[MITgcm-support] Excess cooling at the surface layers

[Jody Klymak]

The OBCS package relaxes to TRef at the boundaries by default.  Either change this in orlanski* or set your TRef to something you would like.  If you are just forcing a surface tide, I'd set TRef to your resting stratification, and then this will be a nudge to that value.   

I have never done regional tidal modeling with MITGCM, but I would also consider using a sponge at the boundaries - Orlanski really won't stop any internal wave reflections beyond mode-1.  See Carter et al 2010 (I think)....

Cheers,  Jody



On Oct 27, 2011, at  7:18 AM, Martin Losch wrote:

> 7degC in 15days corresponds to a surface heat flux of rho*cp*7K*10m/15days > 200W/m^2 for your 10m surface layer.  That's a lot. What about other parameters, such as ETAN?
> 
> I have no experience with Orlanski BCs. As a test you could close all boundaries and see if you still loose so much heat.
> 
> Martin
> 
> 
> On Oct 27, 2011, at 1:51 PM, himansu pradhan wrote:
> 
>> Dear MITgcm users,
>> 
>> I have run my MODEL,( configured for the Bay of Bengal ) for 15days which results in a "normal end".
>> 
>> The input files are : a) 15 level Temperature and Salinity files b) Bathymetry file c) Wind stress files. I have used a Rectangular domain with z- cordinate. The Eastern, Northern and Southern bounderies of the domain are OPEN with Orlanski radiation boundary conditions.
>> 
>> After a normal end, the results of
>> 1) Velocity files have a reasonable magnitude and the circulation is satisfactory ( velocity_OUTPUT_15thday.jpg)...... this is OK.....
>> 
>> 2) but, ??????  the sea surface temperature (OUTPUT_temp_15thday.jpg) after 15 day model integration drops almost by  4-7 degrees   from the initial surface temp (input file:- initial_temp.jpg)
>> The drop of temperature is almost everywhere in the region . 
>> 
>> Also, at the eastern and southern open boundaries the temperature contours seems to be squeezed at some regions as seen in the figure......... i am unable to figure out what is happening here.........???????
>> 
>> OUTPUT_vertical_temp_profile.jpg : - shows depth-time graph of temperature (at one arbitrary point in my region)...... It is seen that the contours shoots up unreasonably ............??????
>> 
>> Do kindly help with any suggestions, hints, clues.................
>> 
>> My data files , input plot of temperature and salinity and output velocity, temperature files are attached in this mail.
>> 
>> Thanking You in advance
>> 
>> Himansu Pradhan
>> Research Scholar, IIT Delhi
>> India. <hi.tar.gz>_______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
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> 
> 
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--
Jody Klymak    
http://web.uvic.ca/~jklymak/