Polar Plateau Research Articles

Opportunities for Terahertz Facilities on the High Plateau

AbstractWhile the summit of the Antarctic Plateau has long been expected to harbor the best ground-based sites for terahertz (THz) frequency astronomical investigations, it is only recently that direct observations of exceptional THz atmospheric transmission and stability have been obtained. These observations, in combination with recent technological advancements in astronomical instrumentation and autonomous field platforms, make the recognition and realization of terahertz observatories on the high plateau feasible and timely. Here, we will explore the context of terahertz astronomy in the era of Herschel, and the crucial role that observatories on the Antarctic Plateau can play. We explore the important scientific questions to which observations from this unique environment may be most productively applied. We examine the importance and complementarity of Antarctic THz astronomy in the light of contemporary facilities such as ALMA, CCAT, SOFIA and (U)LDB ballooning. Finally, building from the roots of THz facilities in Antarctica to present efforts, we broadly highlight future facilities that will exploit the unique advantages of the Polar Plateau and provide a meaningful, lasting astrophysical legacy.

Characterization of Passive Film Formed on AISI 316L Stainless Steel after Magnetoelectropolishing in a Broad Range of Polarization Parameters

AbstractThe aim of the paper is to present the changes in the surface film composition on AISI 316L stainless steel (SS) after electropolishing (EP) and magnetoelectropolishing (MEP) in a broad range of the process conditions. The X‐ray photoelectron spectroscopy surface analyses were performed to reveal the effect of MEP. The EP process has been performed under natural convection (in a stagnant electrolyte), much above the polarization plateau. A series of experiments were carried out on AISI 316L SS samples in accordance with the five‐level composite rotary statistical plan with the variables being the magnetic field intensity B (mT), and the anodic current density i (A dm−2). XP high resolution spectra have been obtained on AISI 316L SS surface concerning Fe 2p, Cr 2p, O 1s, S 2p, P 2p, and C 1s, respectively. The Cr:Fe ratio regarding both metallic M and compound X was also studied and calculated. At the end, the summary results of Cr/Fe = f(B, i) in relation to the corrosion potential, have been compared. The conclusions, concerning the selection of MEP process conditions, regarding the optimum Cr/Fe ratio and corrosion behavior, have been formulated. It was found the Cr:Fe ratio well correlates with the pitting corrosion potential. MEP process can modify not only the rate of dissolution to a determined extent, but also control the corrosion behavior and Cr:Fe ratio results.

History of plains resurfacing in the Scandia region of Mars

We present a preliminary photogeologic map of the Scandia region of Mars with the objective of reconstructing its resurfacing history. The Scandia region includes the lower section of the regional lowland slope of Vastitas Borealis extending about 500–1800 km away from Alba Mons into the Scandia sub-basin below −4800 m elevation. Twenty mapped geologic units express the diverse stratigraphy of the region. We particularly focus on the materials making up the Vastitas Borealis plains and its Scandia sub-region, where erosional processes have obscured stratigraphic relations and made the reconstruction of the resurfacing history particularly challenging. Geologic mapping implicates the deposition, erosion, and deformation/degradation of geologic units predominantly during Late Hesperian and Early Amazonian time (∼3.6–3.3 Ga). During this time, Alba Mons was active, outflow channels were debouching sediments into the northern plains, and basal ice layers of the north polar plateau were accumulating. We identify zones of regional tectonic contraction and extension as well as gradation and mantling. Depressions and scarps within these zones indicate collapse and gradation of Scandia outcrops and surfaces at scales of meters to hundreds of meters. We find that Scandia Tholi display concentric ridges, rugged peaks, irregular depressions, and moats that suggest uplift and tilting of layered plains material by diapirs and extrusion, erosion, and deflation of viscous, sedimentary slurries as previously suggested. These appear to be long-lived features that both pre-date and post-date impact craters. Mesa-forming features may have similar origins and occur along the southern margin of the Scandia region, including near the Phoenix Mars Lander site. Distinctive lobate materials associated with local impact craters suggest impact-induced mobilization of surface materials. We suggest that the formation of the Scandia region features potentially resulted from crustal heating related to Alba Mons volcanism, which acted upon a sequence of lavas, outflow channel sediments, and polar ice deposits centered within the Scandia region. These volatile-enriched sediments may have been in a state of partial volatile melt, resulting in the mobilization of deeply buried ancient materials and their ascent and emergence as sediment and mud breccia diapirs to form tholi features. Similar subsurface instabilities proximal to Alba Mons may have led to surface disruption, as suggested by local and regional scarps, mesas, moats, and knob fields.

