diff --git a/da/co2gridded/statevectorNHgridded.py b/da/co2gridded/statevectorNHgridded.py
index 6e7b22aad58482a183065ecc9f1e5181bfb6d155..7f6946763e5ad9cdc387110dc2fd5540fd7a957c 100755
--- a/da/co2gridded/statevectorNHgridded.py
+++ b/da/co2gridded/statevectorNHgridded.py
@@ -65,7 +65,7 @@ class CO2GriddedStateVector(StateVector):
 
             f = io.ct_read(file, 'read')
 
-            if 'pco2' in file: 
+            if 'pco2' in file or 'cov_ocean' in file: 
                 cov_ocn = f.get_variable('CORMAT')
                 cov = cov_ocn
             elif 'tropic' in file: