[MITgcm-support] Re: single layer run

[Jason Goodman]

On May 13, 2005, at 10:15 AM, Dimitris Menemenlis wrote:

> Martin wrote:
>
>> I am convinced that even in the case of constant (in time) pressure
>> forcing you should end up with a steady state that is non-zero, also
>> in the case of a single layer.
>>
>
> Martin and Sergey, I have been following your discussion with some  
> interest.  I don't understand why a constant in time surface  
> pressure forcing would establish a non-zero circulation at steady  
> state.  Isn't the inverse barometer adjustment meant to insure that  
> there is no such circulation, i.e., that (for a flat ocean) the  
> pressure at the bottom of be constant?

I'd say so.  Martin's equation

f*v + g*d(ssh)/dx + (1/rho0)*dp/dx = 0

leaves out the bottom drag term.  While it is true that a transient  
circulation parallel to atmospheric pressure contours should occur at  
first, the inclusion of a bottom-drag term means the flow will have a  
small down-pressure-gradient component.  Thus, water will pile up in  
the low-atmospheric-pressure zones, until the second two terms in  
Martin's equation balance and the flow goes to zero.  This is a  
stable solution.