diff --git a/cime_config/testdefs/testmods_dirs/cam/outfrq_trcdata_bam_derecho/user_nl_cam b/cime_config/testdefs/testmods_dirs/cam/outfrq_trcdata_bam_derecho/user_nl_cam
index 63698ed56..c45aa9428 100644
--- a/cime_config/testdefs/testmods_dirs/cam/outfrq_trcdata_bam_derecho/user_nl_cam
+++ b/cime_config/testdefs/testmods_dirs/cam/outfrq_trcdata_bam_derecho/user_nl_cam
@@ -1,17 +1,22 @@
 ! these snapshots were constructed to specifically test whether the data read into the
 ! physics buffer by tracer_data in CAM will match the data read by CAM-SIMA bit-for-bit.
 ! this was done by
-! (1) taking a FHIST_C4 snapshot (which has prescribed_ozone and aero)
-! in this case a ne3pg3_fhistc4_gw_drag_cam4_oro snapshot,
+! (1) taking a FHIST_C4 snapshot (which has prescribed_ozone, aero, aerodep_flx, and volcaero)
+!     using a "user_set" location at the beginning of tphysbc, before check_energy_fix
+!     this is because the prescribed data modules run during timestep_init;
+!     the energy fixer will change model state, causing changes in the interpolation,
+!     so the "before" snapshot before the global energy fixer needs to be used.
 ! (2) using nco to zero out the prescribed ozone and aero fields from the snapshot data,
-! to create the "before" snapshot.
-! (3) the "after" snapshot is the original snapshot file (which has non-zero values for prescribed
-! ozone and aerosols)
+!     to create the "before" snapshot:
+!        ncap2 -O -s 'pbuf_ozone=0.0*pbuf_ozone' h1i_v2.nc 0xozone.nc
+!        ncap2 -O -s 'pbuf_sulf=0.0*pbuf_sulf;pbuf_bcar1=0.0*pbuf_sulf;pbuf_bcar2=0.0*pbuf_sulf;pbuf_ocar1=0.0*pbuf_sulf;pbuf_ocar2=0.0*pbuf_sulf;pbuf_sslt1=0.0*pbuf_sulf;pbuf_sslt2=0.0*pbuf_sulf;pbuf_sslt3=0.0*pbuf_sulf;pbuf_sslt4=0.0*pbuf_sulf;pbuf_dust1=0.0*pbuf_sulf;pbuf_dust2=0.0*pbuf_sulf;pbuf_dust3=0.0*pbuf_sulf;pbuf_dust4=0.0*pbuf_sulf;pbuf_VOLC_RAD_GEOM=0.0*pbuf_VOLC_RAD_GEOM;pbuf_VOLC_MMR=0.0*pbuf_VOLC_MMR' 0xozone.nc 0xozone_aero_volcaero.nc
+! (3) the "after" snapshot is the original "before" snapshot file
+!     (which has non-zero values for prescribed ozone and aerosol)
 ! the test will pass iff. the tracer_data utility in CAM-SIMA and the prescribed_ozone/aerosols schemes
 ! can populate the prescribed fields bit-for-bit compared to the original snapshot file.
 
-ncdata = '/glade/campaign/cesm/community/amwg/sima_baselines/cam_sima_test_snapshots/cam_ne3pg3_fhistc4_tracer_data_0xprescribed-ozone-aero_from_cam4_oro_snapshot_derecho_gnu_after_c20251028.nc'
-ncdata_check = '/glade/campaign/cesm/community/amwg/sima_baselines/cam_sima_test_snapshots/cam_ne3pg3_fhistc4_gw_drag_cam4_oro_snapshot_derecho_gnu_after_c20250826.nc'
+ncdata = '/glade/campaign/cesm/community/amwg/sima_baselines/cam_sima_test_snapshots/cam_ne3pg3_fhistc4_tracer_data_0xprescribed-ozone-aero-volcaero_from_energy_fixer_derecho_gnu_before_c20260312.nc'
+ncdata_check = '/glade/campaign/cesm/community/amwg/sima_baselines/cam_sima_test_snapshots/cam_ne3pg3_fhistc4_tracer_data_0xprescribed-ozone-aero-volcaero_from_energy_fixer_derecho_gnu_after_c20260312.nc'
 
 ! tolerances for testing
 ncdata_check_err = .true.
@@ -20,7 +25,7 @@ min_difference = 2e-15
 ! cam4 vertical levels (FHIST_C4 snapshots)
 pver = 26
 
-prescribed_aero_datapath = "/glade/campaign/cesm/cesmdata/inputdata/atm/cam/chem/trop_mozart_aero/aero"
+prescribed_aero_datapath = "${DIN_LOC_ROOT}/atm/cam/chem/trop_mozart_aero/aero"
 prescribed_aero_file = "aero_1.9x2.5_L26_1850-2005_c091112.nc"
 prescribed_aero_filelist = "aero_1.9x2.5_L26_list_c070514.txt"
 prescribed_aero_model = "bulk"
@@ -30,14 +35,14 @@ prescribed_aero_cycle_yr = 0
 prescribed_aero_fixed_tod = 0
 prescribed_aero_fixed_ymd = 0
 
