diff --git a/lib/adf_dataset.py b/lib/adf_dataset.py
index 9b87ecc2f..9f6595b6a 100644
--- a/lib/adf_dataset.py
+++ b/lib/adf_dataset.py
@@ -5,6 +5,7 @@
 import xarray as xr
 
 import adf_utils as utils
+from adf_formula import safe_eval
 warnings.formatwarning = utils.my_formatwarning
 
 # "reference data"
@@ -267,7 +268,12 @@ def load_reference_climo_da(self, case, variablename):
         """Return DataArray from reference (aka baseline) climo file"""
         add_offset, scale_factor = self.get_value_converters(case, variablename)
         fils = self.get_reference_climo_file(variablename)
-        return self.load_da(fils, variablename, add_offset=add_offset, scale_factor=scale_factor)
+        # For obs, the field may be stored under a different name (obs_var_name);
+        # pass it for the direct read while keeping the ADF name for the lookups.
+        obs_name = self.ref_var_nam.get(variablename) if self.adf.compare_obs else None
+        return self.load_da(fils, variablename, derive_obs=self.adf.compare_obs,
+                            obs_var_name=obs_name,
+                            add_offset=add_offset, scale_factor=scale_factor)
 
     def get_reference_climo_file(self, var):
         """Return a list of files to be used as reference (aka baseline) for variable var."""
@@ -353,11 +359,13 @@ def load_reference_regrid_da(self, case, field):
             warnings.warn("\t    WARNING: Did not find regridded file(s) for case: "
                           f"{case}, variable: {field}")
             return None
-        #Change the variable name from CAM standard to what is
-        # listed in variable defaults for this observation field
-        if self.adf.compare_obs:
-            field = self.ref_var_nam[field]
-        return self.load_da(fils, field, add_offset=add_offset, scale_factor=scale_factor)
+        # For obs, the field may be stored under a different name (obs_var_name);
+        # pass it for the direct read while keeping the ADF name (field) for the
+        # derivation and units lookups.
+        obs_name = self.ref_var_nam.get(field) if self.adf.compare_obs else None
+        return self.load_da(fils, field, derive_obs=self.adf.compare_obs,
+                            obs_var_name=obs_name,
+                            add_offset=add_offset, scale_factor=scale_factor)
 
     #------------------
 
@@ -383,17 +391,90 @@ def load_dataset(self, fils, decode_times=True):
             warnings.warn("\t    WARNING: invalid data on load_dataset")
         return ds
 
