Assessment of Port Ocean Prediction System developed under Canada's Oceans Protection Plan : Kitimat Fjord

Canada's Ocean Protection Plan (OPP) was launched in 2016 to support initiatives aimed at protecting our marine environment from anthropogenic pressures. To this end, the oceanography sub-initiative of OPP developed six high-resolution port-scale hydrodynamic models, to improve safe navigation, and provide operational emergency response to events such as marine oil spills. The models were downscaled from the Coastal Ice-Ocean Prediction Systems East and West (CIOPS- E, CIOPS-W). Atmospheric forcing was provided by the High-Resolution Deterministic Prediction System (HRDPS). Model evaluation is an integral part of this development and here the port models are evaluated against available observational data and the parent model using a multiyear hindcast. Evaluations of 48-hour forecasts are performed during a two month period. Additionally, model performance during major storms is examined. In this report the model evaluation for the hydrodynamic model of the port of Kitimat and the approaches to the port is presented. A hindcast was completed for the years 2016 – 2022 and evaluated against a comprehensive set of observations of water levels, currents, and water properties. This evaluation shows that the port ocean prediction system significantly improves representation of water levels and currents over its parent model, CIOPS-W. Water level predictions are improved by as much as 30% in terms of centered root-mean-square error, predominantly in the tidal domain. The model remained stable during major storms but did not yield significant improvements in the prediction of water levels associated with these storms. Strong non-tidal current events in response to outflow winds were well captured in the model. Evaluation of the modelled water properties revealed several areas where the model can be improved in future versions. Sub-optimal initialization of deep water masses was found to inhibit the representation of deep water renewal events, and potentially also contribute to a weaker than observed estuarine circulation. Further, a persistent warm bias in sea surface temperatures in the lower reaches of the fjord system requires further evaluation. Modelled surface currents from the port ocean prediction system were found to improve short term predictions of the trajectories of drifting objects by as much as 50% in terms of instantaneous prediction skill. Currents from the parent model were found to be better suited for longer-term predictions.