Metadata Report for BODC Series Reference Number 1009814

• 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

Neil Brown MK3 CTD

The Neil Brown MK3 conductivity-temperature-depth (CTD) profiler consists of an integral unit containing pressure, temperature and conductivity sensors with an optional dissolved oxygen sensor in a pressure-hardened casing. The most widely used variant in the 1980s and 1990s was the MK3B. An upgrade to this, the MK3C, was developed to meet the requirements of the WOCE project.

The MK3C includes a low hysteresis, titanium strain gauge pressure transducer. The transducer temperature is measured separately, allowing correction for the effects of temperature on pressure measurements. The MK3C conductivity cell features a free flow, internal field design that eliminates ducted pumping and is not affected by external metallic objects such as guard cages and external sensors.

Additional optional sensors include pH and a pressure-temperature fluorometer. The instrument is no longer in production, but is supported (repair and calibration) by General Oceanics.

Specifications

These specification apply to the MK3C version.

Further details can be found in the specification sheet.

RRS James Clark Ross 0A CTD Data Documentation

Introduction

CTD profile data are presented from the cruise James Clark Ross 0A in the Drake Passage (WOCE SR1 Section), as reported by King & Alderson et al. (1994).

Instrumentation and Methodology

Instrumentation Summary

The CTD profiles were taken with a Neil Brown Systems MkIII CTD mounted beneath a bottle rosette. The CTD was fitted with a pressure sensor, conductivity cell, platinum resistance thermometer, and a 10 kHz pinger. No oxygen sensor, fluorometer or transmissometer were attached to the CTD.

Data Acquisition

Lowering rates for the CTD package were generally in the range 0.5-1.0ms^-1 but could be up to 1.5ms^-1. CTD data were logged at 8 frames per second. The CTD deck unit passes raw data to a dedicated Level A microcomputer where 1 second averages are assembled. During this process the Level A calculates the rate of change of temperature and a median sorting routine detects and removes pressure spikes. These data are sent to the Level B for archival. The data are then passed to a Level C workstation for conversion to Pstar format and calibration.

A total of 39 stations were occupied (CTD01 - CTD39). Drake Passage stations for this cruise were CTD02 - CTD31.

Data Processing

The 1 second data passed to the Level C were converted to Pstar format and initially calibrated with coefficients from laboratory calibrations followed by a number of calibration corrections. The up cast data were extracted for merging with the bottle firing codes, on time, thus the CTD variables were reconciled with the bottle samples. Final calibrations were applied using the sample bottle data. Finally, down cast data were extracted, sorted on pressure and averaged to 2db values, with any gaps filled by linear interpolation.

The data were worked up to WOCE standards by the data originators before being supplied to BODC.

BODC Data Processing

No further calibrations were applied to the data received by BODC. BODC were mainly concerned with the screening and banking of the data.

The CTD data were received as 2db averaged pressure sorted down cast data. Parameters were pressure (dbar), temperature (its-90) and salinity (pss-78).

The data were converted into the BODC internal format (PXF) to allow the use of in-house software tools, notably the graphics editor. Spikes in the data were manually flagged 'suspect' by modification of the associated quality control flag. In this way none of the original data values were edited or deleted during quality control. Very little flagging was required for these data. Once screened, the CTD data were loaded into a database under the Oracle relational database management system. The start time stored in the database is the CTD deployment time, and the end time is the time the CTD was removed from the water. Actually these times are more precisely the start and end of data logging. Latitude and longitude are the mean positions between the start and end times calculated from the master navigation in the binary merged file.

References

King, B.A. & Alderson, S.G. et al. (1994). RRS James Clark Ross, WOCE SR1 in Drake Passage. Southampton Oceanography Centre. Unpublished Cruise Report.

Project Information

World Ocean Circulation Experiment (WOCE)

The World Ocean Circulation Experiment (WOCE) was a major international experiment which made measurements and undertook modelling studies of the deep oceans in order to provide a much improved understanding of the role of ocean circulation in changing and ameliorating the Earth's climate.

WOCE had two major goals:

• Goal 1. To develop models to predict climate and to collect the data necessary to test them.

• Goal 2. To determine the representativeness of the Goal 1 observations and to deduce cost effective means of determining long-term changes in ocean circulation.

UK WOCE

The UK made a substantial contribution to the international World Ocean Circulation Experiment (WOCE) project by focusing on two important regions:

1. Southern Ocean - links all the worlds oceans, controlling global climate.
2. North Atlantic - directly affects the climate of Europe.

A major part of the UK effort was in the Southern Ocean and work included:

• Two surveys, in the South Atlantic as part of the WOCE Hydrographic Programme.
• SWINDEX, a year long study of the Antarctic Circumpolar Current (ACC) where it crosses major topography south of Africa.
• ADOX, a study of deep water flow from the Atlantic to the Indian Ocean.
• ACCLAIM, a study of the ACC by altimetry and island measurements.

In the North Atlantic the UK undertook:

• NATRE, a purposeful tracer experiment to look at cross isopycnic processes.
• CONVEX, a study of the deep ocean circulation and its changes.
• VIVALDI, a seven year programme of seasonally repeated surveys to study the upper ocean.
• Long-term observations of ocean climate in the North West Approaches.

Satellite ocean surface topography, temperature and wind data were merged with in situ observations and models to create a complete description of ocean circulation, eddy motion and the way the ocean is driven by the atmosphere.

The surveys were forerunners to the international Global Ocean Observing System (GOOS). GOOS was later established to monitor annual to decadal changes in ocean circulation and heat storage which are vital in the prediction of climate change.

Data Activity or Cruise Information

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 1

Fixed Station Information

Drake Passage

The World Ocean Circulation Experiment (WOCE, 1990-1998) was a major international experiment which made measurements and undertook modelling studies of the deep oceans in order to provide a much improved understanding of the role of ocean circulation in changing and ameliorating the Earth's climate.

The Drake Passage is the narrowest constriction of the Antarctic Circumpolar Current (ACC) - the largest current in the world and connects all three major oceanic basins both horizontally and vertically, thus being a key control in the global overturning circulation.Within the Drake Passage, two repeat hydrographic sections (SR1 and SR1b) were established by WOCE. These were designed to extend measurements collected earlier by the International Southern Ocean Studies (ISOS) programme and have continued beyond the WOCE time-frame.

The original section was SR1 (which also covers part of the A21 one time survey track). Subsequently, the section was shifted to the east (and designated SR1b) in order for it to lie on a satellite ground track as illustrated in the image below.

In addition to the hydrographic measurements, UK research in Drake Passage also includes a network of coastal and deep tide gauges, analysis of satellite altimeter data, and state-of-the-art global numerical modeling.

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: 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.

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