Heidelberg 2015 – wissenschaftliches Programm
UP 9.4: Vortrag
Donnerstag, 26. März 2015, 16:00–16:15, C/gHS
Basal ice-shelf melting in the Weddell Sea inferred from oceanic noble-gas observations — •Oliver Huhn1, Monika Rhein1, and Michael Schröder2 — 1Institute of Environmental Physics, University of Bremen, Germany — 2Alfred-Wegener-Institute, Bremerhaven, Germany
We use oceanic noble-gas observations from the Weddell Sea from the period 1990 to 2013 to infer basal ice-shelf melting and the spatial distribution and temporal variability of the melt water input into the ocean. Helium and neon data were used to compute the glacial melt water contributing to the formation of Antarctic Bottom Water, a substantial water mass in the global ocean and important driver of the Meridional Overturning Circulation.
Oceanic measurement of low-solubility and stable noble-gases helium and neon provide a useful tool to quantify glacial melt water. Atmospheric air with a constant composition of these noble gases is trapped in the ice matrix during formation of the meteoric ice. Due to the enhanced hydrostatic pressure at the base of the floating ice, these gases are completely dissolved, when the ice is melting from below. This leads to an substantial excess of helium and neon in pure glacial melt water.
We find an increasing trend in helium, neon, and, hence, in the glacial melt water content in the deep Weddell Sea. Melt water fractions along a repeated section in the north-western Weddell Sea are almost doubling from 1990 to 2013, indicating increasing melting in the Weddell Sea.