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Abstract: Direct exploration of subglacial lakes buried deep under the Antarctic Ice Sheet has yet to be achieved. However, at retreating margins of the ice sheet, there are a number of locations where former subglacial lakes are emerging from under the ice but remain perennially ice covered. One of these lakes, Hodgson Lake (72°00.549′S, 068°27.708′W) has emerged from under more than 297–465m of glacial ice during the last few thousand years. This paper presents data from a multidisciplinary investigation of the palaeolimnology of this lake through a study of a 3.8m sediment core extracted at a depth of 93.4m below the ice surface. The core was dated using a combination of radiocarbon, optically stimulated luminescence, and relative palaeomagnetic intensity dating incorporated into a chronological model. Stratigraphic analyses included magnetic susceptibility, clast provenance, organic content, carbonate composition, siliceous microfossils, isotope and biogeochemical markers. Based on the chronological model we provisionally assign a well-defined magnetic polarity reversal event at ca 165cm in the lake sediments to the Mono Lake excursion (ca 30–34ka), whilst OSL measurements suggest that material incorporated into the basal sediments might date to 93±9ka. Four stratigraphic zones (A–D) were identified in the sedimentological data. The chronological model suggests that zones A–C were deposited between Marine Isotope Stages 5–2 and zone A during Stage 1, the Holocene. The palaeolimnological record tracks changes in the subglacial depositional environment linked principally to changing glacier dynamics and mass transport and indirectly to climate change. The sediment composition in zones A–C consists of fine-grained sediments together with sands, gravels and small clasts. There is no evidence of overriding glaciers being in contact with the bed reworking the stratigraphy or removing this sediment. This suggests that the lake existed in a subglacial cavity beneath overriding LGM ice. In zone D there is a transition to finer grained sediments characteristic of lower energy delivery coupled with a minor increase in the organic content attributed either to increases in allochthonous organic material being delivered from the deglaciating catchment, a minor increase in within-lake production or to an analytical artefact associated with an increase in the clay fraction. Evidence of biological activity is sparse. Total organic carbon varies from 0.2 to 0.6%, and cannot be unequivocally linked to in situ biological activity as comparisons of δ 13C and C/N values with local reference data suggest that much of it is derived from the incorporation of carbon in catchment soils and gravels and possibly old CO2 in meteoric ice. We use the data from this study to provide guidelines for the study of deep continental subglacial lakes including establishing sediment geochronologies, determining the extent to which subglacial sediments might provide a record of glaciological and environmental change and a brief review of methods to use in the search for life. [Copyright &y& Elsevier]

Abstract: At retreating margins of the Antarctic Ice Sheet, there are a number of locations where former subglacial lakes are emerging from under the ice but remain perennially ice-covered. This paper presents a site description of one of these lakes, Hodgson Lake, situated on southern Alexander Island, west of the Antarctic Peninsula (72° 00.549′ S, 68° 27.708′ W). First, we describe the physical setting of the lake using topographic and geomorphological maps. Second, we determine local ice sheet deglaciation history and the emergence of the lake using cosmogenic isotope dating of glacial erratics cross-referenced to optically stimulated luminescence dating of raised lake shoreline deltas formed during ice recession. Third we describe the physical and chemical limnology including the biological and biogeochemical evidence for life. Results show that the ice mass over Hodgson Lake was at least 295m thick at 13.5ka and has progressively thinned through the Holocene with the lake ice cover reaching an altitude of c. 6.5m above the present lake ice sometime after 4.6ka. Thick perennial ice cover persists over the lake today and the waters have remained isolated from the atmosphere with a chemical composition consistent with subglacial melting of catchment ice. The lake is ultra-oligotrophic with nutrient concentrations within the ranges of those found in the accreted lake ice of subglacial Lake Vostok. Total organic carbon and dissolved organic carbon are present, but at lower concentrations than typically recorded in continental rain. No organisms and no pigments associated with photosynthetic or bacterial activity were detected in the water column using light microscopy and high performance liquid chromatography. Increases in SO4 and cation concentrations at depth and declines in O2 provide some evidence for sulphide oxidation and very minor bacterial demand upon O2 that result in small, perhaps undetectable changes in the carbon biogeochemistry. However, in general the chemical markers of life are inconclusive and abiotic processes such as the diffusion of pore waters into the lake from its benthic sediments are far more likely to be responsible for the increased concentrations of ions at depth. The next phases of this research will be to carry out a palaeolimnological study of the lake sediments to see what they can reveal about the history of the lake in its subglacial state, and a detailed molecular analysis of the lake water and benthos to determine what forms of life are present. Combined, these studies will test some of the methodologies that will be used to explore deep continental subglacial lakes. [Copyright &y& Elsevier]

