diff --git a/cime_config/config_grids.xml b/cime_config/config_grids.xml
index 7c8eb0ff75bd..0d0ed53b9490 100755
--- a/cime_config/config_grids.xml
+++ b/cime_config/config_grids.xml
@@ -406,6 +406,16 @@
       <mask>IcoswISC30E3r5</mask>
     </model_grid>
 
+    <model_grid alias="T62_RRSwISC6to18E3r5" compset="(DATM|XATM|SATM)">
+      <grid name="atm">T62</grid>
+      <grid name="lnd">T62</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">rx1</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
     <model_grid alias="TL319_oQU240wLI" compset="(DATM|XATM|SATM)">
       <grid name="atm">TL319</grid>
       <grid name="lnd">TL319</grid>
@@ -616,6 +626,16 @@
       <mask>IcosXISC30E3r7</mask>
     </model_grid>
 
+    <model_grid alias="TL319_RRSwISC6to18E3r5" compset="(DATM|XATM|SATM)">
+      <grid name="atm">TL319</grid>
+      <grid name="lnd">TL319</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">JRA025</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
     <model_grid alias="TL319_oRRS18to6v3" compset="(DATM|XATM|SATM)">
       <grid name="atm">TL319</grid>
       <grid name="lnd">TL319</grid>
@@ -1340,6 +1360,16 @@
       <mask>IcoswISC30E3r5</mask>
     </model_grid>
 
+    <model_grid alias="ne30pg2_RRSwISC6to18E3r5">
+      <grid name="atm">ne30np4.pg2</grid>
+      <grid name="lnd">ne30np4.pg2</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">r05</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
     <model_grid alias="northamericax4v1_r0125_northamericax4v1" compset="(DOCN|XOCN|SOCN|AQP1)">
       <grid name="atm">ne0np4_northamericax4v1</grid>
       <grid name="lnd">r0125</grid>
@@ -1623,6 +1653,26 @@
       <mask>IcoswISC30E3r5</mask>
     </model_grid>
 
+    <model_grid alias="ne120pg2_r05_RRSwISC6to18E3r5">
+      <grid name="atm">ne120np4.pg2</grid>
+      <grid name="lnd">r05</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">r05</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
+    <model_grid alias="ne120pg2_r025_RRSwISC6to18E3r5">
+      <grid name="atm">ne120np4.pg2</grid>
+      <grid name="lnd">r025</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">r025</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
     <model_grid alias="ne240_ne240" compset="(DOCN|XOCN|SOCN|AQP1)">
       <grid name="atm">ne240np4</grid>
       <grid name="lnd">ne240np4</grid>
@@ -2291,6 +2341,16 @@
       <mask>IcosXISC30E3r7</mask>
     </model_grid>
 
+    <model_grid alias="ne30pg2_r05_RRSwISC6to18E3r5">
+      <grid name="atm">ne30np4.pg2</grid>
+      <grid name="lnd">r05</grid>
+      <grid name="ocnice">RRSwISC6to18E3r5</grid>
+      <grid name="rof">r05</grid>
+      <grid name="glc">null</grid>
+      <grid name="wav">null</grid>
+      <mask>RRSwISC6to18E3r5</mask>
+    </model_grid>
+
     <model_grid alias="ne30pg2_r05_WC14to60E2r3">
       <grid name="atm">ne30np4.pg2</grid>
       <grid name="lnd">r05</grid>
@@ -2601,6 +2661,7 @@
       <file grid="atm|lnd" mask="SOwISC12to60E2r4">$DIN_LOC_ROOT/share/domains/domain.lnd.T62_SOwISC12to60E2r4.210119.nc</file>
       <file grid="atm|lnd" mask="ECwISC30to60E2r1">$DIN_LOC_ROOT/share/domains/domain.lnd.T62_ECwISC30to60E2r1.201007.nc</file>
       <file grid="atm|lnd" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.T62_IcoswISC30E3r5.231121.nc</file>
+      <file grid="atm|lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.T62_RRSwISC6to18E3r5.240328.nc</file>
       <desc>T62 is Gaussian grid:</desc>
     </domain>
 
@@ -2657,6 +2718,8 @@
       <file grid="ice|ocn" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.TL319_IcoswISC30E3r5.231121.nc</file>
       <file grid="atm|lnd" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.lnd.TL319_IcosXISC30E3r7.240326.nc</file>
       <file grid="ice|ocn" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.ocn.TL319_IcosXISC30E3r7.240326.nc</file>
+      <file grid="atm|lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.TL319_RRSwISC6to18E3r5.240328.nc</file>
+      <file grid="ice|ocn" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.TL319_RRSwISC6to18E3r5.240328.nc</file>
       <file grid="atm|lnd" mask="oRRS18to6v3">$DIN_LOC_ROOT/share/domains/domain.lnd.TL319_oRRS18to6v3.220124.nc</file>
       <file grid="ice|ocn" mask="oRRS18to6v3">$DIN_LOC_ROOT/share/domains/domain.ocn.TL319_oRRS18to6v3.220124.nc</file>
       <desc>TL319 is JRA lat/lon grid:</desc>
@@ -2768,6 +2831,8 @@
       <file grid="ice|ocn" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.ne30pg2_IcoswISC30E3r5.231121.nc</file>
       <file grid="atm|lnd" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.lnd.ne30pg2_IcosXISC30E3r7.240326.nc</file>
       <file grid="ice|ocn" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.ocn.ne30pg2_IcosXISC30E3r7.240326.nc</file>
+      <file grid="atm|lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.ne30pg2_RRSwISC6to18E3r5.240328.nc</file>
+      <file grid="ice|ocn" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.ne30pg2_RRSwISC6to18E3r5.240328.nc</file>
       <file grid="atm|lnd" mask="gx1v6">$DIN_LOC_ROOT/share/domains/domain.lnd.ne30pg2_gx1v6.190806.nc</file>
       <file grid="ice|ocn" mask="gx1v6">$DIN_LOC_ROOT/share/domains/domain.ocn.ne30pg2_gx1v6.190806.nc</file>
       <desc>ne30np4.pg2 is Spectral Elem 1-deg grid w/ 2x2 FV physics grid per element:</desc>
@@ -2839,6 +2904,8 @@
       <file grid="ice|ocn" mask="ICOS10">$DIN_LOC_ROOT/share/domains/domain.ocn.ne120pg2_ICOS10.230120.nc</file>
       <file grid="atm|lnd" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.ne120pg2_IcoswISC30E3r5.231121.nc</file>
       <file grid="ice|ocn" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.ne120pg2_IcoswISC30E3r5.231121.nc</file>
+      <file grid="atm|lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.ne120pg2_RRSwISC6to18E3r5.240328.nc</file>
+      <file grid="ice|ocn" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.ocn.ne120pg2_RRSwISC6to18E3r5.240328.nc</file>
       <file grid="atm|lnd" mask="gx1v6">$DIN_LOC_ROOT/share/domains/domain.lnd.ne120pg2_gx1v6.190819.nc</file>
       <file grid="ice|ocn" mask="gx1v6">$DIN_LOC_ROOT/share/domains/domain.ocn.ne120pg2_gx1v6.190819.nc</file>
       <desc>ne120np4 is Spectral Elem 1/4-deg grid w/ 2x2 FV physics grid</desc>
@@ -3077,6 +3144,13 @@
       <desc>IcosXISC30E3r7 is a MPAS ocean grid generated with the jigsaw/compass process using a dual mesh that is a subdivided icosahedron, resulting in a nearly uniform resolution of 30 km.:</desc>
     </domain>
 
