Calibration of Tides in an Operational Forecast System for the Shelikof Straits—Cook Inlet Region of Alaska

This manuscript describes the calibration of tides in an Operational Forecast System (OFS) being developed for the Shelikof Straits - Cook Inlet region of Alaska. As the M2 tidal harmonic constituent is the most dominant in this region, model predictions of the amplitude and phase of this constituent were examined at a series of stations along the axis of the model domain using water elevations as the proxy. Quadratic and logarithmic bottom stress formulations, spatially variable variants of the former, and different levels of stress were tested. Further control was provided by modulating the strength of the open boundary tidal forcing. In all cases, the water elevation phases were accurately predicted by the model and the main source of error was amplitude mismatches. The logarithmic formulation with a bottom roughness of 0.01 m generated the most accurate water elevation predictions. A full tidal simulation was then performed by including nine additional harmonic constituents (S2, N2, K1, M4, O1, M6, Q1, P1, and K2). Here too, the model-predicted water elevation and current phases were very accurate and the errors were generated by amplitude mismatches, which were seen to grow when moving up the model domain towards Anchorage. Next, these simulations will be repeated in a wetting/drying mode using a newly produced Digital Elevation Map (DEM) combining bathymetry and land topography, where it is expected that the model predictions will be further improved.