Flavobacterium sp. AUG42 is a cellulase-producing bacterium isolated from the Antarctic oligochaete Grania sp. (Annelida). In this work, we report that AUG42 produces a glycoside hydrolase cocktail with CMCase, PASCase and cellobiase activities (optimum pHs and temperatures ranging from 5.5 to 6.5 and 40 to 50 °C, respectively). The time-course analyses of the bacterial growth and cellulase production showed that the cocktail has maximal activity at the stationary phase when growing at 16 °C with filter paper as a cellulosic carbon source, among the tested substrates. The analyses of the CAZome and the identification of secreted proteins by shotgun Mass Spectrometry analysis showed that five glycoside hydrolyses are present in the bacterial secretome, which probably cooperate in the degradation of the cellulosic substrates. Two of these glycoside hydrolyses may harbor putative carbohydrate binding modules, both with a cleft-like active site. The cellulolytic cocktail was assayed in saccharification experiments using carboxymethylcellulose as a substrate and results showed the release of glucose (a fermentable sugar) and other reducing-sugars, after 24 h incubation. The ecological relevance of producing cellulases in the Antarctic environment, as well as their potential use in the bio-refinery industry, are discussed. [ABSTRACT FROM AUTHOR]

This paper first gives a brief overview of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)'s struggle to establish Antarctic Marine Protected Areas (MPAs). The paper then addresses the question: what lessons can countries learn from CCAMLR's experience in establishing high seas MPAs under the Biodiversity in Areas Beyond National Jurisdiction (BBNJ) Agreement? The paper finds that the final text of the BBNJ Agreement did largely reflect CCAMLR's experience when it comes to MPAs. This is particularly so with respect to 1) clarification of the relationship between conservation and use; 2) the interpretation and application of a science-based precautionary approach; and 3) consensus-based decision-making process. The paper concludes that the insights CCAMLR provides for navigating geopolitical tensions between major powers is an important reference for the future operation of the BBNJ Agreement. [ABSTRACT FROM AUTHOR]

The Moon has returned into the focus of human endeavors regarding human spaceflight, e.g., with NASA's Artemis program, ESA's Moon Village, and the Russian/Chinese International Lunar Research Station. In difference to the pathfinding missions of the Apollo -era, the goal for these future missions is to stay on the lunar surface for longer durations and inhabit the lunar environment (near-)permanently. This requires a different approach to be affordable, i.e., instead of resupply as mostly used on e.g., the International Space Station, resource management has to include recycling and in-situ utilization. The former especially calls for the application of so-called BLSS to allow providing essential life-support services to the crew without prohibitive resource consumption, which is economically not feasible to achieve with resupplies. Bio-regenerative-life-support systems have been researched for decades, yet the system complexity, technology advancements, and singular aspects as e.g., plant biology require more research, especially if combined as in a greenhouse. For instance, the understanding of how a microbiome develops in a closed environment and what implications the microbiome has on plant growth is still insufficient. Within the EDEN project, the German Aerospace Center built a lunar analogue greenhouse and operated it at the Neumayer-III research station in Antarctica for four years, testing the technology – which was not space hardware – and operations. Derived from this experience the next step in the project is to design and subsequently operate a ground test demonstrator for a lunar greenhouse, as close as possible to the actual space hardware and operations. This paper explains the current design and trade-offs that led to it. Furthermore, the concept of operations is shown to illustrate the demonstrator's utility for researching bioregenerative-life-support. Overall, the system presented is feasible and useful to close the gaps, currently still existing in this field of research, and thus a mission enabler for future long-duration human space exploration missions. • Design of an integrated greenhouse module test demonstrator. • Extensive science program definition. • Mission scenario definition for lunar greenhouse. • Discussion of benefits and open issues. [ABSTRACT FROM AUTHOR]

