diff --git a/CMakeLists.txt b/CMakeLists.txt
index a7e25d98..42f35741 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,7 @@ set (programs
    scm_setup
    gcm_quickstat.j
    scm_run.j
+   construct_extdata_yaml_list.py
    )
 
 install (
diff --git a/construct_extdata_yaml_list.py b/construct_extdata_yaml_list.py
new file mode 100755
index 00000000..95d50d68
--- /dev/null
+++ b/construct_extdata_yaml_list.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+import yaml
+import argparse
+import os
+
+def parse_args():
+    p = argparse.ArgumentParser(description='create extdata master file')
+    p.add_argument('rc_file',type=str,help='GEOS_ChemGridComp.rc file')
+    return vars(p.parse_args())
+
+if __name__ == '__main__':
+
+   args = parse_args()
+   rc_file = args['rc_file']
+
+   f = open(rc_file,"r")
+   temp_text = f.readlines()
+   f.close()
+
+   component_yaml_files = yaml.safe_load("""
+   GOCART:
+   - CFC_GridComp_ExtData.yaml
+   - CH4_GridComp_ExtData.yaml
+   - CO2_GridComp_ExtData.yaml
+   - CO_GridComp_ExtData.yaml
+   - O3_GridComp_ExtData.yaml
+   - Rn_GridComp_ExtData.yaml
+   GOCART2G:
+   - CA2G_GridComp_ExtData.yaml
+   - DU2G_GridComp_ExtData.yaml
+   - NI2G_GridComp_ExtData.yaml
+   - SS2G_GridComp_ExtData.yaml
+   - SU2G_GridComp_ExtData.yaml
+   GAAS:
+   - GAAS_GridComp_ExtData.yaml
+   STRATCHEM:
+   - StratChem_ExtData.yaml
+   GMICHEM:
+   - GMI_ExtData.yaml
+   CARMA:
+   - CARMAchem_GridComp_ExtData.yaml
+   MAM:
+   - MAM7_ExtData.yaml
+   ACHEM:
+   - GEOSachem_ExtData.yaml
+   TR:
+   - TR_ExtData.yaml
+   DNA:
+   - DNA_ExtData.yaml
+   HEMCO:
+   - HEMCOgmi_ExtData.yaml
+   - HEMCOgocart2g_ExtData.yaml
+   Extras:
+   - ChemEnv_ExtData.yaml
+   - WSUB_ExtData.yaml
+   """)
+   components = {}
+   for line in temp_text:
+      if "ENABLE" in line:
+          entry = line.split(":")
+          if ".TRUE." in entry[1]:
+             component_on = True
+          if ".FALSE." in entry[1]:
+             component_on = False
+          key_name = entry[0]
+          component_name = key_name.replace("ENABLE_","")
+          component_name = component_name.lstrip()
+          components[component_name] = component_on
+
+   files_to_use = []
+   for key in components:
+       if key in component_yaml_files and components[key]:
+          files = component_yaml_files[key]
+          for single_file in files:
+              files_to_use.append(single_file)
+
+   extra_files = component_yaml_files["Extras"]
+   for single_file in extra_files:
+       files_to_use.append(single_file)
+
+   f = open("extdata.yaml","w")
+   f.write("subconfigs:\n")
+   for single_file in files_to_use:
+       f.write(" - "+single_file+"\n")
+   f.close()
+       
+
diff --git a/gcm_forecast.tmpl b/gcm_forecast.tmpl
index 53397083..d028e746 100755
--- a/gcm_forecast.tmpl
+++ b/gcm_forecast.tmpl
@@ -598,28 +598,36 @@ endif
 set yearc = `echo $nymdc | cut -c1-4`
 set yearf = `echo $nymdf | cut -c1-4`
 
