Global Applications

The Bluelink global ocean modelling effort represents Australia`s contribution to the Global Ocean Data Assimilation Experiment (GODAE), and its successor, GODAE OceanView, an international collaboration operational oceanography.

Bluelink Global Ocean Model

Time series of along-strait velocity at Lombok Strait, Indonesia

Time series of along-strait velocity at Lombok Strait, Indonesia, from observations (top) and OFAM3 (bottom). Blue indicates flow into the Indian Ocean, and red indicates flow into the Indonesian Seas.

The global ocean model that underpins Bluelink is called the Ocean Forecasting Australia Model (OFAM).  OFAM is based on MOM – a community model developed at GFDL.

Two versions of OFAM have been developed. The first version of OFAM, currently used to underpin the Bluelink operational system, has 10 km resolution around Australia. The latest version (OFAM3) extends the region of 10 km resolution to the globe.

Bluelink Reanalysis

diagram displaying the monthly mean sea-level with velocities.

Monthly mean sea-level from BRAN (version 2p2), with velocities from surface drifting buoys overlaid.

The Bluelink ocean model has been combined with a data assimilation system that blends ocean observations of satellite altimetry, satellite sea-surface temperature, and temperature and salinity from floats and moorings. The resulting reanalysis, called BRAN, provides a time-varying picture of the ocean circulation over the past 20 years.

BRAN is intended to be a resource for the oceanographic research community – enabling better understanding of ocean dynamics and variability.

Operational Forecasting

Map of South Australian coastline displaying sea surface temperatures

Example of a forecast of sea surface temperature off South Australia, using OceanMAPS.

The Bluelink global ocean model and data assimilation system have been implemented operationally at the Bureau of Meteorology. The operational system is called OceanMAPS – the Ocean Modelling Analysis and Prediction System. OceanMAPS produces 7-day forecasts of the ocean every day.

OceanMAPS assimilates satellite and in situ observations of temperature, salinity, and sea-level in near-real time to initialise forecasts of the mesoscale ocean circulation around Australia.

Next Generation Forecast System

As well as development, enhancement, and evaluation of the current ocean forecast/reanalysis system, Bluelink is also developing the next generation forecast system. This includes the development of an Ensemble Kalman Filter (EnKF), based on the Deterministic EnKF (Sakov and Oke, 2008) that will involve a global application of a system that is similar to the TOPAZ system (Sakov et al. 2012).

Selected Publications

Brassington, G. B., T. Pugh, C. Spillman, E. Schulz, H. Beggs, A. Schiller and P. R. Oke, 2007: BLUElink> Development of operational oceanography and servicing in Australia, Journal of Research and Practice in Information Technology, 39, 151-164

Brassington, G. B., 2010: System design for operational ocean forecasting, In: A. Schiller and G. B. Brassington, Operational Oceanography in the 21st Century, doi 10.1007/978-94-007-0332-2, Springer, 2011, 441-486

Oke, P. R., A. Schiller, G. A. Griffin, G. B. Brassington 2005: Ensemble data assimilation for an eddy-resolving ocean model. Quarterly Journal of the Royal Meteorological Society, 131, 3301-3311.

Oke, P. R., and A. Schiller, 2007: Impact of Argo, SST and altimeter data on an eddy-resolving ocean reanalysis. Geophysical Research Letters, 34, L19601, doi:10.1029/2007GL031549.

Oke, P. R., G. B. Brassington, D. A. Griffin and A. Schiller, 2008: The Bluelink Ocean Data Assimilation System (BODAS), Ocean Modelling,21, 46-70,doi:10.1016/j.ocemod.2007.11.002.

Oke, P. R., G. B. Brassington, J. Cummings, M. Martin, F. Hernandez, 2012: GODAE Inter-comparisons in the Tasman and Coral Seas,Journal of Operational Oceanography, 5, 11-24.

Oke, P. R., P. Sakov, M. L. Cahill, J. R. Dunn, R. Fiedler, D. A. Griffin, J. V. Mansbridge, K. R. Ridgway, A. Schiller, 2012: Towards a dynamically balanced eddy-resolving ocean reanalysis: BRAN3, Ocean Modelling67, 52-70,

Oke, P. R., D. A. Griffin, A. Schiller, R. J. Matear, R. Fiedler, J. V. Mansbridge, A. Lenton, M. Cahill, M. A. Chamberlain, K. Ridgway, 2012: Evaluation of a near-global eddy-resolving ocean model, Geoscientific Model Development6, 591-615, doi:10.5194/gmd-6-591-2013.

Sakov, P. and P. R. Oke 2008: A deterministic formulation of the ensemble Kalman filter: an alternative to ensemble square root filters. Tellus-A, 60A, 361-371.

Sakov P., F. Counillon, L. Bertino, K. A. Lisaeter, P. R. Oke, A. Korablev, 2012: TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic, Ocean Science, 8, 633-656

Schiller, A., P. R. Oke, G. B. Brassington, M. Entel, R. Fiedler, D. A. Griffin, and J. V. Mansbridge, 2008: Eddy-resolving ocean circulation in the Asian-Australian region inferred from an ocean reanalysis effort. Progress in Oceanography, 76, 334-365.

Schiller, A., S. E. Wijffels, J. Sprintall, R. Molcard and P. R. Oke, 2010: Pathways of Intraseasonal Variability in the Indonesian ThroughflowRegion. Dynamics of Atmospheres and Oceans, 50, 174-200.