Abstract: Behaviour 2013 (Newcastle Gateshead, UK) 4-8 August 2013

Abstract: The recovery of a 1.5 million yr long ice core from Antarctica represents a keystone of our understanding of Quaternary climate, the progression of glaciation over this time period and the role of greenhouse gas cycles in this progression. Here we tackle the question of where such ice may still be found in the Antarctic ice sheet. We can show that such old ice is most likely to exist in the plateau area of the East Antarctic ice sheet (EAIS) without stratigraphic disturbance and should be able to be recovered after careful pre-site selection studies. Based on a simple ice and heat flow model and glaciological observations, we conclude that positions in the vicinity of major domes and saddle position on the East Antarctic Plateau will most likely have such old ice in store and represent the best study areas for dedicated reconnaissance studies in the near future. In contrast to previous ice core drill site selections, however, we strongly suggest significantly reduced ice thickness to avoid bottom melting. For example for the geothermal heat flux and accumulation conditions at Dome C, an ice thickness lower than but close to about 2500 m would be required to find 1.5 Myr old ice (i.e., more than 700 m less than at the current EPICA Dome C drill site). Within this constraint, the resolution of an Oldest-Ice record and the distance of such old ice to the bedrock should be maximized to avoid ice flow disturbances for example, by finding locations with minimum geothermal heat flux. As the geothermal heat flux is largely unknown for the EAIS, this parameter has to be carefully determined beforehand. In addition, detailed bedrock topography and ice flow history has to be reconstructed for candidates of an Oldest-Ice ice coring site. Finally, we argue strongly for rapid access drilling before any full, deep ice coring activity commences to bring datable samples to the surface and to allow an age check of the oldest ice.

Abstract: In this paper are described measurements at high-altitude of both radiation environment and effects. These measurements comprise cosmic ray neutrons and SBU/MCU on nanoscales devices. Results obtained at Pic-du-Midi, France, and in the city of Puno, Peru, are presented and analyzed. Analyses and cross comparisons based-on MUSCA SEP3 calculations show a good agreement between experimental data and modeling, thus illustrating the importance of the knowledge of the radiation field for a reliable prediction.

Abstract: The ice streams of the George V Coast drain from the large Wilkes Subglacial Basin behind East Antarctica's Transantarctic Mountains, into fragmentary ice shelves exposed to the Southern Ocean. As part of NASA's Operation Ice Bridge, the ICECAP program has been conducting integrated aerogeophysical observations over these glaciers, targeting Mertz Glacier, Ninnis Glacier and the glaciers feeding Cook Ice Shelf, using the resources of the French Polar Institute. Our instrument suite included multifrequency radar, gravimetry, magnetics and the ALAMO (Airborne Laser Altimetry with Mapping Optics) hybrid laser/lidar altimeter system. A primary objective of these observations is to extend and improved the 2003-2009 surface elevation record of GLAS (Geoscience Laser Altimeter System) instrument onboard NASA's ICESat satellite. We can improve on the GLAS only record as small pointing errors in GLAS lead to measurements that deviate from the nominal track by several hundred meters. In areas of high slope, this confounds elevation change due to surface slope with the dH/dt signal. With accurate surface slopes, the impacts of these two effects can be separated. This is particularly important in the coastal ice streams, which have both rapidly changing elevations and high surface slopes. Here we report on a combined ALAMO-GLAS slope corrected surface elevation record for Cook Ice Shelf, and find clear evidence for ice surface lowering over the deep trench that defines fast ice flow in this ice catchment.