[MITgcm-support] Re: specification of surface elevation

[Petter Stenström]

Hi Amy,

the effect of specifying a barotropic flow over the boundary should be
exactly the same as specifying a sea level, shouldn't it? I've been
specifying an incoming tidal wave in estuary experiments through the
condition:

u_b(t) - c*eta/D = u_b0*sin(2*pi*t/T)

where u_b(t) is the time dependent mean velocity over the boundary, eta is
the sea level and u_b0 is the amplitude of the tidal wave. Whether you
specify the velocity or the sea level doesn't matter with this condition,
but the sea level was much more difficult to specify when I tried it.

However, if you prefer to specify the sea level it seems that it is
possible in the later versions of obcs_calc.F. I haven't tried that yet.

Petter

>
> Hi Amy,
>
> I've subscribed you to the MITgcm-support list and forwarded your
> message (below).  And hopefully someone here can help you with the
> surface elevation questions.
>
> Ed
>
> === Forwarded message ===
>
> Hi,
>
> I've used MITgcm to simulate the evolution of the gravity current over
> slope. To my problem, the best way to add tides in the domain is to
> specify the surface elevation of the off-shore open boundary, while
> other approaches like imposing the body force or barotropic velocity on
> the open boundary are not good enough for my purpose.
>
> So would it be feasible to adapt the model to specify the surface
> elevation?  Does that involve a lot of difficulties?
>
> Thank you!
> Amy
>
> --------------------------------------------------------------
>  Amy (Xiaorui) Guan        |  Lamont-Doherty Earth Observatory
>  Graduate Student          |  Oceanography 205E
>  Ocean and Climate Physics |  61 Route 9W
>  Office: 845-365-8529      |  Palisades, NY 10964
> --------------------------------------------------------------
>
> --
> Edward H. Hill III, PhD
> office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
>              Cambridge, MA 02139-4307
> emails:  eh3 at mit.edu                ed at eh3.com
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>
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