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Global Atmospheric Budget of Acetone: Air‐Sea Exchange and the Contribution to Hydroxyl Radicals
Author(s) -
Wang Siyuan,
Apel Eric C.,
Schwantes Rebecca H.,
Bates Kelvin H.,
Jacob Daniel J.,
Fischer Emily V.,
Hornbrook Rebecca S.,
Hills Alan J.,
Emmons Louisa K.,
Pan Laura L.,
Honomichl Shawn,
Tilmes Simone,
Lamarque JeanFrançois,
Yang Mingxi,
Marandino Christa A.,
Saltzman Eric S.,
Bruyn Warren,
Kameyama Sohiko,
Tanimoto Hiroshi,
Omori Yuko,
Hall Samuel R.,
Ullmann Kirk,
Ryerson Thomas B.,
Thompson Chelsea R.,
Peischl Jeff,
Daube Bruce C.,
Commane Róisín,
McKain Kathryn,
Sweeney Colm,
Thames Alexander B.,
Miller David O.,
Brune William H.,
Diskin Glenn S.,
DiGangi Joshua P.,
Wofsy Steven C.
Publication year - 2020
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2020jd032553
Subject(s) - acetone , troposphere , stratosphere , atmospheric sciences , environmental science , peroxyacetyl nitrate , northern hemisphere , seawater , atmospheric chemistry , chemistry , climatology , meteorology , ozone , oceanography , physics , geology , nox , combustion , organic chemistry
Acetone is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere. The oceans impose a strong control on atmospheric acetone, yet the oceanic fluxes of acetone remain poorly constrained. In this work, the global budget of acetone is evaluated using two global models: CAM‐chem and GEOS‐Chem. CAM‐chem uses an online air‐sea exchange framework to calculate the bidirectional oceanic acetone fluxes, which is coupled to a data‐oriented machine‐learning approach. The machine‐learning algorithm is trained using a global suite of seawater acetone measurements. GEOS‐Chem uses a fixed surface seawater concentration of acetone to calculate the oceanic fluxes. 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.