The ice-free topography of Svalbard

We present a first version of the Svalbard ice-free topography (SVIFT1.0) using a mass-conserving approach for mapping glacier ice thickness. SVIFT1.0 is informed by more than 900’000 point-measurements of glacier thickness, totalling almost 8’300 km of thickness profiles. It is publicly available for download. Our estimate for the total ice volume is 6’253km3, equivalent to 1.6cm sea-level rise. The thickness map suggests that 13% of the glacierised area is grounded below sea-level. Thickness values are provided together with a map of error estimates that comprise uncertainties in the thickness surveys as well as in other input variables. Aggregated error estimates are used to define a likely ice-volume range of 5’200-7’400km3. The ice-front thickness of marine-terminating glaciers is a key quantity for ice-loss attribution because it controls the potential ice discharge by iceberg calving into the ocean. We find a mean ice-front thickness of 133m for the archipelago

Couplage d'un spectromètre de masse quadripolaire à un calculateur numérique en temps réel : application à l'étude des processus chimiques

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A new Holocene ice core record from Academy of Sciences ice cap, Severnaya Zemlya?

The possibility of using ice cores for past climatic reconstructions is weil known from Greenland and Antarctica. In the Eurasian Arctic, the archipelago of Severnaya Zemlya is the most eastern one which is covered by a considerable ice cap, giving the opportunity to study regional climate signals from at least the whole Holocene period. The Academy of Sciences Ice Cap (Komsomolets Island) was chosen for a new deep ice core drilling because it is the thickest and coldest ice cap on Severnaya Zemlya. Drilling started in May 1999 within a joint project of the Alfred Wegener Institute (Germany), the Arctic and Antarctic Research Institute, and the Mining Institute (Russia, St. Petersburg both). The device used was the KEMS-112 electromechanical ice core drill, the same type used at Vostok Station, Antarctica. A suitable drilling site was found by airborne radio-echo sounding data and SAR interferometry (ice thickness 720 m). In the 1999 season, the drilling reached a depth of 54 m. The poster presents first results from the study of this main core supplemented by invesrigations of snow pits and shallow cores. Visual stratigraphy, d180 profiles and glaciochemical parameters show the glacier's peculiarity that results from summer melting processes. Sharp signals obtained in snow of the last winter layer were smoothed in deeper layers by infiltrating water. Therefore stratigraphical observations are more difficult than those in glaciers without melting processes, but first isotope data indicate seasonal signals at least in layers with not much infiltration ice. The amount of summer melting ice, detectable by optical stratigraphical studies or density measurements. is an indication for the mean summer temperature. The correlation of summer melting ice with meteorological data will be discussed. Data from dielectric profiling (DEP) of the 54-m main core show considerable peaks in conductivity, which were interpreted as volcano events. Following the resulting chronology, the drilled core represents the last 200 years, with a mean accumulation rate of around 220 mm w.e.a-1. This value is in good accordance with older Russian data from the ice cap investigated. The deep ice-drilling project on Severnaya Zemlya will be continued in 2000

Création de valeur durable dans un contexte de parties prenantes multiples : le cas de la préservation d’un site historique et naturel

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