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Tide phase and Yorig

asked 2022-02-01 15:08:12 +0200

Hello everyone, I'm runnung a simulation just to test how the tides module is working with TPX07. For this purpose I have a real pressure dataset to compare with the model 'zeta' output. The problem is that I don't know how to match the phase of my simulation outputs with my "real" data. In other words, I want the model outputs to coincide in day and hour with my SSH data (highs and low tides). I set all the parameters in crocotools_param, thats the Ymin,Mmin,Dmin,Hmin. It's not clear for me what I have to put on Yorig ... Thanks, Nicolas

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answered 2022-02-01 17:03:36 +0200

Hello Andres, yes I also have problem with the amplitud. If I shift the time series a couple of hours the phase fits. Also, I think the Yorig is being used in the phase corrections done by crocotools (in make_tides.m): % Add a phase correction to be consistent with the 'Yorig' time % t0=t0-24.mjd(Yorig,1,1); then : correc_phase=-phase_mkB(it)-pu(it)+360.t0./periods(it);

The amplitude is like 1m higher in the model, so I m going to take a look to those bottom stress coefficients. Thanks!

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answered 2022-02-01 16:52:13 +0200

I agree with Andres.

Note that the model time is in UTC. Your data is probably given in local time. You need to do the conversion.

If there is still a phase shift after the conversion, then check the sensitivity to bottom friction and also compare with TPXO tides, which are forcing CROCO at the boundaries: do you also have a phase shift with TPXO? ...

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answered 2022-02-01 16:36:39 +0200

andres gravatar image

Hi Nicolas,

I think Yorig is not relevant. It is just to avoid having a very large number in your time vector variable (seconds since Yorig)

How bad is you tidal phase problem? Does shifting the time series by a constant value corrects it? Amplitude is ok?

You could also shift between linear, quadratic, and Roughness length formulation for the bottom stress in the croco.in file

bottom_drag:

RDRG [m/s]: Drag coefficient for linear bottom stress formulation RDRG2: Drag coefficient for constant quadratic bottom stress formulation Zob [m]: Roughness length for Von-Karman quadratic bottom stress formulation Cdb_min: Minimum value of drag coefficient for Von-Karman quadratic bottom stress formulation Cdb_max: Maximum value of drag coefficient for Von-Karman quadratic bottom stress formulation.

or activate the Bottom Boundary Layer module (BBL)

See more info here

https://croco-ocean.gitlabpages.inria... https://croco-ocean.gitlabpages.inria...

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Asked: 2022-02-01 15:08:12 +0200

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Last updated: Feb 01