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Antarctic firn presents an exotic seismological environment in which the behaviors of propagating waves can be significantly at odds with those in other Earth media. We present a condensed view of the nascent field of ambient noise seismology in Antarctic firn-covered media, and highlight multiple unusual and information-rich observations framed through the lens of the firn's important role as a buffer for air temperature anomalies and a complex contributor to ice mass balance. We summarize key results from several recent papers depicting novel wind-excited firn resonances and point to the plethora of ways these observations could facilitate imaging and monitoring of glacial systems at single, isolated seismometers. Finally, we propose significant instrumental and computational objectives necessary to constrain resonance excitation mechanisms and broadly apply these observations as useful monitoring tools in Antarctica. [ABSTRACT FROM AUTHOR]

This paper reports geochemical characteristics of mafic gneisses and granulites collected from four localities in central Dronning Maud Land to evaluate the tectonic setting of their precursor rocks. Precursor rocks for the mafic gneisses and granulites in central Dronning Maud Land were formed in different geological backgrounds and tectonic settings. The mafic gneisses and granulites in the Schirmacher Hills were derived from basaltic rocks in a back-arc setting. Published U–Pb zircon ages and the geochemical variation of the basement rocks indicate their emplacement between 800 and 650 Ma, close to peak metamorphism. While similar protoliths were recognized in the inland nunataks of Hochlinfjellet, in Filchnerfjella the mafic gneisses/granulites were derived from basaltic rocks formed in marginal continental arcs or island arcs. Highly disturbed trace-element patterns indicate that the metamorphic process influenced the geochemical composition during the prograde metamorphic stage. Our results imply that the outcrops in central Dronning Maud Land with different metamorphic ages contain mafic gneisses/granulites from precursor rocks formed under different tectonic settings. [ABSTRACT FROM AUTHOR]

Antarctic firn presents an exotic seismological environment in which the behaviors of propagating waves can be significantly at odds with those in other Earth media. We present a condensed view of the nascent field of ambient noise seismology in Antarctic firn-covered media, and highlight multiple unusual and information-rich observations framed through the lens of the firn's important role as a buffer for air temperature anomalies and a complex contributor to ice mass balance. We summarize key results from several recent papers depicting novel wind-excited firn resonances and point to the plethora of ways these observations could facilitate imaging and monitoring of glacial systems at single, isolated seismometers. Finally, we propose significant instrumental and computational objectives necessary to constrain resonance excitation mechanisms and broadly apply these observations as useful monitoring tools in Antarctica. [ABSTRACT FROM AUTHOR]

This paper describes the Antarctic environment, the mission and work setting at the U.S. research stations, the general population and living conditions, and the healthcare situation. It also dispels some common misconceptions that persist about this environment and about the scope and quality of medicine practiced there. The paper then describes specific ethical issues that arise in this environment, incorporating examples drawn from both the author's experiences and those of his colleagues. The ethics of providing healthcare in resource-poor environments implies two related questions. The first is: What can we do with the available resources? This suggests that clinicians must not only know how to use all available equipment and supplies in the standard manner, but also that they must be willing and able to go beyond standard procedures and improvise, when necessary. The second question is: Of all the things we can do, which ones should we do? This paper addresses both questions in relation to Antarctic medical care. It describes the wide range of activities required of healthcare providers and some specific ethical issues that arise. Finally, it suggests some remedies to ameliorate some of those issues. [ABSTRACT FROM AUTHOR]

Antarctica differs from all other regions in the world, not only from its unique geography, but also in the way humans understand it and have incorporated it into global relations. Considering Antarctica's distinctive landscapes and human relations, this paper discusses aspects of how time is humanly perceived in Antarctica. Basing on elements from different human occupations, nineteenth-century sailor-hunters and current incursions, this discussion approximates different historical groups in their experiences of Antarctica, connecting their personal lives, past and present. Meanwhile, also put into issue are the dualities that separate nature and culture, physical and relative time, and past and present, as well as the related notions of time in itself, perceived time speed and internal time consciousness. [ABSTRACT FROM AUTHOR]

Subglacial lake exploration is of great interest to the science community. RECoverable Autonomous Sonde (RECAS) provides an exploration tool to measure and sample subglacial lake environments while the subglacial lake remains isolated from the glacier surface and atmosphere. This paper presents an electronic control system design of 200 m prototype of RECAS. The proposed electronic control system consists of a surface system, a downhole control system, and a power transfer and communication system. The downhole control system is the core element of RECAS, and is responsible for sonde status monitoring, sonde motion control, subglacial water sampling and in situ analysis. A custom RS485 temperature sensor was developed to cater for the limited size and depth requirements of the system. We adopted a humidity-based measurement to monitor for a housing leak. This condition is because standard leak detection monitoring of water conductivity may be inapplicable to pure ice in Antarctica. A water sampler control board was designed to control the samplers and monitor the on/off state. A high-definition camera system with built-in storage and self-heating ability was designed to perform the video recording in the subglacial lake. The proposed electronic control system is proven effective after a series of tests. [ABSTRACT FROM AUTHOR]

