A new 21.3m firn core was drilled in 2015 at a coastal Antarctic high accumulation site in Adélie Land (66.78°S; 139.56°E, 602ma.s.l.). The core was dated by annual layers counting based on non-sea-salt sulfate and methanesulfonate summer peaks, refined by a comparison between the reconstructed surface mass balance (hereafter, SMB) and the closest available stake data. The mean reconstructed SMB of 75.2 ± 15.0cmw.e. y−1 is consistent with local stake data, and remarkably high for coastal East Antarctica. The resulting inter-annual and sub-annual variations in isotopic records (δ18O and deuterium excess, hereafter d-excess) are explored for 1998–2014 and are systematically compared with a couple of climatic time series: an updated database of Antarctic surface snow isotopic composition, SMB stake data, meteorological observations from Dumont d'Urville station, sea-ice concentration based on passive microwave satellite data, precipitation outputs of atmospheric reanalyses, climate and water stable isotope outputs from the atmospheric general circulation model ECHAM5-wiso, as well as air mass origins diagnosed using 5-days back-trajectories.The mean isotopic values (−19.3 ± 3.1‰ for δ18O and 5.4 ± 2.2‰ for d-excess) are consistent with other coastal Antarctic values. No significant isotope-temperature relationship can be evidenced at any timescale, ruling out a simple interpretation of in terms of local temperature. An observed asymmetry in the δ18O seasonal cycle may be explained by the precipitation of air masses coming from Indian and Pacific/West Antarctic Ice Sheet sectors in autumn and winter times, recorded in the d-excess signal showing outstanding values in austral spring versus autumn. Significant positive trends are observed in the annual d-excess record and local sea-ice extent (135°E–145°E) over the period 1998–2014.However, processes studies focusing on resulting isotopic compositions and particularly the d-excess-δ18O relationship, evidenced as a potential fingerprint of moisture origins, as well as the collection of more isotopic measurements in Adélie Land are needed for an accurate interpretation of our signals.

The TA192A core is a 21.3 m firn core drilled in 2015 at a coastal Antarctic high accumulation site in Adélie Land (66.78 °S; 139.56 °E, 602 m a.s.l.). Chemical elements, i.e. sulfate and methane sulfonic acid , as well as water stable isotope (δ18O and deutérium excess) were analysed at a 4 cm snow equivalent resolution. Non-sea-salt summer and winter sulfate were computed based on Jourdain et Legrand (2002). Records are given in function of firn core depth (in cm w.e.), and time.

Supplement to: Goursaud, Sentia; Masson-Delmotte, Valerie; Favier, Vincent; Preunkert, Suzanne; Legrand, Michel; Minster, Bénédicte; Werner, Martin (2019): Challenges associated with the climatic interpretation of water stable isotope records from a highly resolved firn core from Adélie Land, coastal Antarctica. The Cryosphere, 13(4), 1297-1324