Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

FP5

ASOF-N Résumé de rapport

Project ID: EVK2-CT-2002-00139
Financé au titre de: FP5-EESD
Pays: Germany

Data and data management of CTD profiles and mooring

Result description CTD Data:
CTD (Conductivity, Temperature, Depth) profiles were measured during 10 cruises in 2003, 10 in 2004, 11 in 2005 and 1 cruise in 2006 by AWI, IFMH, IMR, IOPAS, and NPI across Fram Strait, in the East Greenland Current between 74° and 79° N and in the eastern part of the Greenland Sea. A detailed information on the CTD stations can be found at the ASOF-N website.

The current CTD dataset contains 2514 profiles, which can be retrieved via http://www.awi-bremerhaven.de/OZE. A summary of CTD datasets is presented in Tables provided in the documentation.

Instruments:
All institutions used a Sea Bird SBE911plus CTD profiler with a single CT-Sensor package (double CT-Sensor for AWI profilers). The CT sensors were frequently calibrated at Seabird Electronics. In addition salinity samples were taken to correct for sensor drift. The final data have been processed using Seabirds post-processing software which includes all necessary operations. The raw data have a vertical resolution of 0.04dbar but still including noise e.g. due to ship motion. To reduce this noise, data were averaged to a vertical resolution of 1dbar. The number of data cycles averaged in each 1dbar record was stored together with the individual data points.

ASOF-N continued a CTD time series started in 1997, which is now sufficiently long to determine the variability on inter-annual time scales - and also to approach the declared objective of the ASOF cluster to capture variability on decadal time scales.

Result description Mooring Data:
Moorings were deployed and recovered during 15 cruises from 2003 to 2005 by AWI, IFMH, IMR, and NPI across Fram Strait and in the East Greenland Current at 74°N. A detailed map with mooring location is provided in the documentation. The current dataset contains 900 time series, which can be retrieved via http://www.awi-bremerhaven.de/OZE. A summary of mooring records is presented in the documentation.

Instruments:
Most instruments being used in the mooring were current meters. Reliable current measurements were maintained by frequent services (usually before and after deployment). The common current meter type is a rotor current meter from Aanderaa Instruments. In addition to current speed and direction these instruments also measure temperature. CT recorders from Seabird (SBE16, SBE37) were used to measure precise temperature and salinity based on calibrations before deployment and after recovery. The sample rate depends on the different instrument types (and their power consumption and memory size) and ranges between 10 minutes and 2 hours. Data processing was done by the institution that provided the instrument. The standard procedures included converting binary data to engineering units, apply magnetic deviation correction, removing of spikes (small gaps were filled by interpolation and long gaps were filled with a dummy data value, e.g. NaN) and correcting for sensor drifts for example by applying post calibration.

Potential users:
Scientists working in Arctic Ocean research

Archiving and providing the data:
As important as collecting new data about the temporal variability of oceanographic parameters, is the availability of collected data. The ASOF-N partner send their processed and calibrated CTD and/or mooring datasets to the AWI where they are stored together with information about additional dataset available for this region. The data are transferred into a uniform format and archived in AWI's database with general cruise and instrument information. ASOF-N partners have password protected direct access via the Internet or can order complete datasets on CD.

This process has the following key advantages:
Project partners can access all collected data from all over the world via the Internet without delay. This is of great importance especially in the oceanographic community where scientists are often on cruises and answering requests for data are therefore delayed.

Data are provided centrally in a uniform data format. The time consuming process of converting data is performed centrally using a fixed routine. The user accesses a uniform data format and can compare profiles directly without tedious and time-consuming conversion of data formats. The data format supports importing of data using Matlab if desired by the user and can be visualised using the software ODV (Ocean Data View). ODV can be retrieved from http://odv.awi-bremerhaven.de.

In contrast to archives, this working database can be easily edited after the upload. This easy modification of the database allows for a fast correction if comparisons of data sets reveal faulty data points. Furthermore it enables the subsequent expansion of the database. CTD data are processed fast and can made available immediately and data sets that need more time to process e.g. oxygen profiles can be easily added at a later stage without affecting the accessibility of CTD data.

Informations connexes

Contact

Gerd ROHARDT, (Oceanographer)
Tél.: +49-471-48311818
Fax: +49-471-48311797
E-mail