diff --git a/test/testinput/3dvarbump.yml b/test/testinput/3dvarbump.yml
index cf4790ff3..7e85739bc 100644
--- a/test/testinput/3dvarbump.yml
+++ b/test/testinput/3dvarbump.yml
@@ -30,6 +30,7 @@ cost function:
       read:
         io:
           data directory: data_generated/parameters_bump_cor_nicas
+          files prefix: bump
         drivers:
           multivariate strategy: univariate
           read local nicas: true
@@ -40,13 +41,9 @@ cost function:
             - tocn
             - uocn
             - vocn
-          io:
-            files prefix: bump3d
         - model:
             variables:
             - ssh
-          io:
-            files prefix: bump2d
 
     linear variable change:
       input variables: *soca_vars
diff --git a/test/testinput/dirac_soca_cor_nicas_scales.yml b/test/testinput/dirac_soca_cor_nicas_scales.yml
index 29a734fdb..b5b611f25 100644
--- a/test/testinput/dirac_soca_cor_nicas_scales.yml
+++ b/test/testinput/dirac_soca_cor_nicas_scales.yml
@@ -18,6 +18,7 @@ background error:
     read:
       io:
         data directory: data_generated/parameters_bump_cor_nicas_scales
+        files prefix: bump
       drivers:
         multivariate strategy: univariate
         read local nicas: true
@@ -26,15 +27,11 @@ background error:
           variables:
           - socn
           - tocn
-        io:
-          files prefix: bump3d
       - model:
           variables:
           - ssh
           - cicen
           - hicen
-        io:
-          files prefix: bump2d
 
 dirac:
   ixdir: [1, 17, 41, 31, 51, 63, 81, 14, 16, 43]
diff --git a/test/testinput/parameters_bump_cor_nicas.yml b/test/testinput/parameters_bump_cor_nicas.yml
index 2ae19cc6a..cd7ab8bf2 100644
--- a/test/testinput/parameters_bump_cor_nicas.yml
+++ b/test/testinput/parameters_bump_cor_nicas.yml
@@ -19,6 +19,7 @@ background error:
     calibration:
       io:
         data directory: data_generated/parameters_bump_cor_nicas
+        files prefix: bump
       drivers:
         multivariate strategy: univariate
         compute nicas: true
@@ -51,13 +52,9 @@ background error:
           - tocn
           - uocn
           - vocn
-        io:
-          files prefix: bump3d
       - model:
           variables:
           - ssh
-        io:
-          files prefix: bump2d
       output model files:
       - parameter: cor_rh
         file:
diff --git a/test/testinput/parameters_bump_cor_nicas_scales.yml b/test/testinput/parameters_bump_cor_nicas_scales.yml
index 646631932..47ffd5bb1 100644
--- a/test/testinput/parameters_bump_cor_nicas_scales.yml
+++ b/test/testinput/parameters_bump_cor_nicas_scales.yml
@@ -18,6 +18,7 @@ background error:
     calibration:
       io:
         data directory: data_generated/parameters_bump_cor_nicas_scales
+        files prefix: bump
       drivers:
         multivariate strategy: univariate
         compute nicas: true
@@ -33,15 +34,11 @@ background error:
           - tocn
           - uocn
           - vocn
-        io:
-          files prefix: bump3d
       - model:
           variables:
           - ssh
           - cicen
           - hicen
-        io:
-          files prefix: bump2d
       input model files:
       - parameter: rh
         file:
diff --git a/test/testref/dirac_soca_cor_nicas_scales.test b/test/testref/dirac_soca_cor_nicas_scales.test
index d145c4ab4..5dc93104a 100644
--- a/test/testref/dirac_soca_cor_nicas_scales.test
+++ b/test/testref/dirac_soca_cor_nicas_scales.test
@@ -8,9 +8,9 @@ Input Dirac increment:
   hicen   min=0.0000000000000000   max=1.0000000000000000   mean=0.0006086427267194
 Covariance(SABER) * Increment:
   Valid time: 2018-04-15T00:00:00Z
-   socn   min=0.0000000000000000   max=1.0000000000000002   mean=0.0293635005803741
-   tocn   min=0.0000000000000000   max=1.0530523404044794   mean=0.3769034423956199
+   socn   min=0.0000000000000000   max=1.0000000000000002   mean=0.0340141737787489
+   tocn   min=0.0000000000000000   max=1.0048129708997011   mean=0.3536185118881098
     ssh   min=0.0000000000000000   max=0.0000000000000000   mean=0.0000000000000000
    hocn   min=0.0000000000000000   max=0.0000000000000000   mean=0.0000000000000000
   cicen   min=0.0000000000000000   max=0.0000000000000000   mean=0.0000000000000000
-  hicen   min=0.0000000000000000   max=1.0000000000000002   mean=0.2640285296287257
+  hicen   min=0.0000000000000000   max=0.9999999999999998   mean=0.2640285296287256