[MITgcm-support] Tides in channel model

[Ryan Abernathey]

Thanks for the reply Stanislav!

In this case, Qiyu is working with a zonally reentrant channel (similar to
https://mitgcm.readthedocs.io/en/latest/examples/reentrant_channel/reentrant_channel.html),
so there is no open boundary at which to apply tidal forcing. So although
it is a small domain, it is more similar to a global model in this respect.

My understanding was that the most common way to force tides in global
models was via a specified surface pressure field in the EXF package. (E.g.
that's how the LLC4320 simulations were forced.) But I also know there has
been a lot of recent work in this area, so maybe there is a simpler option.

Has anyone tried specifying a body force in analytic form using a custom
code file? Where would be the right place in the code to insert such a
forcing?

Best,
Ryan

On Fri, Dec 3, 2021 at 4:18 AM Stanislav Martyanov <martyanov.sd at gmail.com>
wrote:

> Hello Qiyu,
>
> the easiest way is to generate a simple grid with constant dx (and/or dy)
> with one or several open boundaries specified in OBCS_OPTIONS.h (#define
> ALLOW_OBCS_NORTH, etc). Then, you will need to configure the open boundary
> conditions (if you specify induced tide) and external forcing (if you want
> to set geopotantial): i.e. #define OBCS_ALLOW_TIDES in OBCS_OPTIONS.h, and
> #define EXT_ALLOW_TIDES in EXT_OPTIONS.h
>
> And, of course, you need to set the corresponding filenames with the tidal
> forcing in data.obcs (and in data.exf, if you want geopotential). Note that
> only the normal component of tidal current at the open boundaries is
> currently implemented in the model.
>
> You also should get familiar with the OBCS package where tides can be
> specified (as open boundary conditions), and with the EXF package where
> tides can be added through geopotental.
>
> Best,
> Stanislav
>
> ср, 1 дек. 2021 г. в 21:50, Qiyu Xiao <qx344 at nyu.edu>:
>
>> Dear MITgcm users/developers,
>>
>> If I want to run a channel model with tides, what is the best way to do
>> that? What functions/variables should I change or is there any package for
>> this purpose?
>>
>> Thanks,
>> Qiyu
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