diff --git a/src/compo/mopitt_co_nc2ioda.py b/src/compo/mopitt_co_nc2ioda.py
index 9268a317e..95117ce69 100755
--- a/src/compo/mopitt_co_nc2ioda.py
+++ b/src/compo/mopitt_co_nc2ioda.py
@@ -158,11 +158,11 @@ def _read(self):
                 self.outdata[('datetime', 'MetaData')] = times[flg]
                 self.outdata[('latitude', 'MetaData')] = lats[flg]
                 self.outdata[('longitude', 'MetaData')] = lons[flg]
-                self.outdata[('apriori_term', 'MetaData')] = ap_tc[flg]
+                self.outdata[('apriori_term', 'RtrvlAncData')] = ap_tc[flg]
                 for k in range(nlevs):
-                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'MetaData')
+                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_ak] = ak_tc_dimless[:, k][flg]
-                    varname_pr = ('pressure_level_'+str(k+1), 'MetaData')
+                    varname_pr = ('pressure_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_pr] = hPa2Pa * pr_gd[:, k][flg]
 
                 self.outdata[self.varDict[iodavar]['valKey']] = xr_tc[flg]
@@ -176,13 +176,13 @@ def _read(self):
                     self.outdata[('latitude', 'MetaData')], lats[flg]))
                 self.outdata[('longitude', 'MetaData')] = np.concatenate((
                     self.outdata[('longitude', 'MetaData')], lons[flg]))
-                self.outdata[('apriori_term', 'MetaData')] = np.concatenate((
-                    self.outdata[('apriori_term', 'MetaData')], ap_tc[flg]))
+                self.outdata[('apriori_term', 'RtrvlAncData')] = np.concatenate((
+                    self.outdata[('apriori_term', 'RtrvlAncData')], ap_tc[flg]))
                 for k in range(nlevs):
-                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'MetaData')
+                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_ak] = np.concatenate(
                         (self.outdata[varname_ak], ak_tc_dimless[:, k][flg]))
-                    varname_pr = ('pressure_level_'+str(k+1), 'MetaData')
+                    varname_pr = ('pressure_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_pr] = np.concatenate(
                         (self.outdata[varname_pr], hPa2Pa * pr_gd[:, k][flg]))
 
@@ -199,7 +199,7 @@ def _read(self):
 
         for k in range(nlevs):
             varname = 'averaging_kernel_level_'+str(k+1)
-            vkey = (varname, 'MetaData')
+            vkey = (varname, 'RtrvlAncData')
             self.varAttrs[vkey]['coordinates'] = 'longitude latitude'
             self.varAttrs[vkey]['units'] = ''
 
