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 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.