[MITgcm-support] Re: nonHydrostatic

[Geoffroy Aubry]

Dimitris Menemenlis a écrit :
> Christopher, thank you for explanation.  This is then the answer to 
> Geoffroy's conundrum.  That is, since the only bathymetric feature in 
> his domain is a thin vertical wall that does not come all the way to the 
> surface, salinity is everywhere uniform, and temperature is stably 
> stratified and horizontally homogeneous, I can imagine that his 
> circulation would be marginally stable, meaning that it may be possible 
> to relax to a uniform stratification simply via the explicit diffusion 
> terms, horizontal and vertical, without exciting any motion.  The 
> slightest disturbance to this equilibrium, however, e.g., truncation 
> errors in the salinity diffusion equation, could initiate vertical 
> convection events and currents, exactly as Geoffroy observed.  D.

Hi,

Thank you both for your answers. But there is still something I don't 
understand. First of all, if I do an experiment with vertical 
diffusivities of 10^-5 both for salinity and temperature, I get 
something which can't be physical (velocities of 4m.s^-1). And then, 
when the salinity diffusivity is zero, but not the temperature 
diffusivity, I don't get any velocities. But I still suppose that if I 
wait enough time, I will get a uniform temperature field, but only by a 
diffusive process.
So the thing I don't understand is : why does the salt diffusivity have 
any influence when the salinity is uniform?

-- 
Geoffroy