+    def derive_obs_from_formula(self, ds, variablename):
+        """Compute an observational `variablename` from an obs-specific formula.
+
+        This is the single, consistent mechanism for transforming observational
+        data into a model-comparable field.  It covers both:
+          * derivation from constituents - e.g. PRECT = PRECC + PRECL, and
+          * unit conversion / scaling    - e.g. BURDENSO4 = BURDENSO4 * 1e6
+            (a "self-reference" formula), replacing obs_scale_factor/obs_add_offset.
+        Arbitrary combinations are allowed, e.g. "(PRECC + PRECL) * 86400 * 1000".
+
+        It uses observation-specific variable-defaults attributes, deliberately
+        independent of the model attributes because obs names/formula may differ:
+            obs_derivable_from      - input variable names as they appear in the obs file
+            obs_derivation_formula  - formula written in terms of those obs names
+
+        `variablename` is the ADF variable name (the variable_defaults key), so the
+        lookup is independent of obs_var_name (which only names the stored obs field).
+
+        Returns a DataArray (named `variablename`) or None if no usable obs formula
+        is provided or its inputs are not all present in the file.
+        """
+        vres = self.adf.variable_defaults.get(variablename, {})
+        constits = vres.get("obs_derivable_from")
+        formula  = vres.get("obs_derivation_formula")
+        if not constits or not formula:
+            return None
+        if not all(c in ds.data_vars for c in constits):
+            return None
+        da = safe_eval(formula, {c: ds[c] for c in constits})
+        da.name = variablename
+        return da
+
     # Load DataArray
-    def load_da(self, fils, variablename, **kwargs):
-        """Return xarray DataArray from file(s) w/ optional scale factor, offset, new units."""
+    def load_da(self, fils, variablename, derive_obs=False, obs_var_name=None, **kwargs):
+        """Return xarray DataArray from file(s) w/ optional scale factor, offset, new units.
+
+        `variablename` is the ADF variable name (the variable_defaults key) and is used
+        for the derivation and units lookups.  `obs_var_name`, if given, is the name the
+        variable is stored under in the obs file and is used only for the direct read
+        (observations may store a field under a different name than ADF uses).
+
+        When derive_obs is True and a obs_derivation_formula is provided for the
+        variable, that formula fully defines the transform from the obs file (any
+        combination of derivation from constituents and unit conversion), so it is
+        applied and the obs_scale_factor/obs_add_offset step is skipped.  If no
+        obs formula is provided, behavior is unchanged: read the variable directly
+        and apply scale_factor/add_offset (the obs_* values for observations).
+        """
         ds = self.load_dataset(fils)
         if ds is None:
             warnings.warn(f"\t    WARNING: Load failed for {variablename}")
             return None
-        da = ds[variablename].squeeze()
-        scale_factor = kwargs.get('scale_factor', 1)
-        add_offset = kwargs.get('add_offset', 0)
-        da = da * scale_factor + add_offset
+
+        # Name of the field as stored in the file (obs may rename it); the ADF name
+        # (variablename) is always used for the derivation and defaults/units lookups.
+        read_name = obs_var_name if obs_var_name else variablename
+
+        # Observations: prefer a obs_derivation_formula when present - it fully
+        # defines the transform (derivation and/or scaling), so scale/offset is skipped.
+        da = None
+        applied_obs_formula = False
+        if derive_obs:
+            da = self.derive_obs_from_formula(ds, variablename)
+            if da is not None:
+                da = da.squeeze()
+                applied_obs_formula = True
+
+        if da is None:
+            if read_name in ds.data_vars:
+                da = ds[read_name].squeeze()
+            elif derive_obs:
+                warnings.warn(f"\t    WARNING: obs variable {variablename} (file name "
+                              f"'{read_name}') not found and no usable obs_derivation_formula "
+                              "was provided.")
+                return None
+            else:
+                # Preserve prior behavior (raises if the variable is genuinely missing).
+                da = ds[read_name].squeeze()
+
+        # Apply scale/offset only when an obs formula did not already define the transform.
+        if not applied_obs_formula:
+            scale_factor = kwargs.get('scale_factor', 1)
+            add_offset = kwargs.get('add_offset', 0)
+            da = da * scale_factor + add_offset
         if variablename in self.adf.variable_defaults:
             vres = self.adf.variable_defaults[variablename]
             da.attrs['units'] = vres.get("new_unit", da.attrs.get('units', 'none'))
diff --git a/lib/adf_variable_defaults.yaml b/lib/adf_variable_defaults.yaml
index 7b8803aaf..7ca1623ed 100644
--- a/lib/adf_variable_defaults.yaml
+++ b/lib/adf_variable_defaults.yaml
@@ -1,4 +1,3 @@
-
 #This file lists out variable-specific defaults
 #for plotting and observations.  These defaults
 #are:
@@ -24,16 +23,23 @@
 #                         Currently only accepts "ocean", which means the variable will be masked
 #                         everywhere that isn't open ocean.
 #
+# derivable_from       -> If not present in the available output files, the variable can be derived from
+#                         other variables that are present (e.g. PRECT can be derived from PRECC and PRECL),
+# derivation_formula   -> If derivable_from is specified then an accompanying derivation_fromula must
+#                         also be specified
 #
 # OBSERVATIONS:
 #
-# obs_file     -> Path to observations file.  If only the file name is given, then the file is assumed to
-#                 exist in the path specified by "obs_data_loc" in the config file.
-# obs_name     -> Name of the observational dataset (mostly used for plotting and generated file naming).
-#                 If this isn't present then the obs_file name is used.
-# obs_var_name -> Variable in the observations file to compare against.  If this isn't present then the
-#                 variable name is assumed to be the same as the model variable name.
-#
+# obs_file		 -> Path to observations file.  If only the file name is given, then the file is assumed to
+#                           exist in the path specified by "obs_data_loc" in the config file.
+# obs_name		 -> Name of the observational dataset (mostly used for plotting and generated file naming).
+#                           If this isn't present then the obs_file name is used.
+# obs_var_name		 -> Variable in the observations file to compare against.  If this isn't present then the
+#                           variable name is assumed to be the same as the model variable name.
+# obs_derivable_from	 -> If not present in the available output files, the variable can be derived from
+#                           other observational variables that are present
+# obs_derivation_formula -> If derivable_from is specified then an accompanying derivation_fromula_obs must
+#                           also be specified
 #
 # VECTORS:
 #
@@ -51,12 +57,6 @@
 #
 # DERIVING:
 #
-# derivable_from -> If not present in the available output files, the variable can be derived from
-#                   other variables that are present (e.g. PRECT can be derived from PRECC and PRECL),
-# derivation_formula -> If derivable_from is specified then an accompanying derivation_fromula must
-#                       also be specified
-#
-#
 # Final Note:  Please do not modify this file unless you plan to push your changes back to the ADF repo.
 #              If you would like to modify this file for your personal ADF runs then it is recommended
 #              to make a copy of this file, make modifications in that copy, and then point the ADF to
@@ -1040,8 +1040,6 @@ CLDTOT:
   contour_levels_range: [0.2, 1.1, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1055,8 +1053,6 @@ CLDLOW:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1070,8 +1066,6 @@ CLDHGH:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1085,8 +1079,6 @@ CLDMED:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1101,7 +1093,6 @@ CLOUD:
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
   scale_factor: 100
-  add_offset: 0
   new_unit: "Percent"
   mpl:
     colorbar:
@@ -1118,8 +1109,6 @@ TGCLDLWP:
   contour_levels_range: [0, 400, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-100, 100, 10]
-  scale_factor: 1000
-  add_offset: 0
   new_unit: "g m$^{-2}$"
   mpl:
     colorbar:
@@ -1127,9 +1116,8 @@ TGCLDLWP:
   category: "Clouds"
   obs_file: "TGCLDLWP_ERA5_monthly_climo_197901-202112.nc"
   obs_name: "ERA5"
-  obs_var_name: "TGCLDLWP"
-  obs_scale_factor: 1000
-  obs_add_offset: 0
+  obs_derivable_from: ['TGCLDWP']
+  obs_derivation_formula: "TGCLDWP * 1000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1138,8 +1126,6 @@ TGCLDIWP:
   contour_levels_range: [0, 100, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-50, 50, 5]
-  scale_factor: 1000
-  add_offset: 0
   new_unit: "g m$^{-2}$"
   mpl:
     colorbar:
@@ -1147,9 +1133,8 @@ TGCLDIWP:
   category: "Clouds"
   obs_file: "TGCLDIWP_ERA5_monthly_climo_197901-202112.nc"
   obs_name: "ERA5"
-  obs_var_name: "TGCLDIWP"
-  obs_scale_factor: 1000
-  obs_add_offset: 0
+  obs_derivable_from: ['TGCLDIWP']
+  obs_derivation_formula: "TGCLDIWP * 1000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1177,82 +1162,80 @@ WPTHLP_CLUBB:
 #+++++++++++++++++
 
