[MITgcm-support] Diffusive flux at bottom boundary

[钱钰坤]

Hi all,


I run an idealized simulation with a bump topography in the x-z plane to
see the mixing effects associated with the current-topography interaction.


I get the vertical diffusive flux of potential temperature (diagnostics of DFrE_TH)
at the final step as:



which indicates that there is a spuriously large heating/cooling of temperature
at the bottom grid points.  This is somewhat weired to me.  I guess it is caused
by the verical finite difference of temperature field as kv*(TH[k+1]-TH[k]), where
TH[k+1] is zero below the surface of topography and hence very large gradient
of temperature.


If this is intended, I get very large tendency of TH due to diffusion at the surface
of topography by taking the finite difference as (DFrE_TH[k+1]-DFrE_TH[k]).
However, I am expecting that the topography does not heat the fluid.


So how to explain this?



 Best regards 
 
Yu-Kun Qian (钱钰坤) 
Center for Monsoon and Environment Research 
 Department of Atmospheric Sciences
School of Environmental Science and Engineering 
 Sun Yat-sen University 
No. 135 Xingang West Road, Haizhu District 
Guangzhou, 510275, P.R. China 
Tel; 020-84115227 
Email: qianyk at mail3.sysu.edu.cn      


 
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