Setting up general orthogonal curvilinear grid

[jagoosw]

Hi all,

I was wondering if it is currently possible to setup general orthogonal curvilinear grids like the ones described in this paper. E.g.:

I am attempting to replicate this grid which provides:

LATITUDE_T                                                DOUBLE                       LATITUDE_T                                                
LATITUDE_V                                                DOUBLE                       LATITUDE_V                                                
YC                                                        FLOAT                        LONGITUDE_T LATITUDE_T                                    
HFACC                                                     FLOAT                        LONGITUDE_T LATITUDE_T DEPTH_T                            
LATITUDE_T_bnds                                           DOUBLE                       bnds LATITUDE_T                                           
HFACW                                                     FLOAT                        LONGITUDE_U LATITUDE_T DEPTH_T                            
DEPTH_T_bnds                                              DOUBLE                       bnds DEPTH_T                                              
LONGITUDE_U                                               DOUBLE                       LONGITUDE_U                                               
LONGITUDE_T                                               DOUBLE                       LONGITUDE_T                                               
DEPTH_T                                                   DOUBLE                       DEPTH_T                                                   
XG                                                        FLOAT                        LONGITUDE_U LATITUDE_V                                    
DYG                                                       FLOAT                        LONGITUDE_U LATITUDE_T                                    
YG                                                        FLOAT                        LONGITUDE_U LATITUDE_V                                    
LATITUDE_V_bnds                                           DOUBLE                       bnds LATITUDE_V                                           
DXG                                                       FLOAT                        LONGITUDE_T LATITUDE_V                                    
XC                                                        FLOAT                        LONGITUDE_T LATITUDE_T                                    
DXC                                                       FLOAT                        LONGITUDE_T LATITUDE_V                                    
DYC                                                       FLOAT                        LONGITUDE_U LATITUDE_T                                    
HFACS                                                     FLOAT                        LONGITUDE_T LATITUDE_V DEPTH_T                            

