Global atmospheric budget of acetone: Air-sea exchange and the contribution to hydroxyl radicals

Both model simulations are compared to airborne observations from a recent global-scale, multiseasonal campaign, the NASA Atmospheric Tomography Mission (ATom). We find that both CAM-chem and GEOS-Chem capture the measured acetone vertical distributions in the remote atmosphere reasonably well. The combined observational and modeling analysis suggests that (i) the ocean strongly regulates the atmospheric budget of acetone.

The tropical and subtropical oceans are mostly a net source of acetone, while the high-latitude oceans are a net sink. (ii) CMIP6 anthropogenic emission inventory may underestimate acetone and/or its precursors in the Northern Hemisphere. (iii) The MEGAN biogenic emissions model may overestimate acetone and/or its precursors, and/or the biogenic oxidation mechanisms may overestimate the acetone yields.

(iv) The models consistently overestimate acetone in the upper troposphere-lower stratosphere over the Southern Ocean in austral winter. (v) Acetone contributes up to 30-40% of hydroxyl radical production in the tropical upper troposphere/lower stratosphere.