[MITgcm-support] Model loosing salt

[michael schaferkotter]

A.
can you also let us know the same informations for the temperature and surface elevation? (ie. mean temperature and mean ssh)

michael

On Apr 26, 2016, at 10:56 AM, Abhisek Chakraborty wrote:

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> Dear Martin,
> Thanks for your prompt response. Surely the atmospheric forcing is adding
> up non-zero freshwater flux. I have found the mean salinity is also
> decreasing. I am using OBCS_BALANCE with a non-zero sponge layer. I have
> tried with and without Orlanski OBC at my southern bounday but the results
> are similar. Is it always required to modify the code for balancing the
> tracers for a regional configuration of the model despite of using the
> standard OBCS package?
> With best regards,
> Abhisek
> On 26-Apr-2016 4:54 PM, "Martin Losch" <Martin.Losch at awi.de> wrote:
> 
>> Abhisek,
>> 
>> as far as I can see, you have an open boundary and you use atmospheric
>> surface forcing. Both of them will most likely have non-zero freshwater
>> flux that will change your mean salinity (btw, does the mean salinity also
>> change, or only the surface salinity as shown in your plots?). You could
>> balance the surface freshwater flux with a flag (balanceEmPmR=.TRUE.) at
>> each timestep, but you'd have to code balancing the freshwater flux
>> (implied salinity flux, salt*vVel) through the open boundary yourself.
>> 
>> Martin
>> 
>> On 04/26/2016 11:53 AM, Abhisek Chakraborty wrote:
>> 
>>> Dear All,
>>> 
>>> I am trying to configure Mitgcm (version 65r) for Bay of Bengal with a
>>> constant horizontal resolution of 2km. After 3 years of model runs
>>> (2013-2015) using daily ERA forcing, I found the model is losing
>>> salinity. The domain averaged salinity shows a decreasing trend. The
>>> trend is more prominent for the head Bay. I am using yearly run off
>>> climatology. A figure is attached to show my model domain and salinity
>>> trend.
>>> 
>>> The relevant data files are also attached.  Can anybody please help me
>>> pointing out the possible causes of this decreasing salinity trend?
>>> 
>>> Thanking in advance,
>>> Abhisek
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> MITgcm-support mailing list
>>> MITgcm-support at mitgcm.org
>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>> 
>>> 
>> --
>> Martin Losch
>> Alfred Wegener Institute for Polar and Marine Research
>> Postfach 120161, 27515 Bremerhaven, Germany;
>> Tel./Fax: ++49(0471)4831-1872/1797
>> 
>> 
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>> 
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> 
> <p dir=3D"ltr">Dear Martin,<br>
> Thanks for your prompt response. Surely the atmospheric forcing is adding u=
> p non-zero freshwater flux. I have found the mean salinity is also decreasi=
> ng. I am using OBCS_BALANCE with a non-zero sponge layer. I have tried with=
> and without Orlanski OBC at my southern bounday but the results are simila=
> r. Is it always required to modify the code for balancing the tracers for a=
> regional configuration of the model despite of using the standard OBCS pac=
> kage?<br>
> With best regards,<br>
> Abhisek</p>
> <div class=3D"gmail_quote">On 26-Apr-2016 4:54 PM, &quot;Martin Losch&quot;=
> &lt;<a href=3D"mailto:Martin.Losch at awi.de">Martin.Losch at awi.de</a>&gt; wro=
> te:<br type=3D"attribution"><blockquote class=3D"gmail_quote" style=3D"marg=
> in:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Abhisek,<br>
> <br>
> as far as I can see, you have an open boundary and you use atmospheric surf=
> ace forcing. Both of them will most likely have non-zero freshwater flux th=
> at will change your mean salinity (btw, does the mean salinity also change,=
> or only the surface salinity as shown in your plots?). You could balance t=
> he surface freshwater flux with a flag (balanceEmPmR=3D.TRUE.) at each time=
> step, but you&#39;d have to code balancing the freshwater flux (implied sal=
> inity flux, salt*vVel) through the open boundary yourself.<br>
> <br>
> Martin<br>
> <br>
> On 04/26/2016 11:53 AM, Abhisek Chakraborty wrote:<br>
> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
> x #ccc solid;padding-left:1ex">
> Dear All,<br>
> <br>
> I am trying to configure Mitgcm (version 65r) for Bay of Bengal with a<br>
> constant horizontal resolution of 2km. After 3 years of model runs<br>
> (2013-2015) using daily ERA forcing, I found the model is losing<br>
> salinity. The domain averaged salinity shows a decreasing trend. The<br>
> trend is more prominent for the head Bay. I am using yearly run off<br>
> climatology. A figure is attached to s