- Restore prescribed_ozone_file default and clarify description

- Remove AMIP compset but document how these experiment compsets
  should be created.

Author: Steve Goldhaber

bld/namelist_files/namelist_defaults_cam.xml

@@ -583,9 +583,9 @@
 <carma_soilerosion_file carma="dust">atm/cam/dst/soil_erosion_factor_1x1_c120907.nc</carma_soilerosion_file>
 <carma_emis_file        carma="tholin">atm/waccm/emis/early_earth_haze.nc</carma_emis_file>
 
-<!-- CAM-Chem ozone (2000 climatology) -->
+<!-- Default for ozone is 2000 climatology -->
 <prescribed_ozone_datapath>atm/cam/ozone</prescribed_ozone_datapath>
-<prescribed_ozone_file>ozone_strataero_b.e30_alpha08o.B1850C_MTt4s.ne30_t232_wgx3.330_branch_1850climo_zm_5day_c260415.nc</prescribed_ozone_file>
+<prescribed_ozone_file>ozone_1.9x2.5_L26_2000clim_c091112.nc</prescribed_ozone_file>
 <prescribed_ozone_name>O3</prescribed_ozone_name>
 <prescribed_ozone_type>CYCLICAL</prescribed_ozone_type>
 <prescribed_ozone_cycle_yr>2000</prescribed_ozone_cycle_yr>

cime_config/config_compsets.xml

@@ -94,12 +94,12 @@
     <lname>2000_CAM70%LT%NORESM%GHGCAMoslo_CLM60%FATES-NOCOMP_CICE%PRES_DOCN%DOM_MOSART_DGLC%NOEVOLVE_SWAV_SESP</lname>
   </compset>
 
-  <!-- CAM7 AMIP -->
-
-  <compset>
-    <alias>NFAMIP</alias>
-    <lname>AMIP_CAM70%LT%NORESM%CAMoslo_CLM60%FATES-NOCOMP_CICE%PRES_DOCN%DOM_MOSART_DGLC%NOEVOLVE_SWAV_SESP</lname>
-  </compset>
+  <!-- CAM7 AMIP-style experiments -->
+  <!-- These experiments should use "AMIP" as the time period
+       designation (1979-2021).
+       The name of the specific experiment (e.g., amip, piClim-X (or
+       AerChemMIP)) should appear in the compset alias (shortname).
+  -->
 
   <!-- ********************************* -->
   <!-- Hybrid NorESM / CAM-chem compsets -->