ESCOMP · slevis-lmwg · Aug 23, 2023 · Mar 25, 2021 · Apr 27, 2021 · May 7, 2021
diff --git a/bld/CLMBuildNamelist.pm b/bld/CLMBuildNamelist.pm
@@ -1580,6 +1580,7 @@ sub process_namelist_inline_logic {
   setup_logic_supplemental_nitrogen($opts, $nl_flags, $definition, $defaults, $nl);
   setup_logic_snowpack($opts,  $nl_flags, $definition, $defaults, $nl);
   setup_logic_fates($opts,  $nl_flags, $definition, $defaults, $nl);
+  setup_logic_z0param($opts, $nl_flags, $definition, $defaults, $nl);
   setup_logic_misc($opts, $nl_flags, $definition, $defaults, $nl);
 
   #########################################
@@ -4369,6 +4370,28 @@ sub setup_logic_exice {
 
 #-------------------------------------------------------------------------------
 
+sub setup_logic_z0param {
+   #
+   # Set default z0 paramterization
+   #
+   my ($opts, $nl_flags, $definition, $defaults, $nl) = @_;
+
+   add_default($opts, $nl_flags->{'inputdata_rootdir'}, $definition, $defaults, $nl, 'z0param_method');
+
+   my $z0param_method = remove_leading_and_trailing_quotes($nl->get_value('z0param_method' ));
+   add_default($opts, $nl_flags->{'inputdata_rootdir'}, $definition, $defaults, $nl, 'use_z0m_snowmelt',
+           'z0param_method'=>$z0param_method );
+
+   my $use_z0m_snowmelt = $nl->get_value( 'use_z0m_snowmelt' );
+
+   if ( $z0param_method eq "ZengWang2007" && defined($use_z0m_snowmelt) && value_is_true($use_z0m_snowmelt)) {
+      $log->fatal_error("use_z0m_snowmelt must be .false. when z0param_method = $z0param_method.\n $@");
+   }
+
+}
+
+#-------------------------------------------------------------------------------
+
 sub setup_logic_misc {
    #
    # Set some misc options

diff --git a/bld/namelist_files/namelist_defaults_ctsm.xml b/bld/namelist_files/namelist_defaults_ctsm.xml
@@ -213,7 +213,8 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <zetamaxstable               use_biomass_heat_storage=".true." >2.0d00</zetamaxstable>
 <zetamaxstable phys="clm4_5"                                   >2.0d00</zetamaxstable>
 <zetamaxstable phys="clm5_0"                                   >0.5d00</zetamaxstable>
-<zetamaxstable phys="clm5_1"                                   >0.5d00</zetamaxstable>
+<zetamaxstable phys="clm5_1" z0param_method="ZengWang2007" >0.5d00</zetamaxstable>
+<zetamaxstable phys="clm5_1" z0param_method="Meier2022" >2.0d00</zetamaxstable>
 
 <!-- atm2lnd defaults -->
 <repartition_rain_snow phys="clm5_1" >.true.</repartition_rain_snow>
@@ -324,6 +325,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <itmax_canopy_fluxes structure="standard">40</itmax_canopy_fluxes>
 <itmax_canopy_fluxes structure="fast"    >3</itmax_canopy_fluxes>
 
+
 <!-- Canopy hydrology namelist defaults -->
 <use_clm5_fpi                 phys="clm5_1" >.true.</use_clm5_fpi>
 <interception_fraction        phys="clm5_1" >1.0</interception_fraction>
@@ -495,6 +497,15 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 
 <fates_paramfile>lnd/clm2/paramdata/fates_params_api.25.5.0_12pft_c230628.nc</fates_paramfile>
 
+<!-- ================================================================== -->
+<!-- Default surface roughness parameterization                         -->
+<!-- ================================================================== -->
+
+<z0param_method>ZengWang2007</z0param_method>
+
+<use_z0m_snowmelt z0param_method="Meier2022" >.true.</use_z0m_snowmelt>
+<use_z0m_snowmelt >.false.</use_z0m_snowmelt>
+
 <!-- ========================================================================================  -->
 <!-- clm 5.0 BGC nitrogen model                                                                -->
 <!-- ========================================================================================  -->
@@ -1129,6 +1140,8 @@ lnd/clm2/surfdata_map/release-clm5.0.30/surfdata_C24_hist_78pfts_CMIP6_simyr2000
 lnd/clm2/surfdata_map/release-clm5.0.18/surfdata_0.9x1.25_hist_78pfts_CMIP6_simyr2000_c190214.nc</fsurdat>
 <fsurdat hgrid="1.9x2.5"   sim_year="2000" use_crop=".true." use_vichydro=".false.">
 lnd/clm2/surfdata_map/release-clm5.0.18/surfdata_1.9x2.5_hist_78pfts_CMIP6_simyr2000_c190304.nc</fsurdat>
+<fsurdat hgrid="hcru_hcru"   sim_year="2000">
+lnd/clm2/surfdata_map/release-clm5.0.18/surfdata_360x720cru_78pfts_CMIP6_simyr2000_c170824.nc</fsurdat>
 <fsurdat hgrid="0.125x0.125"  sim_year="2000" use_crop=".true." >
 lnd/clm2/surfdata_map/release-clm5.0.24/surfdata_0.125x0.125_hist_78pfts_CMIP6_simyr2005_c190624.nc</fsurdat>
 <fsurdat hgrid="10x15"     sim_year="2000" use_crop=".true." use_vichydro=".false.">

diff --git a/bld/namelist_files/namelist_definition_ctsm.xml b/bld/namelist_files/namelist_definition_ctsm.xml
@@ -2794,6 +2794,24 @@ the related bulk quantities.
 If .true., run with water isotopes
 </entry>  
 
