The complexity of the climate system means that for the reconstruction of past variations, the use of a multiplicity of proxy indicators is mandatory. Polar ice cores provide a unique source of proxy data because of the variety of indicators which can be obtained by different analyses. This study concentrates on analysis of the isotopic composition and the total air content in the DSS (Dome Summit South) ice core drilled on Law Dome in coastal East Antarctica. The number of analyses and the precision required for the isotopic measurements in a deep polar core study require specific adaptation of classical mass spectrometer techniques. This study presents a new and original sample injection technique which when used in conjunction with an existing mass spectrometer allowed a significant increase in efficiency without affecting the measurement accuracy. Recent studies have questioned the quantitative interpretation of isotope ratio in terms of temperature. In this study of new surface snow samples from Eastern Antarctica we discuss the validity of the spatial isotope/temperature relationship and suggest an estimation of the associated uncertainty. The combined use of deuterium excess data with simulations of a simple isotopic model are also used to give additional information on the origin of the precipitation. In order to understand recent climatic changes, it is essential to place them in the context of climatic natural variability. The unique temporal resolution of the DSS core allows us to study the climate of the last 4,000 years in exceptional detail. Spectral analysis of the record suggests the existence of oscillating modes linked with the ENSO and/or the Antarctic Circumpolar Wave. Finally, analysis of DSS samples for air content provides complementary information about the elevation variation probably encountered by the LawDome during the last climatie transition.
Enregistrements climatiques à Law Dome : variabilité pour les périodes récentes et pour la déglaciation