Per-variable compression means variables may be compressed independently.
Readers access compressed variables transparently, without
knowing they are compressed.
Compressed variables must be stored with chunked storage.
Each chunk is compressed or uncompressed independently.
Permits efficient access to small subsets of a large compressed variable
without uncompressing entire variable
Better compression can be achieved with chunking parameters. For
example, horizontal layers of the atmosphere might
be good chunks for a variable that is fairly uniform within a layer,
such as temperature.