+# Which ExtData are we using
+set  EXTDATA2G_TRUE = `grep -i '^\s*USE_EXTDATA2G:\s*\.TRUE\.'    CAP.rc | wc -l
+
 # Select proper AMIP GOCART Emission RC Files
 # -------------------------------------------
 if( ${EMISSIONS} == AMIP_EMISSIONS) then
     set AMIP_Transition_Date = 20000301
-
-    if( $nymdc < ${AMIP_Transition_Date} ) then
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
-         if( $nymdf > ${AMIP_Transition_Date} ) then
-          set nymdf = ${AMIP_Transition_Date}
-          set oldstring = `grep '^\s*END_DATE:' CAP.rc`
-          set newstring = "END_DATE: $nymdf $nhmsf"
-          /bin/mv CAP.rc CAP.tmp
-                     cat CAP.tmp | sed -e "s?$oldstring?$newstring?g" > CAP.rc
-         endif
+    if( $EXTDATA2G_TRUE == 0 ) then
+       if( $nymdc < ${AMIP_Transition_Date} ) then
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
+            if( $nymdf > ${AMIP_Transition_Date} ) then
+             set nymdf = ${AMIP_Transition_Date}
+             set oldstring = `grep '^\s*END_DATE:' CAP.rc`
+             set newstring = "END_DATE: $nymdf $nhmsf"
+             /bin/mv CAP.rc CAP.tmp
+                        cat CAP.tmp | sed -e "s?$oldstring?$newstring?g" > CAP.rc
+            endif
+       else
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       endif
     else
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
     endif
 
+
     if( $AGCM_LM == 72 ) then
         cp ${AMIP_EMISSIONS_DIRECTORY}/*.rc .
+        cp ${AMIP_EMISSIONS_DIRECTORY}/*.yaml .
     else
-        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc`
+        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc ${AMIP_EMISSIONS_DIRECTORY}/*.yaml`
         foreach file ($files)
           /bin/rm -f `basename $file`
           /bin/rm -f dummy
@@ -655,8 +663,13 @@ if ( $GOCART_DATA_TRUE == 0 && -e GOCARTdata_ExtData.rc         ) /bin/mv
 
 @MP_NO_USE_WSUB# 1MOM and GFDL microphysics do not use WSUB_NATURE
 @MP_NO_USE_WSUB# -------------------------------------------------
-@MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
-@MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+if ($EXTDATA2G_TRUE == 0 ) then
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+else
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.yaml WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/collection:/ s#WSUB_Wvar_positive_05hrdeg.*#/dev/null#' > WSUB_ExtData.yaml
+endif
 @MP_NO_USE_WSUB/bin/rm WSUB_ExtData.tmp
 
 # Generate the complete ExtData.rc
@@ -665,11 +678,20 @@ if(-e ExtData.rc )    /bin/rm -f   ExtData.rc
 set  extdata_files = `/bin/ls -1 *_ExtData.rc`
 
 # Switch to MODIS v6.1 data after Nov 2021
-set MODIS_Transition_Date = 20211101
-if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymdc ) then
-    cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
-else
-    cat $extdata_files > ExtData.rc
+if( $EXTDATA2G_TRUE == 0 ) then
+   set MODIS_Transition_Date = 20211101
+   if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymdc ) then
+       cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
+   else
+       cat $extdata_files > ExtData.rc
+   endif
+endif
+
+if( $EXTDATA2G_TRUE == 1 ) then
+
+  $GEOSBIN/construct_extdata_yaml_list.py GEOS_ChemGridComp.rc
+  touch ExtData.rc
+
 endif
 
 # Move GOCART to use RRTMGP Bands
diff --git a/gcm_regress.j b/gcm_regress.j
index 938e708e..056f0263 100755
--- a/gcm_regress.j
+++ b/gcm_regress.j
@@ -69,6 +69,7 @@ cd $HOMDIR
 cd $EXPDIR/regress
 
 cp $EXPDIR/RC/*.rc     $EXPDIR/regress
+cp $EXPDIR/RC/*.yaml   $EXPDIR/regress
 cp $EXPDIR/GEOSgcm.x   $EXPDIR/regress
 cp $EXPDIR/linkbcs     $EXPDIR/regress
 cp $HOMDIR/*.yaml      $EXPDIR/regress
@@ -209,22 +210,29 @@ set date = `cat cap_restart`
 set nymd0 = $date[1]
 set nhms0 = $date[2]
 
