[MITgcm-support] rbcs advice

[Jody Klymak]

Hi Dimitris,

I wrote you offline as well, but...

On Mar 4, 2014, at  9:06 AM, Dimitris Menemenlis <dmenemenlis at gmail.com> wrote:

> Hi Jody, I think yes.  What grid spacing are you running your regional domain?
> And what resolution (space and time) is your open boundary conditions?

Right now I have hourly (well 3720 s to be an even divisor of an M2 tidal cycle) output on a 5- to 1-km grid, with 1 km near my region of interest, and 5 km at the boundaries.  The forcing of this model was an analytical source function (a couple of internal tide line-sources outside the domain), and the model was spun up for 12 tidal cycles allowing reflections from a rough continental slope to set up.  Probably accurate out to mode 10 or so.  

I am trying to telescope this down to about 100x200 m in a 50x100 km region to look at the non-linear internal waves on a continental slope.  I nest this inside a 400x300 km region using telescoping resolution, and will initialize and force with the larger 1-km grid. 

All the telescoping is to help make the BCs not too important, but it would be nice to make them as close as possible to reduce reflections. 

Thanks!   Jody

> 
> Michael Schodlok has a lot of experience going from
> CS510 (18 km) to 1 km domains, then adding tides,
> and possibly obcs sponge to get rid of some edge artifacts.
> 
> But with sufficiently high-resolution (in time) obcs,
> I am guessing that you will not need sponging at all.
> At least that's the theory.
> Chris Hill was experimenting with "replaying" bits
> of the 1/48th using obcs.  I don't know how far he got.
> 
> Let me know if you want to access the 1/48th output
> and we can figure out best way to proceed.
> 
> Cheers, Dimitris
> 
> On Mar 4, 2014, at 8:50 AM, Jody Klymak <jklymak at uvic.ca> wrote:
> 
>> Do you think its true that I could just force w/ obcs and do away w/ the sponge?  I've used sponges for so long I hadn't thought of giving this a try, but maybe it is all I need to do, and I can ditch rbcs.  Certainly my forcing should have all the modes that could conceivably reach the boundaries by the time my integration is done.  
>> 
>> Second, 1/48th degree global with tides!  That would be very interesting!
> 
> 
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--
Jody Klymak    
http://web.uvic.ca/~jklymak/