##### Attributes #####

Variable                            Name                                Value                                                                   
-------------------------------------------------------------------------------------------------------------------------------------------------
global                              history                             FERRET V6.62   23-Jan-13                                                
global                              Conventions                         CF-1.0                                                                  
LATITUDE_T                          units                               degrees_N                                                               
LATITUDE_T                          long_name                           Latitude on T grid                                                      
LATITUDE_T                          axis                                Y                                                                       
LATITUDE_T                          point_spacing                       uneven                                                                  
LATITUDE_T                          bounds                              LATITUDE_T_bnds                                                         
LATITUDE_V                          units                               degrees_N                                                               
LATITUDE_V                          long_name                           Latitude on V grid                                                      
LATITUDE_V                          axis                                Y                                                                       
LATITUDE_V                          point_spacing                       uneven                                                                  
LATITUDE_V                          bounds                              LATITUDE_V_bnds                                                         
YC                                  missing_value                       -1.0e34                                                                 
YC                                  history                             From 0000000000                                                         
YC                                  long_name                           yc                                                                      
YC                                  long_name_mod                       Y-coordinate of center of cell                                          
YC                                  _FillValue                          -1.0e34                                                                 
YC                                  description                         Y-coordinate of center of cell                                          
HFACC                               missing_value                       -1.0e34                                                                 
HFACC                               history                             From 0000000000                                                         
HFACC                               long_name                           hfacc                                                                   
HFACC                               long_name_mod                       cell open-depth center                                                  
HFACC                               _FillValue                          -1.0e34                                                                 
HFACC                               description                         cell open-depth center                                                  
HFACW                               missing_value                       -1.0e34                                                                 
HFACW                               history                             From 0000000000                                                         
HFACW                               long_name                           hfacw                                                                   
HFACW                               long_name_mod                       cell open-depth west face                                               
HFACW                               _FillValue                          -1.0e34                                                                 
HFACW                               description                         cell open-depth west face                                               
LONGITUDE_U                         units                               degrees_W                                                               
LONGITUDE_U                         long_name                           Longitude on U grid                                                     
LONGITUDE_U                         axis                                X                                                                       
LONGITUDE_U                         point_spacing                       even                                                                    
LONGITUDE_U                         modulo                              360.0                                                                   
LONGITUDE_T                         units                               degrees_W                                                               
LONGITUDE_T                         long_name                           Longitude on T grid                                                     
LONGITUDE_T                         axis                                X                                                                       
LONGITUDE_T                         point_spacing                       even                                                                    
LONGITUDE_T                         modulo                              360.0                                                                   
DEPTH_T                             units                               meters                                                                  
DEPTH_T                             long_name                           Depth of T grid points                                                  
DEPTH_T                             axis                                Z                                                                       
DEPTH_T                             point_spacing                       uneven                                                                  
DEPTH_T                             positive                            down                                                                    
DEPTH_T                             bounds                              DEPTH_T_bnds                                                            
XG                                  missing_value                       -1.0e34                                                                 
XG                                  history                             From 0000000000                                                         
XG                                  long_name                           xg                                                                      
XG                                  long_name_mod                       X-coordinate of corner of cell                                          
XG                                  _FillValue                          -1.0e34                                                                 
XG                                  description                         X-coordinate of corner of cell                                          
DYG                                 missing_value                       -1.0e34                                                                 
DYG                                 history                             From 0000000001                                                         
DYG                                 long_name                           dyg                                                                     
DYG                                 long_name_mod                       Cell face separation in Y along western cell wall (m)                   
DYG                                 _FillValue                          -1.0e34                                                                 
DYG                                 description                         Cell face separation in Y along western cell wall (m)                   
YG                                  missing_value                       -1.0e34                                                                 
YG                                  history                             From 0000000000                                                         
YG                                  long_name                           yg                                                                      
YG                                  long_name_mod                       Y-coordinate of corner of cell                                          
YG                                  _FillValue                          -1.0e34                                                                 
YG                                  description                         Y-coordinate of corner of cell                                          
DXG                                 missing_value                       -1.0e34                                                                 
DXG                                 history                             From 0000000001                                                         
DXG                                 long_name                           dxg                                                                     
DXG                                 long_name_mod                       Cell face separation in X along southern cell wall (m)                  
DXG                                 _FillValue                          -1.0e34                                                                 
DXG                                 description                         Cell face separation in X along southern cell wall (m)                  
XC                                  missing_value                       -1.0e34                                                                 
XC                                  history                             From 0000000000                                                         
XC                                  long_name                           xc                                                                      
XC                                  long_name_mod                       X-coordinate of center of cell                                          
XC                                  _FillValue                          -1.0e34                                                                 
XC                                  description                         X-coordinate of center of cell                                          
DXC                                 missing_value                       -1.0e34                                                                 
DXC                                 history                             From 0000000000                                                         
DXC                                 long_name                           dxc                                                                     
DXC                                 long_name_mod                       Cell center separation in X across western cell wall (m)                
DXC                                 _FillValue                          -1.0e34                                                                 
DXC                                 description                         Cell center separation in X across western cell wall (m)                
DYC                                 missing_value                       -1.0e34                                                                 
DYC                                 history                             From 0000000000                                                         
DYC                                 long_name                           dyc                                                                     
DYC                                 long_name_mod                       Cell center separation in Y across southern cell wall (m)               
DYC                                 _FillValue                          -1.0e34                                                                 
DYC                                 description                         Cell center separation in Y across southern cell wall (m)               
HFACS                               missing_value                       -1.0e34                                                                 
HFACS                               history                             From 0000000000                                                         
HFACS                               long_name                           hfacs                                                                   
HFACS                               long_name_mod                       cell open-depth south face                                              
HFACS                               _FillValue                          -1.0e34                                                                 
HFACS                               description                         cell open-depth south face     

It seems like it should be possible with OrthogonalSphericalShellGrid but I can't work out exactly how to do it. I think that LATITUDE_T should be λᶜᶜᵃ etc. which means that all of these:

