Price Mixed Layer: How do you detrain??

[Raghuram G Murtugudde]

I am trying to do the mixed layer using Price's bulk Richardson number
criterion. It is very simple and is as follows:

Ri_b = g*(delta rho) * h/ rho_0 / (delta u)**2

where delta is the difference between the mixed layer and the level below.
Rho_0 is a reference density,and h is the mixed layer depth.

Price says Ri_b >= 0.65 so entrain if Ri_b < 0.65.

I tried to detrain mass from the mixed layer if Ri_b >0.65 because then
there isn't enough shear to keep the mixed layer that deep. But this causes
a lot of problem for me because of very high frequency oscillations
(entrainment in in one-step and detrainment the next).

Does anybody have any ideas? I can not figure out how Price detrains.

Thanks in advance for all the help.

Ragu

[tmat...@kean.ucs.mun.ca]

In article <1993Jun24.2...@news.columbia.edu>, rg...@cunixf.cc.columbia.edu (Raghuras in advance for all the help.

[Request deleted]

Sorry, this is not a solution to your problem, I am also working on the
Price model, but for biological modelling.

The model presents some weakness on the simulation of the mixed layer
during the winter, and I will be interested to know if you met the same
problem ( it seems you did).

It would be great if you can send to me an explanation to go through this
difficulty.

-Thierry

_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
Thierry Mathieu tmat...@crosby.physics.mun.ca
Memorial University tmat...@kean.ucs.mun.ca
of Newfoundland
Ocean Sciences Centre
Canada
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[ind...@ac.dal.ca]

>
> The model presents some weakness on the simulation of the mixed layer
> during the winter, and I will be interested to know if you met the same
> problem ( it seems you did).
>
> It would be great if you can send to me an explanation to go through this
> difficulty.
>
> -Thierry
>
> _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
> Thierry Mathieu tmat...@crosby.physics.mun.ca
> Memorial University tmat...@kean.ucs.mun.ca
> of Newfoundland
> Ocean Sciences Centre
> Canada
> -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
>

If your problem is that the model predict a shalllower ML than the observed ML
I have the answer.

According to Martin (1986), Price model can provide only a convective
adjustement of the density profile when there is no wind. During winter
when MLD is > 70 or 80 meters the shear from wind-driven current is too weak
at the base of the ML to provide much entrainment mixing.

Ravindran P
Dept of Oceanography
Dalhousie Univ
Halifax, NS, Canada