Issue 182 Fix: Xarray Future Warning

[scrasmussen]

TYPE: bug issue fix

KEYWORDS: Xarray, Python, Aggregation

SOURCE: Soren Rasmussen, NCAR

DESCRIPTION OF CHANGES: Fix for warning of a future switch in xarray. Just switched from Dataset.dims to Dataset.sizes in aggregate_parallel_files.py script to fix it.

ISSUE: Fixes #182

TESTS CONDUCTED: Compared results of new and previous aggregation script, they were identical.

$ nccmp -ds icar_out_2010-09-01_00-00-00.nc icar_out_2010-09-01_00-00-00.nc.orig
Files "icar_out_2010-09-01_00-00-00.nc" and "icar_out_2010-09-01_00-00-00.nc.orig" are identical.

Checklist

• Closes issue Xarray Dataset.dims Future Warning  #182
• Tests added (unit tests and/or regression/integration tests)
• Backwards compatible
• Requires new files? If so, how to generate them.
• Fully documented