An extreme precipitation event in Dronning Maud Land, Antarctica: a case study with the Antarctic Mesoscale Prediction System

An extreme precipitation event that influenced almost the whole polar plateau of Dronning Maud Land, Antarctica, is investigated using Antarctic Mesoscale Prediction System archive data. For the first time a high-resolution atmospheric model especially adapted for polar regions was used for such a study in Dronning Maud Land. The outstanding event of 21–25 February 2003 was connected to a strong north-westerly flow, caused by a blocking high above eastern Dronning Maud Land, that persisted for several days and brought unusually large levels of moisture to the Antarctic Plateau. This weather situation is most effective in bringing precipitation to high-altitude interior Antarctic ice-core drilling sites, where precipitation in the form of diamond dust usually dominates. However, a few such precipitation events per year can account for a large percentage of the annual accumulation, which can cause a strong bias in ice-core data. Additionally, increased temperatures and wind speeds during these events need to be taken into account for the correct climatic interpretation of ice cores. A better understanding of the frequency of occurrence of intermittent precipitation in the interior of Antarctica in past and future climates is necessary for both palaeoclimatological studies and estimates of future sea-level change.

Foehn Winds in the McMurdo Dry Valleys, Antarctica: The Origin of Extreme Warming Events*

Abstract Foehn winds resulting from topographic modification of airflow in the lee of mountain barriers are frequently experienced in the McMurdo Dry Valleys (MDVs) of Antarctica. Strong foehn winds in the MDVs cause dramatic warming at onset and have significant effects on landscape forming processes; however, no detailed scientific investigation of foehn in the MDVs has been conducted. As a result, they are often misinterpreted as adiabatically warmed katabatic winds draining from the polar plateau. Herein observations from surface weather stations and numerical model output from the Antarctic Mesoscale Prediction System (AMPS) during foehn events in the MDVs are presented. Results show that foehn winds in the MDVs are caused by topographic modification of south-southwesterly airflow, which is channeled into the valleys from higher levels. Modeling of a winter foehn event identifies mountain wave activity similar to that associated with midlatitude foehn winds. These events are found to be caused by strong pressure gradients over the mountain ranges of the MDVs related to synoptic-scale cyclones positioned off the coast of Marie Byrd Land. Analysis of meteorological records for 2006 and 2007 finds an increase of 10% in the frequency of foehn events in 2007 compared to 2006, which corresponds to stronger pressure gradients in the Ross Sea region. It is postulated that the intra- and interannual frequency and intensity of foehn events in the MDVs may therefore vary in response to the position and frequency of cyclones in the Ross Sea region.

Short Note: Liquid water formation around rocks and meteorites on Antarctic Polar Plateau ice

Short Note: Liquid water formation around rocks and meteorites on Antarctic Polar Plateau ice

Norway and the ‘winning’ of Australian Antarctica

ABSTRACTEnquiries by Norwegian whalers precipitated the British annexation of the Falkland Island Dependencies and the Ross Dependency. Seeking territory free of British control, Lars Christensen's Norwegian whalers claimed Bouvet Island, which the British believed was theirs. Realisation of the economic value of whaling led Leopold Amery, of the British colonial office to develop Britain's Antarctic domination policy. In pursuit of this policy, the 1926 Imperial Conference formulated a process to claim a sector of Antarctica for Australia. A.G. Price's The Winning of Australian Antarctica describes the role of the Mawson led BANZARE in this process. To gain title to Bouvet Island, the Norwegian Government, dependant on friendly relations with Britain, agreed not to claim territory listed by the Imperial Conference as of ‘special interest’ to Britain. Claims made by whalers who had mapped and named territory in the unlisted area between Kemp and Queen Mary Lands were rejected by the Norwegian prime minister. Following the 1933 Order in Council establishing the Australian Antarctic Territory, Norway raised concerns that the territory included Haakon VII Vidde (polar plateau) and the parts of Dronning (Queen) Maud Land that had been mapped and discovered by Norwegians. Price's contention that Australian Antarctica was ‘won’ is questionable.