+set  EXTDATA2G_TRUE = `grep -i '^\s*USE_EXTDATA2G:\s*\.TRUE\.'    CAP.rc | wc -l`
+
 # Select proper AMIP GOCART Emission RC Files
 # -------------------------------------------
 setenv EMISSIONS @EMISSIONS
 if( @EMISSIONS == AMIP_EMISSIONS ) then
-    set AMIP_Transition_Date = 20000301
+    if( $EXTDATA2G_TRUE == 0 ) then
+       set AMIP_Transition_Date = 20000301
 
-    if( $nymd0 < ${AMIP_Transition_Date} ) then
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
+       if( $nymd0 < ${AMIP_Transition_Date} ) then
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
+       else
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       endif
     else
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
     endif
 
     if( $LM == 72 ) then
         cp ${AMIP_EMISSIONS_DIRECTORY}/*.rc .
+        cp ${AMIP_EMISSIONS_DIRECTORY}/*.yaml .
     else
-        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc`
+        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc ${AMIP_EMISSIONS_DIRECTORY}/*.yaml`
         foreach file ($files)
           /bin/rm -f `basename $file`
           /bin/rm -f dummy
@@ -236,8 +244,13 @@ endif
 
 @MP_NO_USE_WSUB# 1MOM and GFDL microphysics do not use WSUB_NATURE
 @MP_NO_USE_WSUB# -------------------------------------------------
-@MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
-@MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+if ($EXTDATA2G_TRUE == 0 ) then
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+else
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.yaml WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/collection:/ s#WSUB_Wvar_positive_05hrdeg.*#/dev/null#' > WSUB_ExtData.yaml
+endif
 @MP_NO_USE_WSUB/bin/rm WSUB_ExtData.tmp
 
 # Generate the complete ExtData.rc
@@ -246,11 +259,20 @@ if(-e ExtData.rc )    /bin/rm -f   ExtData.rc
 set  extdata_files = `/bin/ls -1 *_ExtData.rc`
 
 # Switch to MODIS v6.1 data after Nov 2021
-set MODIS_Transition_Date = 20211101
-if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymd0 ) then
-    cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
-else
-    cat $extdata_files > ExtData.rc
+if( $EXTDATA2G_TRUE == 0 ) then
+   set MODIS_Transition_Date = 20211101
+   if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymd0 ) then
+       cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
+   else
+       cat $extdata_files > ExtData.rc
+   endif
+endif
+
+if( $EXTDATA2G_TRUE == 1 ) then
+
+  $GEOSBIN/construct_extdata_yaml_list.py GEOS_ChemGridComp.rc
+  touch ExtData.rc
+
 endif
 
 # Move GOCART to use RRTMGP Bands
diff --git a/gcm_run.j b/gcm_run.j
index 0ce85829..a00505ff 100755
--- a/gcm_run.j
+++ b/gcm_run.j
@@ -578,35 +578,43 @@ if( @OCEANtag != DE0360xPE0180 ) then
     endif
 endif
 
