[ecco-support] ECCO Mixed Layer Depths criteria

[Jean-Michel Campin]

Hi,

Just to clarify: The Kara criteria is not based on temp profile but on density profile.
So whether is temp statified of salinity stratified should not matter.
However, as pointed Martha, if thermal expansion coefficient is too small,
the density criteria might become too small.

Jean-Michel

On Tue, May 02, 2017 at 08:19:46PM -0700, Matthew Mazloff wrote:
> In the Southern Ocean (and probably the Arctic too) we often see temperature restratification lagging behind freshwater restratification. Basically initial spring/summer warming is absorbed by the latent heat of melting ice. The water column freshens at the surface but the temperature doesn???t start increasing until much of the ice has melted. I forget the lag time, but it can be something like weeks. Thus the water column has restratified but the T threshold wouldn???t record it until the ice was mostly gone 
> 
> Matt
> 
> 
> > On May 2, 2017, at 8:11 PM, Menemenlis, Dimitris (329C) <Dimitris.Menemenlis at jpl.nasa.gov> wrote:
> > 
> > Hi Martha, I don???t remember exactly why it is that we run into trouble with the Kara MLD definition in polar regions.
> > As you say below, .8 deg C corresponds to a much smaller (factor of 5 to 10) deltaRho in ice-covered oceans,
> > and maybe that???s what caused trouble.
> > 
> > 
> >> On May 2, 2017, at 6:35 PM, Martha Buckley <marthabuckley at gmail.com <mailto:marthabuckley at gmail.com>> wrote:
> >> 
> >> Thanks for pointing this out Dimitris. Is this because the variable nature of the density criteria is based on the thermal expansion coefficient, so one choses too small of a threshold in these regions?  I guess using a variable density criteria is supposed to help remove deep biases in cold regions, but if it messes up regions that have a halocline, this isn't desirable.  What do you recommend using as a MLD criteria in polar regions?
> >> thanks,
> >> Martha
> > 
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