 PRECC:
+  category: "Hydrologic cycle"
   colormap: "Greens"
   contour_levels_range: [0, 20, 1]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 86400000
-  add_offset: 0
   new_unit: "mm d$^{-1}$"
   mpl:
     colorbar:
       label : "mm/d"
-  category: "Hydrologic cycle"
+  derivable_from: ['PRECC']
+  derivation_formula: "PRECC * 86400000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 PRECL:
+  category: "Hydrologic cycle"
   colormap: "Greens"
   contour_levels_range: [0, 20, 1]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 86400000
-  add_offset: 0
   new_unit: "mm d$^{-1}$"
   mpl:
     colorbar:
       label : "mm d$^{-1}$"
-  category: "Hydrologic cycle"
+  derivable_from: ['PRECL']
+  derivation_formula: "PRECL * 86400000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 PRECSC:
+  category: "Hydrologic cycle"
   colormap: "Greens"
   contour_levels_range: [0, 20, 1]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 86400000
-  add_offset: 0
   new_unit: "mm d$^{-1}$"
   mpl:
     colorbar:
       label : "mm d$^{-1}$"
-  category: "Hydrologic cycle"
+  derivable_from: ['PRECSC']
+  derivation_formula: "PRECSC * 86400000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 PRECSL:
+  category: "Hydrologic cycle"
   colormap: "Greens"
   contour_levels_range: [0, 20, 1]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 86400000
-  add_offset: 0
   new_unit: "mm d$^{-1}$"
   mpl:
     colorbar:
       label : "mm d$^{-1}$"
-  category: "Hydrologic cycle"
+  derivable_from: ['PRECSL']
+  derivation_formula: "PRECSL * 86400000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 PRECT:
+  category: "Hydrologic cycle"
   colormap: "Blues"
   contour_levels_range: [0, 20, 1]
   diff_colormap: "seismic"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 86400000
-  add_offset: 0
   new_unit: "mm d$^{-1}$"
   mpl:
     colorbar:
       label : "mm d$^{-1}$"
+  derivable_from: ['PRECL','PRECC']
+  derivation_formula: "(PRECC + PRECL) * 86400000"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
   obs_var_name: "PRECT"
-  category: "Hydrologic cycle"
-  derivable_from: ['PRECL','PRECC']
-  derivation_formula: "PRECC + PRECL"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1275,7 +1258,6 @@ PSL:
   diff_colormap: "PuOr_r"
   diff_contour_range: [-9, 9, 0.5]
   scale_factor: 0.01
-  add_offset: 0
   new_unit: "hPa"
   mpl:
     colorbar:
@@ -1293,7 +1275,6 @@ PS:
   diff_colormap: "PuOr_r"
   diff_contour_range: [-9, 9, 0.5]
   scale_factor: 0.01
-  add_offset: 0
   new_unit: "hPa"
   mpl:
     colorbar:
@@ -1312,8 +1293,6 @@ TREFHT:
   obs_var_name: "TREFHT"
   contour_levels_range: [220,320, 5]
   diff_contour_range: [-10, 10, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "K"
 
 TS:
@@ -1321,8 +1300,6 @@ TS:
   contour_levels_range: [220,320, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "K"
   mpl:
     colorbar:
@@ -1339,8 +1316,6 @@ SST:
   contour_levels_range: [220,320, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "K"
   mpl:
     colorbar:
@@ -1368,16 +1343,17 @@ TAUX:
   vector_name: "Surface_Wind_Stress"
   category: "Surface variables"
   scale_factor: -1
-  add_offset: 0
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
+  obs_file: "TAUX_ERA5_monthly_climo_1degree_197901-202212.nc"
+  obs_name: "ERA5"
+  obs_var_name: "TAUX"
 
 TAUY:
   vector_pair: "TAUX"
   vector_name: "Surface_Wind_Stress"
   category: "Surface variables"
   scale_factor: -1
-  add_offset: 0
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1405,8 +1381,6 @@ TMQ:
   contour_levels_range: [0, 75.0, 5.0]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "kg m$^{-2}$"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1420,8 +1394,6 @@ RELHUM:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Fraction"
   mpl:
     colorbar:
@@ -1438,8 +1410,6 @@ U:
   contour_levels_range: [-10, 90, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "ms$^{-1}$"
   mpl:
     colorbar:
@@ -1458,8 +1428,6 @@ V:
   contour_levels_range: [-10, 90, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "ms$^{-1}$"
   mpl:
     colorbar:
@@ -1502,7 +1470,6 @@ OMEGA500:
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
   scale_factor: 864
-  add_offset: 0
   new_unit: "hPa d$^{-1}$"
   hist_bins: [-105, -100,  -95,  -90,  -85,  -80,  -75,  -70,  -65,  -60,  -55, -50,  -45,  -40,  -35,  -30,  -25,  -20,  -15,  -10,   -5,    0, 5,   10,   15,   20,   25,   30,   35,   40,   45,   50,   55, 60,   65,   70,   75,   80,   85,   90,   95,  100]
 
