regarding mixed layer depth and computation of transport

[mashinde]

Hi,

I have following questions

(1) can ROMS store mixed layer depth in a output file? Is depth of surface boundary layer (Hsbl) is same as mixed layer depth?
(2) How to compute freshwater transport(inflow, outflow and net) and it's time series ?

Thanking you

[kate]

1. Yes, Hsbl is the mixed layer depth, but it is only computed if you are using LMD_MIXING and LMD_SKPP.

2. It depends on what you mean by this. You would need a definition of "freshwater transport", say the amount of water of salinity less than some S_o times a velocity. Do you need it at a point, across some slice, what? I'm sure there must be Matlab scripts out there to do just that.

[mashinde]

Hi Kate,

Thanks for the kind reply. At present I am using GLS with epsilon option because with KPP model blows up after some days.

I am applying ROMS in the Mediterranean sea. Therefore, I want to check inflow i.e. incoming Atlantic freshwater flux and outgoing i.e. outgoing Mediterranean freshwater fluxes and thus net transport, horizontally. I am totally blank, how to compute it and what variables I can use.


Thank you

[saulo]

Hi,

Hsbl is not the mixed layer. It's the boundary layer depth as defined in the KPP parametrization paper by Large et al 94. Basically some function of the surface forcing and density and momentum profile if I'm not mistaken. You can check that by comparing Hsbl with some MLD density difference criteria. I don't think any of the mixing schemes in ROMS outputs MLD. As Kate said, Hsbl only exists for KPP.

[mashinde]

Hi,

After doing some search along with a paper by Large et. al.(1994), I found that the mixed layer depth computation by KPP is based on the critical value of turbulent processes parametrized by a bulk Richardson number. So it is not based on temp or density criterion ????
For more and short description plz see, http://mitgcm.org/public/r2_manual/late ... iagnostics

So, is it good to use mixed layer depth computed by KPP in the model for comparison ?
Is it possible for ROMS developer to add mixed layer depth computation as one of the ROMS output based on Temp or density criterion ?


Thanks

[kate]

I believe the developers would put this in the category of "something to be done in post-processing", not a "ROMS bug". That way, you can code up your favorite algorithm and you'll know exactly what quantity you are dealing with. Perhaps something close has already been done in the Matlab tools.