+    <domain name="RRSwISC6to18E3r5">
+      <nx>4062533</nx>
+      <ny>1</ny>
+      <file grid="ice|ocn">$DIN_LOC_ROOT/share/domains/domain.ocn.RRSwISC6to18E3r5.240328.nc</file>
+      <desc>RRSwISC6to18E3r5 is a MPAS ocean grid generated with the jigsaw/compass process using 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. Additionally, it has ocean in ice-shelf cavities:</desc>
+    </domain>
+
     <!-- ROF (river) grids-->
 
     <domain name="r2">
@@ -3111,6 +3185,8 @@
       <file grid="lnd" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_IcoswISC30E3r5.231121.nc</file>
       <file grid="atm" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_IcosXISC30E3r7.240326.nc</file>
       <file grid="lnd" mask="IcosXISC30E3r7">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_IcosXISC30E3r7.240326.nc</file>
+      <file grid="atm" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_RRSwISC6to18E3r5.240328.nc</file>
+      <file grid="lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_RRSwISC6to18E3r5.240328.nc</file>
       <file grid="lnd" mask="gx1v6">$DIN_LOC_ROOT/share/domains/domain.lnd.r05_gx1v6.191014.nc</file>
       <desc>r05 is 1/2 degree river routing grid:</desc>
     </domain>
@@ -3144,6 +3220,8 @@
       <nx>1440</nx>
       <ny>720</ny>
       <file grid="atm|lnd" mask="IcoswISC30E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.r025_IcoswISC30E3r5.240129.nc</file>
+      <file grid="atm|lnd" mask="RRSwISC6to18E3r5">$DIN_LOC_ROOT/share/domains/domain.lnd.r025_RRSwISC6to18E3r5.240402.nc</file>
+      <desc>r025 is 1/4 degree river routing grid:</desc>
     </domain>
 
     <domain name="mp120v1">
@@ -3601,6 +3679,16 @@
       <map name="ATM2OCN_FMAPNAME_NONLINEAR">cpl/gridmaps/ne30pg2/map_ne30pg2_to_IcosXISC30E3r7_trfvnp2.20240326.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="ne30np4.pg2" ocn_grid="RRSwISC6to18E3r5">
+      <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/ne30pg2/map_ne30pg2_to_RRSwISC6to18E3r5_traave.20240328.nc</map>
+      <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/ne30pg2/map_ne30pg2_to_RRSwISC6to18E3r5_trbilin.20240328.nc</map>
+      <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/ne30pg2/map_ne30pg2_to_RRSwISC6to18E3r5-nomask_trbilin.20240328.nc</map>
+      <map name="OCN2ATM_FMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_ne30pg2_traave.20240328.nc</map>
+      <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_ne30pg2_traave.20240328.nc</map>
+      <map name="ATM2ICE_FMAPNAME_NONLINEAR">cpl/gridmaps/ne30pg2/map_ne30pg2_to_RRSwISC6to18E3r5_trfvnp2.20240328.nc</map>
+      <map name="ATM2OCN_FMAPNAME_NONLINEAR">cpl/gridmaps/ne30pg2/map_ne30pg2_to_RRSwISC6to18E3r5_trfvnp2.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="ne30np4.pg3" ocn_grid="oEC60to30v3">
       <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/ne30pg3/map_ne30pg3_to_oEC60to30v3_mono.200331.nc</map>
       <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/ne30pg3/map_ne30pg3_to_oEC60to30v3_bilin.200331.nc</map>
@@ -3676,6 +3764,14 @@
       <map name="LND2ATM_SMAPNAME">cpl/gridmaps/ne30pg4/map_r05_to_ne30pg4_mono.200331.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="ne30np4.pg2" lnd_grid="r025">
+      <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_traave.20240206.nc</map>
+      <map name="ATM2LND_FMAPNAME_NONLINEAR">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_trfv2.20240206.nc</map>
+      <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_esmfbilin.20240206.nc</map>
+      <map name="LND2ATM_FMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne30pg2_traave.20240206.nc</map>
+      <map name="LND2ATM_SMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne30pg2_traave.20240206.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="ne30np4" lnd_grid="r0125">
       <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne30np4/map_ne30np4_to_r0125_mono.190801.nc</map>
       <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne30np4/map_ne30np4_to_r0125_mono.190801.nc</map>
@@ -3775,22 +3871,6 @@
       <map name="ATM2ROF_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r0125_mono.200707.nc</map>
     </gridmap>
 