Temporal and spatial variation in active layer depth in the McMurdo Sound Region, Antarctica

A soil climate monitoring network, consisting of seven automated weather stations, was established between 1999 and 2003, ranging from Minna Bluff to Granite Harbour and from near sea level to about 1700 m on the edge of the polar plateau. Active layer depth was calculated for each site for eight successive summers from 1999/2000 to 2006/2007. The active layer depth varied from year to year and was deepest in the warm summer of 2001-02 at all recording sites. No trends of overall increase or decrease in active layer depth were evident across the up-to-eight years of data investigated. Average active layer depth decreased with increasing latitude from Granite Harbour (778S, active layer depth of . 90 cm) to Minna Bluff (78.58S, active layer depth of 22 ± 0.4 cm), and decreased with increasing altitude from Marble Point (50 m altitude, active layer depth of 49 ± 9 cm) through to Mount Fleming (1700 m altitude, active layer depth of 6 ± 2 cm). When all data from the sites were grouped together and used to predict active layer depth the mean summer air temperature, mean winter air temperature, total summer solar radiation and mean summer wind speed explained 73% of the variation (R 2 5 0.73). Received 9 December 2008, accepted 8 June 2009

Polarization plateau in an atomic Fermi gas loaded on a three-leg triangular optical lattice

In order to demonstrate that atomic Fermi gas is a good experimental reality in studying unsolved problems in frustrated interacting-spin systems, we numerically examine the Mott core state emerged by loading two-component atomic Fermi gases on triangular optical lattices. Consequently, we find that plateau like structures are observable in the Mott core polarization as a function of the population imbalance. These plateau states are caused by a flexibility that the surrounding metallic region absorbs the excess imbalance to keep the plateau states inside the Mott core. We also find spin patterns peculiar to the plateau states inside the Mott core.

Snow recurrence sets the depth of dry permafrost at high elevations in the McMurdo Dry Valleys of Antarctica

AbstractDry permafrost on Earth is unique to the Antarctic and is found in the upper elevations of the McMurdo Dry Valleys. Despite its widespread presence in the Dry Valleys, the factors that control the distribution of dry permafrost and the ice-cemented ground below it are poorly understood. Here I show, by a combination of theoretical analysis and field observations, that the recurrence of snow can explain the depth of dry permafrost and the location of ice-cemented ground in Antarctica. For data from Linnaeus Terrace at 1600–1650 m elevation in Upper Wright Valley a recurrence intervals of about two years explains the presence of ground ice at 25 cm depth, under 12.5 cm of dry permafrost. Snow recurrence periods longer than 10 years would create only dry permafrost at this site. The snow gradient in University Valley resulting from the windblown snow from the polar plateau creates a corresponding gradient in the depth to ice-cemented ground. On the floor of Beacon Valley, the presence of dry permafrost without underlying ice-cemented ground indicates snow recurrence intervals of more than 10 years and implies that the ancient massive ice in this valley is not stable. Snow recurrence may also set the depth to ground ice on Mars.

North polar region of Mars: Advances in stratigraphy, structure, and erosional modification

