Subtidal velocity mismatch in ROMS vs data

[annaph]

Our group has been developing a realistic estuary-shelf ROMS application over the past few years. We have a persistent problem with poor model skill in replicating subtidal velocities. Comparisons between tidal velocity components produced by ROMS and from field data are reasonably good. When we remove tidal frequencies from the velocity time series, the ROMS output has consistently lower variance (around an order of magnitude smaller) than the data, and does not produce the strong pulses in flow that we see in the data records.

We are wondering if anyone can suggest likely causes for this type of model-data mismatch (e.g. mixing parameter choice, bottom friction, over-smoothed bathymetry,?). If you have come across the same issue, what was your solution? Or is it an inevitable problem?

Thanks very much,
-annaph

[kate]

If you think about what drives the subtidal flows, it's probably coming from the winds. What winds are you using? What spatial and temporal resolution do you have for them?

If your tides are fine, the bathymetry and bottom drag can't be too far off. The vertical mixing scheme could be trouble, but would be affecting vertical stratification more than the pulses you miss.