0.012N) and thiosulfate solution (55 g/l). Standard KIO₃ solutions prepared ashore were run at the beginning of each run. Potassium iodate was reported by the supplier to be >99.4% pure. Reagent and distilled water blanks were determined, to account for presence of oxidising or reducing materials.

Oxygen flask volumes were determined gravimetrically with degassed deionised water to determine flask volumes at ODFs chemistry laboratory. This was done once before using flasks for the first time and periodically thereafter when a suspect bottle volume was detected. The volumetric flasks used in preparing standards were volume-calibrated by the same method, as was the 10 ml Dosimat buret used to dispense standard iodate solution.

Originator's Data Processing Procedures

After temperature and conductivity calibrations were applied, oxygen was converted from µmol/L to µmol/kg using the Mstar software suite written in MATLAB. Bottle and sensor values were also compared using an Mstar script. 166 bottles were analysed for oxygen, but 2 of the comparisons were flagged as questionable. The calibration function obtained by least-squares fitting to the bottle data, and applied by oxy apply cal, was O_cal = O₀ (1.0603 + 0.0005N) + (1.0384 + 0.0007P), where O₀ is the uncalibrated CTD oxygen, N is the station number (1 to 31), and P is pressure. For more information please see the cruise report.

BODC Data Processing Procedures

The oxygen data were supplied to BODC in .csv format. Data were then loaded into BODC's database using established BODC data banking procedures.

The originator's variable was mapped to the appropriate BODC parameter code as follows:

Data Quality Report

The BODC flag 'L' was applied to improbable data which were flagged as such by the originator.

The originator indicated that bottle 8 on CTD08, 10 on CTD15 and 10 on CTD16 were leaking, but did not indicate problems with the oxygen data obtained from these bottles.

References

Carpenter J.H. 1965. The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method. Limnology and Oceanography, 10, 141-143.

Culberson C.H., Knapp G., Stalcup M., Williams R.T. and Zemlyak F., 1991. A comparison of methods for the determination of dissolved oxygen in seawater. WOCE Hydrographic Programme Office, Report 73/91.

Project Information

NOCS National Capability

The National Oceanography Centre Southampton National Capability focuses on long term science concerned with basin/decadal variability of the Ocean.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JR15003_CTD_CTD20

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

World Ocean Circulation Experiment (WOCE) Southern Repeat Section 1B - Falkland Islands to Elephant Island

WOCE Southern Repeat Section 1B is a section across Drake Passage in the South Atlantic Ocean. The nominal end points of the section (to date) are at 52° 55.74' S, 58° 00.00' W (at the south of the Falkland Islands) and 61° 03.05' S, 54° 33.10' W (off Elephant Island at the north end of the Antarctic Peninsula).

The section was first occupied by the R/V Polarstern in 1992 (Gersonde, 1993). The first UK occupation of SR1b followed on RRS Discovery later the same year. The National Oceanography Centre, Southampton (formerly known as Southampton Oceanography Centre), in collaboration with the British Antarctic Survey, have occupied the section most years since 1993 on the RRS James Clark Ross. Additionally, there were three Spanish occupations on R/V Hespérides in February 1995, 1996 and 1998 (Garcia et al., 2002). A Drake Passage summary report for RRS James Clark Ross cruises between 1993 - 2000 has been produced.

A table of cruises which occupied SR1b is presented below with links to the relevant cruise reports (were available).

References

García, M. A., I. Bladé, A. Cruzado, Z. Velásquez, H. García, J. Puigdefàbregas and J. Sospedra, 2002: Observed variability of water properties and transports on the World Ocean Circulation Experiment SR1b section across the Antarctic Circumpolar Current. J. Geophys. Res. 107 (C10) 3162, 10.1029/2000JC000277.

Gersonde, R., 1993: The Expedition Antarktis X/5 of RV Polarstern in 1992. Berichte zur Polarforschung, 131, 167 pp.

Related Fixed Station activities are detailed in Appendix 2

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:

Appendix 1: JR15003_CTD_CTD20

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Appendix 2: Drake Passage - WOCE SR1b

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.