A seasonal deuterium excess signal at Law Dome, coastal eastern Antarctica: A southern ocean signature

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Delmotte, Marc, Masson, Valérie, Jouzel, Jean, Morgan, Vin
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), ICOS-RAMCES (ICOS-RAMCES), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2000
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; East Antarctica; Law Dome; Law Dome Summit; Southern Ocean; Antarc*; Antarctica; ice core; Sea ice
• Online Access: https://hal.science/hal-03103023; https://hal.science/hal-03103023/document; https://hal.science/hal-03103023/file/1999JD901085.pdf; https://doi.org/10.1029/1999JD901085

International audience The snow isotopic composition (6•O and 6D) of two shallow cores fl'om the high accumulation summit region of Law Dome, east Antarctica, was measured at monthly resolution over the 1980-1992 period. While the 8•O or $D signals clearly reflect the local temperature cycle, the deuterium excess (d = 8D-88•O) is shifted with respect to 15t•O cycle by a 4 months lag. Interpretation of this phase lag is investigated using both an Atmospheric General Circulation Model (AGCM), which includes the water isotopic cycles, and a simple isotopic model, which better describes the microphysical processes within the cloud. Using this dual approach, we show that the seasonality of 8•O and d at Law Dome summit results from a combination of the southern ocean temperature cycle (shifted by 2-3 months with respect to the local insolation) and seasonal moisture origin changes due to a strong contribution of the local ocean when ice free. Both approaches are consistent with a dominant temperate to subtropical moisture origin. We thus demonstrate from our present-day subseasonal study that the record of d in the Dome Summit South (DSS) deep ice core represents a potential tool for identifying changes in Southern Ocean temperatures and/or sea ice cover at the scale of the past thousand years.