Isotopic and temperature data from northern Victoria Land ice wedges (East Antarctica)

Ice wedges, with tops located 27 to 55 cm below the ground surface, were studied over several summers between 1998 and 2006 at three sites with differing elevations in northern Victoria Land, East Antarctica. The thermal regime, based on data‐logger measurements over seven years, exhibits very low temperatures. The inferred absence of snow and the high temperature gradients, between the ground surface and the top of ice wedge, may trigger the cracking. A co‐isotopic study of the wedge‐ice oxygen (d18O) and hydrogen (dD) isotopic values shows extremely negative deuterium excess (d=dD‐8*d18O) values with a strong divergence from the expected precipitation. These values suggest that water vapour condensation and sublimation processes play an important role during the formation of these ground‐ice bodies, particularly at high‐elevation sites. Large temperature gradients between the air/ground and permafrost, thin or absent snow cover, low humidity and open cracks during winter ar

Ice wedges, with tops located 27 to 55 cm below the ground surface, were studied over several summers between 1998 and 2006 at three sites with differing elevations in northern Victoria Land, East Antarctica. The thermal regime, based on data‐logger measurements over seven years, exhibits very low temperatures. The inferred absence of snow and the high temperature gradients, between the ground surface and the top of ice wedge, may trigger the cracking. A co‐isotopic study of the wedge‐ice oxygen (d18O) and hydrogen (dD) isotopic values shows extremely negative deuterium excess (d=dD‐8*d18O) values with a strong divergence from the expected precipitation. These values suggest that water vapour condensation and sublimation processes play an important role during the formation of these ground‐ice bodies, particularly at high‐elevation sites. Large temperature gradients between the air/ground and permafrost, thin or absent snow cover, low humidity and open cracks during winter are factors that may control the sublimation processes. In addition, strong katabatic winds acting in the area may enhance sublimation. All these factors explain the less negative ice‐wedge d18O values compared with the precipitation and very negative deuterium excess values found at the sites. Observations of hoarfrost crystals in open fractures, even in summer, and frequent temperature inversions between the air/ground interface and ice‐wedge top support the hypothesis that condensation and sublimation are important processes in ice‐wedge formation. Moreover, sublimated snow may also contribute to the formation process. Only isotopic values found at low‐elevation sites can be explained by both melting‐refreezing and sublimation processes.