Assessment of Port Ocean Prediction System developed under Canada's Oceans Protection Plan : Strait of Canso

Canada's Oceans Protection Plan (OPP) was launched in 2016 to support initiatives aimed at protecting our marine environment from anthropogenic pressures. To this end, the Improving Drift Prediction and Nearshore Modelling 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 performance is assessed against available observational data and contrasted with the parent model CIOPS-E using a multi-year hindcast. Evaluations of 48-hour forecasts are performed during a two-month period. This report reports the assessment of the nested Strait of Canso port models (STC500 and STC100). Water level was found to be well modelled by the three models examined, with the finest resolution (STC100) port model improving scores by ~10%. The analysis showed that only 2.2% of unmodelled variance remains, with the bulk of it in the non-tidal component. Stability of the models was demonstrated with consistent scores and tidal constituents for each of the five years examined. Scores during extreme weather events (six large storms) were found to be within the expected range with the exception of two storms where the models underestimated the harbour seiching. The water level forecast evaluation found the model scores to be within the acceptable range during the 48-hour forecast period. In terms of the evaluation of currents, the port models demonstrated a large improvement over CIOPS-E inshore, and where topography played a role, particularly near the bottom. No significant improvement was found for the stations examined on the open shelf. However, drifter analysis did show a moderate improvement over CIOPS-E in terms of drift scores. Overall port model temperature and salinity scores were close to CIOPS-E but had significant improvements in near-bottom coastal regions, where resolution of bathymetry plays a role. In particular, the port models were able to model over the sill deep water renewal, a process unresolved by CIOPS-E.