Global measurements of isoprene from space: Constraints on emissions and atmospheric oxidation

Isoprene is the dominant non-methane organic compound emitted to the atmosphere, where it drives ozone and aerosol production, modulates the atmosphere's cleansing capacity, and couples with the global nitrogen cycle. Isoprene emissions are highly uncertain, as is the non-linear chemistry coupling isoprene and its primary sink, the hydroxyl radical (OH). Here we present the first global isoprene measurements from space, and show that in combination with measurements of formaldehyde, a high-yield isoprene oxidation product, these data provide new constraints on isoprene emissions and atmospheric oxidation. We find that isoprene:formaldehyde relationships measured from space are broadly consistent with current understanding of isoprene-OH chemistry, with no indication of missing OH recycling at low-NO_x. We further explore these datasets over four global isoprene hotspots and identify key knowledge gaps.