Significant upgrades to the Rapid Air Movement (RAM) Drill were developed and tested by the US Ice Drilling Program in 2016 through 2020 for the U.S. National Science Foundation. The design of the system leverages the existing infrastructure of the RAM Drill with the goal of greatly reducing the logistical burden of deploying the drill while maintaining the ability to drill an access hole in firn and ice to 100m in 40 min or less. In this paper, characteristics of the drill are described, along with a description of the drill performance during the testing at Raven Camp in Greenland and at WAIS Divide Camp in Antarctica. [ABSTRACT FROM AUTHOR]

In this paper, we present an electric-thermal drill with a novel design of a melting head that was developed within the EnEx-RANGE project. The design combines a short melting head with a large surface area of parabolic shape. It was succesfully tested in the laboratory as well as on Alpine glaciers (Langenferner and Mittelbergferner) and at the Ross Ice Shelf in Antarctica. In all these different environments, a high melting speed per specific power of typically 8.8 cm3 w-1 h-1 is achieved that is close to the ideal maximum bound of ~10.5-11.8 cm³ w-1 h-1 when neglecting all heat losses. It has also been demonstrated that the melting probe can be operated with typical equipment of small-scale field camps including a small power generator. [ABSTRACT FROM AUTHOR]

Radar surveys across ice sheets typically measure numerous englacial layers that can often be regarded as isochrones. Such layers are valuable for extrapolating age–depth relationships away from ice-core locations, reconstructing palaeoaccumulation variability, and investigating past ice-sheet dynamics. However, the use of englacial layers in Antarctica has been hampered by underdeveloped techniques for characterising layer continuity and geometry over large distances, with techniques developed independently and little opportunity for inter-comparison of results. In this paper, we present a methodology to assess the performance of automated layer-tracking and layer-dip-estimation algorithms through their ability to propagate a correct age–depth model. We use this to assess isochrone-tracking techniques applied to two test case datasets, selected from CreSIS MCoRDS data over Antarctica from a range of environments including low-dip, continuous layers and layers with terminations. We find that dip-estimation techniques are generally successful in tracking englacial dip but break down in the upper and lower regions of the ice sheet. The results of testing two previously published layer-tracking algorithms show that further development is required to attain a good constraint of age–depth relationships away from dated ice cores. We recommend that auto-tracking techniques focus on improved linking of picked stratigraphy across signal disruptions to enable accurate determination of the Antarctic-wide age–depth structure. [ABSTRACT FROM AUTHOR]

The Antarctic Impulsive Transient Antenna (ANITA) balloon experiment was designed to detect radio signals initiated by high-energy neutrinos and cosmic ray (CR) air showers. These signals are typically discriminated by the polarization and phase inversions of the radio signal. The reflected signal from CRs suffer phase inversion compared to a direct 'tau neutrino' event. In this paper, we study subsurface reflection, which can occur without phase inversion, in the context of the two anomalous up-going events reported by ANITA. It is found that subsurface layers and firn density inversions may plausibly account for the events, while ice fabric layers and wind ablation crusts could also play a role. This hypothesis can be tested with radar surveying of the Antarctic region in the vicinity of the anomalous ANITA events. Future experiments should not use phase inversion as a sole criterion to discriminate between down-going and up-going events, unless the subsurface reflection properties are well understood. [ABSTRACT FROM AUTHOR]

A challenge for future deep-ice coring in central Antarctica is to identify an appropriate inert drilling fluid with no undesirable physical or chemical characteristics. The drilling fluids currently in use (kerosene-based fluids with density-increasing additives, ethanol and n-butyl acetate) are not intelligent choices for the future from safety, environmental and some technological standpoints. Recently proposed drilling fluids based upon ESTISOL™ have high viscosity at low temperatures, which severely limits their application in cold environments. This paper presents our research into the application of low-molecular-weight, fatty-acid esters (FAEs), substances commonly used in the fragrance and flavoring industries. According to available data, selected FAEs are not hazardous to human health. Considering density requirements alone, ethyl butyrate and n-propyl propionate best meet our present needs. The viscosities of these two chemicals are also the lowest among studied FAEs, not exceeding 4 mPa s at temperatures down to -60°C. Both compounds are highly volatile, and insoluble in water. Such properties are attractive, but the applicability of FAEs to deep, cold, ice drilling can be evaluated only after field-based, practical experiments in test boreholes. [ABSTRACT FROM AUTHOR]

A new, clean, hot-water drill system (HWDS) was developed by the Science Management Office, University of Nebraska-Lincoln, for use in the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project to gain access to Subglacial Lake Whillans beneath ~800 m of ice in West Antarctica. One primary borehole was drilled into the basal ice environment of Subglacial Lake Whillans during the initial field season in 2012/13. This paper describes the process of designing, fabricating, assembling, shipping, testing, commissioning and traversing the WISSARD HWDS leading up to the first scientific use of the system. [ABSTRACT FROM AUTHOR]