iceberg trajectory file name

[mathiot]

Context

• With eORCA025, after 30 years the trajectory data can’t be written anyway as it runs out of characters in its file name string. So in eORCA12, it could be about 10 years and in eORCA1 about 120 years.
• The tag used in the iceberg trajectory file name is time step based. It makes it very hard not to overwrite the data when doing an NRUN (as Matthew Menary is doing now).
• Complication to process these files later on.

Analysis

This affect NEMO3.6_STABLE and the trunk when the iceberg model is used and the trajectory saved.

Fix

A possible fix could be to replace in icbtrj.F90:

       IF( lk_mpp ) THEN   ;   WRITE(cl_filename,'("trajectory_icebergs_",I6.6,"_",I4.4,".nc")') ktend, narea-1
       ELSE                ;   WRITE(cl_filename,'("trajectory_icebergs_",I6.6         ,".nc")') ktend

by something like this:

      ! compute initial time step date
      CALL ju2ymds( fjulday, iyear, imonth, iday, zsec )
      WRITE(cldate_ini, '(i4.4,2i2.2)') iyear, imonth, iday

      ! compute last time step date
      zfjulday = fjulday + rdttra(1) / rday * REAL( nitend - nit000 + 1 , wp)
      IF( ABS(zfjulday - REAL(NINT(zfjulday),wp)) < 0.1 / rday )   zfjulday = REAL(NINT(zfjulday),wp)   ! avoid truncation error
      CALL ju2ymds( zfjulday, iyear, imonth, iday, zsec )
      WRITE(cldate_end, '(i4.4,2i2.2)') iyear, imonth, iday

      ! define trajectory output name
      IF( lk_mpp ) THEN   ;   WRITE(cl_filename,'("trajectory_icebergs_",A,"-",A,"_",I4.4,".nc")') TRIM(ADJUSTL(cldate_ini)), TRIM(ADJUSTL(cldate_end)), narea-1
      ELSE                ;   WRITE(cl_filename,'("trajectory_icebergs_",A,"-",A         ,".nc")') TRIM(ADJUSTL(cldate_ini)), TRIM(ADJUSTL(cldate_end))
      ENDIF
      IF ( lwp .AND. nn_verbose_level >= 0) WRITE(numout,'(2a)') 'icebergs, icb_trj_init: creating ',TRIM(cl_filename)

[mathiot]

Change committed in revision 8080 and 8081.