@@ -1544,30 +1511,61 @@ QRS:
 # Category: TOA energy flux
 #+++++++++++++++++
 
+ALBEDO:
+  category: "TOA energy flux"
+  colormap: "Blues"
+  contour_levels_range: [0, 1, .1]
+  diff_colormap: "BrBG"
+  diff_contour_range: [-0.5, 0.5, .05]
+  new_unit: "dimensionless"
+  derivable_from: ['SOLIN','FSNTOA']
+  derivation_formula: "(SOLIN-FSNTOA)/SOLIN"
+  mpl:
+    colorbar:
+      label : "dimensionless"
+  obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
+  obs_name: "CERES-EBAF"
+  obs_derivable_from: ['solar_mon','fsnt']
+  obs_derivation_formula: "(solar_mon-fsnt)/solar_mon"
+
+ALBEDOC:
+  category: "TOA energy flux"
+  colormap: "Blues"
+  contour_levels_range: [0, 1, .05]
+  diff_colormap: "BrBG"
+  diff_contour_range: [-0.3, 0.3, .05]
+  new_unit: "dimensionless"
+  derivable_from: ['SOLIN','FSNTOAC']
+  derivation_formula: "(SOLIN-FSNTOAC)/SOLIN"
+  mpl:
+    colorbar:
+      label : "dimensionless"
+  obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
+  obs_name: "CERES_EBAF"
+  obs_derivable_from: ['solar_mon','toa_sw_clr_c_mon']
+  obs_derivation_formula: "toa_sw_clr_c_mon/solar_mon"
+
 RESTOM:
+  category: "TOA energy flux"
   colormap: "RdBu_r"
   contour_levels_range: [-100, 100, 5]
   diff_colormap: "seismic"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "W m$^{-2}$"
   mpl:
     colorbar:
       label : "W m$^{-2}$"
-  category: "TOA energy flux"
   derivable_from: ['FLNT','FSNT']
   derivation_formula: "FSNT - FLNT"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 SWCF:
+  category: "TOA energy flux"
   colormap: "Blues"
   contour_levels_range: [-150, 50, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1575,19 +1573,15 @@ SWCF:
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
   obs_var_name: "toa_cre_sw_mon"
-  obs_scale_factor: 1
-  obs_add_offset: 0
-  category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 LWCF:
+  category: "TOA energy flux"
   colormap: "Oranges"
   contour_levels_range: [-10, 100, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1595,32 +1589,28 @@ LWCF:
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
   obs_var_name: "toa_cre_lw_mon"
-  category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 FSUTOA:
+  category: "TOA energy flux"
   colormap: "Blues"
   contour_levels_range: [-10, 180, 15]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
       label : "Wm$^{-2}$"
-  category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 FSNT:
+  category: "TOA energy flux"
   colormap: "Blues"
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1628,7 +1618,6 @@ FSNT:
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
   obs_var_name: "fsnt"
-  category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1648,30 +1637,27 @@ FLUT:
   pct_diff_colormap: "PuOr_r"
 
 FLNT:
+  obs_var_name: "toa_lw_all_mon"
   colormap: "Oranges"
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
       label : "Wm$^{-2}$"
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
-  obs_var_name: "toa_lw_all_mon"
   category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
 FLNTC:
+  category: "TOA energy flux"
   colormap: "Oranges"
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1679,7 +1665,6 @@ FLNTC:
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
   obs_var_name: "toa_lw_clr_t_mon"
-  category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1702,8 +1687,6 @@ FSNS:
   contour_levels_range: [-10, 300, 20]
   diff_colormap: "BrBG"
   diff_contour_range: [-24, 24, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1720,8 +1703,6 @@ FSNSC:
   contour_levels_range: [-10, 300, 20]
   diff_colormap: "BrBG"
   diff_contour_range: [-24, 24, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1738,8 +1719,6 @@ FLDS:
   contour_levels_range: [100, 500, 25]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1771,8 +1750,6 @@ LHFLX:
   contour_levels_range: [0, 220, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-45, 45, 5]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -1898,8 +1875,6 @@ CLDTOT_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -1911,8 +1886,6 @@ CLDHGH_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -1924,8 +1897,6 @@ CLDMED_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -1937,8 +1908,6 @@ CLDLOW_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -1950,8 +1919,6 @@ CLD_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -1966,8 +1933,6 @@ CLD_CAL:
 H2O:
   colormap: "PuOr_r"
   diff_colormap: "BrBG"
-  scale_factor: 1
-  add_offset: 0
   new_unit: "mol mol$^{-1}$"
   mpl:
     colorbar:
diff --git a/lib/adf_variable_defaults_cesm.yaml b/lib/adf_variable_defaults_cesm.yaml
index aec6997c0..6a224011e 100644
--- a/lib/adf_variable_defaults_cesm.yaml
+++ b/lib/adf_variable_defaults_cesm.yaml
@@ -28,8 +28,6 @@ AODDUST:
   contour_levels_range: [0.01, 0.6, 0.05]
   diff_colormap: "PuOr_r"
   diff_contour_range: [-0.06, 0.06, 0.01]
-  scale_factor: 1
-  add_offset: 0
   new_unit: ""
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
@@ -40,8 +38,6 @@ AODVIS:
   contour_levels_range: [0.05, 0.6, 0.05]
   diff_colormap: "PuOr_r"
   diff_contour_range: [-0.1, 0.1, 0.01]
-  scale_factor: 1
-  add_offset: 0
   new_unit: ""
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
@@ -52,8 +48,6 @@ AODVISdn:
   contour_levels_range: [0.01, 1.01, 0.05]
   diff_colormap: "PuOr_r"
   diff_contour_range: [-0.4, 0.401, 0.05]
-  scale_factor: 1
-  add_offset: 0
   new_unit: ""
   obs_file: "MOD08_M3_192x288_AOD_2001-2020_climo.nc"
   obs_name: "MODIS"
diff --git a/lib/adf_variable_defaults_era5-1deg.yaml b/lib/adf_variable_defaults_era5-1deg.yaml
index b138e31e7..39f6917f4 100644
--- a/lib/adf_variable_defaults_era5-1deg.yaml
+++ b/lib/adf_variable_defaults_era5-1deg.yaml
@@ -137,441 +137,6 @@ FCTI:
 FICE:
   category: "Microphysics"
 
