HR: 0800h
AN: C51B-1046    [Abstracts]
TI: Isolating the tropical Pacific and Atlantic influences upon simulated Amazonian hydrology and water isotopes
AU: * Kelley, M
EM: maxwell.kelley@cea.fr
AF: LSCE, L'Orme des Merisiers CEA Saclay, Gif sur Yvette cedex, 91191 France
AU: Hoffmann, G
EM: hoffmann@lsce.saclay.cea.fr
AF: LSCE, L'Orme des Merisiers CEA Saclay, Gif sur Yvette cedex, 91191 France
AB: The ECHAM4 GCM outfitted with water isotope physics is used to assess the impacts of SST variations in the Pacific and Atlantic oceans upon isotopic variability of water vapor in the Amazon, the principal moisture source for Andean snowfall. A 128-year control experiment which imposes observed SSTs over the period 1870-1997 is compared to runs in which SST climatology prevails everywhere but in the tropical Pacific (TP) or in the tropical Atlantic (TA). As a result of variance reduction relative to the control, the TP run exhibits an enhancement of the interannual correlation of ENSO with tropical South American rainfall, and hence with the latter's isotopic composition via the amount effect. Analogously, a weak but significant positive correlation between Amazon rainfall and equatorial Atlantic SSTs is amplified in the TA run. Analysis of two rainfall datasets supports an Atlantic influence of this sign; possible mechanisms are discussed. Multidecadal variability in the Amazon is stronger in the TA than in the TP simulation, in contrast to the case for shorter timescales.
DE: 3344 Paleoclimatology
DE: 3374 Tropical meteorology
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting