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@ARTICLE{Pan:1024266,
author = {Pan, Laura L. and Atlas, Elliot L. and Honomichl, Shawn B.
and Smith, Warren P. and Kinnison, Douglas E. and Solomon,
Susan and Santee, Michelle L. and Saiz-Lopez, Alfonso and
Laube, Johannes C. and Wang, Bin and Ueyama, Rei and Bresch,
James F. and Hornbrook, Rebecca S. and Apel, Eric C. and
Hills, Alan J. and Treadaway, Victoria and Smith, Katie and
Schauffler, Sue and Donnelly, Stephen and Hendershot, Roger
and Lueb, Richard and Campos, Teresa and Viciani, Silvia and
D’Amato, Francesco and Bianchini, Giovanni and Barucci,
Marco and Podolske, James R. and Iraci, Laura T. and
Gurganus, Colin and Bui, Paul and Dean-Day, Jonathan M. and
Millán, Luis and Ryoo, Ju-Mee and Barletta, Barbara and
Koo, Ja-Ho and Kim, Joowan and Liang, Qing and Randel,
William J. and Thornberry, Troy and Newman, Paul A.},
title = {{E}ast {A}sian summer monsoon delivers large abundances of
very short-lived organic chlorine substances to the lower
stratosphere},
journal = {Proceedings of the National Academy of Sciences of the
United States of America},
volume = {121},
number = {12},
issn = {0027-8424},
address = {Washington, DC},
publisher = {National Acad. of Sciences},
reportid = {FZJ-2024-02073},
pages = {e2318716121},
year = {2024},
abstract = {Deep convection in the Asian summer monsoon is a
significant transport process for lifting pollutants from
the planetary boundary layer to the tropopause level. This
process enables efficient injection into the stratosphere of
reactive species such as chlorinated very short-lived
substances (Cl-VSLSs) that deplete ozone. Past studies of
convective transport associated with the Asian summer
monsoon have focused mostly on the south Asian summer
monsoon. Airborne observations reported in this work
identify the East Asian summer monsoon convection as an
effective transport pathway that carried record-breaking
levels of ozone-depleting Cl-VSLSs (mean organic chlorine
from these VSLSs ~500 ppt) to the base of the stratosphere.
These unique observations show total organic chlorine from
VSLSs in the lower stratosphere over the Asian monsoon
tropopause to be more than twice that previously reported
over the tropical tropopause. Considering the recently
observed increase in Cl-VSLS emissions and the ongoing
strengthening of the East Asian summer monsoon under global
warming, our results highlight that a reevaluation of the
contribution of Cl-VSLS injection via the Asian monsoon to
the total stratospheric chlorine budget is warranted.The
Asian summer monsoon (ASM), a significant element of the
climate system, has been studied as a regional weather
pattern for centuries. Only in recent decades has its role
in global constituent transport been recognized, largely
owing to observations made from satellites (1). The ASM is
of particular interest because its associated deep
convective systems rapidly transport air masses from the
planetary boundary layer (PBL) in one of the most polluted
regions on the planet to the upper troposphere and lower
stratosphere (UTLS). An annually recurring layer with a
distinct chemical signature and aerosol composition forms at
the tropopause level within the ASM UTLS anticyclone during
boreal summer (2–5). Detailed information on the chemical
and microphysical changes in the UTLS induced by this
annually recurring transport process is necessary for the
accurate representation of the role of the ASM in
chemistry-climate models. Targeted measurements using
high-altitude research aircraft, in addition to ground-based
and balloon-borne observations, provide data essential for
understanding physical processes and constraining
chemistry-climate models. Two prior experiments provided
valuable measurements of trace gases and aerosols in the
region of the ASM anticyclone (6–8). The Asian summer
monsoon Chemical and Climate Impact Project (ACCLIP), a
field campaign conducted in summer 2022 using two
high-altitude aircraft, the NSF National Center for
Atmospheric Research (NCAR) Gulfstream V (GV) and the NASA
WB-57, represents the latest large-scale effort of this
kind. The ACCLIP campaign conducted a total of 29 research
flights over the northwestern Pacific from July 31 to
September 1, 2022, from an airbase in the Republic of Korea
(see SI Appendix, Fig. S1 for flight tracks). The flights
sampled air masses lofted by convection both inside and near
the eastern edge of the ASM anticyclone. The observations
include a large suite of trace gases and aerosols, mostly at
altitudes between 12 and 19 km above sea level (asl), a
layer not accessible by commercial aircraft. The data
represent the largest set of in situ atmospheric composition
measurements in the ASM region (see SI Appendix for further
details).The ASM system has two distinct components, the
South Asian summer monsoon (SASM) and the East Asian summer
monsoon (EASM). These components are controlled by different
heat sources and respond differently to global warming. The
circulation of the EASM is projected to strengthen while
that of the SASM is projected to weaken, although both
systems are projected to have increased precipitation due to
increased moisture content (9). The schematic in Fig. 1A
shows the key elements of the two subcomponents,
highlighting two convergence zones: the Monsoon Trough and
the East Asia Subtropical Front. Up to now, the SASM has
been considered the dominant process for injecting PBL air
masses into the ASM anticyclone at the tropopause level (6,
10–13). The Monsoon Trough was identified as the central
region for convective lofting of PBL air masses (13). A key
outcome of ACCLIP is the identification of the EASM
convection as a more impactful transport pathway for UTLS
chemical composition and stratospheric ozone chemistry than
previously considered.},
cin = {IEK-7},
ddc = {500},
cid = {I:(DE-Juel1)IEK-7-20101013},
pnm = {2112 - Climate Feedbacks (POF4-211)},
pid = {G:(DE-HGF)POF4-2112},
typ = {PUB:(DE-HGF)16},
pubmed = {38483991},
UT = {WOS:001208967600002},
doi = {10.1073/pnas.2318716121},
url = {https://juser.fz-juelich.de/record/1024266},
}