Metadata Report for BODC Series Reference Number 1093473

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

DIMES James Cook Cruise JC041 Underway Meteorology Quality Control

Large sections of the cruise track are within Argentine waters and therefore data are unavailable for these time periods; 06/12/2009 4:29 to 07/12/2009 16:19 and 17/12/2009 07:20 to 20/12/2009 09:58.

Caution should be taken when interpreting the TIR results as there is a large consistent offset between the PTIR and STIR values, with the PTIR values being consistently larger than the STIR values. It appears that the PTIR values may be higher than expected for this time of year and latitude, however, it was concluded that the values are not high enough that the data are completely unreliable and therefore have not been flagged. It is possible that the sensor calibrations are the wrong way round but as there is no way of confirming this, the calibrations have remained the same as the information given in the cruise report. Caution should also be taken when interpreting the PAR results as it is also possible that the sensor calibrations are the wrong way round as this was not stated in the cruise report but the most likely calibrations were chosen for each sensor. The PAR and TIR data are also short in length and only span the time period between 04/12/2009 21:54:30 and 09/12/2009 18:13:30.

Caution should be taken when interpreting the absolute wind channels at times when the bestnav gaps have been filled with the POSMVPOS data, as the calculated ship's northward and eastward velocities which contain regular (every 10 mins or so) and large (changes of 100 cm-s) spikes which may be reflected in these channels. The times when absolute wind have been calculated and the navigation have been filled are below:

Start: 2009/12/16 20:27:30 End: 2009/12/16 20:34:29 Duration: 8 minutes
Start: 2009/12/16 20:36:29 End: 2009/12/16 20:36:29 Duration: 1 minute
Start: 2009/12/16 20:38:30 End: 2009/12/16 20:38:30 Duration: 1 minute

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

Gill Instruments Windsonic Anemometer

The Gill Windsonic is a 2-axis ultrasonic wind sensor that monitors wind speed and direction using four transducers. The time taken for an ultrasonic pulse to travel from the North to the South transducers is measured and compared with the time for a pulse to travel from South to North. Travel times between the East and West transducers are similarly compared. The wind speed and direction are calculated from the differences in the times of flight along each axis. This calculation is independent of environmental factors such as temperature.

Specifications

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

Kipp and Zonen Pyranometer Model CM6B

The CM6B pyranometer is intended for routine global solar radiation measurement research on a level surface. The CM6B features a sixty-four thermocouple junction (series connected) sensing element. The sensing element is coated with a highly stable carbon based non-organic coating, which delivers excellent spectral absorption and long term stability characteristics. The sensing element is housed under two concentric fitting Schott K5 glass domes.

Specifications

Skye Instruments PAR Energy Sensor Model SKE 510

The SKE 510 is suitable for measuring photosynthetically active radiation (PAR) from natural or artificial light sources. The sensor is fully waterproof and guaranteed submersible to 4m depth, and indoor versions are also available.

The instrument uses a blue-enhanced planar diffused silicon detector to measure energy (in W m^-2) over the 400-700 nm waveband. It has a cosine-corrected head and a square spectral response. The sensor can operate over a temperature range of -35 to 70 °C and a humidity range of 0-100% RH.

Specifications

Vaisala Analog Barometers Models PTB100 (A), (B) and PTB101 (B), (C)

The PTB 100 series analog barometers are designed both for accurate barometric measurements at room temperature and for general environmental pressure monitoring over a wide temperature range. The long-term stability of the barometer minimizes the need for field adjustment in many applications.

Physical Specifications

The barometers use the BAROCAP^* silicon capacitive absolute pressure sensor developed by Vaisala for barometric pressure measurements. The BAROCAP^* sensor combines the elasticity characteristics and mechanical stability of a single-crystal silicon with the proven capacitive detection principle.

Sensor Specifications

^* BAROCAP is a registered trademark of Vaisala

Vaisala Temperature and Relative Humidity HMP Sensors

A family of sensors and instruments (sensors plus integral displays or loggers) for the measurement of air temperature and relative humidity. All are based on a probe containing a patent (HUMICAP) capacitive thin polymer film capacitanece humidity sensor and a Pt100 platinum resistance thermometer. The probes are available with a wide range of packaging, cabling and interface options all of which have designations of the form HMPnn or HMPnnn such as HMP45 and HMP230. Vaisala sensors are incorporated into weather stations and marketed by Campbell Scientific.

All versions operate at up to 100% humidity. Operating temperature ranges vary between models, allowing users to select the version best suited to their requirements.

Further details can be found in the manufacturer's specification sheets for the HMP 45 series, HMP 70 series and HMP 230 series.

Trimble Applanix Position and Orientation Systems for Marine Vessels (POSMV)

The Position and Orientation Systems for Marine Vessels (POSMV) is a real time kinematic (RTK) and differential global positioning system (DGPS) receiver for marine navigation. It includes an inertial system that provides platform attitude information. The instrument provides accurate location, heading, velocity, attitude, heave, acceleration and angular rate measurements.

There are three models of Applanix POSMV, the POS MV 320, POS MV Elite and the POS MV WaveMaster. POS MV 320 and POS MV WaveMaster are designed for use with multibeam sonar systems, enabling adherence to IHO (International Hydrographic Survey) standards on sonar swath widths of greater than ± 75 degrees under all dynamic conditions. The POS MV Elite offers true heading accuracy without the need for dual GPS installation and has the highest degree of accuracy in motion measurement for marine applications.