-    <gridmap atm_grid="ne120np4.pg2" lnd_grid="r025">
-      <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_traave.20240206.nc</map>
-      <map name="ATM2LND_FMAPNAME_NONLINEAR">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_trfv2.20240206.nc</map>
-      <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_esmfbilin.20240206.nc</map>
-      <map name="LND2ATM_FMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne120pg2_traave.20240206.nc</map>
-      <map name="LND2ATM_SMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne120pg2_traave.20240206.nc</map>
-    </gridmap>
-
-    <gridmap atm_grid="ne30np4.pg2" lnd_grid="r025">
-      <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_traave.20240206.nc</map>
-      <map name="ATM2LND_FMAPNAME_NONLINEAR">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_trfv2.20240206.nc</map>
-      <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne30pg2_to_r025_esmfbilin.20240206.nc</map>
-      <map name="LND2ATM_FMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne30pg2_traave.20240206.nc</map>
-      <map name="LND2ATM_SMAPNAME">cpl/gridmaps/ne120pg2/map_r025_to_ne30pg2_traave.20240206.nc</map>
-    </gridmap>
-
     <gridmap atm_grid="ne120np4" ocn_grid="oRRS18to6v3">
       <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/ne120np4/map_ne120np4_to_oRRS18to6v3_mono.20200702.nc</map>
       <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/ne120np4/map_ne120np4_to_oRRS18to6v3_mono.20200702.nc</map>
@@ -3839,6 +3919,14 @@
       <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/IcoswISC30E3r5/map_IcoswISC30E3r5_to_ne120pg2_traave.20231121.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="ne120np4.pg2" ocn_grid="RRSwISC6to18E3r5">
+      <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_RRSwISC6to18E3r5_traave.20240328.nc</map>
+      <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_RRSwISC6to18E3r5_trbilin.20240328.nc</map>
+      <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_RRSwISC6to18E3r5-nomask_trbilin.20240328.nc</map>
+      <map name="OCN2ATM_FMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_ne120pg2_traave.20240328.nc</map>
+      <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_ne120pg2_traave.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="ne120np4.pg2" lnd_grid="r05">
       <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r05_mono.200331.nc</map>
       <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r05_bilin.200331.nc</map>
@@ -3846,11 +3934,24 @@
       <map name="LND2ATM_SMAPNAME">cpl/gridmaps/ne120pg2/map_r05_to_ne120pg2_mono.200331.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="ne120np4.pg2" lnd_grid="r025">
+      <map name="ATM2LND_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_traave.20240328.nc</map>
+      <map name="ATM2LND_FMAPNAME_NONLINEAR">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_trfv2.20240206.nc</map>
+      <map name="ATM2LND_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_trbilin.20240328.nc</map>
+      <map name="LND2ATM_FMAPNAME">cpl/gridmaps/r025/map_r025_to_ne120pg2_traave.20240328.nc</map>
+      <map name="LND2ATM_SMAPNAME">cpl/gridmaps/r025/map_r025_to_ne120pg2_traave.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="ne120np4.pg2" rof_grid="r05">
       <map name="ATM2ROF_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r05_mono.200331.nc</map>
       <map name="ATM2ROF_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r05_bilin.200331.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="ne120np4.pg2" rof_grid="r025">
+      <map name="ATM2ROF_FMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_traave.20240328.nc</map>
+      <map name="ATM2ROF_SMAPNAME">cpl/gridmaps/ne120pg2/map_ne120pg2_to_r025_trbilin.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="ne240np4" ocn_grid="gx1v6">
       <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/ne240np4/map_ne240np4_to_gx1v6_aave_110428.nc</map>
       <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/ne240np4/map_ne240np4_to_gx1v6_aave_110428.nc</map>
@@ -4368,6 +4469,14 @@
       <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/IcoswISC30E3r5/map_IcoswISC30E3r5_to_T62_traave.20231121.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="T62" ocn_grid="RRSwISC6to18E3r5">
+      <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/T62/map_T62_to_RRSwISC6to18E3r5_traave.20240328.nc</map>
+      <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/T62/map_T62_to_RRSwISC6to18E3r5-nomask_trbilin.20240328.nc</map>
+      <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/T62/map_T62_to_RRSwISC6to18E3r5_esmfpatch.20240328.nc</map>
+      <map name="OCN2ATM_FMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_T62_traave.20240328.nc</map>
+      <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_T62_traave.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="TL319" ocn_grid="oQU240wLI">
       <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/TL319/map_TL319_to_oQU240wLI_traave.20240509.nc</map>
       <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/TL319/map_TL319_to_oQU240wLI-nomask_trbilin.20240509.nc</map>
@@ -4512,6 +4621,14 @@
       <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/IcosXISC30E3r7/map_IcosXISC30E3r7_to_TL319_traave.20240326.nc</map>
     </gridmap>
 
+    <gridmap atm_grid="TL319" ocn_grid="RRSwISC6to18E3r5">
+      <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/TL319/map_TL319_to_RRSwISC6to18E3r5_traave.20240328.nc</map>
+      <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/TL319/map_TL319_to_RRSwISC6to18E3r5-nomask_trbilin.20240328.nc</map>
+      <map name="ATM2OCN_VMAPNAME">cpl/gridmaps/TL319/map_TL319_to_RRSwISC6to18E3r5_esmfpatch.20240328.nc</map>
+      <map name="OCN2ATM_FMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_TL319_traave.20240328.nc</map>
+      <map name="OCN2ATM_SMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_TL319_traave.20240328.nc</map>
+    </gridmap>
+
     <gridmap atm_grid="TL319" ocn_grid="oRRS18to6v3">
       <map name="ATM2OCN_FMAPNAME">cpl/gridmaps/TL319/map_TL319_to_oRRS18to6v3_aave.220124.nc</map>
       <map name="ATM2OCN_SMAPNAME">cpl/gridmaps/TL319/map_TL319_to_oRRS18to6v3_bilin.220124.nc</map>
@@ -4892,6 +5009,10 @@
       <map name="OCN2ROF_SMAPNAME">cpl/gridmaps/IcosXISC30E3r7/map_IcosXISC30E3r7_to_r05_traave.20240326.nc</map>
     </gridmap>
 
+    <gridmap rof_grid="r05" ocn_grid="RRSwISC6to18E3r5">
+      <map name="OCN2ROF_SMAPNAME">cpl/gridmaps/RRSwISC6to18E3r5/map_RRSwISC6to18E3r5_to_r05_traave.20240328.nc</map>
+    </gridmap>
+
     <gridmap rof_grid="r05" ocn_grid="EC30to60E2r2">
       <map name="OCN2ROF_SMAPNAME">cpl/cpl6/map_EC30to60E2r2_to_r05_neareststod.220728.nc</map>
     </gridmap>
@@ -5002,6 +5123,11 @@
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_rx1_to_IcoswISC30E3r5_cstmnn.r150e300.20231121.nc</map>
     </gridmap>
 
