[MITgcm-support] Mixed layer depth from 1deg grid, global ocean simulation

[Krishnakumar Rajagopalan]

Hi All,

I found a good publication, COREs  (by Griffies et. al)  that show MLD computed by some OGCMs and observed. And there is good agreement between the MITgcm results and that of other models. Martin had actually pointed me to this reference sometime ago, for lambda salt. I should have done a better literature search. My apologies.

Cheers

Krishnakumar



________________________________
 From: Krishnakumar Rajagopalan <krishna_raj_2010 at yahoo.com>
To: "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org> 
Sent: Monday, September 17, 2012 11:27 AM
Subject: [MITgcm-support] Mixed layer depth from 1deg grid, global ocean simulation
 

Hi All,

We have  results  of Mixed Layer Depth (MLD)  from a 1deg grid configured for global ocean simulation after a spin up of 2000 years. The grid has 23 levels with successive (downward) layer thicknesses of 10m, 10m, 15m , 20m, ... , 500m, 500m. In Figure1,  subfigures  a(i) and a(ii) show the MLD in February and June respectively from Monterey and Levitus, 1997 (ML1997), in the Pacific Ocean.  Subfigure b(i) and b(ii) show results from MITgcm computations for the same months.  In all cases the MLD has been computed with a density change from the ocean surface of 0.125 (sigma units). In February (winter season in northern hemisphere), MITgcm results seem to underpredict the MLD in the North Eastern Pacific whereas it overestimates MLD near the sea off Japan. However in
 the summer season (June) , the differences between the two (ML1997 and MITgcm) are much smaller. (For the other months in the year, the differences in MLD range roughly from those between February and June). 

The configuration for the global simulation closely resembles that of Gael Forget (JPO; June 2010) .We are also using the KPP scheme and the GMREDI scheme, both in the default mode as Gael Forget had done. (I am attaching the data, data.gmredi data.pkg files here. Please note that although the data file is configured for sources/sinks, these are not currently switched on in the model runs. We are also not modeling the sea ice). The forcing is similar to the 4deg global_ocean_simulation tutorial except that a Qsw field (Fig 2 shows the annual Qsw field) is also used since the KPP
 scheme is switched on. The zonal and meridional wind stresses are from the DaSilva database. 


We would love to hear your comments on the difference in MLD between MITgcm model results and ML1997. Also is there any publication that focuses on MLD results from MITgcm global simulations?


Thanks a lot


Best regards


Krishnakumar

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