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This data set contains replicate measurements of D17O from a 92-m deep section of core at Summit, Greenland and other operational data necessary to reconstruct figures presented in Davidge et al., 2022. Details of the entire dataset and a description of the relevant methods can be found in Davidge et al., 2022. The names of each sheet indicate the corresponding figure numbers. The D17O record spans about two years of accumulation. Discrete measurements by laser spectroscopy are provided at 1.4-cm resolution. For the purpose of method development, continuous-flow measurements are provided with nine replicates and are averaged to multiple depth resolutions as described in Davidge et al., 2022. 

Hercules Dome, Antarctica, has long been identified as a prospective deep ice core site due to the undisturbed internal layering, climatic setting and potential to obtain proxy records from the Last Interglacial (LIG) period when the West Antarctic ice sheet may have collapsed. We performed a geophysical survey using multiple ice-penetrating radar systems to identify potential locations for a deep ice core at Hercules Dome. The surface topography, as revealed with recent satellite observations, is more complex than previously recognized. The most prominent dome, which we term ‘West Dome’, is the most promising region for a deep ice core for the following reasons: (1) bed-conformal radar reflections indicate minimal layer disturbance and extend to within tens of meters of the ice bottom; (2) the bed is likely frozen, as evidenced by both the shape of the measured vertical ice velocity profiles beneath the divide and modeled ice temperature using three remotely sensed estimates of geothermal flux and (3) models of layer thinning have 132 ka old ice at 45–90 m above the bed with an annual layer thickness of ~1 mm, satisfying the resolution and preservation needed for detailed analysis of the LIG period.