+    <gridmap ocn_grid="RRSwISC6to18E3r5" rof_grid="rx1">
+      <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_rx1_to_RRSwISC6to18E3r5_cstmnn.r50e100.20240328.nc</map>
+      <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_rx1_to_RRSwISC6to18E3r5_cstmnn.r50e100.20240328.nc</map>
+    </gridmap>
+
     <gridmap ocn_grid="oQU240wLI" rof_grid="JRA025">
       <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_JRA025_to_oQU240wLI_cstmnn.r150e300.20240516.nc</map>
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_JRA025_to_oQU240wLI_cstmnn.r150e300.20240516.nc</map>
@@ -5092,6 +5218,11 @@
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_JRA025_to_IcosXISC30E3r7_cstmnn.r150e300.20240326.nc</map>
     </gridmap>
 
+    <gridmap ocn_grid="RRSwISC6to18E3r5" rof_grid="JRA025">
+      <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_JRA025_to_RRSwISC6to18E3r5_cstmnn.r250e1250_58NS.20240328.nc</map>
+      <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_JRA025_to_RRSwISC6to18E3r5_cstmnn.r50e100.20240328.nc</map>
+    </gridmap>
+
     <gridmap ocn_grid="oRRS18to6v3" rof_grid="JRA025">
       <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_JRA025_to_oRRS18to6v3_smoothed.r50e100.220124.nc</map>
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_JRA025_to_oRRS18to6v3_smoothed.r50e100.220124.nc</map>
@@ -5182,11 +5313,21 @@
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_r05_to_IcosXISC30E3r7_cstmnn.r150e300.20240326.nc</map>
     </gridmap>
 
+    <gridmap ocn_grid="RRSwISC6to18E3r5" rof_grid="r05">
+      <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_r05_to_RRSwISC6to18E3r5.cstmnn.r250e1250_58NS.20240328.nc</map>
+      <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_r05_to_RRSwISC6to18E3r5_cstmnn.r50e100.20240328.nc</map>
+    </gridmap>
+
     <gridmap ocn_grid="IcoswISC30E3r5" rof_grid="r025">
       <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_r025_to_IcoswISC30E3r5_cstmnn.r150e300.20240401.nc</map>
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_r025_to_IcoswISC30E3r5_cstmnn.r150e300.20240401.nc</map>
     </gridmap>
 
+    <gridmap ocn_grid="RRSwISC6to18E3r5" rof_grid="r025">
+      <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_r025_to_RRSwISC6to18E3r5.cstmnn.r250e1250_58NS.20240328.nc</map>
+      <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_r025_to_RRSwISC6to18E3r5_cstmnn.r50e100.20240328.nc</map>
+    </gridmap>
+
     <gridmap ocn_grid="WC14to60E2r3" rof_grid="r0125">
       <map name="ROF2OCN_ICE_RMAPNAME">cpl/cpl6/map_r0125_to_WC14to60E2r3_smoothed.r150e300.200929.nc</map>
       <map name="ROF2OCN_LIQ_RMAPNAME">cpl/cpl6/map_r0125_to_WC14to60E2r3_smoothed.r150e300.200929.nc</map>
diff --git a/components/elm/bld/namelist_files/namelist_definition.xml b/components/elm/bld/namelist_files/namelist_definition.xml
index 0f8b03dfec38..55206b5de6b4 100644
--- a/components/elm/bld/namelist_files/namelist_definition.xml
+++ b/components/elm/bld/namelist_files/namelist_definition.xml
@@ -1423,7 +1423,7 @@ Representative concentration pathway for future scenarios [radiative forcing at
 
 <entry id="mask" type="char*20" category="default_settings"
        group="default_settings"
-       valid_values="USGS,gx3v7,gx1v6,navy,test,tx0.1v2,tx1v1,T62,TL319,cruncep,oEC60to30v3,oEC60to30v3wLI,ECwISC30to60E1r2,EC30to60E2r2,WC14to60E2r3,WCAtl12to45E2r4,SOwISC12to60E2r4,ECwISC30to60E2r1,oRRS18to6,oRRS18to6v3,oRRS15to5,oARRM60to10,oARRM60to6,ARRM10to60E2r1,oQU480,oQU240,oQU240wLI,oQU120,oRRS30to10v3,oRRS30to10v3wLI,360x720cru,NLDASww3a,NLDAS,tx0.1v2,ICOS10,IcoswISC30E3r5,IcosXISC30E3r7">
+       valid_values="USGS,gx3v7,gx1v6,navy,test,tx0.1v2,tx1v1,T62,TL319,cruncep,oEC60to30v3,oEC60to30v3wLI,ECwISC30to60E1r2,EC30to60E2r2,WC14to60E2r3,WCAtl12to45E2r4,SOwISC12to60E2r4,ECwISC30to60E2r1,oRRS18to6,oRRS18to6v3,oRRS15to5,oARRM60to10,oARRM60to6,ARRM10to60E2r1,oQU480,oQU240,oQU240wLI,oQU120,oRRS30to10v3,oRRS30to10v3wLI,360x720cru,NLDASww3a,NLDAS,tx0.1v2,ICOS10,IcoswISC30E3r5,IcosXISC30E3r7,RRSwISC6to18E3r5">
 Land mask description
 </entry>
 
diff --git a/components/mpas-ocean/bld/namelist_files/namelist_defaults_mpaso.xml b/components/mpas-ocean/bld/namelist_files/namelist_defaults_mpaso.xml
index 2880bf2ce5cb..6b9b14eb4e85 100644
--- a/components/mpas-ocean/bld/namelist_files/namelist_defaults_mpaso.xml
+++ b/components/mpas-ocean/bld/namelist_files/namelist_defaults_mpaso.xml
@@ -54,6 +54,7 @@
 <config_dt ocn_grid="FRISwISC04to60E3r1">'00:04:00'</config_dt>
 <config_dt ocn_grid="FRISwISC02to60E3r1">'00:02:00'</config_dt>
 <config_dt ocn_grid="FRISwISC01to60E3r1">'00:01:00'</config_dt>
+<config_dt ocn_grid="RRSwISC6to18E3r5">'00:05:00'</config_dt>
 <config_time_integrator>'split_explicit_ab2'</config_time_integrator>
 <config_number_of_time_levels>2</config_number_of_time_levels>
 