+<!-- ========================================================================================  -->
+<!-- Namelist options related to surface roughness                                             -->
+<!-- ========================================================================================  -->
+
+<entry id="z0param_method" type="char*64" category="clm_physics"
+       group="clm_inparm" valid_values="ZengWang2007,Meier2022" >
+Parameterization/parameters to use for surface roughness
+ZengWang2007: Zeng and Wang 2007
+Meier2022: Meier et al. in prep. 2022
+</entry>
+
+<entry id="use_z0m_snowmelt" type="logical" category="clm_physics"
+       group="clm_inparm" valid_values="" >
+If FALSE use constant snow z0m
+If TRUE use parameterization of snow z0m as a function of accumulated
+snow melt of Brock et al. (2006)
+</entry>
+
 <!-- ========================================================================================  -->
 <!-- Namelist options related to initInterp                                                    -->
 <!-- ========================================================================================  -->

diff --git a/cime_config/testdefs/testlist_clm.xml b/cime_config/testdefs/testlist_clm.xml
@@ -17,6 +17,15 @@
       <option name="wallclock">00:20:00</option>
     </options>
   </test>
+  <test name="SMS_D_Ln6" grid="f09_g17" compset="I1850Clm50BgcNoAnthro" testmods="clm/Meier2022_surf_rough">
+    <machines>
+      <machine name="cheyenne" compiler="intel" category="aux_clm"/>
+    </machines>
+    <options>
+      <option name="wallclock">00:20:00</option>
+      <option name="comment"  >Meier Surface roughness with no-anthro compset</option>
+    </options>
+  </test>
   <test name="SMS_Ld5" grid="f09_g17" compset="I1850Clm45BgcCru" testmods="clm/default">
     <machines>
       <machine name="cheyenne" compiler="intel" category="ctsm_sci"/>
@@ -1154,6 +1163,37 @@
       <option name="comment"  >include a long Clm45 test, and include a production intel test of Clm45</option>
     </options>
   </test>
+  <test name="ERS_Ly3" grid="f10_f10_mg37" compset="I2000Clm51BgcCrop" testmods="clm/Meier2022_surf_rough">
+    <machines>
+      <machine name="cheyenne" compiler="intel" category="aux_clm"/>
+    </machines>
+    <options>
+      <option name="wallclock">01:40:00</option>
+      <option name="comment"  >include a long exact restart test with Meier surface roughness</option>
+    </options>
+  </test>
+  <test name="SMS_D" grid="f10_f10_mg37" compset="I2000Clm51Bgc" testmods="clm/Meier2022_surf_rough">
+    <machines>
+      <machine name="cheyenne" compiler="intel" category="aux_clm"/>
+      <machine name="cheyenne" compiler="gnu"   category="aux_clm"/>
+      <machine name="izumi"    compiler="nag"   category="aux_clm"/>
+      <machine name="izumi"    compiler="intel" category="aux_clm"/>
+      <machine name="izumi"    compiler="gnu"   category="aux_clm"/>
+    </machines>
+    <options>
+      <option name="wallclock">00:20:00</option>
+      <option name="comment"  >include a short DEBUG test with Meier surface roughness without crop</option>
+    </options>
+  </test>
+  <test name="ERS_D" grid="f10_f10_mg37" compset="I1850Clm51Sp" testmods="clm/Meier2022_surf_rough">
+    <machines>
+      <machine name="cheyenne" compiler="intel" category="aux_clm"/>
+    </machines>
+    <options>
+      <option name="wallclock">00:20:00</option>
+      <option name="comment"  >Exact restart short DEBUG SP test with Meier surface roughness</option>
+    </options>
+  </test>
   <test name="ERS_Ly6_Mmpi-serial" grid="1x1_smallvilleIA" compset="IHistClm50BgcCropQianRs" testmods="clm/cropMonthOutput">
     <machines>
       <machine name="izumi" compiler="intel" category="aux_clm"/>

diff --git a/cime_config/testdefs/testmods_dirs/clm/Meier2022_surf_rough/include_user_mods b/cime_config/testdefs/testmods_dirs/clm/Meier2022_surf_rough/include_user_mods
@@ -0,0 +1 @@
+../default
diff --git a/cime_config/testdefs/testmods_dirs/clm/Meier2022_surf_rough/user_nl_clm b/cime_config/testdefs/testmods_dirs/clm/Meier2022_surf_rough/user_nl_clm
@@ -0,0 +1,4 @@
+z0param_method = 'Meier2022'
+use_z0m_snowmelt = .true.
+paramfile = '$DIN_LOC_ROOT/lnd/clm2/paramdata/ctsm51_params.RMz0.c220304.nc'
+
diff --git a/doc/ChangeLog b/doc/ChangeLog
@@ -1,4 +1,105 @@
 ===============================================================
+Tag name: ctsm5.1.dev137
+Originator(s): Ronny Meier,  slevis (Samuel Levis,UCAR/TSS,303-665-1310)
+Date: Tue Aug 22 14:34:53 MDT 2023
+One-line Summary: Surface roughness modifications
+
+Purpose and description of changes
+----------------------------------
+
+Surface roughness (z0) modifications that appear in this publication:
+https://doi.org/10.5194/gmd-15-2365-2022
+
+When changing the namelist input z0param_method from ZengWang2007 (default)
+to Meier2022 the following modifications are activated:
+
+- A new parameterization of the vegetation surface roughness based on
+Raupach (1992) with optimized parameters to match the data collected in
+Hu et al. (2020) for different types of vegetation. This requires several new
+PFT-specific input parameters in the parameter file.
+- A spatially explicit z0m input field for bare soil based on the data of
+Prigent et al. (2005). This may be activated specifically by the user through
+the namelist input use_z0mg_2d. This requires a new input variable in the
+fsurdat file.
+- The parameterization of z0m for snow based on accumulated snow melt as
+proposed in Brock et al. (2006). This may be activated specifically by the
+user through the namelist input use_z0m_snowmelt.
+- The parameterization of Yang et al. (2008) for z0h and z0q over bare soil,
+snow, and glaciers.
+- The study in GMD also proposes new globally constant values for the
+z0m of bare soil, snow, and ice. To "activate" those the parameter file needs
+to be changed at the moment. The original and modified parameter files and
+fsurdat files will be shared by ftp.
+
+Open issues/questions (discussed with @ekluzek, @dlawrenncar, @olyson):
+
+- How to incorporate the data of Prigent et al. (2005) in the surfdata
+generation. I will write an email about this to Catherine Prigent.
+- One statement marked in CanopyFluxesMod should probably be changed when
+using Meier2022 (i.e., Yang et al. (2008) formulation should be used instead
+of Zeng and Dickinson (1998)).
+- At the moment one needs to change the parameter file to switch between the
+original and proposed globally constant z0m values for bare soil, snow, and
+ice. This is obviously not very user friendly and prone to mistakes.
+- The introduction of Yang et al. (2008) frequently results in z0h and z0q
+larger than z0m. This is only rarely observed in the field and in contradiction
+to the theory that z0h and z0q should be smaller because heat and water vapor
+need to be transported through molecular diffusion in the surface sublayer.
+
+
+Significant changes to scientifically-supported configurations
+--------------------------------------------------------------
+
+Does this tag change answers significantly for any of the following physics configurations?
+(Details of any changes will be given in the "Answer changes" section below.)
+
+    [Put an [X] in the box for any configuration with significant answer changes.]
+
+[ ] clm5_1
+
+[ ] clm5_0
+
+[ ] ctsm5_0-nwp
+
+[ ] clm4_5
+
+
+Bugs fixed or introduced
+------------------------
+CTSM issues fixed (include CTSM Issue #):
+Fixes #1316
+Fixes #1596
+
+Notes of particular relevance for users
+---------------------------------------
+Details already discussed in the description above.
+
+Notes of particular relevance for developers:
+---------------------------------------------
+Changes to tests or testing:
+New tests are in place for this new code.
+
+Testing summary:
+----------------
+ [PASS means all tests PASS; OK means tests PASS other than expected fails.]
+
+  regular tests (aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing):
+
+    cheyenne ---- OK 
+    izumi ------- OK
+
+Answer changes
+--------------
+Changes answers relative to baseline:
+ No, unless user chooses to run in non-default Meier2022 mode.
+
+Other details
+-------------
+Pull Requests that document the changes (include PR ids):
+ https://github.com/ESCOMP/ctsm/pull/2045
+
+===============================================================
+===============================================================
 Tag name: ctsm5.1.dev136
 Originator(s): jedwards (Jim Edwards), sacks (Bill Sacks)
 Date: Tue Aug 22 13:10:28 MDT 2023

diff --git a/doc/ChangeSum b/doc/ChangeSum
@@ -1,5 +1,6 @@
 Tag                   Who      Date  Summary
 ============================================================================================================================
+    ctsm5.1.dev137   slevis 08/23/2023 Surface roughness modifications
     ctsm5.1.dev136 multiple 08/22/2023 Change order of history fields to improve performance on derecho
     ctsm5.1.dev135   slevis 08/21/2023 Rename hist fields to track them down more easily
     ctsm5.1.dev134   rgknox 08/16/2023 Migration of FATES to share normal soil BGC call sequence and functionality