Variation of accumulation rates over the last eight centuries on the East Antarctic Plateau derived from volcanic signals in ice cores

Abstract

[1] Volcanic signatures in ice-core records provide an excellent means to date the cores and obtain information about accumulation rates. From several ice cores it is thus possible to extract a spatio-temporal accumulation pattern. We show records of electrical conductivity and sulfur from 13 firn cores from the Norwegian-USA scientific traverse during the International Polar Year 2007-2009 (IPY) through East Antarctica. Major volcanic eruptions are identified and used to assess century-scale accumulation changes. The largest changes seem to occur in the most recent decades with accumulation over the period 1963-2007/08 being up to 25% different from the long-term record. There is no clear overall trend, some sites show an increase in accumulation over the period 1963 to present while others show a decrease. Almost all of the sites above 3200 m above sea level (asl) suggest a decrease. These sites also show a significantly lower accumulation value than large-scale assessments both for the period 1963 to present and for the long-term mean at the respective drill sites. The spatial accumulation distribution is influenced mainly by elevation and distance to the ocean (continentality), as expected. Groundpenetrating radar data around the drill sites show a spatial variability within 10-20% over several tens of kilometers, indicating that our drill sites are well representative for the area around them. Our results are important for large-scale assessments of Antarctic mass balance and model validation.

Regional Antarctic snow accumulation over the past 1000 years

“…This is parallel to an increase in temperature (derived from stable isotopes) and thus most likely caused thermodynamically (Altnau et al, 2015). Anschütz et al (2009Anschütz et al ( , 2011 found no clear overall trend in SMB based on data from a traverse from coastal DML to the South Pole, with an increase at some sites and a decrease at others. However, above 3200 m, all sites exhibited a decrease in SMB since 1963. report that SMB data from a traverse between Dome Fuji and EPICA DML is strongly influenced by topography and is found to be approximately 15 % higher in the second half of the 20th century than averages over centennial or millennial averages.…”

Spatial and temporal variability of snow accumulation rate on the East Antarctic ice divide between Dome Fuji and EPICA DML

“…An example of such efforts is the Norwegian-USA traverse (IPY) through East Antarctica. The traverse has provided new data sets for the SMB based on ground-based accumulation measurements through large parts of DML to the South Pole (Anschütz et al, 2009(Anschütz et al, , 2011Müller et al, 2010).…”

“…In addition, Isaksson et al (1999) found that a general increase in accumulation rate, particularly in the latter part of the 20th century, was not necessarily the case for the whole polar plateau of DML. More recently, Anschütz et al (2011) presented results from the Norwegian-USA scientific traverse. They reported that the largest changes seem to have occurred in the most recent decades with accumulation rates over the period 1963-2007/08 being up to 25 % different from the long-term record.…”

“…The black thick trace is also a part of the JASE traverse. The green dotted trace is the route of the Norwegian-USA traverse in the same 2007/2008 season (Anschütz et al, 2011). Site names related to it are indicated with green letters.…”

“…3b, 4b and 9c. The surface slope is known to strongly influence the spatial distribution of the accumulation rate at various locations on the polar plateau (e.g., the Syowa-South Pole traverse - Endo and Fujiwara, 1973, the Dome FujiSyowa route -Fujita et al, 2002b;Furukawa et al, 1996, the DML-South Pole traverse - Anschütz et al, 2009Anschütz et al, , 2011Müller et al, 2010and near Dome C and Talos Dome -Frezzotti et al, 2005 because the combination of the prevailing wind, the steepness of the slope and the local surface topography determines the depositional environment.…”