HR: 15:25h
AN: C43D-08 INVITED     [Abstracts]
TI: Stable Isotopes in Precipitation and the South American Summer Monsoon - Observations and Model Results
AU: * Vuille, M
EM: mathias@geo.umass.edu
AF: Climate System Research Center, University of Massachusetts, 611 North Pleasant Street, Amherst, MA 01003 United States
AU: Werner, M
EM: martin.werner@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Postbox 10 01 64, Jena, 07701 Germany
AB: The South American Summer Monsoon (SASM) is a major component of the South American climate system during the austral wet season. A number of proxy records throughout the continent seem to have captured past variations in its strength and/or location on various time scales. Stable isotopic records (e.g. from ice cores or speleothems) are amongst the most prominent such proxies. Unfortunately little is known about the climatic controls on stable isotopes in precipitation at low latitudes and the available observational data are scarce and of very short record lengths. Here we employ a high-resolution Atmospheric General Circulation Model (AGCM), the ECHAM-4 T106 model, fitted with stable isotopic tracers, to investigate the relationship between interannual variations in monsoon strength and the stable isotopic composition of precipitation over tropical South America. Special emphasis will be given to the relative importance of the SASM versus other potential forcing mechanisms such as ENSO. We will show that the relative influence of SASM and ENSO on the stable isotopic composition of precipitation varies regionally. In addition our results suggest that the effects of the two climate modes on stable isotopes counterbalance each other in some regions, while they reinforce each other in other parts of South America.
DE: 9360 South America
DE: 4522 El Ni¤o
DE: 1863 Snow and ice (1827)
DE: 1040 Isotopic composition/chemistry
DE: 1620 Climate dynamics (3309)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting