. New NetCDF utilities: ncagg for aggregation and ncflag for CF-Convention flags

Abstract
Motivated by work with GOES-R Space Weather NetCDF data products, two general tools have been developed that may have utility to others who interact with NetCDF datasets. The first is ncagg, which performs aggregation of NetCDF files. In addition to simply concatenating files along arbitrary dimensions, ncagg can also subset variables and dimensions, regularize dimensions by adding fill values, bound domains, and deduplicate records. Furthermore ncagg is metadata aware and aggregates metadata according to configurable strategies. The second utility is ncflag, which provides a high level interface to CF-Convention compliant flags that are characterized by flag_values, flag_meanings, and possibly flag_masks metadata. Ncflag provides an automated, convenient, and efficient alternative to manual and/or static methods involving hardcoded bit masks and comparisons. Contrary to previous, more error prone methods, ncflag encourages expressions in terms of flag_meanings. Both ncagg and ncflag are open source, each have a command line interface, expose an interface for use in Python code, and are available for install via pip.