diff --git a/src/compo/tropomi_no2_nc2ioda.py b/src/compo/tropomi_no2_nc2ioda.py
index 32f67f008..c9295ed1d 100755
--- a/src/compo/tropomi_no2_nc2ioda.py
+++ b/src/compo/tropomi_no2_nc2ioda.py
@@ -116,15 +116,13 @@ def _read(self):
                 self.outdata[('latitude', 'MetaData')] = lats
                 self.outdata[('longitude', 'MetaData')] = lons
                 self.outdata[('quality_assurance_value', 'MetaData')] = qa_value
-                self.outdata[('troposphere_layer_index', 'MetaData')] = trop_layer
-                self.outdata[('air_mass_factor_total', 'MetaData')] = total_airmass
-                self.outdata[('air_mass_factor_troposphere', 'MetaData')] = trop_airmass
-                self.outdata[('tropospheric_averaging_kernel_precision', 'MetaData')] = kernel_err
-                self.outdata[('averaging_kernel_precision', 'MetaData')] = kernel_err_total
+                self.outdata[('troposphere_layer_index', 'RtrvlAncData')] = trop_layer
+                self.outdata[('air_mass_factor_total', 'RtrvlAncData')] = total_airmass
+                self.outdata[('air_mass_factor_troposphere', 'RtrvlAncData')] = trop_airmass
                 for k in range(nlevs):
-                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'MetaData')
+                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_ak] = avg_kernel[..., k].ravel()
-                    varname_pr = ('pressure_level_'+str(k+1), 'MetaData')
+                    varname_pr = ('pressure_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_pr] = ak[k] + bk[k]*ps[...].ravel()
             else:
                 self.outdata[('datetime', 'MetaData')] = np.concatenate((
@@ -135,21 +133,17 @@ def _read(self):
                     self.outdata[('longitude', 'MetaData')], lons))
                 self.outdata[('quality_assurance_value', 'MetaData')] = np.concatenate((
                     self.outdata[('quality_assurance_value', 'MetaData')], qa_value))
-                self.outdata[('troposphere_layer_index', 'MetaData')] = np.concatenate((
-                    self.outdata[('troposphere_layer_index', 'MetaData')], trop_layer))
-                self.outdata[('air_mass_factor_total', 'MetaData')] = np.concatenate((
-                    self.outdata[('air_mass_factor_total', 'MetaData')], total_airmass))
-                self.outdata[('air_mass_factor_troposphere', 'MetaData')] = np.concatenate((
-                    self.outdata[('air_mass_factor_troposphere', 'MetaData')], trop_airmass))
-                self.outdata[('tropospheric_averaging_kernel_precision', 'MetaData')] = np.concatenate((
-                    self.outdata[('tropospheric_averaging_kernel_precision', 'MetaData')], kernel_err))
-                self.outdata[('averaging_kernel_precision', 'MetaData')] = np.concatenate((
-                    self.outdata[('averaging_kernel_precision', 'MetaData')], kernel_err_total))
+                self.outdata[('troposphere_layer_index', 'RtrvlAncData')] = np.concatenate((
+                    self.outdata[('troposphere_layer_index', 'RtrvlAncData')], trop_layer))
+                self.outdata[('air_mass_factor_total', 'RtrvlAncData')] = np.concatenate((
+                    self.outdata[('air_mass_factor_total', 'RtrvlAncData')], total_airmass))
+                self.outdata[('air_mass_factor_troposphere', 'RtrvlAncData')] = np.concatenate((
+                    self.outdata[('air_mass_factor_troposphere', 'RtrvlAncData')], trop_airmass))
                 for k in range(nlevs):
-                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'MetaData')
+                    varname_ak = ('averaging_kernel_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_ak] = np.concatenate(
                         (self.outdata[varname_ak], avg_kernel[..., k].ravel()))
-                    varname_pr = ('pressure_level_'+str(k+1), 'MetaData')
+                    varname_pr = ('pressure_level_'+str(k+1), 'RtrvlAncData')
                     self.outdata[varname_pr] = np.concatenate(
                         (self.outdata[varname_pr], ak[k] + bk[k]*ps[...].ravel()))
             for ncvar, iodavar in obsvars.items():
@@ -176,7 +170,7 @@ def _read(self):
 
         for k in range(nlevs):
             varname = 'averaging_kernel_level_'+str(k+1)
-            vkey = (varname, 'MetaData')
+            vkey = (varname, 'RtrvlAncData')
             self.varAttrs[vkey]['coordinates'] = 'longitude latitude'
             self.varAttrs[vkey]['units'] = ''
 
diff --git a/test/testoutput/mopitt_co.nc b/test/testoutput/mopitt_co.nc
index 1390a3b32..75a31a4e8 100644
--- a/test/testoutput/mopitt_co.nc
+++ b/test/testoutput/mopitt_co.nc
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:26fbf37673b15ccb4d4d9a3e64136cb3134bd34cb0b01366375c06b60a1e4edb
-size 209576
+oid sha256:701e5b8d31f6b56d5d3113a618f05cf99c7c59611333c3904828df8ff314b9ad
+size 210411
diff --git a/test/testoutput/tropomi_no2.nc b/test/testoutput/tropomi_no2.nc
index 2d4f1f2d4..7b2697a0a 100644
--- a/test/testoutput/tropomi_no2.nc
+++ b/test/testoutput/tropomi_no2.nc
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:f04e576a00685f8828643903b85527b68b8a54eacd1c7a1072e0ca242b69a7c6
-size 226603
+oid sha256:0a528ea147d921f7493fd9e266ab4f99aa8cfbc9a342df8d6665ee43da8b02f5
+size 220745