Establishing Confidence in Marine Forecast Systems: The Design and Skill Assessment of the New York Harbor Observation and Prediction System, Version 3 (NYHOPS v3)

We briefly describe the new NYHOPS v3 OFS (Operational hydrodynamic Forecast System) and quantify its performance against National Ocean Service (NOS) standard OFS evaluation metrics. Given the relatively large area of the NYHOPS v3 OFS (including the NY/NJ Harbor estuary, Long Island Sound, and their coastal ocean), and the proliferation of sensor networks, the presented skill assessment is one of the most extensive performed to date: model results are compared to in situ observations of water level, currents, temperature, salinity, and waves from over 100 locations, collected in a 2 year period. The model's ability io describe the hydrodynamic conditions in the extensive area it is employed is remarkable. The average index of agreement for water level is 0.98, for currents is 0.87, for water temperature is 0.98, for salinity is 0.77, and for significant wave heights is 0.88. Respective, average root-mean-square errors are: 10cm for water level, 13cm/s and 9° for currents, 1.4°C for water temperatures, 2.8psu for salinities, and 32cm for significant wave heights.