We have remapped the geology of the north polar plateau on Mars, Planum Boreum, and the surrounding plains of Vastitas Borealis using altimetry and image data along with thematic maps resulting from observations made by the Mars Global Surveyor, Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter spacecraft. New and revised geographic and geologic terminologies assist with effectively discussing the various features of this region. We identify 7 geologic units making up Planum Boreum and at least 3 for the circumpolar plains, which collectively span the entire Amazonian Period. The Planum Boreum units resolve at least 6 distinct depositional and 5 erosional episodes. The first major stage of activity includes the Early Amazonian (∼3 to 1 Ga) deposition (and subsequent erosion) of the thick (locally exceeding 1000 m) and evenly-layered Rupes Tenuis unit (A brt), which ultimately formed approximately half of the base of Planum Boreum. As previously suggested, this unit may be sourced by materials derived from the nearby Scandia region, and we interpret that it may correlate with the deposits that regionally underlie pedestal craters in the surrounding lowland plains. The second major episode of activity during the Middle to Late Amazonian ( ∼ < 1 Ga) began with a section of dark, sand-rich and light-toned ice-rich irregularly-bedded sequences (Planum Boreum cavi unit, A bb c) along with deposition of evenly-bedded light-toned ice- and moderate-toned dust-rich layers (Planum Boreum 1 unit, A bb 1). These units have transgressive and gradational stratigraphic relationships. Materials in Olympia Planum underlying the dunes of Olympia Undae are interpreted to consist mostly of the Planum Boreum cavi unit (A bb c). Planum Boreum materials were then deeply eroded to form spiral troughs, Chasma Boreale, and marginal scarps that define the major aspects of the polar plateau's current regional topography. Locally- to regionally-extensive (though vertically minor) episodes of deposition of evenly-bedded, light- and dark-toned layered materials and subsequent erosion of these materials persisted throughout the Late Amazonian. Sand saltation, including dune migration, is likely to account for much of the erosion of Planum Boreum, particularly at its margin, alluding to the lengthy sedimentological history of the circum-polar dune fields. Such erosion has been controlled largely by topographic effects on wind patterns and the variable resistance to erosion of materials (fresh and altered) and physiographic features. Some present-day dune fields may be hundreds of kilometers removed from possible sources along the margins of Planum Boreum, and dark materials, comprised of sand sheets, extend even farther downwind. These deposits also attest to the lengthy period of erosion following emplacement of the Planum Boreum 1 unit. We find no evidence for extensive glacial flow, topographic relaxation, or basal melting of Planum Boreum materials. However, minor development of normal faults and wrinkle ridges may suggest differential compaction of materials across buried scarps. Timing relations are poorly-defined mostly because resurfacing and other uncertainties prohibit precise determinations of surface impact crater densities. The majority of the stratigraphic record may predate the recent (<20 Ma) part of the orbitally-driven climate record that can be reliably calculated. Given the strong stratigraphic but loose temporal constraints of the north polar geologic record, a comparison of north and south polar stratigraphy permits a speculative scenario in which major Amazonian depositional and erosional episodes driven by global climate activity is plausible.

Recent aeolian erosion and deposition in the north polar plateau of Mars

Background: Planum Boreum, the north polar plateau of Mars, displays four extensive low-albedo regions covered with widespread sedimentary deposits that are thick enough to partly or completely suppress the signature of the residual water ice that forms the uppermost zone of the polar layered deposits. These sedimentary deposits appear to have a source primarily in a buried sedimentary layer preferentially exposed along the walls and floors of some polar troughs. The deposits extend and drape over circum-polar dunes. Method: The data analyses in this research were conducted with Geographic Information Systems (GIS) mapping tools. The following data sets have been used: (1) Mars Odyssey (MO) Thermal Emission Imaging System (THEMIS) summer north polar visible light mosaics at 18 m/pixel and 32 m /pixel, as well as 18 m/pixel visible multiband images (THEMIS mosaic provided by P.H. Christensen and the THEMIS Team, Arizona State U.), (2) Mars Express (MEX) High Resolution Stereo Camera (HRSC) images at 10 m/pixel, (3) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow-angle (NA; >1.4 m/pixel) and a wide-angle image mosaic, 64 pixels/degree, (4) Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera images at resolutions that range from 31.8 cm/pixel (with 1 x 1 binning) to 63.5 cm/pixel (with 2 x 2 binning), (5) MGS Mars Orbiter Laser Altimeter (MOLA) 512 pixels/degree digital elevation models, and (6) MEX OMEGA Vis/IR imaging spectrometer. False color maps have been derived from OMEGA data in which all three color planes are proportional to albedo (0.1: level 0, 0.45: level 255). The red plane scales inversely with the fraction of the area covered by ice, derived from the band strength at 1.5 μm (factor of 0 for 30% fractional ice coverage within the pixel, factor of 1 for ice-free pixels). The H2O ice spectral signatures have been observed by OMEGA in November 2004, during early northern summer (Ls 109° to 114°). The incidence at the time of observations was nearly optimal for such latitude regions (57.6°). Sampling on the ground was 1.7 to 2 km. Conclusion: The most recent history of the north polar plateau of Mars includes highly dynamic sedimentary processes involving large-scale wind-driven mass transfer from Planum Boreum towards its periphery. The proposed polar processes involved: (I) retreat along undulations within upper layered deposits (ULD), thereby exposing underlying dark sedimentary deposits, (II) mobilization of these deposits to form extensive dark mantles, which are water-ice free and that terminate in circum-polar terrains, and (III) complete removal of these deposits leading to the exhumation of pre-existing