Satellite operators struggle to communicate with their satellites over Europe in the UHF amateur band (430–440 MHz) due to high power in-orbit interference. Statistical characterisation of the interference beyond average interference levels using in-orbit measurements is useful for the design of suitable countermeasures. Some recent studies have started to investigate both the frequency and time behaviour of the interference, but more measurements are needed to cover the whole UHF amateur band. In this paper, we use the Local Mean Envelope (LME) method to analyse the time and frequency characteristics of in-orbit radio interference from the LUME-1 satellite, measured in the 437 MHz band. Satellite measurements were performed on a TOTEM Software-Defined Radio (SDR), in orbit over Europe and Antarctica and the results were downloaded for analysis on the ground. The average power spectrum and the variability of the LME for different time windows in the 437 MHz band are presented. The data analysis also includes the coefficient of variation of the LME to study the dispersion of the interference. The results are compared to previous measurements in the 435 MHz band using the same method. The new results are found to differ compared with previous measurements on the 435 MHz band. The bandwidth of the band-limited signals measured at 435 MHz was found to be 300 kHz, and at 437 MHz, 200 kHz wide for this dataset. Also, the interference power was found to be higher for 437 MHz. In both cases the interference behaviour is highly non-Gaussian, suggesting that typical communication countermeasures will not be sufficient. Although more measurements are needed for better spatial resolution, our findings may contribute to explaining why satellite operations are difficult on these bands. A better knowledge of the time and frequency variability of the interference can indicate which mitigation techniques are required and are efficient to improve satellite communication in that band. • Average interference power and the spread in envelope was higher in the 437.28 MHz band than in the 435 MHz band. • A 200 kHz band-limited interference signal was detected at 437.28 MHz in contrast with the 300 kHz bandwidth of the signal at 435 MHz. • The interference behaviour is highly non-Gaussian. • Countermeasures assuming Additive White Gaussian Noise (AWGN) will not be realistic in this band. • Interference measured explains challenges experienced by operators of small satellites. [ABSTRACT FROM AUTHOR]

The ISS-CREAM instrument is the modified version of the Cosmic Ray Energetics And Mass (CREAM) experiment, which was flown on balloons multiple times over Antarctica and later installed on the International Space Station (ISS). Its primary objective is to measure the energy spectra of individual cosmic-ray elements for the charge range of Z = 1 to Z = 26, in the energy range of ∼ 1012 to ∼ 1015 eV. The instrument comprises a tungsten/scintillator calorimeter and a pixelated silicon charge detector as primary detectors to determine the energy and charge of cosmic rays. Additionally, it includes top and bottom scintillator counting detectors and a boronated scintillator detector to differentiate between electrons and hadrons for multi-TeV electron measurements. The ISS-CREAM instrument was installed on the ISS in August 2017 and operated until February 2019. This paper provides an overview of the instrument, focusing on its detectors, trigger systems, common electronics, and power systems. The paper highlights the modifications made to these components to optimize their performance for ISS operations. [ABSTRACT FROM AUTHOR]

The spatiotemporal variation characteristics of midlatitude summer nighttime anomaly (MSNA) are essential for ionospheric modeling in the MSNA region. Based on GIM TEC, COSMIC NmF2, COSMIC IEC (Integrate Electron Content), and GPS TEC, this paper analyzes the spatiotemporal variation characteristics of MSNA during the low and middle solar activity period. First, we use the fourth-order Fourier function to fit the TEC, NmF2, and IEC. Second, we calculate an MSNA index and give its spatiotemporal distribution during the low and middle solar activity period. Third, on the basis of GIM TEC and GPS TEC, we describe the spatiotemporal distribution of TEC peak moments from October to January (Oct-Jan) and May to August (May-Aug). Our detailed analysis shows the following: (1) MSNA in the Southern Hemisphere is most significant in Oct-Jan. Moreover, MSNA in the Northern Hemisphere is most significant in May-Aug. (2) MSNA mainly occurs in three regions: South America and Antarctica, Western Europe to eastern North America, and Northeast Asia to the Pacific. (3) When solar activity increases, the MSNA region in the Northern Hemisphere becomes smaller, and the MSNA index is unchanged. Moreover, the MSNA region in the Southern Hemisphere is unchanged, but the MSNA index increases. (4) From Oct-Jan, there are some apparent differences between the east and west sides of the MSNA region of the Antarctic Peninsula. The peak moments of TEC in the west region concentrate before midnight (20:00–22:00 LT), and the peak moments of TEC in the east region concentrate after midnight (00:00–08:00 LT). As the level of solar activity increases, the peak moments in the eastern region are significantly shifted to later local time. (5) As the level of solar activity increases, the incidence of MSNA at three GPS stations (OHI300ATA, YSSK00RUS, and BRST00FRA) shows a decreasing trend. [ABSTRACT FROM AUTHOR]

