The ODF data team originated from the intensive demands of the WOCE Hydrographic Program and continues with our management of GO-SHIP and other hydrographic programs. Our team has developed on-board processes to ensure the highest quality of hydrographic and CTD data.
To attain our high standards, we employ the following:
- Shipboard Website and Data Server
ODF runs a website on the ship's intranet that streamlines data distribution, data submission, and communication among the science party using the following features:
- The front page contains a dashboard with estimated time of arrival while in-transit to the next station and a real-time track map.
- While on-station, this widget displays and periodically refreshes the current wire-out, allowing scientists to see the current status of the cast from their workstations or bunks.
- Preliminary processed sensor data, such as CTD salinity, is available immediately after the cast has completed.
- Analysts can submit data through the website after discrete water samples have been processed, which automatically validates and merges data into a relational database.
- Data Quality Control
Beginning with the selection of instruments and sensors to be used for data acquisition, ODF data technicians evaluate each detail that will result in the best possible hydrographic data. Data are reviewed and processed shipboard whenever possible, and corrected as necessary to meet or exceed established data standards.
The following conditions / problems can affect data that we collect/process:
- Manufacturer / model no. / serial no. of each sensor and CTD deployed
- Sensor calibration dates, drift between calibrations, and damage / repair history
- Equipment problems, ship-board repairs, change-outs (winch / wire, rosette / carousel, deck unit, CTD, sensors)
- Storage of rosette between casts ideally out of wind / sunlight, similar temperature to outside air
- Software / hardware problems and bugs during acquisition and processing
- Potential freezing issues in sub-zero air temperatures
- Organic matter contamination causing sensor noise or offsets (jellyfish, etc.)
- Sea state - rough seas can cause:
- Collision of rosette / instruments with ship at deployment or recovery
- Lack of proper equilibration time for CTD / sensors at cast start
- Misleading density inversions caused by rosette agitating / mixing water
- Stress / kinks in wire (signal problems, wire breakage / loss of package)
- Electrical problems - shorts caused by water leakage can cause:
- Signal spiking from intermittent bad connections
- Loss of power or signal (sensors, CTD, cabling between sensors and CTD, carousel, wire, slip-rings, deck unit, computer)
- Bottle data: mis-trips or collection errors, analysis or calibration problems
Once issues have been documented, problems are fixed where possible and data are corrected.
- De-spike / offset data by linear interpolation through nearby values
- Use upcast instead of downcast data if problems are not correctable
- Apply polynomial corrections using fits of differences between:
- bottle and CTD values
- primary and secondary sensors
as a function of:
- Time / station
- Temperature / conductivity
With corrections applied, data quality is evaluated by comparing:
- Pre- and post-cruise calibrations - considering:
- Equipment mis-handling or damage during cruise or shipment
- Observed sensor shifts during cruise
- Historical drift tendencies in sensor calibrations
- Down and up profiles of same cast
- Data from nearby casts
- Cruise data with historical data
Quality Control Links
- Data Processing
ODF uses data processing software and techniques that were developed internally and provide exceptional fitting of CTD and hydrographic data. The software is regularly updated to take full advantage of the latest coding standards and improvements. Processing is performed continually on-board by ODF personnel, allowing for real-time quality control and timely delivery of data.
The software is all-encompassing with the ability to process raw data, perform quality control with automated data flagging, easily visualize the finalized data, and export to netCDF using standardized conventions. Users have the ability to get the highest quality data out of their measurements.
For quotes and/or additional information please contact Susan Becker.
ODF works with the following Oceanographic Data Centers:
- NSF / Earth Cube
- GO-SHIP CCHDO
- GO-SHIP / CLIVAR - Hawaii ADCP
- WOCE - JODC ADCP Data
- NOAA - NCEI