Re: [ferret_users] Regridding from a regular grid to natural coordinates defined by along/cross isotherms, isobars, bathymetry, streamlines etc.

[Ryo Furue <furue@xxxxxxxxxx>]

Hi Sybren,

It's just occurred to me that curve linear coordinates may be what you want.  You can make plots using the "SHADE var, lon, lat" form (https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/working-with-special-data-sets/CURVILINEAR-COORDINATE-DATA) to plot your variable in your curve linear coordinates and you can even regrid it onto your coordinates using CURV_TO_RECT_MAP (https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/appendix-a-external-functions/CURV-TO-RECT-MAP).  Perhaps I should explore this avenue next time.

Ryo

 

Van: Ryo Furue <furue@xxxxxxxxxx>
Datum: dinsdag, 4 mei 2021 om 18:19
Aan: Drijfhout, S.S. (Sybren) <s.s.drijfhout@xxxxx>
CC: ferret_users@xxxxxxxx <ferret_users@xxxxxxxx>
Onderwerp: Re: [ferret_users] Regridding from a regular grid to natural coordinates defined by along/cross isotherms, isobars, bathymetry, streamlines etc.

Hi Sybren,

 

In theory I have to map xv(i,j) to xvnew(I,jstar)  with jstar=j-j1

Ferret wants me to define a new y-axis but does not allow me to define ystar by a let command, and using j and ja gives errors because of recursive problems.  

Has anybody experience with regridding to something like streamline-coordinates and/or does anybody know how to perform such a regridding operation in ferret?

 

I do that using Fortran. I didn't even consider using Ferret. . . . But I guess you can at least define xstar(i) and ystar(i) for a single curve.  Then you can get the values along the curve using the SAMPLEXY(var, xstar, ystar) function.  Save the result and move on to the next curve. . . . Finally, you combine these "layers" in the ystar direction.

 

In my Fortran code, I just shift the array in the j direction by j1.

 

Regards,

Ryo

 

 

 

Sybren