+# Which ExtData are we using
+set  EXTDATA2G_TRUE = `grep -i '^\s*USE_EXTDATA2G:\s*\.TRUE\.'    CAP.rc | wc -l`
+
 # Select proper AMIP GOCART Emission RC Files
 # -------------------------------------------
 if( ${EMISSIONS} == AMIP_EMISSIONS ) then
-    set AMIP_Transition_Date = 20000301
-
-    # Before 2000-03-01, we need to use AMIP.20C which has different
-    # emissions (HFED instead of QFED) valid before 2000-03-01. Note
-    # that if you make a change to anything in $EXPDIR/RC/AMIP or
-    # $EXPDIR/RC/AMIP.20C, you might need to make a change in the other
-    # directory to be consistent. Some files in AMIP.20C are symlinks to
-    # that in AMIP but others are not.
-
-    if( $nymdc < ${AMIP_Transition_Date} ) then
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
-         if( $nymdf > ${AMIP_Transition_Date} ) then
-          set nymdf = ${AMIP_Transition_Date}
-          set oldstring = `grep '^\s*END_DATE:' CAP.rc`
-          set newstring = "END_DATE: $nymdf $nhmsf"
-          /bin/mv CAP.rc CAP.tmp
-                     cat CAP.tmp | sed -e "s?$oldstring?$newstring?g" > CAP.rc
-         endif
+    if( $EXTDATA2G_TRUE == 0 ) then
+       set AMIP_Transition_Date = 20000301
+
+       # Before 2000-03-01, we need to use AMIP.20C which has different
+       # emissions (HFED instead of QFED) valid before 2000-03-01. Note
+       # that if you make a change to anything in $EXPDIR/RC/AMIP or
+       # $EXPDIR/RC/AMIP.20C, you might need to make a change in the other
+       # directory to be consistent. Some files in AMIP.20C are symlinks to
+       # that in AMIP but others are not.
+
+       if( $nymdc < ${AMIP_Transition_Date} ) then
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP.20C
+            if( $nymdf > ${AMIP_Transition_Date} ) then
+             set nymdf = ${AMIP_Transition_Date}
+             set oldstring = `grep '^\s*END_DATE:' CAP.rc`
+             set newstring = "END_DATE: $nymdf $nhmsf"
+             /bin/mv CAP.rc CAP.tmp
+                        cat CAP.tmp | sed -e "s?$oldstring?$newstring?g" > CAP.rc
+            endif
+       else
+            set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       endif
     else
-         set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
+       set AMIP_EMISSIONS_DIRECTORY = $EXPDIR/RC/AMIP
     endif
 
     if( $AGCM_LM == 72 ) then
         cp ${AMIP_EMISSIONS_DIRECTORY}/*.rc .
+        cp ${AMIP_EMISSIONS_DIRECTORY}/*.yaml .
     else
-        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc`
+        set files = `/bin/ls -1 ${AMIP_EMISSIONS_DIRECTORY}/*.rc ${AMIP_EMISSIONS_DIRECTORY}/*.yaml`
         foreach file ($files)
           /bin/rm -f `basename $file`
           /bin/rm -f dummy
@@ -636,21 +644,37 @@ if ( $GOCART_DATA_TRUE == 0 && -e GOCARTdata_ExtData.rc         ) /bin/mv
 
 @MP_NO_USE_WSUB# 1MOM and GFDL microphysics do not use WSUB_NATURE
 @MP_NO_USE_WSUB# -------------------------------------------------
-@MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
-@MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+if ($EXTDATA2G_TRUE == 0 ) then
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.rc WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > WSUB_ExtData.rc
+else
+   @MP_NO_USE_WSUB/bin/mv WSUB_ExtData.yaml WSUB_ExtData.tmp
+   @MP_NO_USE_WSUBcat WSUB_ExtData.tmp | sed -e '/collection:/ s#WSUB_Wvar_positive_05hrdeg.*#/dev/null#' > WSUB_ExtData.yaml
+endif
 @MP_NO_USE_WSUB/bin/rm WSUB_ExtData.tmp
 
+
+
 # Generate the complete ExtData.rc
 # --------------------------------
 if(-e ExtData.rc )    /bin/rm -f   ExtData.rc
 set  extdata_files = `/bin/ls -1 *_ExtData.rc`
 
