diff --git a/compass/ocean/tests/utility/combine_topo/__init__.py b/compass/ocean/tests/utility/combine_topo/__init__.py
index 091419c54b..173253ba5e 100644
--- a/compass/ocean/tests/utility/combine_topo/__init__.py
+++ b/compass/ocean/tests/utility/combine_topo/__init__.py
@@ -170,13 +170,10 @@ def _modify_bedmachine(self):
         grounded_mask = np.logical_or(np.logical_or(mask == 1, mask == 2),
                                       mask == 4).astype(float)
 
-        bedmachine['bathymetry'] = bedmachine.bed.where(ocean_mask, 0.)
-        bedmachine['ice_draft'] = \
-            (bedmachine.surface -
-                bedmachine.thickness).where(ocean_mask, 0.)
+        bedmachine['bathymetry'] = bedmachine.bed
+        bedmachine['ice_draft'] = bedmachine.surface - bedmachine.thickness
         bedmachine.ice_draft.attrs['units'] = 'meters'
-        bedmachine['thickness'] = \
-            bedmachine.thickness.where(ocean_mask, 0.)
+        bedmachine['thickness'] = bedmachine.thickness
 
         bedmachine['ice_mask'] = ice_mask
         bedmachine['grounded_mask'] = grounded_mask
@@ -231,11 +228,6 @@ def _remap_bedmachine(self):
         logger = self.logger
         logger.info('Remap BedMachineAntarctica to GEBCO 1/80 deg grid')
 
-        config = self.config
-
-        section = config['combine_topo']
-        renorm_thresh = section.getfloat('renorm_thresh')
-
         in_filename = 'BedMachineAntarctica-v3_mod.nc'
         out_filename = 'BedMachineAntarctica_on_GEBCO_low.nc'
         gebco_filename = 'GEBCO_2023_0.0125_degree.nc'
@@ -265,16 +257,6 @@ def _remap_bedmachine(self):
         for field in ['bathymetry', 'ice_draft', 'thickness']:
             bedmachine_on_gebco_low[field].attrs['unit'] = 'meters'
 
-        # renormalize the fields based on the ocean masks
-        ocean_mask = bedmachine_on_gebco_low.ocean_mask
-
-        valid = ocean_mask > renorm_thresh
-        norm = ocean_mask.where(valid, 1.)
-        norm = 1. / norm
-        for field in ['bathymetry', 'ice_draft', 'thickness']:
-            bedmachine_on_gebco_low[field] = \
-                norm * bedmachine_on_gebco_low[field].where(valid, 0.)
-
         bedmachine_on_gebco_low.to_netcdf(out_filename)
         logger.info('  Done.')
 
@@ -305,17 +287,22 @@ def _combine(self):
         bedmachine_bathy = bedmachine.bathymetry
         valid = bedmachine_bathy.notnull()
         bedmachine_bathy = bedmachine_bathy.where(valid, 0.)
+        bedmachine_bathy = bedmachine_bathy.where(bedmachine_bathy < 0., 0.)
 
         combined['bathymetry'] = \
-            alpha * gebco.bathymetry.where(gebco.bathymetry < 0, 0.) + \
+            alpha * gebco.bathymetry.where(gebco.bathymetry < 0., 0.) + \
             (1.0 - alpha) * bedmachine_bathy
+        bathy_mask = xr.where(combined.bathymetry < 0., 1.0, 0.0)
+
         for field in ['ice_draft', 'thickness']:
-            combined[field] = bedmachine[field]
+            combined[field] = bathy_mask * bedmachine[field]
         for field in ['bathymetry', 'ice_draft', 'thickness']:
             combined[field].attrs['unit'] = 'meters'
 
-        fill = {'ice_mask': 0., 'grounded_mask': 0.,
-                'ocean_mask': combined['bathymetry'] < 0.}
+        combined['bathymetry_mask'] = bathy_mask
+
+        fill = {'ice_draft': 0., 'thickness': 0., 'ice_mask': 0.,
+                'grounded_mask': 0., 'ocean_mask': combined.bathymetry_mask}
 
         for field, fill_val in fill.items():
             valid = bedmachine[field].notnull()
diff --git a/compass/ocean/tests/utility/combine_topo/combine_topo.cfg b/compass/ocean/tests/utility/combine_topo/combine_topo.cfg
index 28c94f0fe3..f8d9cc2ec9 100644
--- a/compass/ocean/tests/utility/combine_topo/combine_topo.cfg
+++ b/compass/ocean/tests/utility/combine_topo/combine_topo.cfg
@@ -6,7 +6,7 @@ antarctic_filename = BedMachineAntarctica-v3.nc
 global_filename = GEBCO_2023.nc
 
 # the name of the output topography file, to be copied to the bathymetry database
-cobined_filename = BedMachineAntarctica_v3_and_GEBCO_2023_0.0125_degree_20240323.nc
+cobined_filename = BedMachineAntarctica_v3_and_GEBCO_2023_0.0125_degree_20240611.nc
 
 # the target and minimum number of MPI tasks to use in remapping
 ntasks = 512
@@ -15,7 +15,3 @@ min_tasks = 128
 # latitudes between which the topography datasets get blended
 latmin = -62.
 latmax = -60.
-
-# the threshold for masks below which interpolated variables are not
-# renormalized
-renorm_thresh = 1e-3