diff --git a/bld/namelist_files/namelist_defaults_ctsm.xml b/bld/namelist_files/namelist_defaults_ctsm.xml
index 67348d8ca2..cac69edf02 100644
--- a/bld/namelist_files/namelist_defaults_ctsm.xml
+++ b/bld/namelist_files/namelist_defaults_ctsm.xml
@@ -956,21 +956,17 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_GSWP3v1"
 >hgrid=1.9x2.5 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_GSWP3v1"
->hgrid=1.9x2.5 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
+<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." phys="clm5_1"
+>hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nex=10 do_transient_pfts=.false. lnd_tuning_mode=clm5_1_GSWP3v1 use_excess_ice=.true.
 </init_interp_attributes>
-
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_CRUv7"
->hgrid=1.9x2.5 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
+<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." phys="clm6_0"
+>hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nex=10 do_transient_pfts=.false. lnd_tuning_mode=clm6_0_GSWP3v1 use_excess_ice=.true.
 </init_interp_attributes>
 
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_1_GSWP3v1"
+<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_CRUv7"
 >hgrid=1.9x2.5 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
 
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_GSWP3v1"
->hgrid=1.9x2.5 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
-</init_interp_attributes>
 <!-- specific low resolution grids should use the 1-degree file for just CLM5.0 -->
 <!-- matches for clm5_0 physics with CAM7.0 -->
 <init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_cam7.0"
@@ -1033,16 +1029,6 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 >hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
 
-<!-- clm5_1 physics -->
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_1_cam7.0"
->hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.true.
-</init_interp_attributes>
-
-<!-- clm6_0 physics -->
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam7.0"
->hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.true.
-</init_interp_attributes>
-
 <!-- MPAS -->
 <init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_cam7.0"
 			hgrid="mpasa480"
@@ -1109,7 +1095,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 </init_interp_attributes>
 
 <!-- 2013 IC's - exact match for CONUS grid ... -->
-<init_interp_attributes sim_year="2013" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam7.0"
+<init_interp_attributes sim_year="2013" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_cam7.0"
 			hgrid="ne0np4CONUS.ne30x8" use_cn=".false." maxpft="17"
 >hgrid=ne0np4CONUS.ne30x8 maxpft=17 mask=tx0.1v2 use_cn=.false. use_crop=.false. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
@@ -1197,16 +1183,6 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 >hgrid=ne0np4.ARCTICGRIS.ne30x8 maxpft=17 mask=tx0.1v2 use_cn=.false. use_crop=.false. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
 
-<!-- clm5_1 physics -->
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_1_cam6.0"
->hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.true.
-</init_interp_attributes>
-
-<!-- clm6_0 physics -->
-<init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam6.0"
->hgrid=0.9x1.25 maxpft=79 mask=gx1v7 use_cn=.true. use_crop=.true. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.true.
-</init_interp_attributes>
-
 <!-- MPAS -->
 <init_interp_attributes sim_year="2000" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_cam6.0"
 			hgrid="mpasa480"
@@ -1287,13 +1263,13 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 </init_interp_attributes>
 
 <!-- 2003 -->
-<init_interp_attributes sim_year="2003" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm5_0_cam6.0"
+<init_interp_attributes sim_year="2003" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam7.0"
                         hgrid="1.9x2.5" use_cn=".false." maxpft="17"
 >hgrid=1.9x2.5 maxpft=17 mask=gx1v7 use_cn=.false. use_crop=.false. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
 
 <!-- 2013 IC's - exact match for CONUS grid ... -->
-<init_interp_attributes sim_year="2013" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam6.0"
+<init_interp_attributes sim_year="2013" use_cndv=".false." use_fates=".false." lnd_tuning_mode="clm6_0_cam7.0"
 			hgrid="ne0np4CONUS.ne30x8" use_cn=".false." maxpft="17"
 >hgrid=ne0np4CONUS.ne30x8 maxpft=17 mask=tx0.1v2 use_cn=.false. use_crop=.false. irrigate=.true. glc_nec=10 do_transient_pfts=.false. use_excess_ice=.false.
 </init_interp_attributes>
@@ -1381,13 +1357,13 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25" mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="18500101" sim_year="1850" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".false."
-         lnd_tuning_mode="clm5_1_GSWP3v1" use_init_interp=".true."
+         phys="clm5_1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 <finidat hgrid="0.9x1.25" mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="18500101" sim_year="1850" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".false."
-         lnd_tuning_mode="clm6_0_GSWP3v1" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1425,11 +1401,11 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
          lnd_tuning_mode="clm5_1_GSWP3v1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.2/clmi.I2000Clm50BgcCrop.2011-01-01.1.9x2.5_gx1v7_gl4_simyr2000_c240223.nc
 </finidat>
-<!-- NB: This pSASU finidat is from an 1850 spin-up -->
+<!-- NB: This pSASU finidat is from an f09 1850 (rather than f19 2000) spin-up -->
 <finidat hgrid="1.9x2.5"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20110101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm6_0_GSWP3v1" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1514,7 +1490,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm5_1_cam7.0" use_init_interp=".true."
+         phys="clm5_1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1523,7 +1499,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm6_0_cam7.0" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1588,7 +1564,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm5_1_cam7.0" use_init_interp=".true."
+         phys="clm5_1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1652,7 +1628,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm6_0_cam7.0" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1727,7 +1703,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm5_1_cam6.0" use_init_interp=".true."
+         phys="clm5_1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1735,7 +1711,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm6_0_cam6.0" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1800,7 +1776,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm5_1_cam6.0" use_init_interp=".true."
+         phys="clm5_1" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>
 
@@ -1865,7 +1841,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <finidat hgrid="0.9x1.25"    maxpft="79"  mask="gx1v7" use_cn=".true." use_cndv=".false." use_fates=".false."
          ic_ymd="20000101" sim_year="2000" do_transient_pfts=".false." use_excess_ice=".true."
          ic_tod="0" glc_nec="10" use_crop=".true." irrigate=".true."
-         lnd_tuning_mode="clm6_0_cam6.0" use_init_interp=".true."
+         phys="clm6_0" use_init_interp=".true."
 >lnd/clm2/initdata_esmf/ctsm5.3/ctsm52026_f09_pSASU.clm2.r.0421-01-01-00000.nc
 </finidat>