-#+++++++++++
-# Category: Aerosols
-#+++++++++++
-
-#List of zonal areosols
-aerosol_zonal_list: ["BC","POM","SO4","SOA","NH4HSO4","DUST","SeaSalt"]
-
-AODDUST:
-  category: "Aerosols"
-  colormap: "Oranges"
-  contour_levels_range: [0.01, 0.6, 0.05]
-  diff_colormap: "PuOr_r"
-  diff_contour_range: [-0.06, 0.06, 0.01]
-  scale_factor: 1
-  add_offset: 0
-  new_unit: ""
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-AODVIS:
-  category: "Aerosols"
-  colormap: "Oranges"
-  contour_levels_range: [0.05, 0.6, 0.05]
-  diff_colormap: "PuOr_r"
-  diff_contour_range: [-0.1, 0.1, 0.01]
-  scale_factor: 1
-  add_offset: 0
-  new_unit: ""
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-AODVISdn:
-  category: "Aerosols"
-  colormap: "jet"
-  contour_levels_range: [0.01, 1.01, 0.05]
-  diff_colormap: "PuOr_r"
-  diff_contour_range: [-0.4, 0.401, 0.05]
-  scale_factor: 1
-  add_offset: 0
-  new_unit: ""
-  obs_file: "MOD08_M3_192x288_AOD_2001-2020_climo.nc"
-  obs_name: "MODIS"
-  obs_var_name: "AOD_550_Dark_Target_Deep_Blue_Combined_Mean_Mean"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-BURDENBC:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  diff_colormap: "RdBu_r"
-  obs_file: "BURDENBC_MERRA2_monthly_climo_1degree_200001-202506.nc"
-  obs_var_name: "BURDENBC"
-  obs_name: "MERRA2"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
-
-BURDENDUST:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  diff_contour_range: [-1000, 1100, 100]
-  diff_colormap: "RdBu_r"
-  obs_file: "BURDENDUST_CAMS_monthly_climo_1degree_200301-202412.nc"
-  obs_var_name: "BURDENDUST"
-  obs_name: "CAMS"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
-
-BURDENPOM:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  diff_colormap: "RdBu_r"
-
-
-BURDENSEASALT:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  diff_contour_range: [-200, 200, 25]
-  diff_colormap: "RdBu_r"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  obs_file: "BURDENSEASALT_CAMS_monthly_climo_1degree_200301-202412.nc"
-  obs_var_name: "BURDENSEASALT"
-  obs_name: "CAMS"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
-
-BURDENSO4:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  diff_colormap: "RdBu_r"
-  obs_file: "BURDENSO4_CAMS_monthly_climo_1degree_200301-202412.nc"
-  obs_name: "CAMS"
-  obs_var_name: "BURDENSO4"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
-
-BURDENSOA:
-  category: "Aerosols"
-  colormap: "plasma_r"
-  scale_factor: 1000000
-  add_offset: 0
-  new_unit: 'g m$^{-2}$'
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  diff_colormap: "RdBu_r"
-
-DMS:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  scale_factor: 1000000000.0
-  new_unit: "ppbv"
-
-SO2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  scale_factor: 1000000000.0
-  new_unit: "ppbv"
-
-SOAG:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  scale_factor: 1000000000.0
-  new_unit: "ppbv"
-
-BC:
-  colormap: "RdBu_r"
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-  category: "Aerosols"
-  derivable_from: ["bc_a1", "bc_a4"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-POM:
-  colormap: "RdBu_r"
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-  category: "Aerosols"
-  derivable_from: ["pom_a1", "pom_a4"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-SO4:
-  colormap: "RdBu_r"
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-  category: "Aerosols"
-  derivable_from: ["so4_a1", "so4_a2", "so4_a3"]
-  derivable_from_cam_chem: ["so4_a1", "so4_a2", "so4_a3", "so4_a5"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-SOA:
-  colormap: "RdBu_r"
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-  category: "Aerosols"
-  derivable_from: ["soa_a1", "soa_a2"]
-  derivable_from_cam_chem: ["soa1_a1", "soa2_a1", "soa3_a1", "soa4_a1", "soa5_a1", "soa1_a2", "soa2_a2", "soa3_a2", "soa4_a2", "soa5_a2"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-DUST:
-  colormap: "RdBu_r"
-  contour_levels: [0,0.1,0.25,0.4,0.6,0.8,1.4,2,3,4,8,12,30,48,114,180]
-  non_linear: True
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-  category: "Aerosols"
-  derivable_from: ["dst_a1", "dst_a2", "dst_a3"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
-SeaSalt:
-  colormap: "RdBu_r"
-  contour_levels: [0,0.05,0.075,0.2,0.3,0.4,0.7,1,1.5,2,4,6,15,24,57,90]
-  non_linear: True
-  diff_colormap: "BrBG"
-  scale_factor: 1000000000
-  add_offset: 0
-  new_unit: '$\mu$g/m3'
-  mpl:
-    colorbar:
-      label : '$\mu$g/m3'
-      ticks: [0.05,0.2,0.4,1,2,6,24,90]
-    diff_colorbar:
-      label : '$\mu$g/m3'
-      ticks: [-10,8,6,4,2,0,-2,-4,-6,-8,-10]
-  category: "Aerosols"
-  derivable_from: ["ncl_a1", "ncl_a2", "ncl_a3"]
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-  
-bc_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-bc_a4:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-dst_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-dst_a2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-dst_a3:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-ncl_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-ncl_a2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-ncl_a3:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-num_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-num_a2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-num_a3:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-num_a4:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-num_a5:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-pom_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-pom_a4:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-so4_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-so4_a2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-so4_a3:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-soa_a1:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-soa_a2:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0e-9
-  new_unit: "ug/kg"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-SAD_TROP:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0
-  new_unit: "cm2/cm3"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-SAD_AERO:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0
-  new_unit: "cm2/cm3"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-SAD_SULFC:
-  category: "Aerosols"
-  colormap: "jet"
-  diff_colormap: "gist_ncar"
-  scale_factor: 1.0
-  new_unit: "cm2/cm3"
-  pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
-  pct_diff_colormap: "PuOr_r"
-
 #+++++++++++++++++
 # Category: Budget
 #+++++++++++++++++
@@ -1476,8 +1041,6 @@ CLDTOT:
   contour_levels_range: [0.2, 1.1, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1491,8 +1054,6 @@ CLDLOW:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1506,8 +1067,6 @@ CLDHGH:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1521,8 +1080,6 @@ CLDMED:
   contour_levels_range: [0, 1.05, 0.05]
   diff_colormap: "BrBG"
   diff_contour_range: [-0.4, 0.4, 0.05]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Fraction"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1554,8 +1111,6 @@ TGCLDLWP:
   contour_levels_range: [0, 400, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-100, 100, 10]
-  scale_factor: 1000
-  add_offset: 0
   new_unit: "g m$^{-2}$"
   mpl:
     colorbar:
@@ -1563,9 +1118,8 @@ TGCLDLWP:
   category: "Clouds"
   obs_file: "TGCLDLWP_ERA5_monthly_climo_1degree_197901-202112.nc"
   obs_name: "ERA5"
-  obs_var_name: "TGCLDLWP"
-  obs_scale_factor: 1000
-  obs_add_offset: 0
+  obs_derivable_from: ['TGCLDWP']
+  obs_derivation_formula: "TGCLDWP * 1000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1574,8 +1128,6 @@ TGCLDIWP:
   contour_levels_range: [0, 100, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-50, 50, 5]
-  scale_factor: 1000
-  add_offset: 0
   new_unit: "g m$^{-2}$"
   mpl:
     colorbar:
@@ -1583,9 +1135,8 @@ TGCLDIWP:
   category: "Clouds"
   obs_file: "TGCLDIWP_ERA5_monthly_climo_1degree_197901-202112.nc"
   obs_name: "ERA5"
-  obs_var_name: "TGCLDIWP"
-  obs_scale_factor: 1000
-  obs_add_offset: 0
+  obs_derivable_from: ['TGCLDIWP']
+  obs_derivation_formula: "TGCLDIWP * 1000"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1688,6 +1239,7 @@ PRECT:
   obs_var_name: "PRECT"
   category: "Hydrologic cycle"
   derivable_from: ['PRECL','PRECC']
+  derivation_formula: "PRECC + PRECL"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -1751,8 +1303,6 @@ TS:
   contour_levels_range: [220,320, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "K"
   mpl:
     colorbar:
@@ -1769,8 +1319,6 @@ SST:
   contour_levels_range: [220,320, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "K"
   mpl:
     colorbar:
@@ -1841,8 +1389,6 @@ TMQ:
   contour_levels_range: [0, 75.0, 5.0]
   diff_colormap: "BrBG"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "kg m$^{-2}$"
   obs_file: "ERAI_all_climo.nc"
   obs_name: "ERAI"
@@ -1856,8 +1402,6 @@ RELHUM:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Fraction"
   mpl:
     colorbar:
@@ -1874,8 +1418,6 @@ U:
   contour_levels_range: [-10, 90, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "ms$^{-1}$"
   mpl:
     colorbar:
@@ -1894,8 +1436,6 @@ V:
   contour_levels_range: [-10, 90, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "ms$^{-1}$"
   mpl:
     colorbar:
@@ -1985,14 +1525,13 @@ RESTOM:
   contour_levels_range: [-100, 100, 5]
   diff_colormap: "seismic"
   diff_contour_range: [-10, 10, 0.5]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "W m$^{-2}$"
   mpl:
     colorbar:
       label : "W m$^{-2}$"
   category: "TOA energy flux"
   derivable_from: ['FLNT','FSNT']
+  derivation_formula: "FSNT - FLNT"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
 
