Ice suppression on child grid fails when writing restarts through XIOS

Versions v4.2.x
1

Hi!

For the following I’m applying NEMO 4.2.2 and XIOS2 (rev2634)

I am running a nested configuration consisting of a global parent grid with one child (1) at this level and a therein embedded secondary child (2 ; grandchild) - a nest in a nest.

Both parent and child (1) cover regions where ice can appear while the grandchild (2) is in an ice-free region. Consequently I’d like to suppress the ice model on the gandchild grid (nn_ice =0 in 2_namelist_cfg). This works fine until restarts are written. I’m using xios to read and write restarts and somehow an unknown context for the ice restart for the grandchild is tried to be accessed:

In file "iccontext.cpp", function "void cxios_context_handle_create(xios::CContext **, const char *, int)", line 54 -> Context 2_^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ unknown

I tried to find the correct location in the code to make it dependent from the actual grid’s nn_ice but could not find it yet. Any advice on how to fix this, is very much appreciated.

Notes: setting nn_ice = 2 also for the granchild works fine but reduces performance substantially.

Thank you!
Franziska

2

I think the problem comes from these lines in stpmf.F90

      IF( kstp + nn_fsbc - 1 == nitrst .AND. lwxios ) THEN
#if defined key_si3
                             CALL iom_swap(                     cw_icerst_cxt )
                             CALL iom_init_closedef(            cw_icerst_cxt )
                             CALL iom_setkt( kstp - nit000 + 1, cw_icerst_cxt )
#endif

Could you try to add a test on nn_ice in the IF statement ?

      IF( kstp + nn_fsbc - 1 == nitrst .AND. lwxios ) THEN
#if defined key_si3
         IF( nn_ice == 2 ) THEN
                             CALL iom_swap(                     cw_icerst_cxt )
                             CALL iom_init_closedef(            cw_icerst_cxt )
                             CALL iom_setkt( kstp - nit000 + 1, cw_icerst_cxt )
         ENDIF
#endif
         IF( ln_abl      ) THEN
                             CALL iom_swap(                     cw_ablrst_cxt )
                             CALL iom_init_closedef(            cw_ablrst_cxt )
                             CALL iom_setkt( kstp - nit000 + 1, cw_ablrst_cxt )
         ENDIF
      ENDIF
3

Thanks @smasson, that solved the problem. :+1:

4

This also needs to be implemented in NEMO 5 (stpmlf.F90 and stprk3.F90).

Tested and approved for MLF using IF( nn_ice /=0 ) instead of IF( nn_ice ==2 )