Tidal modeling

S. Howard and L. Padman

We use a suite of programs to define tidal height and current variability on the western Antarctic Peninsula (WAP) shelf. We use a 2-D circum-Antarctic tidal model (CATS) to examine the barotropic tidal field. The tidal range is ~1.5 m at spring tide, and tides are mainly diurnal. Note that the correct channel depth (~500 m) under George VI Ice Shelf must be used to get reasonable height predictions from CATS in the WAP region. Over most of the domain, tidal currents are small, only a few cm/s However, along the shelf break, patches of strong currents (up to ~20 cm/s) are predicted due to excitation of diurnal topographic vorticity waves. The spatial distribution of depth-averaged tides is different in preliminary runs of our 3-D POM-based tides model with stratification. This model suggests that semidiurnal baroclinicity is weak, but there may be some semidiurnal internal tides generated as the second harmonic of diurnal flows across the upper continental slope. We have not yet included realistically-varying stratification, so these tentative conclusions might change.

Proposed future work includes updating CATS with the new WAP bathymetry grid developed by WHOI, running a finer-grid barotropic model for just the Peninsula region, running an assimilation model with data from SO GLOBEC bottom pressure recorders and coastal tide gauges in the region, and adding realistic, spatially varying stratification to the 3-D model and making runs for different seasons.