DMS Uplift by Tropical Cyclones as a Source of SO₂ in the Upper Troposphere

Airborne observations from ACCLIP on 2 August 2022, combined with Lagrangian particle dispersion model back trajectories, reveal that SO₂ mixing ratios at 14–16 km were enhanced by a factor of 4–6 in regions influenced by tropical cyclones (TCs). These enhancements are linked to rapid lofting of marine dimethyl sulfide (DMS) into the upper troposphere (UT). GEOS-Chem simulations indicated that on 31 July 2022, TC-scale circulation injected DMS into the UT within hours, with a mean flux of 9.4 kg hr⁻¹ across 0.5–12 km and 8.4% of emissions penetrating above 12 km, consistent with observations of elevated DMS at the same altitudes. Because of its low solubility and longer UT lifetime (59.2 vs. 5.7 hr at the surface), DMS sustains SO₂ production that is largely resistant to wet scavenging. This TC-driven pathway provides a significant natural SO₂ source in the UT, with implications for aerosol–cloud–climate interactions.