[MITgcm-support] Tracer equation

[Neill Mackay]

Hi all,

I am using offline MITgcm to advect a tracer in 3D with velocity fields derived from a satellite altimetry product. There are small divergences in the horizontal velocity fields, and I'm wondering what their effect might be. I've run some tests with Kz=0 and there does not appear to be any numerical diffusion going on.

In section 2.16.1 of the MITgcm manual, it states that the advection part of the advection-diffusion equation is:

nabla . (uC) - C nabla . u

where u is the velocity field and C the tracer concentration, and that the term 'C nabla . u' is "required to retain local
conservation in conjunction with the linear implicit free-surface".

So my question is, is this term still subtracted from nabla . (uC) away from the surface in the event that the divergence of u is non-zero?

Thanks,

Neill.
 

 		 	   		  
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