Dating late Cenozoic erosional surfaces in Victoria Land, Antarctica, with cosmogenic neon in pyroxenes

AbstractWe present21Ne exposure ages of erosional glaciogenic rock surfaces on nunataks in northern Victoria Land, Antarctica: i) in the Prince Albert Mountains and ii) near Mesa Range. These nunataks are located directly at the margin of the polar plateau and therefore provide an immediate record of ice volume changes of the East Antarctic Ice Sheet, not biased by ice shelf grounding or narrow valley sections downstream the outlet glaciers. The sampling locations overlook the present ice surface by less than 200 m, but were last covered by ice 3.5 Mabp(minimum age, not corrected for erosion). This strongly indicates that the ice sheet has not been substantially thicker than today since at least the early Pliocene, which supports the hypothesis of a stable East Antarctic Ice Sheet. First absolute ages are reported for the alpine topography above the erosive trimline that typically marks the upper limit of glacial activity in northern Victoria Land. Unexpectedly low nuclide concentrations suggest that erosion rates on the alpine topography are considerably higher due to the steep slopes than those affecting flat erosional surfaces carrying Antarctic tors.

Functional diversity of soils along environmental gradients in the Ross Sea region, Antarctica

The University of Wisconsin Antarctic Soils database was used to examine soils at four sites along a latitudinal gradient that included Rennick Glacier (72°S), Taylor Valley (77°S), Hatherton Glacier (80°S), and Beardmore Glacier (85°S). The soils, derived from glacial drifts ranging from Holocene to Pliocene in age, were stratified at each site by microclimate into subxerous (coastal), xerous (valley floors and sidewalls), and ultraxerous (edge of polar plateau). Analysis of variance and principal components analysis were used to determine the relative influence of latitude, longitude (soil climate along the valley profile), and time of exposure on soil properties and diversity. Time of exposure is the most important factor influencing functional diversity of soils, including depths of staining, coherence, visible salts, and ghosts; depth of ice-cemented permafrost; maximum color-development equivalence; salt and weathering stages; thickness of the salt pan; salt concentration in the salt-enriched layer, and the profile salt content to 70 cm. Soil climate is important with regards to the amount of available moisture, which generally decreases from the coast inland. Soil climate is important with regards to most of the properties, primarily salt content and depth to ice-cemented permafrost; however, soil climate is interactive with time of exposure as the youngest glacial deposits are often along the coast and the oldest deposits are in ultraxerous, upland-valley cirques. Soil differences within a specific soil climate zone were minimal along the latitudinal gradient except for salt chemistry. The proportion of nitrate in soil–water extracts increased and the proportion of sulfate decreased with an increase in latitude. The results of this study have important implications regarding terrestrial biodiversity and ecosystem functioning.

Accumulation and Erosion of Mars' South Polar Layered Deposits

Mars' polar regions are covered with ice-rich layered deposits that potentially contain a record of climate variations. The sounding radar SHARAD on the Mars Reconnaissance Orbiter mapped detailed subsurface stratigraphy in the Promethei Lingula region of the south polar plateau, Planum Australe. Radar reflections interpreted as layers are correlated across adjacent orbits and are continuous for up to 150 kilometers along spacecraft orbital tracks. The reflectors are often separated into discrete reflector sequences, and strong echoes are seen as deep as 1 kilometer. In some cases, the sequences are dipping with respect to each other, suggesting an interdepositional period of erosion. In Australe Sulci, layers are exhumed, indicating recent erosion.

Filtration d’une solution de billes en polyéthylène à l’aide d’un dispositif de Couette-Taylor : comparaison à la plasmaphérèse

In this study, water solutions containing polyethylen rigid balls were filtered comparatively to bovine blood using a dynamic filtration device equipped with a membrane fixed to a high speed rotating cylinder. Two types of membranes, nylon and it polycarbonate, were tested. The influence of the geometry of the filter and its speed of rotation on filtration flux is studied. Results show that the filtration of rigid balls solution doesn’t obey to same mechanisms that observed in plasmapheresis. The concentration polarization plateau disappears.

