The MLS Level 2 data are stored in the Aura-specific implementation of the HDF-EOS (v5) format, as described in the HDF-EOS Aura File Format Guidelines1 . Briefly, the MLS standard products are stored in individual Level 2 Geophysical Product files (L2GP) within appropriately named swaths. The files contain vertical profiles of geophysical parameters on a fixed set of pressures (typically spaced at 6 surfaces per decade change in pressure).