Integration of Continuous Water Column Information

Hughes Clarke and Lamplugh (CHS)

Chair Funding

Recent development of high speed underway oceanographic profilers as a joint project between the CHS/DFO and Brooke Ocean Technology (BOT) have produced an operational system (the MVP100/200/300) that is now in use on a subset of CHS swath sonar survey platforms.

Cross section of the sound speed structure on the edge of Georges Bank

(Colour range 10m/s, 45 km long profile from 0-100m)

Whilst at this point in time, routine deployment of these sensors only takes place at periods of ~ every hour, as part of OMG field trials it has been shown that these systems can provide water column data as frequently as once every minute. Such high-density data is currently of little practical use, however as commercial software tools are not available to handle a dynamically varying water column.

We have developed software to linearly interpolate the water mass between discrete profiles. These interpolated profiles can be applied as a unique water column for each ping so that the effect of a continuously changing watermass may be mimicked. The maximum time period over which such interpolation is justified has been explored (by examining the resulting errors when compared to the true water mass). At this time, interpolation of time periods much more than 30 minutes is considered to be of minimal value as it is clear that the time and length scales over which the water mass can change are shorter than this. This provides a clear guide as to the optimal use of these underway profiling instruments.