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@ARTICLE{Wu:839892,
author = {Wu, Xue and Griessbach, Sabine and Hoffmann, Lars},
title = {{E}quatorward dispersion of a high-latitude volcanic plume
and its relation to the {A}sian summer monsoon: a case study
of the {S}arychev eruption in 2009},
journal = {Atmospheric chemistry and physics},
volume = {17},
number = {21},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2017-07470},
pages = {13439 - 13455},
year = {2017},
abstract = {Tropical volcanic eruptions have been widely studied for
their significant contribution to stratospheric aerosol
loading and global climate impacts, but the impact of
high-latitude volcanic eruptions on the stratospheric
aerosol layer is not clear and the pathway of transporting
aerosol from high latitudes to the tropical stratosphere is
not well understood. In this work, we focus on the
high-latitude volcano Sarychev (48.1° N, 153.2° E),
which erupted in June 2009, and the influence of the Asian
summer monsoon (ASM) on the equatorward dispersion of the
volcanic plume. First, the sulfur dioxide (SO2) emission
time series and plume height of the Sarychev eruption are
estimated with SO2 observations of the Atmospheric Infrared
Sounder (AIRS) and a backward trajectory approach using the
Lagrangian particle dispersion model Massive–Parallel
Trajectory Calculations (MPTRAC). Then, the transport and
dispersion of the plume are simulated using the derived SO2
emission time series. The transport simulations are compared
with SO2 observations from AIRS and validated with aerosol
observations from the Michelson Interferometer for Passive
Atmospheric Sounding (MIPAS). The MPTRAC simulations show
that about $4 \%$ of the sulfur emissions were transported
to the tropical stratosphere within 50 days after the
beginning of the eruption, and the plume dispersed towards
the tropical tropopause layer (TTL) through isentropic
transport above the subtropical jet. The MPTRAC simulations
and MIPAS aerosol data both show that between the potential
temperature levels of 360 and 400 K, the equatorward
transport was primarily driven by anticyclonic Rossby wave
breaking enhanced by the ASM in boreal summer. The volcanic
plume was entrained along the anticyclone flows and reached
the TTL as it was transported southwestwards into the deep
tropics downstream of the anticyclone. Further, the ASM
anticyclone influenced the pathway of aerosols by isolating
an "aerosol hole" inside of the ASM, which was surrounded by
aerosol-rich air outside. This transport barrier was best
indicated using the potential vorticity gradient approach.
Long-term MIPAS aerosol detections show that after entering
the TTL, aerosol from the Sarychev eruption remained in the
tropical stratosphere for about 10 months and ascended
slowly. The ascent speed agreed well with the ascent speed
of the water vapor tape recorder. Furthermore, a
hypothetical MPTRAC simulation for a wintertime eruption was
carried out. It is shown that under winter atmospheric
circulations, the equatorward transport of the plume would
be suppressed by the strong subtropical jet and weak wave
breaking events. In this hypothetical scenario, a
high-latitude volcanic eruption would not be able to
contribute to the tropical stratospheric aerosol layer.},
cin = {JSC},
ddc = {550},
cid = {I:(DE-Juel1)JSC-20090406},
pnm = {511 - Computational Science and Mathematical Methods
(POF3-511)},
pid = {G:(DE-HGF)POF3-511},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000415092300001},
doi = {10.5194/acp-17-13439-2017},
url = {https://juser.fz-juelich.de/record/839892},
}