TY  - JOUR
AU  - Aghedo, A.M.
AU  - Rast, S.
AU  - Schultz, M. G.
TI  - Sensitivity of tracer transport to model resolution, prescribed meteorology and tracer lifetime in the general circulation model ECHAM5
JO  - Atmospheric chemistry and physics
VL  - 10
SN  - 1680-7316
CY  - Katlenburg-Lindau
PB  - EGU
M1  - PreJuSER-9339
SP  - 3385 - 3396
PY  - 2010
N1  - 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.
AB  - 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.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000276663600017
UR  - https://juser.fz-juelich.de/record/9339
ER  -