EAMxx: Add namelist vars for disabling P3 subgrid cldfrac

components/eamxx/cime_config/namelist_defaults_scream.xml

@@ -223,6 +223,10 @@ be lost if SCREAM_HACK_XML is not enabled.
       <deposition_nucleation_exponent type="real" doc="Deposition nucleation exponent factor">0.304</deposition_nucleation_exponent>
       <ice_sedimentation_factor type="real" doc="Ice sedimentation fall speed factor">1.0</ice_sedimentation_factor>
       <do_ice_production type="logical" doc="Flag to turn on ice production processes (loss processes unaffected)">true</do_ice_production>
+      <!-- flags to override subgrid coud fraction by setting them to 1 everywhere if true -->
+      <set_cld_frac_l_to_one type="logical" doc="set P3 input liquid cloud fraction to 1 everywhere">false</set_cld_frac_l_to_one>
+      <set_cld_frac_r_to_one type="logical" doc="set P3 input rain cloud fraction to 1 everywhere"  >false</set_cld_frac_r_to_one>
+      <set_cld_frac_i_to_one type="logical" doc="set P3 input ice cloud fraction to 1 everywhere"   >false</set_cld_frac_i_to_one>
     </p3>
 
     <!-- SHOC macrophysics -->

components/eamxx/src/physics/p3/eamxx_p3_process_interface.cpp

@@ -280,7 +280,7 @@ void P3Microphysics::initialize_impl (const RunType /* run_type */)
   p3_preproc.set_variables(m_num_cols,nk_pack,pmid,pmid_dry,pseudo_density,pseudo_density_dry,
                         T_atm,cld_frac_t,
                         qv, qc, nc, qr, nr, qi, qm, ni, bm, qv_prev,
-                        inv_exner, th_atm, cld_frac_l, cld_frac_i, cld_frac_r, dz);
+                        inv_exner, th_atm, cld_frac_l, cld_frac_i, cld_frac_r, dz, runtime_options);
   // --Prognostic State Variables:
   prog_state.qc     = p3_preproc.qc;
   prog_state.nc     = p3_preproc.nc;

components/eamxx/src/physics/p3/eamxx_p3_process_interface.hpp

@@ -105,23 +105,26 @@ class P3Microphysics : public AtmosphereProcess
         th_atm(icol,ipack) = PF::calculate_theta_from_T(T_atm_pack,pmid_pack);
         // Cloud fraction
         // Set minimum cloud fraction - avoids division by zero
-        cld_frac_l(icol,ipack) = ekat::max(cld_frac_t_pack,mincld);
-        cld_frac_i(icol,ipack) = ekat::max(cld_frac_t_pack,mincld);
-        cld_frac_r(icol,ipack) = ekat::max(cld_frac_t_pack,mincld);
+        // Alternatively set fraction to 1 everywhere to disable subgrid effects
+        cld_frac_l(icol,ipack) = runtime_opts.set_cld_frac_l_to_one ? 1 : ekat::max(cld_frac_t_pack,mincld);
+        cld_frac_i(icol,ipack) = runtime_opts.set_cld_frac_i_to_one ? 1 : ekat::max(cld_frac_t_pack,mincld);
+        cld_frac_r(icol,ipack) = runtime_opts.set_cld_frac_r_to_one ? 1 : ekat::max(cld_frac_t_pack,mincld);
 
