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. Polar ice core water isotope records are commonly used to infer past changes in Antarctictemperature, motivating an improved understanding and quantification of thetemporal relationship between δ18 O and temperature. This canbe achieved using simulations performed by atmospheric general circulationmodels equipped with water stable isotopes. Here, we evaluate the skills ofthe high-resolution water-isotope-enabled atmospheric general circulationmodel ECHAM5-wiso (the European Centre Hamburg Model) nudged to EuropeanCentre for Medium-Range Weather Forecasts (ECMWF) reanalysis usingsimulations covering the period 1960–2013 over the Antarctic continent. We compare model outputs with field data, first with a focus on regionalclimate variables and second on water stable isotopes, using our updateddataset of water stable isotope measurements from precipitation, snow, andfirn–ice core samples. ECHAM5-wiso simulates a large increase in temperaturefrom 1978 to 1979, possibly caused by a discontinuity in the EuropeanReanalyses (ERA) linked to the assimilation of remote sensing data startingin 1979. Although some model–data mismatches are observed, the (precipitation minusevaporation) outputs are found to be realistic products for surface massbalance. A warm model bias over central East Antarctica and a cold model biasover coastal regions explain first-order δ18 O model biasesby too-strong isotopic depletion on coastal areas and underestimateddepletion inland. At the second order, despite these biases, ECHAM5-wisocorrectly captures the observed spatial patterns of deuterium excess. Theresults of model–data comparisons for the inter-annual δ18 O standard deviation differ when using precipitation or ice core data. Furtherstudies should explore the importance of deposition and post-depositionprocesses affecting ice core signals and not resolved in the model. These results build trust in the use of ECHAM5-wiso outputs to investigatethe spatial, seasonal, and inter-annual δ18 O –temperaturerelationships. We thus make the first Antarctica-wide synthesis of priorresults. First, we show that local spatial or seasonal slopes are not acorrect surrogate for inter-annual temporal slopes, leading to the conclusionthat the same isotope–temperature slope cannot be applied for the climaticinterpretation of Antarctic ice core for all timescales. Finally, we explorethe phasing between the seasonal cycles of deuterium excess and δ18 O as a source of information on changes in moisturesources affecting the δ18 O –temperature relationship. The fewavailable records and ECHAM5-wiso show different phase relationships incoastal, intermediate, and central regions. This work evaluates the use of the ECHAM5-wiso model as a tool for theinvestigation of water stable isotopes in Antarctic precipitation and callsfor extended studies to improve our understanding of such proxies.

climate of the past

Water stable isotope spatio-temporal variability in Antarctica in 1960–2013: observations and simulations from the ECHAM5-wiso atmospheric general circulation model