Tide phase and Yorig

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 …

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


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


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? …

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
then :

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