Merge branch 'jonbob/cime/fix-highres-grid' (PR #1384)

Add entry for ne120np4_oRRS18to6v3_ICG to config_grids.xml

This PR adds an entry for the ne120np4_oRRS18to6v3_ICG grid to
config_grids.xml, which was inadvertently left out from the high-res
configuration. It also includes a domain definition for the
corresponding ocn/ice grid, oRRS18to6v3_ICG.

[BFB]

cime_config/acme/config_grids.xml

@@ -490,6 +490,12 @@
       <alias>ne30_oECv3_ICG</alias>
     </grid>
 
+    <grid compset="(CAM5.+CLM.+MPASO%SPUNUP)">
+      <sname>ne120np4_oRRS18to6v3_ICG</sname>
+      <lname>a%ne120np4_l%ne120np4_oi%oRRS18to6v3_ICG_r%r0125_m%oRRS18to6v3_g%null_w%null</lname>
+      <alias>ne120_oRRS18v3_ICG</alias>
+    </grid>
+
     <grid compset="(DOCN|XOCN|SOCN|AQUAP)">
       <sname>ne60np4_ne60np4</sname>
       <alias>ne60_ne60</alias>
@@ -1327,6 +1333,14 @@
       <file ocn_mask="oRRS18to6v3">domain.ocn.oRRS18to6v3.170111.nc</file>
     </domain>
 
+    <domain name="oRRS18to6v3_ICG">
+      <nx>3693225</nx>
+      <ny>1</ny>
+      <desc>oRRS18to6v3_ICG is an MPAS ocean grid with a mesh density function that is roughly proportional to the Rossby radius of deformation, with 18 km gridcells at low and 6 km gridcells at high latitudes.  This version of initial conditions is spun-up from a G compset run:</desc>
+      <file ice_mask="oRRS18to6v3">domain.ocn.oRRS18to6v3.170111.nc</file>
+      <file ocn_mask="oRRS18to6v3">domain.ocn.oRRS18to6v3.170111.nc</file>
+    </domain>
+
 
     <!-- ROF (river) grids-->