HR: 14:40h
AN: C43D-05    [Abstracts]
TI: Water Isotopes in a Warmer World : Lessons from General Circulation Model Based Simulations.
AU: * Jouzel, J
EM: jouzel@lsce.saclay.cea.fr
AF: IPSL/Laboratoire des Sciences du Climat et de l'Environnement, Orme des merisiers, Gif sur Yvette, 91191 France
AU: Hoffmann, G
EM: hoffmann@lsce.saclay.cea.fr
AF: IPSL/Laboratoire des Sciences du Climat et de l'Environnement, Orme des merisiers, Gif sur Yvette, 91191 France
AU: Masson-Delmotte, V
EM: masson@lsce.saclay.cea.fr
AF: IPSL/Laboratoire des Sciences du Climat et de l'Environnement, Orme des merisiers, Gif sur Yvette, 91191 France
AU: Koster, R
EM: koster@janus.gsfc.nasa.gov
AF: Global Modeling and Assimilation Office, NASA/Goddard Space Flight Center, Greenbelt, 20771 United States
AU: Schmidt, G
EM: gschmidt@giss.nasa.gov
AF: Center for Climate Systems Research, Columbia University, 2880 Broadway, New York, 10025 United States
AB: Isotopic versions of atmospheric general circulation models (IGCMs) have been developed by several modeling groups over the last two decades. Their initial applications have focused on past climates (e.g. the Last Glacial Maximum: 20,000 years ago) with the aim of improving the interpretation of paleodata gathered from various archives, particularly polar ice cores. IGCMs are also ideal tools for predicting how the distributions of stable water isotopes (HDO and H218O) in atmospheric water vapor and precipitation will evolve in a warmer world. With this in mind, a 2*CO2 isotopic experiment was performed more than 10 years ago using the NASA/GISS low-resolution IGCM. As expected, this simulation produced isotopically heavier precipitation at high latitudes. Somewhat surprisingly, though, the simulation also produced slightly lighter precipitation in some mid-latitude areas and consistently lighter precipitation in tropical and equatorial regions. In these latter areas, d18O in precipitation is decreased by up to 3 permil, leading to the suggestion that some type of "compensation effect" (decreases in tropical d18O making up for increases in high latitude d18O) may be operating. Warmer climate experiments have now been conducted with the ECHAM IGCM and with new isotopic versions of the NASA/GISS model. We will review these more recent results and examine them in view of a possible isotopic compensation effect between high latitude and tropical regions.
DE: 3344 Paleoclimatology
DE: 1704 Atmospheric sciences
DE: 1719 Hydrology
DE: 1854 Precipitation (3354)
DE: 1040 Isotopic composition/chemistry
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting