diff --git a/scripts/exregional_run_fcst.sh b/scripts/exregional_run_fcst.sh
index 5963fd6bcf..513aa66345 100755
--- a/scripts/exregional_run_fcst.sh
+++ b/scripts/exregional_run_fcst.sh
@@ -410,20 +410,22 @@ done
 #
 #-----------------------------------------------------------------------
 #
-for f_nm_path in ${FIXclim}/*; do
-  f_nm=$( basename "${f_nm_path}" )
-  pre_f="${f_nm%%.*}"
-
-  if [ "${pre_f}" = "merra2" ]; then
-    mnth=$( printf "%s\n" "${f_nm}" | grep -o -P '(?<=2014.m).*(?=.nc)' )
-    symlink="${run_dir}/aeroclim.m${mnth}.nc"
-  else
-    symlink="${run_dir}/${pre_f}.dat"
-  fi
-  target="${f_nm_path}"
-  create_symlink_to_file target="$target" symlink="$symlink" \
+if [ "${USE_MERRA_CLIMO}" = "TRUE" ]; then
+  for f_nm_path in ${FIXclim}/*; do
+    f_nm=$( basename "${f_nm_path}" )
+    pre_f="${f_nm%%.*}"
+
+    if [ "${pre_f}" = "merra2" ]; then
+      mnth=$( printf "%s\n" "${f_nm}" | grep -o -P '(?<=2014.m).*(?=.nc)' )
+      symlink="${run_dir}/aeroclim.m${mnth}.nc"
+    else
+      symlink="${run_dir}/${pre_f}.dat"
+    fi
+    target="${f_nm_path}"
+    create_symlink_to_file target="$target" symlink="$symlink" \
                          relative="${relative_link_flag}"
-done
+  done
+fi
 #
 #-----------------------------------------------------------------------
 #
diff --git a/tests/WE2E/test_configs/grids_extrn_mdls_suites_community/config.grid_RRFS_CONUS_3km_ics_FV3GFS_lbcs_FV3GFS_suite_GFS_v15_thompson_mynn_lam3km.sh b/tests/WE2E/test_configs/grids_extrn_mdls_suites_community/config.grid_RRFS_CONUS_3km_ics_FV3GFS_lbcs_FV3GFS_suite_GFS_v15_thompson_mynn_lam3km.sh
index f391b26886..03dbd2c381 100644
--- a/tests/WE2E/test_configs/grids_extrn_mdls_suites_community/config.grid_RRFS_CONUS_3km_ics_FV3GFS_lbcs_FV3GFS_suite_GFS_v15_thompson_mynn_lam3km.sh
+++ b/tests/WE2E/test_configs/grids_extrn_mdls_suites_community/config.grid_RRFS_CONUS_3km_ics_FV3GFS_lbcs_FV3GFS_suite_GFS_v15_thompson_mynn_lam3km.sh
@@ -13,6 +13,8 @@ PREEXISTING_DIR_METHOD="rename"
 PREDEF_GRID_NAME="RRFS_CONUS_3km"
 CCPP_PHYS_SUITE="FV3_GFS_v15_thompson_mynn_lam3km"
 
+USE_MERRA_CLIMO="TRUE"
+
 EXTRN_MDL_NAME_ICS="FV3GFS"
 EXTRN_MDL_NAME_LBCS="FV3GFS"
 USE_USER_STAGED_EXTRN_FILES="TRUE"
diff --git a/ush/config_defaults.sh b/ush/config_defaults.sh
index 702cf4db8d..c3090cc8bc 100644
--- a/ush/config_defaults.sh
+++ b/ush/config_defaults.sh
@@ -1333,6 +1333,15 @@ RUN_TASK_VX_ENSPOINT="FALSE"
 #
 #-----------------------------------------------------------------------
 #
+# Flag that determines whether MERRA2 aerosol climatology data and
+# lookup tables for optics properties are obtained
+#
+#-----------------------------------------------------------------------
+#
+USE_MERRA_CLIMO="FALSE"
+#
+#-----------------------------------------------------------------------
+#
 # Set the array parameter containing the names of all the fields that the
 # MAKE_SFC_CLIMO_TN task generates on the native FV3-LAM grid.
 #
diff --git a/ush/generate_FV3LAM_wflow.sh b/ush/generate_FV3LAM_wflow.sh
index d19a58b52c..db65baec21 100755
--- a/ush/generate_FV3LAM_wflow.sh
+++ b/ush/generate_FV3LAM_wflow.sh
@@ -618,18 +618,20 @@ fi
 #
 #-----------------------------------------------------------------------
 #
-print_info_msg "$VERBOSE" "
+if [ "${USE_MERRA_CLIMO}" = "TRUE" ]; then
+  print_info_msg "$VERBOSE" "
 Copying MERRA2 aerosol climatology data files from system directory
 (FIXaer/FIXlut) to a subdirectory (FIXclim) in the experiment directory:
   FIXaer = \"${FIXaer}\"
   FIXlut = \"${FIXlut}\"
   FIXclim = \"${FIXclim}\""
 
