https://doi.org/10.5194/gmd-2021-51 Preprint. Discussion started: 14 April 2021 c Author(s) 2021. CC BY 4.0 License. Australian tidal currents – assessment of a barotropic model (COMPAS v1.3.0 rev6631) with an unstructured grid. David A. Griffin1, Mike Herzfeld1, Mark Hemer1 and Darren Engwirda2 1Oceans and Atmosphere, CSIRO, Hobart, TAS 7000, Australia 2Center for Climate Systems Research, Columbia University, New York City, NY, USA and NASA Goddard Institute for 5 Space Studies, New York City, NY, USA Correspondence to: David Griffin (
[email protected]) Abstract. While the variations of tidal range are large and fairly well known across Australia (less than 1 m near Perth but more than 14 m in King Sound), the properties of the tidal currents are not. We describe a new regional model of Australian 10 tides and assess it against a validation dataset comprising tidal height and velocity constituents at 615 tide gauge sites and 95 current meter sites. The model is a barotropic implementation of COMPAS, an unstructured-grid primitive-equation model that is forced at the open boundaries by TPXO9v1. The Mean Absolute value of the Error (MAE) of the modelled M2 height amplitude is 8.8 cm, or 12 % of the 73 cm mean observed amplitude. The MAE of phase (10°), however, is significant, so the M2 Mean Magnitude of Vector Error (MMVE, 18.2 cm) is significantly greater. The Root Sum Square over the 8 major 15 constituents is 26% of the observed amplitude.. We conclude that while the model has skill at height in all regions, there is definitely room for improvement (especially at some specific locations).