[MITgcm-support] Vertical heat balance in the ocean

[Shatwell, Peter A]

Hello helpful MITgcm community,

I’m using the DDrake coupled configuration with a cube-sphere (C24) grid with 15 vertical levels (more details in Ferreira et al. 2010, https://doi.org/10.1175/2009JCLI3197.1), and I am trying to close the vertical heat balance in the model ocean.

I have computed vertical profiles of the advective vertical heat flux (diagnostic ADVr_TH) and the total diffusive vertical heat flux (diagnostics DFrE_TH and DFrI_TH). These advective and diffusive fluxes almost exactly balance throughout the water column (see attached figure), consistent with the traditional ‘upwelling-diffusion’ vertical balance of Munk ’66 and others (I’ve plotted it such that a positive flux is downwards i.e. a warming effect).

However, there is a strong departure from this balance in the top ~130 m of the ocean, indicating strong net upward cooling. Apparently penetrating shortwave radiation in the model could balance this cooling, but I am not sure how to properly confirm this. Are there existing model diagnostics to plot the shortwave penetration? Or could I estimate it from other outputs?

Or is there something else that could provide a warming effect near the ocean surface? Or should I expect this balance to even hold at all?

Thanks and all the best,

Peter

--
Peter Shatwell
PhD student at MPECDT
Space and Atmospheric Physics
Imperial College London
Huxley 714
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