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<pre>Hi Matt,</pre>
<pre>I now turned all of the sponge in the OBCS package off and instead I use the RBCS package to restore T/S over a sponge. As far as I can tell this seems to work... </pre>
<pre>Can anyone tell me though what the best way to deal with open boundaries is? Is it best to have U/V prescribed via OBCS and T/S restored in a sponge layer using RBCS? Or is there a better way?</pre>
<pre>cheers,</pre>
<pre>Andreas </pre>
<pre><br></pre>
<pre><br></pre>
<pre>You are sponging 40 points in. Is that the problem - is it restoring to 0 because of that?
Try with
OBCSsponge_Salt=.FALSE.,
OBCSsponge_Theta=.FALSE.,
And see if that helps?
Matt
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> MITgcm-support <mitgcm-support-bounces@mitgcm.org> on behalf of Dimitris Menemenlis <dmenemenlis@gmail.com><br>
<b>Sent:</b> Monday, 22 June 2020 12:36 AM<br>
<b>To:</b> MITgcm Support <mitgcm-support@mitgcm.org><br>
<b>Subject:</b> Re: [MITgcm-support] [EXTERNAL] topography with OBCS</font>
<div> </div>
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<div>Hi Andreas, I had assumed that your initial tests were an attempt to reproduce a small region from a larger-domain simulation. If you don’t extract the U/V/T/S OBCS fields from the correct locations in the larger-domain simulation, you might end up with
a mask mismatch issue. But based on your discussion with Martin, this seems not to be the case.<br>
<br>
If your simulations are easy to repeat, you could you try turning off<br>
useOBCSsponge = .FALSE.,<br>
useOBCSbalance = .FALSE.,<br>
and then turning these back on one at a time in order to isolate the bug.<br>
I don’t think that the bug lives in useOBCSprescribe for 3D variables.<br>
<br>
Dimitris<br>
<br>
> On Jun 21, 2020, at 2:57 AM, Andreas Klocker <andreas.klocker@utas.edu.au> wrote:<br>
> <br>
> Dimitris,<br>
> What do you mean by extracting my boundary conditions at the correct location?<br>
> cheers,<br>
> Andreas<br>
> <br>
> From: MITgcm-support <mitgcm-support-bounces@mitgcm.org> on behalf of Dimitris Menemenlis <dmenemenlis@gmail.com><br>
> Sent: Friday, 19 June 2020 1:12 PM<br>
> To: MITgcm Support <mitgcm-support@mitgcm.org><br>
> Subject: Re: [MITgcm-support] [EXTERNAL] topography with OBCS<br>
> <br>
> Hi Andreas, are you sure that you are extracting your boundary conditions at the correct location?<br>
> You could be off by one grid cell, which could cause this problem. Dimitris<br>
> <br>
> <br>
>> On Jun 18, 2020, at 6:21 PM, Andreas Klocker <andreas.klocker@utas.edu.au> wrote:<br>
>> <br>
>> Hi,<br>
>> <br>
>> I am trying to set up a regional model configuration with OBCS. For some reason the model seems to introduce salinities where I actually have bathymetry (see attached figure; bathymetry left, salinities right). Salinities this low definitely do not exist
in the files containing the bounday conditions. Is it necessary to set the open boundary exactly to where I have ocean, or should the bathymetry file take care of this by telling the model there should be nothing happening in case of zero water depth?<br>
>> <br>
>> Here's my data.obcs file:<br>
>> <br>
>> # Open-boundaries<br>
>> &OBCS_PARM01<br>
>> <br>
>> OB_Iwest = 600*1,<br>
>> OB_Ieast = 600*-1,<br>
>> OB_Jsouth = 2600*1,<br>
>> OB_Jnorth = 2600*-1,<br>
>> <br>
>> useOBCSsponge = .TRUE.,<br>
>> useOBCSbalance = .TRUE.,<br>
>> useOBCSprescribe = .TRUE.,<br>
>> <br>
>> useOrlanskiWest = .FALSE.,<br>
>> useOrlanskiEast = .FALSE.,<br>
>> useOrlanskiSouth = .FALSE.,<br>
>> useOrlanskiNorth = .FALSE.,<br>
>> <br>
>> OBWuFile = 'OWU',<br>
>> OBWvFile = 'OWV',<br>
>> OBWtFile = 'OWT',<br>
>> OBWsFile = 'OWS',<br>
>> <br>
>> OBEuFile = 'OEU',<br>
>> OBEvFile = 'OEV',<br>
>> OBEtFile = 'OET',<br>
>> OBEsFile = 'OES',<br>
>> <br>
>> OBSuFile = 'OSU',<br>
>> OBSvFile = 'OSV',<br>
>> OBStFile = 'OST',<br>
>> OBSsFile = 'OSS',<br>
>> <br>
>> OBNuFile = 'ONU',<br>
>> OBNvFile = 'ONV',<br>
>> OBNtFile = 'ONT',<br>
>> OBNsFile = 'ONS',<br>
>> <br>
>> # OBCS_monitorFreq= 86400.,<br>
>> # OBCS_monSelect = 1,<br>
>> &<br>
>> <br>
>> # Orlanski parameters<br>
>> &OBCS_PARM02<br>
>> # Cmax=0.45,<br>
>> # cVelTimeScale=1000.,<br>
>> &<br>
>> <br>
>> &OBCS_PARM03<br>
>> Urelaxobcsinner=864000.,<br>
>> Urelaxobcsbound=86400.,<br>
>> Vrelaxobcsinner=864000.,<br>
>> Vrelaxobcsbound=86400.,<br>
>> spongeThickness=40.,<br>
>> &<br>
>> <br>
>> Thanks in advance!<br>
>> Andreas<br>
>> <br>
>> <br>
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