MLO is the site of the longest running measurements of atmospheric CO₂, begun in the late 1950s by Charles Keeling. MLO offers a unique testing environment for the Mini-LHR, as the altitude helps ensure the atmosphere sampled represents the “background” signal of the atmosphere. At this site in 2013, we added a methane (CH₄) measurement channel, improved automation, synching observations to AERONET’s preprogrammed schedule (an observation every 15 minutes), and decreased scan time to less than a minute. An early CO₂ scan is shown from Melroy et al., 2015.