Opened 3 months ago

Last modified 3 months ago

#2505 new Defect

NESTING tools: Bathymetry at bdy of AGRIF-nest is not consistent with parent bathymetry

Reported by: andrea.gierisch Owned by: systeam
Priority: low Milestone:
Component: AGRIF Version: release-4.0
Severity: minor Keywords: AGRIF, NESTING, release-4.0.2
Cc: andrea.gierisch

Description

Context

I use release4.0.2/tools/NESTING (revision 12273) to create an AGRIF nest. When running NEMO4.0.2 with the resulting 1_domain_cfg.nc and domain_cfg_updated.nc, an error message says that the bathymetry at the boundary is not consistent between child and parent:

 ERROR bathymetry merge at the southern border ji,jj,jk          44           2          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          45           2          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          46           2          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          44           3          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          45           3          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          46           3          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          44           4          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          45           4          37
   6.70534153693853        34.8481484050435     
 ERROR bathymetry merge at the southern border ji,jj,jk          46           4          37
   6.70534153693853        34.8481484050435     

Analysis

Reason for the error message: e3t_0 differs for 1 coarse grid cell and the according 9 fine grid cells.
The same grid cell was mentioned in the output of agrif_create_bathy.exe saying that an isolated ocean grid cell had been removed at level 37. I suspected that something goes wrong when removing the isolated ocean grid cells in combination with updating the parent grid, and therefore I commented out the respective calls to bathymetry_control:

  • src/agrif_create_bathy.f90

     
    326326  ! compute G0%gdepw_ps and G1%gdepw_ps 
    327327  CALL get_partial_steps(G0)  
    328328  CALL get_partial_steps(G1) 
    329   CALL bathymetry_control(G0%Bathy_level) 
     329  ! CALL bathymetry_control(G0%Bathy_level) 
    330330   
    331331  ! --------------------------------------- 
    332332  ! Bathymetry at the boundaries (npt_copy)                       
  • src/agrif_partial_steps.f90

     
    210210!!$ 
    211211!!$    ENDIF 
    212212 
    213     CALL bathymetry_control(grid%bathy_level) 
     213    ! CALL bathymetry_control(grid%bathy_level) 
    214214    ! 
    215215    ! initialization to the reference z-coordinate 
    216216    !  

This work-around fixes the inconsistency between 1_domain_cfg.nc and domain_cfg_updated.nc. However, I don't know what bad side-effect my crude "fix" introduces. Hence, I hope that someone with more insight into NESTING can suggest a better fix.
If it helps, I can share my namelists etc. and a screenshot of the faulty e3t_0 variable.

Recommendation

Just some guesses/ideas:

  • Update the parent/child bathymetry after having removed isolated ocean cells from the child/parent grid?
  • Or restrict bathymetry_control to run only in the inner domain of the child and not on those grid cells along the boundary which should have the exact same bathymetry as the parent?

Commit History (0)

(No commits)

Attachments (3)

e3t_lev37_child-domain.png (1.1 KB) - added by andrea.gierisch 3 months ago.
e3t of child domain
e3t_lev37_parent-domain_zoom.png (1.8 KB) - added by andrea.gierisch 3 months ago.
e3t of parent domain
namelist_nest1 (2.4 KB) - added by andrea.gierisch 3 months ago.

Download all attachments as: .zip

Change History (5)

Changed 3 months ago by andrea.gierisch

e3t of child domain

Changed 3 months ago by andrea.gierisch

e3t of parent domain

comment:1 Changed 3 months ago by jchanut

Andrea, could you provide the namelist used by the NESTING tool, please ? Jérôme

Changed 3 months ago by andrea.gierisch

comment:2 Changed 3 months ago by andrea.gierisch

Sure, Jérôme, I have attached it now.
Thanks for looking into this issue!

PS: Do you know what I need to do in order to tell this trac-system here to send me an e-mail whenever there is a new comment to my ticket? My name is added to to the "CC"-field of this form, but I nevertheless didn't receive a notification about your reply…
Edit: OK, I got a notification about my own comment now, so it seems to work in principle. Maybe the e-mail about your comment just got lost or so.

Last edited 3 months ago by andrea.gierisch (previous) (diff)
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