Ranges of moisture-source temperature estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles

Abstract

Abstract.A single isotope ratio (δD or δ 18 O) of water is widely used as an air-temperature proxy in Antarctic ice core records. These isotope ratios, however, do not solely depend on air-temperature but also on the extent of distillation of heavy isotopes out of atmospheric water vapor from an oceanic moisture source to a precipitation site. The temperature changes at the oceanic moisture source ( T source ) and at the precipitation site ( T site ) can be retrieved by using deuterium-excess (d) data. A new d record from Dome Fuji, Antarctica spanning the past 360 000 yr is presented and compared with records from Vostok and EPICA Dome C ice cores. In previous studies, to retrieve T source and T site information, different linear regression equations were proposed using theoretical isotope distillation models. A major source of uncertainty lies in the coefficient of regression, β site which is related to the sensitivity of d to T site . We show that different ranges of temperature and selections of isotopic model outputs may increase the value of β site by more than a factor of two. To explore the impacts of this coefficient on reconstructed temperatures, we apply for the first time the exact same methodology to the isotope records from the three Antarctica ice cores. We show that uncertainties in the β site coefficient strongly affect (i) the glacial-interglacial magnitude of T source ; (ii) the imprint of obliquity in T source and in the site-source temperature gradient. By contrast, we highlight the robustness of T site reconstruction using water isotopes records.

What controls deuterium excess in global precipitation?

“…From their study with an idealised model, and using monthly mean data for the initialisation, Johnsen et al (1989) concluded that SST and RH changes could both play a role for d variations observed in a Greenland ice core. Noting that GCM (global circulation model) simulations show only small glacial-to-interglacial changes in mean oceanic RH, it has been proposed that d in Antarctic ice core records can be interpreted as a moisture source SST signal only (Vimeux et al, 1999;Stenni et al, 2001;Uemura et al, 2012), revoking the earlier interpretation as a proxy of moisture source RH (Jouzel et al, 1982). This interpretation as source SST has later been extended also to Greenland ice cores (MassonDelmotte et al, 2005).…”

A brief history of ice core science over the last 50 yr

“…This link has further been confirmed for polar snow Petit et al, 1991;Ciais and Jouzel, 1994); its use for extracting information about moisture sources was developed in the eighties (Jouzel et al, 1982;White et al, 1988;Dansgaard et al, 1989;Johnsen et al, 1989). Since then, δD and δ 18 O are quite systematically measured in order to provide such additional information from ice cores drilled in both Antarctica (Jouzel et al, 1982;Vimeux et al, 1999Vimeux et al, , 2002Cuffey and Vimeux, 2001;Stenni et al, 2001Stenni et al, , 2003Stenni et al, , 2010Uemura et al, 2004Uemura et al, , 2012 and Greenland (Masson- Jouzel et al, 2007b), where deuterium excess is also used as a marker of rapid climatic changes .…”

Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

“…The present-day conditions at these three dry and particularly cold sites depict differences in the distance to open ocean, elevation (within 577 m), albedo (within 3 %), wind speed (a factor of two), accumulation (within 15 %) and mean annual temperature (within 2.5 • C) ( Table 1). MIS 5 is characterized by large precession parameter variations, together with large glacial-interglacial changes in Antarctic temperature, and is featured with warmer-than-present reconstructed interglacial temperatures (Sime et al, 2009;Stenni et al, 2010;Masson-Delmotte et al, 2011;Uemura et al, 2012). Figure 3 displays the δO 2 /N 2 records from Dome F (transferred on AICC2012 using volcanic matching (Appendix B), Fujita et al, 2015;Kawamura et al, 2007), EDC and Vostok (both on their respective AICC2012 chronologies, Veres et al, 2013;Bazin et al, 2013) from 100 to 150 ka.…”