@@ -83,6 +84,7 @@
 <config_hmix_scaleWithMesh ocn_grid="FRISwISC04to60E3r1">.true.</config_hmix_scaleWithMesh>
 <config_hmix_scaleWithMesh ocn_grid="FRISwISC02to60E3r1">.true.</config_hmix_scaleWithMesh>
 <config_hmix_scaleWithMesh ocn_grid="FRISwISC01to60E3r1">.true.</config_hmix_scaleWithMesh>
+<config_hmix_scaleWithMesh ocn_grid="RRSwISC6to18E3r5">.true.</config_hmix_scaleWithMesh>
 <config_maxMeshDensity>-1.0</config_maxMeshDensity>
 <config_hmix_use_ref_cell_width>.false.</config_hmix_use_ref_cell_width>
 <config_hmix_ref_cell_width>30.0e3</config_hmix_ref_cell_width>
@@ -104,6 +106,7 @@
 <config_use_mom_del2 ocn_grid="FRISwISC04to60E3r1">.true.</config_use_mom_del2>
 <config_use_mom_del2 ocn_grid="FRISwISC02to60E3r1">.true.</config_use_mom_del2>
 <config_use_mom_del2 ocn_grid="FRISwISC01to60E3r1">.true.</config_use_mom_del2>
+<config_use_mom_del2 ocn_grid="RRSwISC6to18E3r5">.true.</config_use_mom_del2>
 <config_mom_del2>10.0</config_mom_del2>
 <config_mom_del2 ocn_grid="oEC60to30v3">1000.0</config_mom_del2>
 <config_mom_del2 ocn_grid="oEC60to30v3wLI">1000.0</config_mom_del2>
@@ -119,6 +122,7 @@
 <config_mom_del2 ocn_grid="FRISwISC04to60E3r1">154.0</config_mom_del2>
 <config_mom_del2 ocn_grid="FRISwISC02to60E3r1">77.0</config_mom_del2>
 <config_mom_del2 ocn_grid="FRISwISC01to60E3r1">38.5</config_mom_del2>
+<config_mom_del2 ocn_grid="RRSwISC6to18E3r5">100.0</config_mom_del2>
 <config_use_tracer_del2>.false.</config_use_tracer_del2>
 <config_tracer_del2>10.0</config_tracer_del2>
 
@@ -149,6 +153,7 @@
 <config_mom_del4 ocn_grid="FRISwISC04to60E3r1">4.37e08</config_mom_del4>
 <config_mom_del4 ocn_grid="FRISwISC02to60E3r1">5.46e07</config_mom_del4>
 <config_mom_del4 ocn_grid="FRISwISC01to60E3r1">6.83e06</config_mom_del4>
+<config_mom_del4 ocn_grid="RRSwISC6to18E3r5">3.2e09</config_mom_del4>
 <config_mom_del4_div_factor>1.0</config_mom_del4_div_factor>
 <config_use_tracer_del4>.false.</config_use_tracer_del4>
 <config_tracer_del4>0.0</config_tracer_del4>
@@ -165,6 +170,7 @@
 <config_use_Redi ocn_grid="oRRS30to10v3wLI">.false.</config_use_Redi>
 <config_use_Redi ocn_grid="oRRS18to6v3">.false.</config_use_Redi>
 <config_use_Redi ocn_grid="oRRS15to5">.false.</config_use_Redi>
+<config_use_Redi ocn_grid="RRSwISC6to18E3r5">.false.</config_use_Redi>
 <config_Redi_closure>'constant'</config_Redi_closure>
 <config_Redi_constant_kappa>400.0</config_Redi_constant_kappa>
 <config_Redi_constant_kappa ocn_forcing="datm_forced_restoring">400.0</config_Redi_constant_kappa>
@@ -203,6 +209,7 @@
 <config_use_GM ocn_grid="oRRS30to10v3wLI">.false.</config_use_GM>
 <config_use_GM ocn_grid="oRRS18to6v3">.false.</config_use_GM>
 <config_use_GM ocn_grid="oRRS15to5">.false.</config_use_GM>
+<config_use_GM ocn_grid="RRSwISC6to18E3r5">.false.</config_use_GM>
 <config_GM_closure>'EdenGreatbatch'</config_GM_closure>
 <config_GM_closure ocn_grid="EC30to60E2r2">'constant'</config_GM_closure>
 <config_GM_closure ocn_grid="WC14to60E2r3">'constant'</config_GM_closure>
@@ -399,6 +406,7 @@
 <config_land_ice_flux_mode ocn_grid="FRISwISC04to60E3r1">'pressure_only'</config_land_ice_flux_mode>
 <config_land_ice_flux_mode ocn_grid="FRISwISC02to60E3r1">'pressure_only'</config_land_ice_flux_mode>
 <config_land_ice_flux_mode ocn_grid="FRISwISC01to60E3r1">'pressure_only'</config_land_ice_flux_mode>
+<config_land_ice_flux_mode ocn_grid="RRSwISC6to18E3r5">'pressure_only'</config_land_ice_flux_mode>
 <config_land_ice_flux_formulation>'Jenkins'</config_land_ice_flux_formulation>
 <config_land_ice_flux_useHollandJenkinsAdvDiff>.false.</config_land_ice_flux_useHollandJenkinsAdvDiff>
 <config_land_ice_flux_attenuation_coefficient>10.0</config_land_ice_flux_attenuation_coefficient>
@@ -417,6 +425,7 @@
 <config_land_ice_flux_explicit_topDragCoeff ocn_grid="FRISwISC04to60E3r1">4.48e-3</config_land_ice_flux_explicit_topDragCoeff>
 <config_land_ice_flux_explicit_topDragCoeff ocn_grid="FRISwISC02to60E3r1">4.48e-3</config_land_ice_flux_explicit_topDragCoeff>
 <config_land_ice_flux_explicit_topDragCoeff ocn_grid="FRISwISC01to60E3r1">4.48e-3</config_land_ice_flux_explicit_topDragCoeff>
+<config_land_ice_flux_explicit_topDragCoeff ocn_grid="RRSwISC6to18E3r5">4.48e-3</config_land_ice_flux_explicit_topDragCoeff>
 <config_land_ice_flux_ISOMIP_gammaT>1e-4</config_land_ice_flux_ISOMIP_gammaT>
 <config_land_ice_flux_rms_tidal_velocity>5e-2</config_land_ice_flux_rms_tidal_velocity>
 <config_land_ice_flux_jenkins_heat_transfer_coefficient>0.011</config_land_ice_flux_jenkins_heat_transfer_coefficient>
@@ -430,6 +439,7 @@
 <config_land_ice_flux_jenkins_heat_transfer_coefficient ocn_grid="FRISwISC04to60E3r1">0.00295</config_land_ice_flux_jenkins_heat_transfer_coefficient>
 <config_land_ice_flux_jenkins_heat_transfer_coefficient ocn_grid="FRISwISC02to60E3r1">0.00295</config_land_ice_flux_jenkins_heat_transfer_coefficient>
 <config_land_ice_flux_jenkins_heat_transfer_coefficient ocn_grid="FRISwISC01to60E3r1">0.00295</config_land_ice_flux_jenkins_heat_transfer_coefficient>
+<config_land_ice_flux_jenkins_heat_transfer_coefficient ocn_grid="RRSwISC6to18E3r5">0.00295</config_land_ice_flux_jenkins_heat_transfer_coefficient>
 <config_land_ice_flux_jenkins_salt_transfer_coefficient>3.1e-4</config_land_ice_flux_jenkins_salt_transfer_coefficient>
 <config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="oEC60to30v3wLI">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
 <config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="ECwISC30to60E1r2">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
@@ -441,6 +451,7 @@
 <config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="FRISwISC04to60E3r1">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
 <config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="FRISwISC02to60E3r1">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
 <config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="FRISwISC01to60E3r1">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
+<config_land_ice_flux_jenkins_salt_transfer_coefficient ocn_grid="RRSwISC6to18E3r5">8.42e-5</config_land_ice_flux_jenkins_salt_transfer_coefficient>
 
