diff --git a/da/ct/statevector.py b/da/ct/statevector.py
index 511b4a942d902c57a3e54a27b80fd9f45f6a1236..ccfed8f59a296c451922a7080c6253442c444453 100755
--- a/da/ct/statevector.py
+++ b/da/ct/statevector.py
@@ -67,7 +67,10 @@ class CtStateVector(StateVector):
         f_bio   = io.CT_Read(file_bio_cov,'read')
 
         cov_ocn = f_ocn.GetVariable('CORMAT')
-        cov_bio = f_bio.GetVariable('qprior')
+        if f_bio.variables.has_key('covariance'):
+            cov_bio = f_bio.GetVariable('covariance')  # newly created CTDAS covariance files
+        else:
+            cov_bio = f_bio.GetVariable('qprior')  # old CarbonTracker covariance files
 
         dummy   = f_ocn.close()
         dummy   = f_bio.close()
@@ -82,7 +85,7 @@ class CtStateVector(StateVector):
         nbio    = cov_bio.shape[0]
 
         fullcov[0:nbio,0:nbio]                  = cov_bio
-        fullcov[nbio:nbio+nocn,nbio:nbio+nocn]  = 0.16 *np.dot(cov_ocn,cov_ocn)
+        fullcov[nbio:nbio+nocn,nbio:nbio+nocn]  = cov_ocn
         fullcov[nocn+nbio,nocn+nbio]            = 1.e-10