diff --git a/testing_and_setup/compass/ocean/isomip_plus/viz/__main__.py b/testing_and_setup/compass/ocean/isomip_plus/viz/__main__.py
index 52136ca259..d43fcde650 100644
--- a/testing_and_setup/compass/ocean/isomip_plus/viz/__main__.py
+++ b/testing_and_setup/compass/ocean/isomip_plus/viz/__main__.py
@@ -37,7 +37,7 @@ def main():
     dsMesh = xarray.open_dataset('{}/init.nc'.format(folder))
 
     ds = xarray.open_mfdataset('{}/timeSeriesStatsMonthly*.nc'.format(folder),
-                               concat_dim='Time')
+                               concat_dim='Time', combine='nested')
 
     if args.streamfunctions:
         compute_barotropic_streamfunction(dsMesh, ds, folder)
diff --git a/testing_and_setup/compass/ocean/isomip_plus/viz/plot.py b/testing_and_setup/compass/ocean/isomip_plus/viz/plot.py
index 1484603c38..2b8c34838c 100644
--- a/testing_and_setup/compass/ocean/isomip_plus/viz/plot.py
+++ b/testing_and_setup/compass/ocean/isomip_plus/viz/plot.py
@@ -56,7 +56,7 @@ def __init__(self, inFolder='.', outFolder='plots', expt=0):
 
         self.ds = xarray.open_mfdataset(
             '{}/timeSeriesStatsMonthly*.nc'.format(self.inFolder),
-            concat_dim='Time')
+            concat_dim='Time', combine='nested')
 
         try:
             os.makedirs(self.outFolder)
@@ -226,7 +226,7 @@ def __init__(self, inFolder='.', outFolder='plots', expt=0,
 
         self.ds = xarray.open_mfdataset(
             '{}/timeSeriesStatsMonthly*.nc'.format(self.inFolder),
-            concat_dim='Time')
+            concat_dim='Time', combine='nested')
 
         self._compute_section_x_z()
 
diff --git a/testing_and_setup/compass/ocean/isomip_plus/viz/streamfunction.py b/testing_and_setup/compass/ocean/isomip_plus/viz/streamfunction.py
index f0e9e49bac..b42cb6caa3 100644
--- a/testing_and_setup/compass/ocean/isomip_plus/viz/streamfunction.py
+++ b/testing_and_setup/compass/ocean/isomip_plus/viz/streamfunction.py
@@ -371,7 +371,8 @@ def _interpolate_horizontal_transport_zlevel(ds, z, outFileName):
 
     bar.finish()
 
-    dsOut = xarray.open_mfdataset(fileNames, concat_dim='Time')
+    dsOut = xarray.open_mfdataset(fileNames, concat_dim='Time',
+                                  combine='nested')
 
     dsOut['xtime_startMonthly'] = ds.xtime_startMonthly
     dsOut['xtime_endMonthly'] = ds.xtime_endMonthly
@@ -529,7 +530,7 @@ def _horizontally_bin_overturning_streamfunction(ds, dsMesh, x, osfFileName,
 
     bar.finish()
 
-    dsOSF = xarray.open_mfdataset(fileNames, concat_dim='nx')
+    dsOSF = xarray.open_mfdataset(fileNames, concat_dim='nx', combine='nested')
     dsOSF['xtime_startMonthly'] = ds.xtime_startMonthly
     dsOSF['xtime_endMonthly'] = ds.xtime_endMonthly
     dsOSF['x'] = x