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@ARTICLE{Aghedo:9339,
author = {Aghedo, A.M. and Rast, S. and Schultz, M. G.},
title = {{S}ensitivity of tracer transport to model resolution,
prescribed meteorology and tracer lifetime in the general
circulation model {ECHAM}5},
journal = {Atmospheric chemistry and physics},
volume = {10},
issn = {1680-7316},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {PreJuSER-9339},
pages = {3385 - 3396},
year = {2010},
note = {This work was carried out during the doctoral work of AMA,
sponsored by the ZEIT foundation through the International
Max Planck Research School on Earth System Modelling
(IMPRS-ESM). SR and MGS acknowledge funding from the EU
project RETRO (EVK2-CT-2002-00170). We are grateful to the
ECMWF for providing the reanalysis data, and to Erich
Roeckner, Marco Giorgetta, and Kevin W Bowman for their
useful comments, and also to Luis Kornblueh for the
technical assistance. The model runs were performed on the
Sun Computing system (YANG) at the Max Planck Institute for
Meteorology, Hamburg and the NEC SX-6 computer at the German
Climate Computing Centre ("Deutsches Klimarechenzentrum").
We thank the editor, Peter Haynes, and appreciate the
comments of Kenneth Bowman, and three other anonymous
referees, which have significantly improve the manuscript.},
abstract = {Atmospheric transport of traces gases and aerosols plays an
important role in the distribution of air pollutants and
radiatively active compounds. For model simulations of
chemistry-climate interactions it is important to know how
the transport of tracers depends on the geographical
resolution of the general circulation model. However, this
aspect has been scarcely investigated until now. Here, we
analyse tracer transport in the ECHAM5 general circulation
model using 6 independent idealized tracers with constant
lifetimes, which are released in two different altitudes at
the surface and in the stratosphere, respectively. Model
resolutions from T21L19 to T106L31 were tested by performing
multi-annual simulations with prescribed sea surface
temperatures and sea ice fields of the 1990s. The impacts of
the tracer lifetime were investigated by varying the
globally uniform exponential decay time between 0.5 and 50
months. We also tested the influence of using prescribed
meteorological fields (ERA40) instead of climatological sea
surface temperature and sea ice fields. Meridional transport
of surface tracers decreases in the coarse resolution model
due to enhanced vertical mixing, with the exception of the
advection into the tropical region, which shows an
inconsistent trend between the resolutions. Whereas, the
meridional transport of tracers released in the stratosphere
was enhanced with higher model resolutions, except in the
transport from tropical stratosphere to the Southern
Hemisphere, which exhibits an increase trend with increasing
model resolution. The idealized tracers exhibit a seasonal
cycle, which is modulated by the tracer lifetime. In
comparison to the run with prescribed sea surface
temperature and sea ice fields, the simulation with
prescribed meteorological fields did not exhibit significant
change in the meridional transport, except in the exchange
of stratospheric tracers between both hemispheres, where it
causes about $100\%$ increase. The import of the surface
tracers into the stratosphere is increased by up to a factor
of 2.5, and the export from the stratosphere into the
troposphere was increased by up to $60\%$ when prescribed
meteorological fields is used. The ERA40 simulation also
showed larger interannual variability (up to $24\%$ compared
to $12\%$ in the standard simulations). Using our surface
tracers released in either the northern or Southern
Hemisphere, respectively, we calculate inter-hemispheric
transport times between 11 and 17 months, consistent with
values reported in the literature. While this study cannot
be used to relate differences in model results to specific
changes in transport processes, it nevertheless provides
some insight into the characteristics of tracer transport in
the widely used ECHAM5 general circulation model.},
keywords = {J (WoSType)},
cin = {ICG-2},
ddc = {550},
cid = {I:(DE-Juel1)VDB791},
pnm = {Atmosphäre und Klima},
pid = {G:(DE-Juel1)FUEK406},
shelfmark = {Meteorology $\&$ Atmospheric Sciences},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000276663600017},
url = {https://juser.fz-juelich.de/record/9339},
}