Tide model references

[timay91]

Hello,

When computing ocean and load tides from global tide models (FES, DTU, GOT, EOT) is it safe to assume these tides are referenced to each individual models computed MSS or are they referenced to a common MSL reference through pyTMD? I want to accurately compare tide models to each other. Do I need to make an MDT surface for each model from its calculated MSS to a common tide free vertical datum or is pytmd doing that in the background?

Thanks,

[tsutterley]

That is an absolutely fantastic question. For all the models pyTMD currently supports, there is no z0 term. And so I think it is fair to assume that they are all in reference to the MSS. However, if there is a data assimilating model that did not take into account the 18.6 year modulations in lunar tides, there might be some wonkiness. That being said, I take them as equivalent when comparing. I don't add a z0 term within pyTMD if the model doesn't provide one.