@@ -2001,8 +1540,6 @@ SWCF:
   contour_levels_range: [-150, 50, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2010,8 +1547,6 @@ SWCF:
   obs_file: "CERES_EBAF_Ed4.1_2001-2020.nc"
   obs_name: "CERES_EBAF_Ed4.1"
   obs_var_name: "toa_cre_sw_mon"
-  obs_scale_factor: 1
-  obs_add_offset: 0
   category: "TOA energy flux"
   pct_diff_contour_levels: [-100,-75,-50,-40,-30,-20,-10,-8,-6,-4,-2,0,2,4,6,8,10,20,30,40,50,75,100]
   pct_diff_colormap: "PuOr_r"
@@ -2021,8 +1556,6 @@ LWCF:
   contour_levels_range: [-10, 100, 5]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2039,8 +1572,6 @@ FSUTOA:
   contour_levels_range: [-10, 180, 15]
   diff_colormap: "BrBG"
   diff_contour_range: [-15, 15, 1]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2054,8 +1585,6 @@ FSNT:
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2087,8 +1616,6 @@ FLNT:
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2105,8 +1632,6 @@ FLNTC:
   contour_levels_range: [120, 320, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2137,8 +1662,6 @@ FSNS:
   contour_levels_range: [-10, 300, 20]
   diff_colormap: "BrBG"
   diff_contour_range: [-24, 24, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2155,8 +1678,6 @@ FSNSC:
   contour_levels_range: [-10, 300, 20]
   diff_colormap: "BrBG"
   diff_contour_range: [-24, 24, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2173,8 +1694,6 @@ FLDS:
   contour_levels_range: [100, 500, 25]
   diff_colormap: "BrBG"
   diff_contour_range: [-20, 20, 2]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2206,8 +1725,6 @@ LHFLX:
   contour_levels_range: [0, 220, 10]
   diff_colormap: "BrBG"
   diff_contour_range: [-45, 45, 5]
-  scale_factor: 1
-  add_offset: 0
   new_unit: "Wm$^{-2}$"
   mpl:
     colorbar:
@@ -2333,8 +1850,6 @@ CLDTOT_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -2346,8 +1861,6 @@ CLDHGH_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -2359,8 +1872,6 @@ CLDMED_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -2372,8 +1883,6 @@ CLDLOW_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -2385,8 +1894,6 @@ CLD_CAL:
   contour_levels_range: [0, 105, 5]
   diff_colormap: "RdBu_r"
   diff_contour_range: [-40, 40, 5]
-  scale_factor: 1.
-  add_offset: 0
   new_unit: "Percent"
   obs_file: "CALIPSO_GOCCP_3.1.2_climo_200606-202012.nc"
   obs_name: "CALIPSO"
@@ -2401,8 +1908,6 @@ CLD_CAL:
 H2O:
   colormap: "PuOr_r"
   diff_colormap: "BrBG"
-  scale_factor: 1
-  add_offset: 0
   new_unit: "mol mol$^{-1}$"
   mpl:
     colorbar:
diff --git a/lib/adf_variable_defaults_noresm.yaml b/lib/adf_variable_defaults_noresm.yaml
index ae0f5cc11..4c625a065 100644
--- a/lib/adf_variable_defaults_noresm.yaml
+++ b/lib/adf_variable_defaults_noresm.yaml
@@ -173,8 +173,8 @@ cb_BC:
   obs_file: "BURDENBC_MERRA2_monthly_climo_1degree_200001-202506.nc"
   obs_var_name: "BURDENBC"
   obs_name: "MERRA2"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
+  obs_derivable_from: ['BURDENBC']
+  obs_derivation_formula: "BURDENBC * 1e6"
 
