release-noresm2.0.11: Capability to run the SST pacemaker experiments

cime_config/usermods_dirs/n1850_SST_pacemaker_Kuroshio/Readme.md

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+**Important usage Notes**
+
+External data format:
+
+The external SST file and pcmask must match the model domain and resolution.
+
+External SST file dimensions: (y, x, time)
+
+Time Handling:
+
+SST is applied at the current model timestep via the send buffer. Thus the time index (nstep_strm) should be aligned. (line 451 in ocn_comp_mct.F90)
+
+Branch runs:
+
+If starting from a specific model year (e.g., year 1320), the time index nstep_strm must account for prior simulation years. That is,
+
+nstep_strm = int(time) - int(time0) - 481434 ! (corresponding to year 1319 * 365 - 1)
+
+Hybrid runs:
+
+No special alignment is required; the time index can be set relative to the model start
+
+nstep_strm = int(time) - int(time0) - 1
+
+The current implementation hard-codes the time index for reading SST. We are trying to fix this with a dynamic approach that calculates the correct time index automatically, avoiding the need for hard-coded values.
+
+Mask Replacement:
+
+To run SST pacemaker experiments in a different region, provide a new mask file and update the pcmask variable.

cime_config/usermods_dirs/n1850_SST_pacemaker_Kuroshio/SourceMods/src.blom/Readme.md

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+Small modifications were made to the BLOM source code to enable reading and initialization of the pacemaker mask variable (pcmask) from an external NetCDF file.
+These updates allow BLOM to include region-specific SST forcing (overiding the BLOM SST) directly during grid initialization.
+
+Files Modified:
+
+1. mod_grid.F90
+
+  Added declaration of the new variable pcmask to the grid module.
+
+  Ensures the mask is initialized together with other grid variables in inivar_grid().
+
+2. geoenv_file.F
+
+  Updated to read the pacemaker_mask variable from the pacemaker_mask.nc file.
+
+  Integrated pcmask loading alongside other grid fields.
+
+  Ensures the mask is available globally after grid initialization.
+
+Description of pcmask:
+
+  Variable name: pcmask
+
+  Source file: pacemaker_mask.nc
+
+The mask has 1.0 in the core of the pacemaker region to 0.0 at the edges of the region (smooth tapering).
+
+Current configuration:
+
+The mask is set for the Kuroshio region in the North Pacific.
+
+Location of the file: 
+
+  /cluster/work/users/hra063/So_t/pacemaker_mask.nc