Pandora spectrometer instrument spectroscopy is used to measure columnar amounts of trace gases in the atmosphere. These gases (O₃, NO₂, CH₂O) absorb specific wavelengths of light from the sun in the ultraviolet-visible spectrum.

Using the theoretical solar spectrum as a reference, Pandora determines trace gas amounts using differential optical absorption spectroscopy (DOAS). This principle attributes differences in spectra measured by Pandora to the presence of trace gases within the atmosphere (i.e. the difference between the theoretical solar spectrum and measured spectrum is caused by absorption of trace gas species). Read more..