Aircraft vertical profile measurements for evaluation of satellite retrievals of long-lived trace gases

Accurate measurement of the composition of the Earth’s atmosphere is foundational to understanding climate and air quality. Space-based observations provide an attractive method of observing the Earth’s atmosphere, providing the potential for high-frequency, near-global coverage. Observations from space rely on remote-sensing approaches, which in turn require measurements to be made in the atmosphere (so-called “in situ” measurements) to calibrate and evaluate the remote sensing approach. Airborne measurements made from aircraft provide a unique pathway to evaluate satellite retrievals with accurate in situ measurements traceable to a global standard. This chapter outlines how specific intensive airborne campaigns provide essential satellite retrieval evaluation in both direct and indirect manners, on global to regional scales.