Intercomparison of Atmospheric Carbonyl Sulfide (TransCom‐COS): 2. Evaluation of Optimized Fluxes Using Ground‐Based and Aircraft Observations

Jin Ma*, Marine Remaud, Philippe Peylin, Prabir Patra, Yosuke Niwa, Christian Rodenbeck, Mike Cartwright, Jeremy Harrison, Martyn Chipperfield, Richard Pope, Christopher Wilson, Sauveur Belviso, Stephen Montzka, Isaac Vimont, Fred Moore, Elliot L. Atlas, Efrat Schwartz, Maarten Krol

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


We present a comparison of atmospheric transport models that simulate carbonyl sulfide (COS). This is part II of the ongoing Atmospheric Transport Model Inter-comparison Project (TransCom–COS). Differently from part I, we focus on seven model intercomparison by transporting two recent COS inversions of NOAA surface data within TM5-4DVAR and LMDz models. The main goals of TransCom-COS part II are (a) to compare the COS simulations using the two sets of optimized fluxes with simulations that use a control scenario (part I) and (b) to evaluate the simulated tropospheric COS abundance with aircraft-based observations from various sources. The output of the seven transport models are grouped in terms of their vertical mixing strength: strong and weak mixing. The results indicate that all transport models capture the meridional distribution of COS at the surface well. Model simulations generally match the aircraft campaigns HIAPER Pole-To-Pole Observations (HIPPO) and Atmospheric Tomography Mission (ATom). Comparisons to HIPPO and ATom demonstrate a gap between observed and modeled COS over the Pacific Ocean at 0–40°N, indicating a potential missing source in the free troposphere. The effects of seasonal continental COS uptake by the biosphere, observed on HIPPO and ATom over oceans, is well reproduced by the simulations. We found that the strength of the vertical mixing within the column as represented in the various atmospheric transport models explains much of the model to model differences. We also found that weak-mixing models transporting the optimized flux derived from the strong-mixing TM5 model show a too strong seasonal cycle at high latitudes.
Original languageEnglish
Article numbere2023JD039198
JournalJournal of Geophysical Research: Atmospheres
Issue number18
Publication statusPublished - 27 Sept 2023


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