Highlighting the impact of anthropogenic OCS emissions on the
stratospheric sulfur budget with in-situ observations
Abstract
Carbonyl sulfide (OCS) is an important atmospheric sulfur species that
plays a dominant role in the formation of (non-volcanic) stratospheric
sulfate aerosol in the middle stratosphere. Major uncertainties in
surface sources and sinks and inconsistent model representation of
vertical transport limit understanding of OCS distribution, particularly
in the sparsely sampled upper atmosphere. During the 2022 Asian Summer
Monsoon Chemical & CLimate Impact Project (ACCLIP) campaign in-situ
measurements of OCS in the Upper Troposphere and Lower Stratosphere
(UTLS) at the eastern edge of the Asian Summer Monsoon anticyclone
(ASM), showed significant OCS enhancements (>750 ppt) near
the tropopause from convectively influenced air parcels. Here we compare
these novel Asian UTLS measurements with long term satellite
observations and regional measurements to broaden understanding of OCS
trends and its transport by the ASM. Trajectory analysis identifies the
main source regions for deep convective lofting and demonstrates ASM
entrainment of OCS enriched parcels in the UTLS, allowing evaluation of
global model predictions for OCS’s stratospheric influence. The ACCLIP
dataset provides vital in-situ validation of limited vertically resolved
OCS data in a region of significant anthropogenic emissions, which
serves to enhance our understanding of the global sulfur budget.