Specifications

POS MV 320

POS MV WaveMaster

POS MV Elite

¹ One Sigma, depending on quality of differential corrections
² Whichever is greater, for periods of 20 seconds or less

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

DIMES James Cook Cruise JC041 Underway Meteorology Instrumentation

The meteorology suite of sensors forms part of the NMFD surfmet system and is mounted on the foremast at a height of approximately 17.1 m above the waterline. Parameters measured include wind speed and direction, air temperature, humidity and atmospheric pressure. There were also a pair of optical sensors mounted on gimbals on each side of the ship measuring total irradiance (TIR) and photo-synthetically active radiation (PAR). The gimbals were cleaned at the beginning of the cruise.

Details of these sensors are shown in the table below:

DIMES James Cook Cruise JC041 Underway Meteorology Processing

Originator's Data Processing

Data from the meteorological suite of sensors were logged daily by the onboard logging system (TECHSAS). The data storage method used was NetCDF and pseudo-NMEA (ASCII). The NetCDF data files were manually parsed through an application in order to convert them to RVS format for data processing. Data were transferred from the TECHSAS system to the user Unix area and reformatted into Mstar format NetCDF using NOC-generated Mstar processing scripts on a daily basis. Transfer and formatting was achieved via Matlab. Further details of the originator's data processing is detailed in the cruise report. The following files were submitted to BODC:

Data streams

BODC Data Processing

All Mstar formatted channels, which were 1 minute averaged bins, were reformatted to the internal QXF format (1 min data cycle intervals) via the nearest neighbour method. The ASCII formatted channels of 1 second cycles were also reformatted to the internal QXF format via the nearest neighbour method.

Relative wind speed (ERWSSS01) and direction (ERWDSS01) were corrected for the ship's velocity, to absolute wind speed (EWSBSS01) and absolute direction (EWDASS01) using relative wind speed in m s^-1, relative wind direction, the ship's eastward and northward velocities and the ship's heading. An anemometer orientation correction of 180 degrees was applied.

It was identified that some of the channels in the surfmet ASCII file did not contain the correctly corresponding data. This could have occurred when the data streams were parsed or by the wiring being changed over. The pressure channel actually contained the SPAR data, the SPAR channel contained the STIR data and the humidity channel contained the pressure data. The following tables show how the variables within the files were mapped to appropriate BODC parameter codes:

met Mstar file

surfmet ASCII file

Calibration

The voltages from the TIR and PAR channels were calibrated from volts to W m^-2 using the manufacturer's calibration sheets.
PTIR (port-side) (CVLTRP01) was calibrated using the Kipp and Zoden CM6B 973134 calibration sheet, using the equation: W m^-2= output volts * (1/10.96 x10⁶).
STIR (starboard-side) (CVLTRS01) was calibrated using the Kipp and Zoden CM6B 973135 calibration sheet, using the equation: W m^-2= output volts * (1/11.84 x10⁶).

It was unclear where the PAR Skye SKE 510 sensors where located on the ship (starboard or port-side). Therefore, in order to determine which sensor calibration was the most appropriate to use for each channel, the channels were calibrated using both sensor calibrations. Which manufacturers calibration was chosen for each PAR channel was based upon which resulting calibrated values reflected their corresponding TIR channel the most, i.e. as PAR is about 45% of TIR, where TIR is the largest PAR should be expected to be the largest, and vice versa.

This resulted in PPAR (port-side) (DVLTRPSD) being calibrated using the SKYE 28561 calibration: W m^-2= output volts * (1/10.17 x10⁶), and SPAR (starboard-side) (DVLTRSSD) being calibrated using the sensor SKYE 28562 calibration: W m^-2= output volts * (1/10.86 x10⁶). In order to eliminate shading effect, the two PAR sensor values were merged by taking the greater value out of the port and starboard sensors and the channel DWIRRXMX was created.

All reformatted and calibrated data were visualised using the in-house Edserplo software. Suspect and missing data were marked by adding an appropriate quality control flag.

Project Information

Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) project document

DIMES is a US/UK field program aimed at measuring diapycnal and isopycnal mixing in the Southern Ocean, along the tilting isopycnals of the Antarctic Circumpolar Current.

The Meridional Overturning Circulation (MOC) of the ocean is a critical regulator of the Earth's climate processes. Climate models are highly sensitive to the representation of mixing processes in the southern limb of the MOC, within the Southern Ocean, although the lack of extensive in situ observations of Southern Ocean mixing processes has made evaluation of mixing somewhat difficult. Theories and models of the Southern Ocean circulation have been built on the premise of adiabatic flow in the ocean interior, with diabatic processes confined to the upper-ocean mixed layer. Interior diapycnal mixing has often been assumed to be small, but a few recent studies have suggested that diapycnal mixing might be large in some locations, particularly over rough bathymetry. Depending on its extent, this interior diapycnal mixing could significantly affect the overall energetics and property balances for the Southern Ocean and in turn for the global ocean. The goals of DIMES are to obtain measurements that will help us quantify both along-isopycnal eddy-driven mixing and cross-isopycnal interior mixing.

DIMES includes tracer release, isopycnal following RAFOS floats, microstructure measurements, shearmeter floats, EM-APEX floats, a mooring array in Drake Passage, hydrographic observations, inverse modeling, and analysis of altimetry and numerical model output.

DIMES is sponsored by the National Science Foundation (U.S.), Natural Environment Research Council (U.K) and British Antarctic Survey (U.K.)

For more information please see the official project website at DIMES

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: