[MITgcm-support] Ferrari et al. 2010 BVP method for GM

[Christopher L. Wolfe]

Hi all,

I've implemented the boundary value method for calculating the GM eddy streamfunction as described in Ferrari et al. (Ocean Modell. 2010). I find that it produces much smoother GM overturning streamfunctions and has better interaction with unstratified regions than plain GM. The implementation introduces two new source files: gmredi_calc_psi_bvp.F solves the boundary value problem using solve_tridiagonal_W.F, which is simply solve_tridiagonal.F modified to work on W-levels.

I've included diffs which may be used to patch gmredi_calc_tensor.F, gmredi_check.F, gmredi_diagnostics_init.F, GMREDI.h, and gmredi_readparms.F. The diffs are against checkpoint61z, but these files haven't changed in months or years, so the diffs should work against later checkpoints.

The BV method can be turned on by #defining GM_BOLUS_BVP in GMREDI_OPTIONS.h or in your build file and setting GM_UseBVP = .TRUE. in data.gmredi. The BV method makes use of the advective form of GM, so GM_BOLUS_ADVEC must also be #defined and GM_AdvForm = .TRUE. set in data.gmredi.

Turning on the BV method introduces the parameters GM_BVP_ModeNumber and GM_BVP_cMin to data.gmredi and the diagnostics GM_BVPcW and GM_BVPcS, which are the WKB internal wave speeds calculated at W and S points.

If anyone has any questions or comments on the implementation, don't hesitate to contact me.

Cheers,
Christopher

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Dr. Christopher L. Wolfe              	   858-534-4560
Climate, Atmospheric Science, and Physical Oceanography
Scripps Institution of Oceanography, UCSD  clwolfe at ucsd.edu
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