Imprints of sea ice, wind patterns, and atmospheric systems on summer water isotope signatures at Hercules Névé, East Antarctica

Abstract. This study investigated the influence of summer climate variability on water isotopes (δ18O, δ2H, and deuterium excess[dexc]) in a Hercules Névé ice core from Antarctica. High-resolution ERA5 reanalysis data for the austral summer (DJF, 1979–2015) were used to assess the relative contributions of temperature, precipitation, wind patterns (v- and u-winds), ocean condition (sea ice concentration [SIC] and sea surface temperature [SST]), and large-scale circulation system (Amundsen Sea Low [ASL] and Zonal Wave-3 [ZW3]) to isotopic variability. The results show that higher temperatures and precipitation coincide with isotopically enriched δ18O, confirming their combined role in controlling isotopic enrichment. Wind patterns also contribute meaningfully but in a more complex way: enhanced southerly winds (positive v-wind anomalies) tend to increase δ18O by transporting relatively warm, moisture-rich air from lower latitudes, whereas stronger westerly winds (positive u-wind anomalies) are associated with more depleted isotopic values, likely reflecting colder or more distant moisture sources. Additionally, the dexc exhibits a positive correlation with SIC and negative correlations with SST, providing valuable insights into moisture source processes in the study region during austral summer. Variations in the ASL and ZW3 further modulate heat and moisture transport, reinforcing their role as key atmospheric drivers of isotopic variability. Taken together, these findings suggest that the summer isotope record at Hercules Névé reflects not only local temperature changes but also the broader imprint of ocean–atmosphere interactions, including sea-ice variability and large-scale circulation patterns. This study highlights the potential of coastal Antarctic ice cores to provide improved constraints on coupled climate processes and to refine paleoclimate reconstructions for the Ross Sea region.