-aerodep_flx_datapath           = '/glade/campaign/cesm/cesmdata/inputdata/atm/cam/chem/trop_mozart_aero/aero'
+aerodep_flx_datapath           = '${DIN_LOC_ROOT}/atm/cam/chem/trop_mozart_aero/aero'
 aerodep_flx_file               = 'aerosoldep_monthly_1849-2006_1.9x2.5_c090803.nc'
 aerodep_flx_specifier          = 'BCDEPWET', 'BCPHODRY', 'BCPHIDRY', 'OCDEPWET', 'OCPHODRY', 'OCPHIDRY', 'DSTX01DD', 'DSTX02DD', 'DSTX03DD',
      'DSTX04DD', 'DSTX01WD', 'DSTX02WD', 'DSTX03WD', 'DSTX04WD'
 aerodep_flx_type               = 'INTERP_MISSING_MONTHS'
 aerodep_flx_cycle_yr = 0
 
-prescribed_ozone_datapath = "/glade/campaign/cesm/cesmdata/inputdata/atm/cam/ozone"
+prescribed_ozone_datapath = "${DIN_LOC_ROOT}/atm/cam/ozone"
 prescribed_ozone_file = "ozone_1.9x2.5_L26_1850-2005_c091112.nc"
 prescribed_ozone_filelist = "UNSET"
 prescribed_ozone_name = "O3"
@@ -46,8 +51,12 @@ prescribed_ozone_fixed_tod = 0
 prescribed_ozone_fixed_ymd = 0
 prescribed_ozone_cycle_yr = 0
 
+prescribed_volcaero_datapath = "${DIN_LOC_ROOT}/atm/cam/volc"
+prescribed_volcaero_file = "CCSM4_volcanic_1850-2008_prototype1.nc"
+
 hist_output_frequency;h1: 1*nsteps
 hist_max_frames;h1: 1
 hist_add_inst_fields;h1:ozone
 hist_add_inst_fields;h1:sulf_D,bcar1_D,bcar2_D,ocar1_D,ocar2_D,sslt1_D,sslt2_D,sslt3_D,sslt4_D,dust1_D,dust2_D,dust3_D,dust4_D
+hist_add_inst_fields;h1:VOLC_MMR,VOLC_RAD_GEOM,VOLC_MASS,VOLC_MASS_C
 hist_precision;h1: REAL64
diff --git a/src/data/physconst.F90 b/src/data/physconst.F90
index c73989dca..e560b1c87 100644
--- a/src/data/physconst.F90
+++ b/src/data/physconst.F90
@@ -46,7 +46,7 @@ module physconst
    !! \htmlinclude physconst.html
    ! Constants based off share code or defined in physconst
    real(kind_phys), public, parameter :: avogad      = real(shr_const_avogad, kind_phys)     ! Avogadro's number (molecules kmole-1)
-   real(kind_phys), public, parameter :: boltz       = real(shr_const_boltz, kind_phys)      ! Boltzman's constant (J K-1 molecule-1)
+   real(kind_phys), public, parameter :: boltz       = real(shr_const_boltz, kind_phys)      ! Boltzmann's constant (J K-1)
    real(kind_phys), public, parameter :: cday        = real(shr_const_cday, kind_phys)       ! sec in calendar day (seconds)
    real(kind_phys), public, parameter :: cpliq       = real(shr_const_cpfw, kind_phys)       ! specific heat of fresh h2o (J K-1 kg-1)
    real(kind_phys), public, parameter :: cpice       = real(shr_const_cpice, kind_phys)      ! specific heat of ice (J K-1 kg-1)
diff --git a/src/data/physconst.meta b/src/data/physconst.meta
index 72b6c8237..3f1c00839 100644
--- a/src/data/physconst.meta
+++ b/src/data/physconst.meta
@@ -7,7 +7,7 @@
 [ avogad ]
   standard_name = avogadro_number
   long_name = Avogadro's Number
-  units = molecules mole-1
+  units = molecules kmol-1
   type = real | kind = kind_phys
   dimensions = ()
   protected = True
diff --git a/src/data/registry.xml b/src/data/registry.xml
index 83ba849e0..25573d5e4 100644
--- a/src/data/registry.xml
+++ b/src/data/registry.xml
@@ -1707,6 +1707,20 @@
       <ic_file_input_names>dust4 pbuf_dust4 cnst_dust4</ic_file_input_names>
     </variable>
 
+    <!-- Prescribed volcanic aerosol (CAM4, CAM5) -->
+    <variable local_name="VOLC_MMR"
+              standard_name="VOLC_MMR"
+              units="kg kg-1" type="real" constituent="true">
+      <dimensions>horizontal_dimension vertical_layer_dimension</dimensions>
+      <ic_file_input_names>VOLC_MMR pbuf_VOLC_MMR</ic_file_input_names>
+    </variable>
+    <variable local_name="VOLC_RAD_GEOM"
+              standard_name="VOLC_RAD_GEOM"
+              units="m" type="real" constituent="true">
+      <dimensions>horizontal_dimension vertical_layer_dimension</dimensions>
+      <ic_file_input_names>VOLC_RAD_GEOM pbuf_VOLC_RAD_GEOM</ic_file_input_names>
+    </variable>
+
     <!-- Zhang McFarlane (ZM) Variables -->
     <variable local_name="ql"
               standard_name="in_cloud_water_vapor_mixing_ratio_wrt_moist_air_and_condensed_water_due_to_deep_convection"