 cb_SULFATE:
   category: "Aerosols"
@@ -190,8 +190,8 @@ cb_SULFATE:
   obs_file: "BURDENSO4_CAMS_monthly_climo_1degree_200301-202412.nc"
   obs_name: "CAMS"
   obs_var_name: "BURDENSO4"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
+  obs_derivable_from: ['BURDENSO4']
+  obs_derivation_formula: "BURDENSO4 * 1e6"
 
 cb_isoprene:
   category: "Aerosols"
@@ -242,8 +242,8 @@ cb_DUST:
   obs_file: "BURDENDUST_CAMS_monthly_climo_1degree_200301-202412.nc"
   obs_var_name: "BURDENDUST"
   obs_name: "CAMS"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
+  obs_derivable_from: ['BURDENDUST']
+  obs_derivation_formula: "BURDENDUST * 1e6"
 
 cb_OM:
   category: "Aerosols"
@@ -287,8 +287,8 @@ cb_SALT:
   obs_file: "BURDENSEASALT_CAMS_monthly_climo_1degree_200301-202412.nc"
   obs_var_name: "BURDENSEASALT"
   obs_name: "CAMS"
-  obs_scale_factor: 1000000
-  obs_add_offset: 0
+  obs_derivable_from: ['BURDENSEASALT']
+  obs_derivation_formula: "BURDENSEASALT * 1e6"
 
 cb_SO2:
   category: "Aerosols"
diff --git a/lib/plotting_functions.py b/lib/plotting_functions.py
index c54cfdc0f..4d3ab777a 100644
--- a/lib/plotting_functions.py
+++ b/lib/plotting_functions.py
@@ -774,8 +774,11 @@ def make_polar_plot(wks, case_nickname,
     ax1.set_title(case_title, loc='left', fontsize=6) #fontsize=tiFontSize
 
     if obs:
-        obs_var = kwargs["obs_var_name"]
-        obs_title = kwargs["obs_file"][:-3]
+        # obs_var_name is optional; fall back to the obs field's name (e.g. for a
+        # formula-derived obs field) so the title still names the variable.
+        obs_var = kwargs.get("obs_var_name") or getattr(d2, "name", "") or ""
+        _obs_file = kwargs.get("obs_file", "")
+        obs_title = _obs_file[:-3] if _obs_file.endswith(".nc") else _obs_file
         base_title = r"$\mathbf{Baseline}:$"+obs_title+"\n"+r"$\mathbf{Variable}:$"+f"{obs_var}"
         ax2.set_title(base_title, loc='left', fontsize=6) #fontsize=tiFontSize
     else:
@@ -1021,8 +1024,14 @@ def plot_map_vect_and_save(wks, case_nickname, base_nickname,
     ax[0].set_title(case_title, loc='left', fontsize=tiFontSize)
 
     if obs:
-        obs_var = kwargs["obs_var_name"]
-        obs_title = kwargs["obs_file"][:-3]
+        # obs_var_name is optional; when absent (e.g. a formula-derived obs field)
+        # fall back to the obs field's own name so the title still names the variable.
+        _ofld = locals().get("obsfld")
+        if _ofld is None:
+            _ofld = locals().get("uobsfld_nowrap")
+        obs_var = kwargs.get("obs_var_name") or getattr(_ofld, "name", "") or ""
+        _obs_file = kwargs.get("obs_file", "")
+        obs_title = _obs_file[:-3] if _obs_file.endswith(".nc") else _obs_file
         base_title = r"$\mathbf{Baseline}:$"+obs_title+"\n"+r"$\mathbf{Variable}:$"+f"{obs_var}"
         ax[1].set_title(base_title, loc='left', fontsize=tiFontSize)
     else:
@@ -1268,8 +1277,14 @@ def plot_map_and_save(wks, case_nickname, base_nickname,
     ax[0].set_title(case_title, loc='left', fontsize=tiFontSize)
 
