Thanks. One very important feature that simple in situ monitors don’t provide is total column CO2. That’s the average concentration from the ground up to the t

Thanks. One very important feature that simple in situ monitors don’t provide is total column CO2. That’s the average concentration from the ground up to the top of atmosphere. The satellites, and advanced ground measurements, get total column CO2 by observing the behavior of slices of the solar spectrum that are affected by CO2. Basically, the gas absorbs some wavelengths and re-emits in others.