Permafrost distribution and active‐layer depths in the McMurdo Dry Valleys, Antarctica

AbstractThe McMurdo Dry Valleys (MDVs) constitute the largest ice‐free area (6700 km2) in Antarctica. Permafrost is ubiquitous in the region and is present as ground ice or buried ice, ice‐cemented permafrost and dry‐frozen permafrost. Using a combined dataset that includes more than 800 shallow (&lt;1.5 m) excavations, we provide a map at a scale of 1:2 million showing the distribution of permafrost in the MDVs. Our data suggest that about 55% of the permafrost is ice cemented, 43% is dry frozen and ground/buried ice comprises at least 2% of the area. Permafrost form is related to climatic zone, age of sediments and local site factors. Ice is present in ice‐cored alpine moraines and coastal tills of Holocene age in hummocky drifts of late Quaternary age (ca. &lt;115 ka); however, it is also present in Miocene‐aged sublimation till in Beacon Valley. Ice‐cemented permafrost is present not only in coastal areas (subxerous climatic zone) and in sediments of late Quaternary age, but also in soils of pre‐Quaternary‐age in ultraxerous regions along the polar plateau. Dry‐frozen permafrost exists along the floors and lower sidewalls of larger ice‐free valleys (xerous climatic zone) in sediments of pre‐late Quaternary age. Dry‐frozen permafrost, which may be unique to Antarctica, appears to form from sublimation of moisture in ice‐cemented permafrost over time. Active‐layer depths are 45 to 70 cm in coastal areas and in the eastern half of Wright and Taylor Valleys, 20 to 45 cm in other ice‐free areas within 60 km of McMurdo Sound, and &lt;20 cm along the polar plateau. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Antarctic polar plateau snow surface conversion of deposited oxidized mercury to gaseous elemental mercury with fractional long-term burial

The role of the vast Antarctic polar plateau in the global mercury cycle was previously relatively unknown. Here, for the first time, mercury concentrations in snow and air, combined with vertical flux measurements at the South Pole (November–December 2003 and November 2005) have provided considerable insight into the cycling of this element through the Antarctic environment. These insights include observations showing atmospheric oxidized mercury depositing to the snow pack, subsequent photoreduction, and emissions of gaseous elemental mercury from the snow pack. Oxidized mercury (e.g., reactive gaseous mercury and fine particulate mercury) showed high concentrations (100–1000 pg m −3) in the near-surface air, with these concentrations strongly correlated with vertical mixing rates and showing rapid surface deposition. This suggests that the troposphere over Antarctica is enhanced in oxidized mercury, with mercury cycling between elemental and oxidized states, and between the atmosphere and snow pack. Based on these limited measurements at South Pole, we estimate that the Antarctic polar plateau could sequester as much as 60 metric tons of Hg annually. These data also suggest that there could be a seasonal cycling of atmospheric mercury oxidation, deposition, and re-emission via photoreduction of 490 metric tons annually. This cycling is restricted to the annual sunlit period and peaks 3–4 weeks after solar maximum. To our knowledge, these provisional values represent the first estimates of the mercury balance and cycling for the extensive Antarctic polar plateau.

Ion exchange membrane modification by weak electrolytes and glycine: reduction and elimination of the concentration polarization plateau in electrodialysis

The problematic polarization plateau in electrodialysis is simply reduced and then eliminated by a weak electrolyte addition, which modifies deeply the membrane behavior: we obtain a new membrane without polarization. This extraordinary result permits also to explain classical problems in electrodialysis, particularly the origin of the overlimiting current in the cation exchange membrane.

Ten years from the Antarctic Sub-millimeter Telescope and Remote Observatory

Beginning with the winter season of 1995 and for the next ten years, the Antarctic Sub-mm Telescope and Remote Observatory (AST/RO, Stark et al. 1997; Stark et al. 2001; &lt;http://www.cfa.harvard.edu/ASTRO/&gt;), a 1.7m diameter, offset Gregorian telescope located at an altitude of 2847m at the Amundsen-Scott South Pole Station collected sub-mm and Terahertz data in the 1.3mm to 200μm wavelength bands. From its location just a few hundred meters away from the geophysical South Pole, AST/RO was the first sub-mm telescope to over-winter on the polar plateau, a location uniquely suited to high quality sub-mm observations due its very low humidity, high atmospheric stability and thin troposphere (Chamberlin et al. 1997).