ALBERT

Description: We report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. core-break force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run.

Description: We report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. core-break force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run.

Description: This data collection contains readings of accumulation stake along the approximately 800 km long traverse route Neumayer-Kottas-Kohnen, Dronning Maud Land, Antarctica. By comparing the readings of an individual stake in two different seasons the amount of surface accumulation (i.e. snow deposition) or erosion (e.g. from sublimation of wind scour) can be determined. Stake readings were conducted approximately every year starting from season 1995/1996 to 2005/2006 as part of the European Project for Ice Coring In Antarctica (EPICA). The readings were carried out by a dedicated two to three person team accompanying the traverse from Neumayer station to Kohnen station. The readings were performed by a simple measurement of the visible length of the stake above the snow surface. For tilted stakes, the vertical height above the surface as well as the length of the stake was measured. New stakes were deployed when less than about 1.5 m of the previous stake was visible or a stake was lost (e.g. from breaking off or falling over and finally get burried in snow). Consequently, at some locations more than one stake is visible for several years (e.g. when the average snow accumulation was rather low). In those cases all visible stakes were recorded at the same location of such a stake cluster and added to the table as Height_1, Height 2, Height 3). Positions were measured with a simple GPS with coarse acquisition accuracy (order of several meters to tens of meters), which is sufficiently accurate to separate different stake locations (usually 500 m apart and horizontal displacement smaller than about 150 m/a, with largest displacements on the Ekström ice shelf). In very few cases, empty lines originate from missing stakes and the required position. In very few cases, a second line with the same coordinate corresponds to the same location with a fourth stake deployed as a new stake. From Neumayer station to Kottas camp stakes were deployed at approximately a 500 m interval. As the spatial variation of accumulation on the polar plateau is smaller than in the lower foreland (in this case the Ritscherflya) the stake distances was increased to 1 km to several kilometers from Kottas camp onto the polar plateau to Kohnen station. Additional field comments made by observing personal were removed from the files. However, original field notes in notebooks are available from AWI's Archive for German Polar Research (Oerter et al., 2013). Although surface accumulation is still one of the major unknowns to determine the the total surface mass balance of the Antarctic ice sheet, especially under climate change, direct long-term observations of surface accumulation are still one of the major gaps in field observations (Eisen et al., 2008). This time series of stake readings provides the basis for calculation the change in accumulation in space and time (e.g. Rotschky et al., 2007). It is thus fundamental for a decade-long record of the spatio-temporal characteristics of surface accumulation, which can be put into context to meteorological and oceanographic changes in the region.

Description: We report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. corebreak force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run.