λᶜᶜᵃ :: A,  λᶠᶜᵃ :: A,  λᶜᶠᵃ :: A,  λᶠᶠᵃ :: A,
φᶜᶜᵃ :: A,  φᶠᶜᵃ :: A,  φᶜᶠᵃ :: A,  φᶠᶠᵃ :: A, zᵃᵃᶜ :: R, zᵃᵃᶠ :: R,
Δxᶜᶜᵃ :: A, Δxᶠᶜᵃ :: A, Δxᶜᶠᵃ :: A, Δxᶠᶠᵃ :: A,
Δyᶜᶜᵃ :: A, Δyᶜᶠᵃ :: A, Δyᶠᶜᵃ :: A, Δyᶠᶠᵃ :: A, Δz :: FT,
Azᶜᶜᵃ :: A, Azᶠᶜᵃ :: A, Azᶜᶠᵃ :: A, Azᶠᶠᵃ :: A,

look like they're provided, but some of them are 1D vectors, not 2D arrays which I assume they would need to be?

[glwagner]

@simone-silvestri is working on this

[simone-silvestri]

For the OrthogonalSphericalShellGrid all metric terms and coordinates should be two-dimensional unless you are willing to construct an alias and extend all relevant methods (which is a bit complicated and annoying, see #3343). If you have one-dimensional arrays you can just repeat them to make them two-dimensional.

Btw, I am working here https://github.com/simone-silvestri/OrthogonalSphericalShellGrids.jl/blob/main/src/OrthogonalSphericalShellGrids.jl at a warped grid that handles the north pole by stretching the grid so that the singularity is in Russia (if you are interested we can work together on it).
I still have a couple of issues to iron out but apart from that it looks like the grid is working well.

[glwagner]

If the metrics are 1D, doesn't that mean this is some flavor of LatitudeLongitudeGrid?

It would be nice to provide a feature that allows us to construct a LatitudeLongitudeGrid with a shifted pole, eg just through keyword arg in the constructor...

[jagoosw]

Thank you both this is very helpful, I've made some progress in constructing one of the ORAC tripolar grids from this MIT GCM run which I think I've nearly succeeded in except for some erroneous NaN filling of the metrics on the land/sea borders.

I'll keep you posted and share when I get it working.

Edit: the GECCO2 grid looks like it works fine out of the box (just is lower resolution so would be nice to find a grid file for GECCO3 that doesn't have the metrics in land areas all filled with NaNs)

[glwagner]

@jagoosw strongly suggest you contribute this to Simone's package!

[glwagner]

We should really discuss over there on a relevant PR but one question here: you're saying the metrics are filled with NaN? I think it'll be hard to recover those, and that's quite annoying! Or is the problem that the initial condition does not cover all wet / active cells? We need tools for fixing that latter problem, and it'd be best to put it in ClimaOcean I think

[jagoosw]

The problem here was that a different group (GECCO I think) provided grids with large holes of NaN values in the in-active metrics, but I've solved this by finding a more complete grid file.

[jagoosw]

Hi both, sorry for the delay getting back to you on this I had to work on other things, but just as a quick update:

I think I've got the ORCA025 grid correctly working now - the main pain was the north fold boundary but I've got that sorted now. Previously there was a scar across the seam but I've finally worked out how to replicate their boundary condition correctly as you can see in these maps of surface divergence.

And the maximum surface divergence is 9.074297719206137e-5 which seems reasonable.

So far this is just a bunch of scripts but I will put it is useful. @simone-silvestri do you think your package is the best place for this?

I would also hope that the same code would work for different MITgcm tripolar grids, as is at least for ORCA2 1/4 and 1/12 since they have the same northern boundary condition.

[glwagner]

Wow that's amazing

[simone-silvestri]

Looks very good! If you want to contribute this grid to the package I was thinking it might be a good idea to migrate it to the CliMA organization. In this way, we can have a lightweight registered package containing the grids that can be used by ClimaOcean

[simone-silvestri]

@jagoosw do you have slack? Maybe it is easier for us to coordinate there