Net surface heat and freshwater flux variables

Hi Folks,

I am interested in using ACCESS OM-2 output to force surface conditions of an Antarctic regional model.

In particular, I would need the net heat flux into the ocean surface, taking into account atmspheric exchange + heat exchange due to sea ice formation. For example, I can see output variables such as net-sfc-heating: surface ocean heat flux coming through coupler and mass transfer, shf-hflux-from-runoff: temperature_flux_due_to_runoff_expressed_as_heat_flux_into_sea_water - but it’s not clear from that metadata at least if I should be combining several of these fields together.

Likewise, I’d also need the net freshwater flux ‘felt’ by the ocean model, which is presumably E-P + sea ice melt/freeze. I see a few variables such as melt: water_flux_into_sea_water_due_to_sea_ice_thermodynamics, sfc_salt_flux: downward_sea_ice_basal_salt_flux, but again I’m not sure if I’m capturing all of the required components.

I have looked through the metadata, but it’s not exactly clear to me if I’m looking at the correct variables.

I’d greatly appreciate any pointers!

David Gwyther

1 Like

Hi Dave,

For heat flux, you need:
net_sfc_heating + frazil_3d_int_z

In ACCESS-OM2, the frazil heat flux is distributed in depth through the ocean (though mostly surface concentrated). The frazil_3d_int_z diagnostic is the vertical integral of this, which you could approximate as a surface flux.

For freshwater flux (mass flux of freshwater) you need:
That includes all freshwater fluxes from the atmosphere, runoff and sea ice.

You also need to account for the salt fluxes (mass flux of salt):
sfc_salt_flux_restore + sfc_salt_flux_ice

These should all be available at daily resolution for the IAF here:
If you need the heat and freshwater flux components separated out they are also available there.


Thanks @adele157 !

1 Like

Hi Adele

Where would you recommend that I look in order to understand what all of these variables represent, how they’re calculated, etc? I can see the metadata for them in netcdf files, but I was hoping there might be a more detailed explanation of all the variables and how they’re calculated? The MOM5 elements document doesn’t give specific variable info, and I can’t see anything like this in the COSIMA recipe notebooks or the access-om2 wiki.

Apologies if I’m missing something really obvious!


I’m not sure there is more info anywhere on diagnostics. I suggest asking here or looking in the code.

It might be useful to look at this example code to see how we combine the freshwater and salt fluxes when calculating surface water mass transformation.

In case anyone else has the same question, more details on the components of the surface heat budget can be found in these two posts:

1 Like