 <!-- advection -->
 <config_vert_advection_method>'flux-form'</config_vert_advection_method>
@@ -469,6 +480,7 @@
 <config_implicit_top_drag_coeff ocn_grid="FRISwISC04to60E3r1">4.48e-3</config_implicit_top_drag_coeff>
 <config_implicit_top_drag_coeff ocn_grid="FRISwISC02to60E3r1">4.48e-3</config_implicit_top_drag_coeff>
 <config_implicit_top_drag_coeff ocn_grid="FRISwISC01to60E3r1">4.48e-3</config_implicit_top_drag_coeff>
+<config_implicit_top_drag_coeff ocn_grid="RRSwISC6to18E3r5">4.48e-3</config_implicit_top_drag_coeff>
 <config_loglaw_bottom_roughness>1.0e-3</config_loglaw_bottom_roughness>
 <config_loglaw_layer_depth_max>10.0</config_loglaw_layer_depth_max>
 <config_loglaw_bottom_drag_min>2.5e-3</config_loglaw_bottom_drag_min>
@@ -555,6 +567,7 @@
 <config_btr_dt ocn_grid="FRISwISC04to60E3r1">'0000_00:00:05'</config_btr_dt>
 <config_btr_dt ocn_grid="FRISwISC02to60E3r1">'0000_00:00:02.5'</config_btr_dt>
 <config_btr_dt ocn_grid="FRISwISC01to60E3r1">'0000_00:00:01.25'</config_btr_dt>
+<config_btr_dt ocn_grid="RRSwISC6to18E3r5">'0000_00:00:05'</config_btr_dt>
 <config_n_btr_cor_iter>2</config_n_btr_cor_iter>
 <config_vel_correction>.true.</config_vel_correction>
 <config_btr_subcycle_loop_factor>2</config_btr_subcycle_loop_factor>
@@ -601,6 +614,7 @@
 <config_check_ssh_consistency ocn_grid="FRISwISC04to60E3r1">.false.</config_check_ssh_consistency>
 <config_check_ssh_consistency ocn_grid="FRISwISC02to60E3r1">.false.</config_check_ssh_consistency>
 <config_check_ssh_consistency ocn_grid="FRISwISC01to60E3r1">.false.</config_check_ssh_consistency>
+<config_check_ssh_consistency ocn_grid="RRSwISC6to18E3r5">.false.</config_check_ssh_consistency>
 <config_filter_btr_mode>.false.</config_filter_btr_mode>
 <config_prescribe_velocity>.false.</config_prescribe_velocity>
 <config_prescribe_thickness>.false.</config_prescribe_thickness>
@@ -1126,6 +1140,7 @@
 <config_AM_mocStreamfunction_enable ocn_grid="FRISwISC04to60E3r1">.true.</config_AM_mocStreamfunction_enable>
 <config_AM_mocStreamfunction_enable ocn_grid="FRISwISC02to60E3r1">.true.</config_AM_mocStreamfunction_enable>
 <config_AM_mocStreamfunction_enable ocn_grid="FRISwISC01to60E3r1">.true.</config_AM_mocStreamfunction_enable>
+<config_AM_mocStreamfunction_enable ocn_grid="RRSwISC6to18E3r5">.true.</config_AM_mocStreamfunction_enable>
 <config_AM_mocStreamfunction_compute_interval>'0000-00-00_01:00:00'</config_AM_mocStreamfunction_compute_interval>
 <config_AM_mocStreamfunction_output_stream>'mocStreamfunctionOutput'</config_AM_mocStreamfunction_output_stream>
 <config_AM_mocStreamfunction_compute_on_startup>.true.</config_AM_mocStreamfunction_compute_on_startup>
@@ -1213,6 +1228,7 @@
 <config_AM_conservationCheck_enable ocn_grid="FRISwISC04to60E3r1">.true.</config_AM_conservationCheck_enable>
 <config_AM_conservationCheck_enable ocn_grid="FRISwISC02to60E3r1">.true.</config_AM_conservationCheck_enable>
 <config_AM_conservationCheck_enable ocn_grid="FRISwISC01to60E3r1">.true.</config_AM_conservationCheck_enable>
+<config_AM_conservationCheck_enable ocn_grid="RRSwISC6to18E3r5">.true.</config_AM_conservationCheck_enable>
 <config_AM_conservationCheck_compute_interval>'dt'</config_AM_conservationCheck_compute_interval>
 <config_AM_conservationCheck_output_stream>'conservationCheckOutput'</config_AM_conservationCheck_output_stream>
 <config_AM_conservationCheck_compute_on_startup>.false.</config_AM_conservationCheck_compute_on_startup>
@@ -1224,6 +1240,7 @@
 <config_AM_conservationCheck_compute_on_startup ocn_grid="FRISwISC04to60E3r1">.true.</config_AM_conservationCheck_compute_on_startup>
 <config_AM_conservationCheck_compute_on_startup ocn_grid="FRISwISC02to60E3r1">.true.</config_AM_conservationCheck_compute_on_startup>
 <config_AM_conservationCheck_compute_on_startup ocn_grid="FRISwISC01to60E3r1">.true.</config_AM_conservationCheck_compute_on_startup>
+<config_AM_conservationCheck_compute_on_startup ocn_grid="RRSwISC6to18E3r5">.true.</config_AM_conservationCheck_compute_on_startup>
 <config_AM_conservationCheck_write_on_startup>.false.</config_AM_conservationCheck_write_on_startup>
 <config_AM_conservationCheck_write_on_startup ocn_grid="SOwISC12to60E2r4">.true.</config_AM_conservationCheck_write_on_startup>
 <config_AM_conservationCheck_write_on_startup ocn_grid="ECwISC30to60E2r1">.true.</config_AM_conservationCheck_write_on_startup>
@@ -1233,6 +1250,7 @@
 <config_AM_conservationCheck_write_on_startup ocn_grid="FRISwISC04to60E3r1">.true.</config_AM_conservationCheck_write_on_startup>
 <config_AM_conservationCheck_write_on_startup ocn_grid="FRISwISC02to60E3r1">.true.</config_AM_conservationCheck_write_on_startup>
 <config_AM_conservationCheck_write_on_startup ocn_grid="FRISwISC01to60E3r1">.true.</config_AM_conservationCheck_write_on_startup>
+<config_AM_conservationCheck_write_on_startup ocn_grid="RRSwISC6to18E3r5">.true.</config_AM_conservationCheck_write_on_startup>
 <config_AM_conservationCheck_write_to_logfile>.true.</config_AM_conservationCheck_write_to_logfile>
 <config_AM_conservationCheck_restart_stream>'conservationCheckRestart'</config_AM_conservationCheck_restart_stream>
 
