filename structure: halo_<campaign>_<instrument>_<level>_<variable>_v<version>_<date><time>.nc
campaign: campaign name abbreviation
nars = NARVAL South, narn = NARVAL North, nar2 = NARVAL2, nawd = NAWDEX
instrument: instrument name abbreviation
cr00 = cloud radar, mwr00 = microwave radiometer, sonde = dropsondes
level: data level according to GODAE data level structure
variable: variable abbreviation
''any'' for multiple variables in a data set and ''tb'' for microwave radiomer brightness temperatures
version: version of data set in data base, starting with 00
date: day of flight
time: time of start of data set in each file