Hobart

Seminar abstract

Friday 10 August 2007, 11.30 am
CSIRO Auditorium, Hobart

David Griffin
CSIRO Marine and Atmospheric Research
and
LCDR Aaron Young
Royal Australian Navy

Bluelink I and II: the status of Australia's fledgling short-term ocean forecasting system

Last week in Sydney, (10am, 2 Aug, at Garden Island, to be precise) the ribbon was cut and several VIPs congratulated the Bureau of Meteorology, CSIRO and Royal Australian Navy for bringing into existence Australia's first eddy-resolving, short term ocean forecasting system. The system runs operationally now at the Bureau, and is the fruit of the $15m Bluelink project commenced by the three agencies in 2002.

At the heart of the system is a global ocean model with a variable-resolution grid telescoping from 10km around Australia to 200km in the Atlantic . In free-running mode, this model produces simulations of ocean features that even hardened model-skeptics have to admit are very realistic. To have those swirling eddies occur at the right place and time, however, is a challenge. To do it with any accuracy 10 days after the latest available ocean observation is an even bigger challenge. Ocean surface topography data from the Envisat and Jason-1 altimeters, along with AMSR-E sea surface temperature and Argo temperature and salinity profiles are assimilated by Multivariate Ensemble Optimal Interpolation - a method that uses past runs of the model to learn how to use observations of eg, sea level to intelligently correct many model variables, at many locations and depths.

While forecasting is a key project goal, there are also many uses of an ocean hindcast. The model has now been run in this mode for 1992-2006 (twice actually) as part of the development process and also to provide our best estimate of the history of ocean currents, temperatures and salinities over the last 15 years.

For a global model, 10km is a very fine grid but it is still not really fine enough for coastal dynamics. Other limitations are that the vertical spacing of layers is 10m, and there is no tidal forcing. The solution is to nest a finer-resolution model - the Relocatable Ocean-Atmosphere Model within the global model. ROAM can be very quickly configured for any region using a Graphical User Interface. It then obtains ocean and atmospheric boundary conditions and runs nested models of both.

Both these systems are now up and running. Their status and performance will be reviewed, and a demonstration given of how RAN use the forecasts, which are now public: http://www.bom.gov.au/oceanography/forecasts/index.shtml.

We are very pleased with what has been achieved, but there is still much room for improvement. Bluelink II, already into the first of four years, will achieve this and also expand the scope of the project to include the littoral zone.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Karen Wild-Allen, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5010
Thomas Kunz, (Biological seminars) CSIRO Marine and Atmospheric Research
(03) 6232 5076
Annabel Ozimec (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5462
Sandra Zicus, Antarctic Climate and Ecosystems CRC (03) 6226 7888
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 6/08/07