diff --git a/ocw/utils.py b/ocw/utils.py
index 8f2c8c14..e23697c1 100755
--- a/ocw/utils.py
+++ b/ocw/utils.py
@@ -435,7 +435,14 @@ def calc_subregion_area_mean_and_std(dataset_array, subregions):
         lons = dataset0.lons
         lats = dataset0.lats
     subregion_array = np.zeros(lons.shape)
-    mask_array = dataset_array[0].values[0, :].mask
+    # Check if the array is a masked array
+    if hasattr(dataset_array[0].values[0, :], 'mask'):
+        mask_array = dataset_array[0].values[0, :].mask
+    else:
+        x = dataset_array[0].values[0, :]
+        #check where the missing values exist
+        masked_array = ma.array(x, mask=np.equal(x,None))
+        mask_array = masked_array.mask        
     # dataset0.values.shsape[0]: length of the time dimension
     # spatial average
     t_series = ma.zeros([ndata, dataset0.values.shape[0], len(subregions)])