         // update rain cloud fraction given neighboring levels using max-overlap approach.
-        for (int ivec=0;ivec<Spack::n;ivec++)
-        {
-          // Hard-coded max-overlap cloud fraction calculation.  Cycle through the layers from top to bottom and determine if the rain fraction needs to
-          // be updated to match the cloud fraction in the layer above.  It is necessary to calculate the location of the layer directly above this one,
-          // labeled ipack_m1 and ivec_m1 respectively.  Note, the top layer has no layer above it, which is why we have the kstr index in the loop.
-          Int lev = ipack*Spack::n + ivec;  // Determine the level at this pack/vec location.
-          Int ipack_m1 = (lev - 1) / Spack::n;
-          Int ivec_m1  = (lev - 1) % Spack::n;
-          if (lev != 0) { /* Not applicable at the very top layer */
-            cld_frac_r(icol,ipack)[ivec] = cld_frac_t(icol,ipack_m1)[ivec_m1]>cld_frac_r(icol,ipack)[ivec] ?
-                                              cld_frac_t(icol,ipack_m1)[ivec_m1] :
-                                              cld_frac_r(icol,ipack)[ivec];
+        if ( !runtime_opts.set_cld_frac_r_to_one ) {
+          for (int ivec=0;ivec<Spack::n;ivec++)
+          {
+            // Hard-coded max-overlap cloud fraction calculation.  Cycle through the layers from top to bottom and determine if the rain fraction needs to
+            // be updated to match the cloud fraction in the layer above.  It is necessary to calculate the location of the layer directly above this one,
+            // labeled ipack_m1 and ivec_m1 respectively.  Note, the top layer has no layer above it, which is why we have the kstr index in the loop.
+            Int lev = ipack*Spack::n + ivec;  // Determine the level at this pack/vec location.
+            Int ipack_m1 = (lev - 1) / Spack::n;
+            Int ivec_m1  = (lev - 1) % Spack::n;
+            if (lev != 0) { /* Not applicable at the very top layer */
+              cld_frac_r(icol,ipack)[ivec] = cld_frac_t(icol,ipack_m1)[ivec_m1]>cld_frac_r(icol,ipack)[ivec] ?
+                                                cld_frac_t(icol,ipack_m1)[ivec_m1] :
+                                                cld_frac_r(icol,ipack)[ivec];
+            }
           }
         }
         //
@@ -152,6 +155,8 @@ class P3Microphysics : public AtmosphereProcess
     view_2d       cld_frac_i;
     view_2d       cld_frac_r;
     view_2d       dz;
+    // Add runtime_options as a member variable
+    P3F::P3Runtime runtime_opts;
     // Assigning local variables
     void set_variables(const int ncol, const int npack,
            const view_2d_const& pmid_, const view_2d_const& pmid_dry_,
@@ -161,7 +166,8 @@ class P3Microphysics : public AtmosphereProcess
            const view_2d& nc_, const view_2d& qr_, const view_2d& nr_, const view_2d& qi_,
            const view_2d& qm_, const view_2d& ni_, const view_2d& bm_, const view_2d& qv_prev_,
            const view_2d& inv_exner_, const view_2d& th_atm_, const view_2d& cld_frac_l_,
-           const view_2d& cld_frac_i_, const view_2d& cld_frac_r_, const view_2d& dz_
+           const view_2d& cld_frac_i_, const view_2d& cld_frac_r_, const view_2d& dz_,
+           const P3F::P3Runtime& runtime_options
            )
     {
       m_ncol = ncol;
@@ -190,6 +196,7 @@ class P3Microphysics : public AtmosphereProcess
       cld_frac_i = cld_frac_i_;
       cld_frac_r = cld_frac_r_;
       dz = dz_;
+      runtime_opts = runtime_options;
     } // set_variables
   }; // p3_preamble
   /* --------------------------------------------------------------------------------------------*/

components/eamxx/src/physics/p3/p3_functions.hpp

@@ -131,6 +131,9 @@ struct Functions
     Scalar deposition_nucleation_exponent = 0.304;
     Scalar ice_sedimentation_factor = 1.0;
     bool do_ice_production = true;
+    bool set_cld_frac_l_to_one = false;
+    bool set_cld_frac_i_to_one = false;
+    bool set_cld_frac_r_to_one = false;
 
     void load_runtime_options_from_file(ekat::ParameterList& params) {
       max_total_ni = params.get<double>("max_total_ni", max_total_ni);
@@ -153,6 +156,9 @@ struct Functions
       deposition_nucleation_exponent = params.get<double>("deposition_nucleation_exponent", deposition_nucleation_exponent);
       ice_sedimentation_factor = params.get<double>("ice_sedimentation_factor", ice_sedimentation_factor);
       do_ice_production = params.get<bool>("do_ice_production", do_ice_production);
+      set_cld_frac_l_to_one = params.get<bool>("set_cld_frac_l_to_one", set_cld_frac_l_to_one);
+      set_cld_frac_i_to_one = params.get<bool>("set_cld_frac_i_to_one", set_cld_frac_i_to_one);
+      set_cld_frac_r_to_one = params.get<bool>("set_cld_frac_r_to_one", set_cld_frac_r_to_one);
     }
 
   };