Adds MAM4xx: Aerosol Cloud Interactions (ACI) interface

components/eamxx/cime_config/namelist_defaults_scream.xml

@@ -234,6 +234,12 @@ be lost if SCREAM_HACK_XML is not enabled.
       <Ckm type="real" doc="Eddy diffusivity coefficient for momentum">0.1</Ckm>
     </shoc>
 
+    <!-- MAM4xx-ACI -->
+    <mam4_aci inherit="atm_proc_base">
+      <wsubmin type="real" doc="Minimum diagnostic sub-grid vertical velocity">0.001</wsubmin>
+      <top_level_mam4xx type="integer" doc="Top level for MAM4xx">6</top_level_mam4xx>
+    </mam4_aci>
+
     <!-- CLD fraction -->
     <cldFraction inherit="atm_proc_base"/>
 
@@ -481,6 +487,33 @@ be lost if SCREAM_HACK_XML is not enabled.
     <surf_sens_flux    >0.0</surf_sens_flux>
     <surf_lw_flux_up   >0.0</surf_lw_flux_up>
     <surf_mom_flux     type="array(real)">0.0,0.0</surf_mom_flux>
+    <!-- Note: MAM4xx-ACI needs dry aerosol diameter (dgnum), currently set to aitken model nominal diameter, remove it once all of MAM4xx is integrated -->
+    <dgnum type="real" doc="Dry aerosol particles diameter in meters">2.6e-08</dgnum>
+        <bc_c1 type="real">0.0</bc_c1>
+    <bc_c3 type="real">0.0</bc_c3>
+    <bc_c4 type="real">0.0</bc_c4>
+    <dst_c1 type="real">0.0</dst_c1>
+    <dst_c3 type="real">0.0</dst_c3>
+    <so4_c1 type="real">0.0</so4_c1>
+    <so4_c2 type="real">0.0</so4_c2>
+    <so4_c3 type="real">0.0</so4_c3>
+    <pom_c1 type="real">0.0</pom_c1>
+    <pom_c3 type="real">0.0</pom_c3>
+    <pom_c4 type="real">0.0</pom_c4>
+    <soa_c1 type="real">0.0</soa_c1>
+    <soa_c2 type="real">0.0</soa_c2>
+    <soa_c3 type="real">0.0</soa_c3>
+    <nacl_c1 type="real">0.0</nacl_c1>
+    <nacl_c2 type="real">0.0</nacl_c2>
+    <nacl_c3 type="real">0.0</nacl_c3>
+    <mom_c1 type="real">0.0</mom_c1>
+    <mom_c2 type="real">0.0</mom_c2>
+    <mom_c3 type="real">0.0</mom_c3>
+    <mom_c4 type="real">0.0</mom_c4>
+    <num_c1 type="real">0.0</num_c1>
+    <num_c2 type="real">0.0</num_c2>
+    <num_c3 type="real">0.0</num_c3>
+    <num_c4 type="real">0.0</num_c4>
     <!-- default ne1024 initial condition files do not have these, so init to zero here -->
     <!-- TODO: delete this once we can tell the AD that some fields can be inited by procs -->
     <qc hgrid="ne256np4|ne1024np4">0.0</qc>

components/eamxx/cime_config/testdefs/testmods_dirs/scream/mam4xx/aci/shell_commands

@@ -0,0 +1,23 @@
+
+#Default scream has 10 tracers, MAM4xx adds another 31 making a total of 41 tracer
+#Set total number of tracers to 41. We are using append here as last entry wins while parsing xml options
+./xmlchange --append SCREAM_CMAKE_OPTIONS="SCREAM_NUM_TRACERS 41"
+
+#modify initial condition file to get aerosol species ICs
+$CIMEROOT/../components/eamxx/scripts/atmchange initial_conditions::Filename='$DIN_LOC_ROOT/atm/scream/init/screami_mam4xx_ne4np4L72_c20240208.nc' -b
+
+# Add spa as RRTMG needs spa
+$CIMEROOT/../components/eamxx/scripts/atmchange physics::atm_procs_list="mac_aero_mic,spa,rrtmgp" -b
+
+# Replace spa with mam4_aci to invoke mam4 aci scheme
+$CIMEROOT/../components/eamxx/scripts/atmchange mac_aero_mic::atm_procs_list="tms,shoc,cldFraction,mam4_aci,p3" -b
+
+#Set precribed ccn to false so that P3 uses input from ACI
+$CIMEROOT/../components/eamxx/scripts/atmchange p3::do_prescribed_ccn=false -b
+
+#Set predicted ccn to true so that P3 uses input from ACI
+$CIMEROOT/../components/eamxx/scripts/atmchange p3::do_predict_nc=true -b
+
+
+
+

components/eamxx/src/physics/mam/CMakeLists.txt

@@ -42,7 +42,8 @@ add_subdirectory(${EXTERNALS_SOURCE_DIR}/mam4xx ${CMAKE_BINARY_DIR}/externals/ma
 # EAMxx mam4xx-based atmospheric processes
 add_library(mam
   eamxx_mam_microphysics_process_interface.cpp
-  eamxx_mam_optics_process_interface.cpp)
+  eamxx_mam_optics_process_interface.cpp
+  eamxx_mam_aci_process_interface.cpp)
 target_compile_definitions(mam PUBLIC EAMXX_HAS_MAM)
 add_dependencies(mam mam4xx)
 target_include_directories(mam PUBLIC