The _FillValue CF property.
Note that this attribute is used primarily for writing data to disk and is independent of the missing data mask. It may, however, get used when unmasking data array elements.
The recommended way of retrieving the missing data value is with the fill_value method.
Examples
>>> f._FillValue = -1.0e30
>>> f._FillValue
-1e+30
>>> del f._FillValue
Mask the data array where it equals a missing data value:
>>> f.setitem(cf.masked, condition=f.fill_value()) DCH