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

[Krishnakumar Rajagopalan]

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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