OFAM is based on version 4.0d of the Modular Ocean Model, using a hybrid mixed layer model. The horizontal grid has 1191 and 968 points in the zonal and meridional directions respectively; with 1/10 degree horizontal resolution around Australia (90-180E, south of 17). Outside of this domain, the horizontal resolution decreases to 0.9 degrees across the Pacific and Indian basins (to 10E, 60W and 40N) and to 2 degrees in the Atlantic Ocean. OFAM has 47 vertical levels, with 10 m resolution down to 200 m depth. The topography for OFAM is a composite of topography sources including dbdb2 and GEBCO. Horizontal diffusion is zero. Horizontal viscosity is resolution and state-dependent according to the Smagorinsky viscosity scheme (Griffies and Hallberg 2000). BRAN is a multi-year integration of OFAM that assimilates observations using an ensemble optimal interpolation (EnOI) scheme that uses a stationary ensemble of intraseasonal model anomalies, obtained from a non-assimilating model run. Observations include along-track SLA (atSLA) from altimeters and tide gauges, in situ T and S observations and satellite SST.