separating hadv term into zeta and eta components

[mafeluna]

Recently there was a post about separating the horizontal advection of momentum into the zeta and eta components. I am trying to do the same thing for the momentum equations as well as for the tracer equations. The code compiles, runs and the new variables u_xadv, u_yadv, ubar_xadv........,s_xadv, s_yadv,....
are created in the diagnostic file. It looks like the separation for tracers was done successfully since s_hadv=s_xadv+s_yadvv (same for temperature). But the eta and zeta components of momentum do not add up to the total horizontal advection. My understanding is that ROMS calculate the horizontal momentum advection in generalized curvilinear coordinates as

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What I was trying to do in the code was to calculate the two components as
mometum zeta advection =

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momentum eta advection =

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Is this correct?

if someone has any thoughts about this I will appreciate it.

[arango]

Yes, this is correct. This term is derived from alternative version of the nonlinear equations that includes absolute vorticity (planetary plus relative) in the advection term. I updated the code to include the ξ- and η-components of horizontal advection, viscosity and diffusion. See following ticket for details.