Towards Improved Operational Wave Modelling at the Bureau of Meteorology.

The Bureau of Meteorology produces deterministic and ensemble forecasts for numerical weather prediction (NWP). The Bureau's operational wave forecast is currently limited to a global deterministic model (AUSWAVEG3). The current system has multi-resolution grid with a spatial resolution of 6 kilometres around Australia. It is therefore not able to accurately represent the transformation of deep-water waves to near shore and can exclude sub grid scale features such as islands or reefs. Over the past year a few smaller pilot projects highlighted the capability of variable resolution modelling around Australian coasts. The Bureau is trialling a new national coastal wave forecast system (AUSWAVE-NAT). AUSWAVE-NAT is nested within the Bureau's operational global wave model and currently produces research forecasts two times per day in near-real time. The wave model is driven by the Bureau's operational NWP model (ACCESS-G3) and incorporates ocean currents (OceanMAPS4.0i), with a spatial resolution of around 10 kilometres. The wave mesh incorporates a range of high-resolution bathymetric data, including Lidar bathymetry, and in particular high-resolution bathymetry for the Great Barrier Reef. As the approach uses an unstructured mesh, the size increases from about 10 kilometres (open ocean) to around 250 to 500 metres at the coast. The wave model is expected to extend the Bureau's capability to provide more accurate nearshore wave forecasts. This presentation will give an overview of the variable resolution national coastal wave forecast system and presents initial results, verification, and an overview of some use cases. [ABSTRACT FROM AUTHOR]