diff --git a/components/mpas-ocean/cime_config/buildnml b/components/mpas-ocean/cime_config/buildnml
index 47076dee726a..99c028a8808b 100755
--- a/components/mpas-ocean/cime_config/buildnml
+++ b/components/mpas-ocean/cime_config/buildnml
@@ -365,6 +365,20 @@ def buildnml(case, caseroot, compname):
             ic_date = '20240314'
             ic_prefix = 'mpaso.IcosXISC30E3r7.rstFromPiControlSpinup-chrysalis'
 
+    elif ocn_grid == 'RRSwISC6to18E3r5':
+        decomp_date = '20240404'
+        decomp_prefix = 'partitions/mpas-o.graph.info.'
+        restoring_file = 'sss.PHC2_monthlyClimatology.RRSwISC6to18E3r5.20240327.nc'
+        analysis_mask_file = 'RRSwISC6to18E3r5_mocBasinsAndTransects20210623.nc'
+        ic_date = '20240327'
+        ic_prefix = 'mpaso.RRSwISC6to18E3r5'
+        if ocn_ic_mode == 'spunup':
+            logger.warning("WARNING: The specified compset is requesting ocean ICs spunup from a G-case")
+            logger.warning("         But no file available for this grid.")
+        if ocn_ismf == 'data':
+            data_ismf_file = 'prescribed_ismf_paolo2023.RRSwISC6to18E3r5.20240327.nc'
+
+
     #--------------------------------------------------------------------
     # Set OCN_FORCING = datm_forced_restoring if restoring file is available
     #--------------------------------------------------------------------
@@ -491,7 +505,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<immutable_stream name="mesh"')
             lines.append('                  type="none"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ocn_pio_typename))
@@ -500,7 +515,8 @@ def buildnml(case, caseroot, compname):
             lines.append('/>')
             lines.append('<immutable_stream name="input"')
             lines.append('                  type="input"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ocn_pio_typename))
@@ -521,7 +537,8 @@ def buildnml(case, caseroot, compname):
             lines.append('-->')
             lines.append('<immutable_stream name="restart"')
             lines.append('                  type="input;output"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ocn_pio_typename))
@@ -540,7 +557,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<stream name="output"')
             lines.append('        type="output"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -826,7 +844,8 @@ def buildnml(case, caseroot, compname):
             lines.append('<stream name="eddyProductVariablesOutput"')
             lines.append('        type="output"')
             lines.append('        precision="single"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1206,7 +1225,8 @@ def buildnml(case, caseroot, compname):
             lines.append('<stream name="timeSeriesStatsMonthlyOutput"')
             lines.append('        type="output"')
             lines.append('        precision="single"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1252,7 +1272,7 @@ def buildnml(case, caseroot, compname):
             lines.append('    <var name="atmosphericPressure"/>')
             lines.append('    <var name="normalMLEvelocity"/>')
             lines.append('    <var name="vertMLEBolusVelocityTop"/>')
-            if not ocn_grid.startswith("oRRS1"):
+            if not (ocn_grid.startswith("oRRS1") or ocn_grid.startswith("RRSwISC6")):
                 lines.append('    <var name="normalGMBolusVelocity"/>')
                 lines.append('    <var name="vertGMBolusVelocityTop"/>')
                 lines.append('    <var name="cGMphaseSpeed"/>')
@@ -1438,7 +1458,8 @@ def buildnml(case, caseroot, compname):
             lines.append('<stream name="timeSeriesStatsMonthlyMaxOutput"')
             lines.append('        type="output"')
             lines.append('        precision="single"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1502,7 +1523,8 @@ def buildnml(case, caseroot, compname):
             lines.append('<stream name="timeSeriesStatsMonthlyMinOutput"')
             lines.append('        type="output"')
             lines.append('        precision="single"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1607,7 +1629,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<stream name="timeSeriesStatsMonthlyRestart"')
             lines.append('        type="input;output"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1623,7 +1646,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<stream name="timeSeriesStatsMonthlyMaxRestart"')
             lines.append('        type="input;output"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
@@ -1639,7 +1663,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<stream name="timeSeriesStatsMonthlyMinRestart"')
             lines.append('        type="input;output"')
-            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS"):
+            if ocn_grid.startswith("oRRS1") or ocn_grid.startswith("FRIS") \
+                    or ocn_grid.startswith("RRSwISC6"):
                 lines.append('        io_type="pnetcdf,cdf5"')
             else:
                 lines.append('        io_type="{}"'.format(ocn_pio_typename))
diff --git a/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml b/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
index 1d8330ac86ef..dee59f726e25 100644
--- a/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
+++ b/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
@@ -30,6 +30,7 @@
 <config_dt ice_grid="FRISwISC04to60E3r1">240.0</config_dt>
 <config_dt ice_grid="FRISwISC02to60E3r1">120.0</config_dt>
 <config_dt ice_grid="FRISwISC01to60E3r1">60.0</config_dt>
+<config_dt ice_grid="RRSwISC6to18E3r5">900.0</config_dt>
 <config_calendar_type>'noleap'</config_calendar_type>
 <config_start_time>'2000-01-01_00:00:00'</config_start_time>
 <config_stop_time>'none'</config_stop_time>
@@ -89,6 +90,7 @@
 <config_initial_latitude_north ice_grid="ARRM10to60E2r1">75.0</config_initial_latitude_north>
 <config_initial_latitude_north ice_grid="oRRS30to10v3wLI">85.0</config_initial_latitude_north>
 <config_initial_latitude_north ice_grid="oRRS18to6v3">85.0</config_initial_latitude_north>
+<config_initial_latitude_north ice_grid="RRSwISC6to18E3r5">85.0</config_initial_latitude_north>
 <config_initial_latitude_south>-60.0</config_initial_latitude_south>
 <config_initial_latitude_south ice_grid="oEC60to30v3wLI">-75.0</config_initial_latitude_south>
 <config_initial_latitude_south ice_grid="ECwISC30to60E1r2">-75.0</config_initial_latitude_south>
@@ -103,6 +105,7 @@
 <config_initial_latitude_south ice_grid="ARRM10to60E2r1">-85.0</config_initial_latitude_south>
 <config_initial_latitude_south ice_grid="oRRS30to10v3wLI">-85.0</config_initial_latitude_south>
 <config_initial_latitude_south ice_grid="oRRS18to6v3">-85.0</config_initial_latitude_south>
+<config_initial_latitude_south ice_grid="RRSwISC6to18E3r5">-85.0</config_initial_latitude_south>
 <config_initial_velocity_type>'uniform'</config_initial_velocity_type>
 <config_initial_uvelocity>0.0</config_initial_uvelocity>
 <config_initial_vvelocity>0.0</config_initial_vvelocity>
@@ -166,6 +169,7 @@
 <config_dynamics_subcycle_number ice_grid="FRISwISC04to60E3r1">1</config_dynamics_subcycle_number>
 <config_dynamics_subcycle_number ice_grid="FRISwISC02to60E3r1">1</config_dynamics_subcycle_number>
 <config_dynamics_subcycle_number ice_grid="FRISwISC01to60E3r1">1</config_dynamics_subcycle_number>
+<config_dynamics_subcycle_number ice_grid="RRSwISC6to18E3r5">2</config_dynamics_subcycle_number>
 <config_rotate_cartesian_grid>true</config_rotate_cartesian_grid>
 <config_include_metric_terms>true</config_include_metric_terms>
 <config_elastic_subcycle_number>120</config_elastic_subcycle_number>
diff --git a/components/mpas-seaice/cime_config/buildnml b/components/mpas-seaice/cime_config/buildnml
index 8337fcfc7061..5522d8ac6511 100755
--- a/components/mpas-seaice/cime_config/buildnml
+++ b/components/mpas-seaice/cime_config/buildnml
@@ -318,6 +318,16 @@ def buildnml(case, caseroot, compname):
             grid_date = '20240314'
             grid_prefix = 'mpassi.IcosXISC30E3r7.rstFromPiControlSpinup-chrysalis'
 