-check_for_preexist_dir_file "${FIXclim}" "delete"
-mkdir_vrfy -p "${FIXclim}"
+  check_for_preexist_dir_file "${FIXclim}" "delete"
+  mkdir_vrfy -p "${FIXclim}"
 
-cp_vrfy "${FIXaer}/merra2.aerclim"*".nc" "${FIXclim}/"
-cp_vrfy "${FIXlut}/optics"*".dat" "${FIXclim}/"
+  cp_vrfy "${FIXaer}/merra2.aerclim"*".nc" "${FIXclim}/"
+  cp_vrfy "${FIXlut}/optics"*".dat" "${FIXclim}/"
+fi
 #
 #-----------------------------------------------------------------------
 #
diff --git a/ush/setup.sh b/ush/setup.sh
index ee49750ae9..88dcab21e5 100755
--- a/ush/setup.sh
+++ b/ush/setup.sh
@@ -790,6 +790,30 @@ check_var_valid_value \
 #
 #-----------------------------------------------------------------------
 #
+# Make sure that USE_MERRA_CLIMO is set to a valid value.
+#
+#-----------------------------------------------------------------------
+#
+check_var_valid_value "USE_MERRA_CLIMO" "valid_vals_USE_MERRA_CLIMO"
+#
+# Set USE_MERRA_CLIMO to either "TRUE" or "FALSE" so we don't
+# have to consider other valid values later on.
+#
+USE_MERRA_CLIMO=$(echo_uppercase $USE_MERRA_CLIMO)
+if [ "${USE_MERRA_CLIMO}" = "TRUE" ] || \
+   [ "${USE_MERRA_CLIMO}" = "YES" ]; then
+  USE_MERRA_CLIMO="TRUE"
+elif [ "${USE_MERRA_CLIMO}" = "FALSE" ] || \
+     [ "${USE_MERRA_CLIMO}" = "NO" ]; then
+  USE_MERRA_CLIMO="FALSE"
+fi
+# Force to "TRUE" in case of FV3_GFS_v15_thompson_mynn_lam3km:
+if [ "${CCPP_PHYS_SUITE}" = "FV3_GFS_v15_thompson_mynn_lam3km" ]; then
+  USE_MERRA_CLIMO="TRUE"
+fi
+#
+#-----------------------------------------------------------------------
+#
 # Make sure that FCST_MODEL is set to a valid value.
 #
 #-----------------------------------------------------------------------
diff --git a/ush/valid_param_vals.sh b/ush/valid_param_vals.sh
index a8bd0ae721..c421441309 100644
--- a/ush/valid_param_vals.sh
+++ b/ush/valid_param_vals.sh
@@ -78,3 +78,4 @@ valid_vals_FVCOM_WCSTART=("warm" "WARM" "cold" "COLD")
 valid_vals_COMPILER=("intel" "gnu")
 valid_vals_SUB_HOURLY_POST=("TRUE" "true" "YES" "yes" "FALSE" "false" "NO" "no")
 valid_vals_DT_SUBHOURLY_POST_MNTS=("1" "01" "2" "02" "3" "03" "4" "04" "5" "05" "6" "06" "10" "12" "15" "20" "30")
+valid_vals_USE_MERRA_CLIMO=("TRUE" "true" "YES" "yes" "FALSE" "false" "NO" "no")