     if obs:
-        obs_var = kwargs["obs_var_name"]
-        obs_title = kwargs["obs_file"][:-3]
+        # obs_var_name is optional; when absent (e.g. a formula-derived obs field)
+        # fall back to the obs field's own name so the title still names the variable.
+        _ofld = locals().get("obsfld")
+        if _ofld is None:
+            _ofld = locals().get("uobsfld_nowrap")
+        obs_var = kwargs.get("obs_var_name") or getattr(_ofld, "name", "") or ""
+        _obs_file = kwargs.get("obs_file", "")
+        obs_title = _obs_file[:-3] if _obs_file.endswith(".nc") else _obs_file
         base_title = r"$\mathbf{Baseline}:$"+obs_title+"\n"+r"$\mathbf{Variable}:$"+f"{obs_var}"
         ax[1].set_title(base_title, loc='left', fontsize=tiFontSize)
     else:
@@ -1466,8 +1481,11 @@ def plot_zonal_mean_and_save(wks, case_nickname, base_nickname,
     case_title = r"$\mathbf{Test}:$"+f"{case_nickname}\nyears: {case_climo_yrs[0]}-{case_climo_yrs[-1]}"
 
     if obs:
-        obs_var = kwargs["obs_var_name"]
-        obs_title = kwargs["obs_file"][:-3]
+        # obs_var_name is optional; fall back to the obs field's name (e.g. for a
+        # formula-derived obs field) so the title still names the variable.
+        obs_var = kwargs.get("obs_var_name") or getattr(bdata, "name", "") or ""
+        _obs_file = kwargs.get("obs_file", "")
+        obs_title = _obs_file[:-3] if _obs_file.endswith(".nc") else _obs_file
         base_title = r"$\mathbf{Baseline}:$"+obs_title+"\n"+r"$\mathbf{Variable}:$"+f"{obs_var}"
     else:
         base_title = r"$\mathbf{Baseline}:$"+f"{base_nickname}\nyears: {baseline_climo_yrs[0]}-{baseline_climo_yrs[-1]}"
@@ -1716,8 +1734,11 @@ def plot_meridional_mean_and_save(wks, case_nickname, base_nickname,
     case_title = r"$\mathbf{Test}:$"+f"{case_nickname}\nyears: {case_climo_yrs[0]}-{case_climo_yrs[-1]}"
 
     if obs:
-        obs_var = kwargs["obs_var_name"]
-        obs_title = kwargs["obs_file"][:-3]
+        # obs_var_name is optional; fall back to the obs field's name (e.g. for a
+        # formula-derived obs field) so the title still names the variable.
+        obs_var = kwargs.get("obs_var_name") or getattr(bdata, "name", "") or ""
+        _obs_file = kwargs.get("obs_file", "")
+        obs_title = _obs_file[:-3] if _obs_file.endswith(".nc") else _obs_file
         base_title = r"$\mathbf{Baseline}:$"+obs_title+"\n"+r"$\mathbf{Variable}:$"+f"{obs_var}"
     else:
         base_title = r"$\mathbf{Baseline}:$"+f"{base_nickname}\nyears: {baseline_climo_yrs[0]}-{baseline_climo_yrs[-1]}"
diff --git a/scripts/plotting/meridional_mean.py b/scripts/plotting/meridional_mean.py
index f4e058098..eb26f6c21 100644
--- a/scripts/plotting/meridional_mean.py
+++ b/scripts/plotting/meridional_mean.py
@@ -170,7 +170,21 @@ def meridional_mean(adfobj):
                     continue
 
                 #Extract variable of interest
-                odata = oclim_ds[data_var].squeeze()  # squeeze in case of degenerate dimensions
+                if adfobj.compare_obs and data_var not in oclim_ds:
+                    # Derived obs variable (e.g. ALBEDO from solar_mon/fsnt): the obs
+                    # file stores the constituents, not the field itself, so build it
+                    # from obs_derivation_formula.  The formula already encodes any unit
+                    # scaling, so obs_scale_factor/obs_add_offset are skipped below.
+                    odata = adfobj.data.derive_obs_from_formula(oclim_ds, var)
+                    if odata is None:
+                        warnings.warn(f"obs variable {var} not found and not derivable, "
+                                      f"skipping meridional mean plot of {var}")
+                        continue
+                    odata = odata.squeeze()
+                    derived_obs = True
+                else:
+                    odata = oclim_ds[data_var].squeeze()  # squeeze in case of degenerate dimensions
+                    derived_obs = False
                 mdata = mclim_ds[var].squeeze()
 
                 # APPLY UNITS TRANSFORMATION IF SPECIFIED:
@@ -184,8 +198,9 @@ def meridional_mean(adfobj):
                     odata = odata * vres.get("scale_factor",1) + vres.get("add_offset", 0)
                     # update units
                     odata.attrs['units'] = vres.get("new_unit", odata.attrs.get('units', 'none'))
-                # Or for observations
-                else:
+                # Or for observations (skip scaling when the obs field was built by a
+                # formula, which already encodes any conversion)
+                elif not derived_obs:
                     odata = odata * vres.get("obs_scale_factor",1) + vres.get("obs_add_offset", 0)
                     # Note: we are going to assume that the specification ensures the conversion makes the units the same.
                     #       Doesn't make sense to add a different unit.