EurOCEAN 2000 - Vlaams Instituut voor de Zee

The establishment of a data bank for tomography data is an important measure for
dissemination and also to make tomography more accepted and widely used as "standard" data
for research and for future monitoring/forecasting applications such as GOOS. Within
OCTOPUS a data bank for European tomography data is established consisting of four
modules.
ƒ File server where acoustic tomography and environmental data sets are archived. These
sets are handled using NetCDF and ASCII protocols.
ƒ Oracle data base which records catalogues and metadata such as cruise summary,
experiment and mooring descriptions.
ƒ Web server which provides access to the catalogue and data sets. This server is
dynamically linked to the Oracle data base and to the file server.
ƒ FTP server which stores project results such as project documentation, file format
description, software and data examples.
INSTRUMENT SERVICE AND DEVELOPMENTS
In the framework of OCTOPUS, an SME-based service capability for tomography instruments
has been established by ORCA in Brest/France. Furthermore, technical developments, such as
the establishment of testing, servicing, calibration procedures and protocols, have been carried
out that will make the instruments more operationally useable. On the basis of these protocols a
number of tomography instruments have been already serviced by ORCA.
A further development concerns the creation of a graphical man-machine interface under
MATLAB for the tomography instruments used by the participants, to facilitate the procedures
for preparation, deployment and recovery of the instruments. The interface is used to
ƒ test the individual instrument modules as well as the integrated system,
ƒ measure the instrument delays, gains and clock/emitter/navigation frequencies,
ƒ calibrate the pressure/temperature sensors and the instrument clock,
ƒ perform operational tests before deployment and after recovery of instruments, and finally,
ƒ create a disk image of a recovered instrument, to be used for the generation of Level-0
files
In addition to the initial plan of OCTOPUS, developments have been undertaken to facilitate
the operational and multi-purpose use of tomography instruments, in response to
recommendations made at the Oceanobs99 conference. A first step is to use tomography
sources to also provide sound signals for tracking RAFOS floats. Two transmitter modules of
existing sources have been already modified to allow transmission of RAFOS signals and are
currently tested in the framework of a nationally-funded tomography experiment in the
Labrador Sea.
Secondly, steps have been taken in the direction of the future requirement of real-time data
transmission. Tests have been initiated for surface-satellite data transmissions from a mooring,
and for relaying data from simple subsurface instruments inductively along the mooring wire to
the surface element. Once this approach is mastered, in theory any instrument with underwater
connectors for accessing the data can be equipped with an inductive modem for extraction of
data and transmission to the satellite float. Future projects should address this particular issue
for tomography instruments.
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