 # Switch to MODIS v6.1 data after Nov 2021
-set MODIS_Transition_Date = 20211101
-if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymdc ) then
-    cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
-else
-cat $extdata_files > ExtData.rc
+if( $EXTDATA2G_TRUE == 0 ) then
+   set MODIS_Transition_Date = 20211101
+   if ( ${EMISSIONS} == OPS_EMISSIONS && ${MODIS_Transition_Date} <= $nymdc ) then
+       cat $extdata_files | sed 's|\(qfed2.emis_.*\).006.|\1.061.|g' > ExtData.rc
+   else
+   cat $extdata_files > ExtData.rc
+   endif
+endif
+
+if( $EXTDATA2G_TRUE == 1 ) then
+
+  $GEOSBIN/construct_extdata_yaml_list.py GEOS_ChemGridComp.rc
+  touch ExtData.rc
+
 endif
 
 # Move GOCART to use RRTMGP Bands
diff --git a/gcm_setup b/gcm_setup
index 228aa262..47d1a26f 100755
--- a/gcm_setup
+++ b/gcm_setup
@@ -1774,14 +1774,14 @@ echo $GROUP > $HOME/.GROUProot
 #      Copy Model Executable and RC Files to Experiment Directory
 #######################################################################
 
-  mkdir -p  $EXPDIR/RC
+mkdir -p  $EXPDIR/RC
 
-  # Copy over all files and subdirs in install/etc, keeping symlinks
-  cp -RP $GEOSDIR/etc/* $EXPDIR/RC
+# Copy over all files and subdirs in install/etc, keeping symlinks
+cp -RP $GEOSDIR/etc/* $EXPDIR/RC
 
-  # Remove templated files in RC as they are unneeded and confusing for experiments
-  rm -f $EXPDIR/RC/*.tmpl
-  rm -f $EXPDIR/RC/fvcore_layout.rc
+# Remove templated files in RC as they are unneeded and confusing for experiments
+rm -f $EXPDIR/RC/*.tmpl
+rm -f $EXPDIR/RC/fvcore_layout.rc
 
 if ( $LINKX == "TRUE" ) then
   if ( -e $GEOSBIN/GEOSgcm.x ) ln -s $GEOSBIN/GEOSgcm.x $EXPDIR
diff --git a/scm_run.j b/scm_run.j
index cd6106a9..0c380aeb 100755
--- a/scm_run.j
+++ b/scm_run.j
@@ -4,7 +4,7 @@
 #@BATCH_JOBNAME
 #@BATCH_GROUP
 
-umask 022 
+umask 022
 limit stacksize unlimited
 
 setenv ARCH `uname`
@@ -26,4 +26,6 @@ setenv EXPDIR  @EXPDIR
 
 cd $EXPDIR
 
+@EXTDATA2G $GEOSBIN/construct_extdata_yaml_list.py GEOS_ChemGridComp.rc
+
 $RUN_CMD 1 ./GEOSgcm.x
diff --git a/scm_setup b/scm_setup
index c95e3e4e..73474441 100755
--- a/scm_setup
+++ b/scm_setup
@@ -91,6 +91,8 @@ usage ()
    echo "  Optional argument: "
    echo "    --num_levels: number of levels (72, 71, 91, 132, 137, and 181 allowed)."
    echo
+   echo "    --extdata2g: run with extdata2g"
+   echo
    echo
 }
 
@@ -101,6 +103,7 @@ selected_case=NULL
 expdir=NULL
 account=NULL
 nlev=72
+use_extdata2g=FALSE
 
 while [ "${1+defined}" ]
 do
@@ -125,6 +128,10 @@ do
          nlev=$1
          shift
          ;;
+      "--extdata2g")
+         shift
+         use_extdata2g=TRUE
+         ;;
       "--help" | "-h")
          usage
          exit 0
@@ -423,19 +430,28 @@ mkdir -p $expdir/ExtData
 
 year=$(cat $expdir/cap_restart | cut -c1-4)
 
