[MITgcm-support] calc_r_star

[Dimitris Menemenlis]

Elja, did anyone reply to your questions?

> I am using the example of the cube-sphere integration with sea-ice on the 
> cs32 grid (mitgcm_contrib/high_res_cube/README.cs32).
> 
> Now, I would like to add a tidal potential. Therefore, I added a couple of 
> lines in 'external_forcing.f' to calculate the gradient of this tidal 
> potential field, both in zonal and meridional direction, covering the entire 
> body. However, I immediately get the next error message: ABNORMAL END: S/R 
> CALC_R_STAR

One way to impose a tidal potential is to use the atmospheric pressure loading
term: "#define ATMOSPHERIC_LOADING" in CPP_OPTIONS.h and then specify it either
as pLoadFile, as apressurefile if you use pkg/exf, or by writing your own
routine to specify pload directly.

> Currently, I am using the cubed sphere coordinate system. I want to apply a
> tidal potential, which is known in spherical coordinates and I need to
> calculate the gradient of this potential field. So, first of all, I need to
> transform the potential function from spherical coordinates into cubed sphere
> coordinates. Next, I have to calculate the gradient.

I may be missing the point here but why do you want to compute the gradients? 
All you need to provide is the tidal potential, so a simple bi-linear 
interpolation to the cube-sphere grid "tracer" coordinates should suffice, no?

Dimitris