fix some cf issues

modules/util/util.py

@@ -279,9 +279,9 @@ def check_oblique(satzen, test_angle=70.0):
         return True
 
 
-def get_average(tile_2d):
+def get_median(tile_2d):
     tile = tile_2d.flatten()
-    return np.nanmean(tile)
+    return np.nanmedian(tile)
 
 
 def get_grid_values_all(h5f, grid_name, scale_factor_name='scale_factor', add_offset_name='add_offset',