-if [[ "$year" -lt  "2000" ]]
+if [[ $use_extdata2g == TRUE ]]
 then
-   echo "Before 2000, using AMIP.20C"
-   /bin/cp $INSTALLDIR/etc/AMIP.20C/*.rc $expdir
+   /bin/cp $INSTALLDIR/etc/*.yaml $expdir
+   /bin/cp $INSTALLDIR/etc/AMIP/*.yaml $expdir
+   /bin/mv $expdir/WSUB_ExtData.yaml $expdir/WSUB_ExtData.tmp
+   cat $expdir/WSUB_ExtData.tmp | sed -e '/collection:/ s#WSUB_Wvar_positive_05hrdeg.*#/dev/null#' > $expdir/WSUB_ExtData.yaml
+   /bin/rm $expdir/WSUB_ExtData.tmp
 else
-   echo "After 2000, using AMIP"
-   /bin/cp $INSTALLDIR/etc/AMIP/*.rc $expdir
-fi
+   if [[ "$year" -lt  "2000" ]]
+   then
+      echo "Before 2000, using AMIP.20C"
+      /bin/cp $INSTALLDIR/etc/AMIP.20C/*.rc $expdir
+   else
+      echo "After 2000, using AMIP"
+      /bin/cp $INSTALLDIR/etc/AMIP/*.rc $expdir
+   fi
 
-# Turn off wsub as we are 1moment
-/bin/mv $expdir/WSUB_ExtData.rc $expdir/WSUB_ExtData.tmp
-cat $expdir/WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > $expdir/WSUB_ExtData.rc
-/bin/rm $expdir/WSUB_ExtData.tmp
+   # Turn off wsub as we are 1moment
+   /bin/mv $expdir/WSUB_ExtData.rc $expdir/WSUB_ExtData.tmp
+   cat $expdir/WSUB_ExtData.tmp | sed -e '/^WSUB_NATURE/ s#ExtData.*#/dev/null#' > $expdir/WSUB_ExtData.rc
+   /bin/rm $expdir/WSUB_ExtData.tmp
+fi
 
 /bin/cp $SCMDIR/general/* $expdir
 
@@ -462,6 +478,7 @@ then
   padlev=${temp:(-${#digits})}
 
   $ISED "s/L72/L${nlev}/g" $expdir/*.rc
+  $ISED "s/L72/L${nlev}/g" $expdir/*.yaml
 
   $ISED "/AGCM_LM:/c\AGCM_LM: ${nlev}" $expdir/AGCM.rc
   $ISED "/AGCM.LM:/c\AGCM.LM: ${nlev}" $expdir/AGCM.rc
@@ -477,13 +494,20 @@ fi
 /bin/ln -s $CHMDIR/g5gcm $expdir/ExtData
 /bin/ln -s $CHMDIR/chemistry $expdir/ExtData
 
-if [[ -e $expdir/ExtData.rc ]]
+if [[ $use_extdata2g == TRUE ]]
 then
-   /bin/rm -f  $expdir/ExtData.rc
-fi
+   echo "USE_EXTDATA2G: .true." >> $expdir/CAP.rc
+   EXTDATA2G=""
+else
+   if [[ -e $expdir/ExtData.rc ]]
+   then
+      /bin/rm -f  $expdir/ExtData.rc
+   fi
 
-extdata_files=`/bin/ls -1 $expdir/*_ExtData.rc`
-cat $extdata_files > $expdir/ExtData.rc
+   extdata_files=`/bin/ls -1 $expdir/*_ExtData.rc`
+   cat $extdata_files > $expdir/ExtData.rc
+   EXTDATA2G="# ONLY FOR ExtData2G"
+fi
 
 # Handle scm_run.j
 
@@ -510,6 +534,7 @@ s?@BATCH_TASKS?$BATCH_TASKS?g
 s?@BATCH_TIME?$BATCH_TIME?g
 s?@BATCH_GROUP?$BATCH_GROUP?g
 s?@BATCH_JOBNAME?$BATCH_JOBNAME?g
+s?@EXTDATA2G?$EXTDATA2G?g
 EOF
 
 $ISED -f $expdir/sedfile $expdir/scm_run.j