[MITgcm-support] Using a sponge layer to relax temperature

[Stroman, Ashley]

Hi Dustin.

Oh ok. I didn’t know about the modification. That’s really helpful as I quite like the RBCS package. I’ll check it out.

Best,
Ashley
On Mar 2, 2015, at 1:44 PM, Dustin Carroll <dcarroll at uoregon.edu<mailto:dcarroll at uoregon.edu>> wrote:

Hi Ashley,

Ryan has good advice here. if you need to relax your plume and boundary temperature at different timescales, Roberta Sciascia added a nice mod. to RBCS pkg under MITgcm_contrib/sciascia/rbcs that allows for multiple RBCS fields with independent relaxation times. You can then have multiple masks / relaxation files (i.e., one for your plume and one for the boundaries).

Dustin

On Mar 2, 2015, at 10:31 AM, Stroman, Ashley <acs08g at my.fsu.edu<mailto:acs08g at my.fsu.edu>> wrote:

Well, I already use the RBCS package to force a plume in the middle of the domain, so I didn’t try using the RBCS package for the temperature on the boundaries because I wasn’t sure if you could use the RBCS package twice in one simulation.

-Ashley
On Mar 2, 2015, at 1:28 PM, Ryan Abernathey <ryan.abernathey at gmail.com<mailto:ryan.abernathey at gmail.com>> wrote:

Just wanted to point out, as a possible alternative, the RBCS package.
http://mitgcm.org/public/r2_manual/latest/online_documents/node237.html

RBCS allows you to relax to model fields to some prescribed field (with a variable relaxation rate) throughout the whole domain. It is somewhat simpler to use and understand than OBCS.

If you don't need actual open boundary features (e.g. Orlanski, inflow / outflow), RBCS is more than adequate for making sponge layers.

-Ryan

On Mon, Mar 2, 2015 at 12:56 PM, Stroman, Ashley <acs08g at my.fsu.edu<mailto:acs08g at my.fsu.edu>> wrote:
Hi Dustin.

I have two specific questions regarding my problem:

1.) Is it possible to use Orlanski for momentum on the boundaries, while also using a sponge layer to restore temperature to the initial conditions on the boundaries? I’m not sure if both are allowed, and I’ve had no luck finding this answer online.

2.) What is the difference between useOBCSsponge and OBCSsponge_Theta in the data.obcs file? My thought is that the latter is specifically used for theta while the former is not, but I am not 100% positive. There’s not much information on the latter parameter except that it turns on the theta sponge along the boundaries, so I’m not sure if the parameter is used, 1) what it specifically means, and 2) what is additionally required.

Thanks.
Ashley
On Feb 27, 2015, at 8:06 PM, Dustin Carroll <spanishcastlemagik at gmail.com<mailto:spanishcastlemagik at gmail.com>> wrote:

Hi Ashley,

Can you provide a bit more information on the problem you are having? I find that the more specific you are, the easier it is for people to help on this support group.

Section 6.3.1 in the docs (see below) describes how to set up your data.obcs file, also look at verification/exp4 for an example w/ open boundaries.
http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html

If you want to restore your boundaries to the prescribed ICs then you’ll need to generate binary files for each boundary that is specified in data.obcs,

Cheers,
Dustin


On Feb 27, 2015, at 11:56 AM, Stroman, Ashley <acs08g at my.fsu.edu<mailto:acs08g at my.fsu.edu>> wrote:

Hello.

I am wanting to use the OBCS package to implement a sponge layer on the boundaries to relax temperature to the initial conditions. I am having trouble finding what is needed in terms of the data.obcs file as well as any any additional binary files for temperature that are required. Can someone shed some light on this? Thanks.

Best,
Ashley Stroman
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