dnowacki-usgs
commented
3 months ago Depth-varying high-frequency cutoffs are already implemented in stglib, although the cutoff specifications are not presently specified by the user. The cutoff used is the more conservative of:
- the index where the pressure transfer function (to relate pressure PSD to surface-elevation PSD) becomes >= 0.1
- the noise cutoff frequency as defined in Jones & Monismith (2007)
For frequencies greater than the index as defined above, a f^-4 tail is applied, and then the resulting full PSD is used to compute the wave statistics. This is for the waves computed from pressure, i.e. those not with a puv_ prefix.
For PUV, statistics are computed with both the specified fixed cutoffs, as well as those with the dynamic cutoffs and tails applied.
Are you looking for more granularity than this?
It would be super helpful to have the option to use a depth varying high frequency cutoff when obtaining wave stats for a vector. We have this in our current matlab wave stat routine as shown below:
uht = elevation of velocity data, sv ff = a fudge factor to allow us to account for things like platform sinking and any other reason we might not be able to measure the theoretically highest frequency possible waves, this should be an optional input variable
depf = burst_mean_depth - uht+ ff;
hf_cut = (9.81/(4pidepf))^0.5;