The Asian Summer Monsoon (ASM) has garnered attention in recent years for its impacts on the composition of the upper troposphere and lower stratosphere (UTLS) via deep convection. A recent observational effort into this mechanism, the Asian summer monsoon Chemical and CLimate Impact Project (ACCLIP), sampled the composition of the ASM UTLS over the northwestern Pacific during boreal summer 2022 using two airborne platforms. In this work, we integrate Lagrangian trajectory modeling with convective cloud top observations to diagnose ASM convective transport which contributed to ACCLIP airborne observations. This diagnostic is applied to explore the properties of convective transport associated with prominent ASM sub-systems, revealing that convective transport along the East Asia Subtropical Front generally contained more pollutants than from South Asia, for species ranging in lifetime from days to months. The convective transport diagnostic is used to isolate three convective transport events over eastern Asia which had distinct chemical tracer relationship slopes, indicating the different economical behaviors of the contributing source regions. One of these transport events is explored in greater detail, where a polluted air mass was sampled from convection over the Northeast China Plain. This event was largely confined to 12-15 km altitude, which may be high enough to impact the composition of the stratosphere. Overall, the presented diagnosis of convective transport contribution to ACCLIP airborne sampling indicates a key scientific success of the campaign and enables process studies of the climate interactions from the two ASM sub-system.

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.