VOTE DC-8 1996/01/23-1996/02/18
  ch4: da_Methane-mixing-ratio-(ppbv) [ppbv]
  co: da_Carbon-Monoxide-mixing-ratio-(ppbv) [ppbv]
  co2: da_Carbon-Dioxide-mixing-ratio-(ppmv) [ppmv]
  h2o: lh_Water-Vapor-mixing-ratio-(ppmv) [ppmv]
  n2o: da_Nitrous-Oxide-mixing-ratio-(ppbv) [ppbv]
  no: no_NO-(pptv) [pptv]
  noy: ny_NOy-(pptv) [pptv]
  o3: o3_O3-(ppbv) [ppbv]
  pressure: dp_Pressure-millibars [mbar]
  temperature: dp_Static-Air-Temperature-Kelvins [K]
  theta: dp_Potential-Temperature-Kelvins [K]