I am using a sigma-level ocean model, so that I have dh (layer thicknesses), salinity and bathymetry (bottom depth) for some area (lon-lat box). Now, I would like to calculate the amount of salt at different depth-ranges, so I need to interpolate the salinity to different z-levels. If I do some simple linear interpolation of the profiles, the mass is not conserved and the total amounts from original data and new interpolated data differ.

What is the best way to interpolate the sigma-levels to z-levels so that the mass is conserved in the end?

  • $\begingroup$ You cab use some interpolation routine that hydrodynamic models are already using. For instance, you could take the RELAX routine from HYCOM (hycom.org/attachments/063_hycom_users_guide.pdf, Section 9.3) and use that directly. It uses Rainer Bleck's approach to piecewise constant fields. $\endgroup$
    – arkaia
    Commented Apr 12 at 7:11


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