+    elif ice_grid == 'RRSwISC6to18E3r5':
+        decomp_date = '20240404'
+        decomp_prefix = 'partitions/mpas-seaice.graph.info.'
+        grid_date = '20240327'
+        grid_prefix = 'mpassi.RRSwISC6to18E3r5'
+        data_iceberg_file = 'Iceberg_Climatology_Merino.RRSwISC6to18E3r5.20240327.nc'
+        if ice_ic_mode == 'spunup':
+            logger.warning("WARNING: The specified compset is requesting seaice ICs spunup from a G-case")
+            logger.warning("         But no file available for this grid.")
+
     elif ice_grid == 'ICOS10':
         grid_date = '211015'
         grid_prefix = 'seaice.ICOS10'
@@ -451,7 +461,8 @@ def buildnml(case, caseroot, compname):
             lines.append('<streams>')
             lines.append('<immutable_stream name="mesh"')
             lines.append('                  type="none"')
-            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS"):
+            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS") \
+                    or ice_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ice_pio_typename))
@@ -460,7 +471,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<immutable_stream name="input"')
             lines.append('                  type="input"')
-            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS"):
+            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS") \
+                    or ice_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ice_pio_typename))
@@ -482,7 +494,8 @@ def buildnml(case, caseroot, compname):
             lines.append('')
             lines.append('<immutable_stream name="restart"')
             lines.append('                  type="input;output"')
-            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS"):
+            if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS") \
+                    or ice_grid.startswith("RRSwISC6"):
                 lines.append('                  io_type="pnetcdf,cdf5"')
             else:
                 lines.append('                  io_type="{}"'.format(ice_pio_typename))
@@ -498,8 +511,9 @@ def buildnml(case, caseroot, compname):
             if ice_ic_mode == 'spunup':
                 lines.append('<immutable_stream name="restart_ic"')
                 lines.append('                  type="input"')
-                if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS"):
-                    lines.append('                  io_type="pnetcdf,cdf5"')
+                if ice_grid.startswith("oRRS1") or ice_grid.startswith("FRIS") \
+                        or ice_grid.startswith("RRSwISC6"):
+                        lines.append('                  io_type="pnetcdf,cdf5"')
                 else:
                     lines.append('                  io_type="{}"'.format(ice_pio_typename))
 
diff --git a/driver-mct/cime_config/config_component_e3sm.xml b/driver-mct/cime_config/config_component_e3sm.xml
index 2895650d2426..2a52c9fb7c30 100755
--- a/driver-mct/cime_config/config_component_e3sm.xml
+++ b/driver-mct/cime_config/config_component_e3sm.xml
@@ -245,6 +245,7 @@
       <value compset="_SOCN"                     >CESM1_MOD</value>
       <value compset="_MPASO"                    >CESM1_MOD</value>
       <value compset="_MPASSI.*_MPASO"           >RASM_OPTION1</value>
+      <value compset="_MPASSI.*_MPASO" grid="oi%RRSwISC6to18E3r5">RASM_OPTION2</value>
     </values>
     <group>run_coupling</group>
     <file>env_run.xml</file>