Transport by Asian Summer Monsoon Convection to the Upper Troposphere and Lower Stratosphere During ACCLIP (2022)

Abstract

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 region 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 for species ranging in lifetime from days to months, transport from convection along the East Asia Subtropical Front was generally associated with more UTLS pollutants than transport from convection over South Asia. The convective transport diagnostic is used to isolate three convective transport events over eastern Asia which had distinct chemical tracer relationship behaviors, 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 which may have been high enough in altitude 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-systems.