The Larsemann Hills, near Prydz Bay is a key region to understand past glacial dynamics in East Antarctica. However, multi-proxy dating constraints for this area indicate an uncertain chronology for deglaciation history during the Last Glacial Period (LGP). In this paper, we report two 26Al exposure ages and eighteen 10Be exposure ages for bedrock samples to better understand past glacial histories. The minimum exposure ages range from 82.84 ± 4.67 ka to 15.1 ± 1.95 ka corresponding to Marine Isotope Stages (MIS) 5–2, and fourteen of these samples date from before the global Last Glacial Maximum (c. 19–26.5 ka). Analysis of 10Be and 26Al concentrations implies a complex deglaciation history, and surface lowering of bedrock may have caused systematic age underestimation. Further comparisons between two adjacent regions in the Mirror Peninsula reveal two major deglaciations involving the Lambert Glacier / Amery Ice Shelf System dated at 61.78 ka to 82.84 ka and 21.98 ka to 49.5 ka during the LGP. • We present new evidence for studying glacial history of Larsemann Hills, Antarctica. • Cosmogenic nuclides 10Be and 26Al dating method is applied for better analysis. • Two major deglaciation events occurred regionally within MIS 2–3 and MIS 4–5. • The exposure age and elevation show a highly significant positive correlation. • Multi-proxy and adjacent evidence are summarized and compared with this study. [ABSTRACT FROM AUTHOR]

This paper introduces a new method for the simultaneous determination of lead, aluminum, and iron in plant samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ETAAS). The method is suitable for covering a wide range of concentrations for all three elements, by utilizing two spectral lines for Al and employing the wavelength-selected absorbance (WSA) approach, which combines the reading of absorbance signals at both the central and wing parts of the spectral lines. The method was validated against certified reference materials and was then applied in a large-scale analysis of Antarctic flora collected from Nelson Island in the South Shetland Islands, Antarctica. The method was found to be a useful biomonitoring tool for assessing Pb pollution in various plant materials, including lichens, mosses, grass and mushrooms, while Al and Fe contents may serve as normalizing elements in calculations of environmental indices. The observed Pb levels in lichens (median content 0.19 mg Pb/kg) were lower than those reported in other Antarctic regions. These findings indicate that the Stansbury Peninsula on Nelson Island is relatively unaffected by local pollution, compared to other Antarctic regions, and that the data might serve as an example of background levels in the South Shetland Islands. [Display omitted] • The method rapidly determines Pb, Al, and Fe in a single run. • Advanced features extend the calibration range over >4 orders of magnitude. • A wide working range enables analysis of various plant types. • We present some of the first published data on Pb in Antarctic mushrooms and grass. • Low levels of Pb indicate minimal pollution in the study area. [ABSTRACT FROM AUTHOR]

The Northeast Greenland Ice Stream (NEGIS) is the main artery for ice discharge from the northeast sector of the Greenland Ice Sheet (GrIS) to the North Atlantic. Understanding the past, present and future stability of the NEGIS with respect to atmospheric and oceanic forcing is of global importance as it drains around 17% of the GrIS and has a sea-level equivalent of 1.6 m. This paper reconstructs the deglacial and Holocene history of Nioghalvfjerdsbræ (or 79N Glacier); a major outlet of the NEGIS. At high elevation (>900 m asl) autochthonous blockfield, a lack of glacially moulded bedrock and pre LGM exposure ages point to a complex exposure/burial history extending back over half a million years. However, post Marine Isotope Stage 12, enhanced glacial erosion led to fjord incision and plateaux abandonment. Between 900 and 600 m asl the terrain is largely unmodified by glacial scour but post LGM erratics indicate the advection of cold-based ice through the fjord. In contrast, below ∼600 m asl Nioghalvfjerdsfjorden exhibits a geomorphological signal indicative of a warm-based ice stream operating during the last glacial cycle. Dated ice marginal landforms and terrain along the fjord walls show initial thinning rates were slow between ∼23 and 10 ka, but post-10 ka it is evident that Nioghalvfjerdsfjorden deglaciated extremely quickly with complete fjord deglaciation below ∼500 m asl between 10.0 and 8.5 ka. Both increasing air and ocean temperatures were pivotal in driving surface lowering and submarine melt during deglaciation, but the final withdrawal of ice through Nioghalvfjerdsfjorden was facilitated by the action of marine ice sheet instability. Our estimates show that thinning and retreat rates reached a maximum of 5.29 ma−1 and 613 ma−1, respectively, as the ice margin withdrew westwards. This would place the Early Holocene disintegration of this outlet of the NEGIS at the upper bounds of contemporary thinning and retreat rates seen both in Greenland and Antarctica. Combined with recent evidence of ice stream shutdown during the Holocene, as well as predictions of changing ice flow dynamics within downstream sections of the NEGIS catchment, this suggests that significant re-organisation of the terminal zone of the ice stream is imminent over the next century. • The Northeast Greenland Ice Stream (NEGIS) thinned slowly between 23–10ka as ice retreated across the continental shelf. • At the opening of the Holocene rising air & ocean temperatures drove surface lowering & basal melt. • Between 10-8.5ka marine ice sheet instability further enhanced grounding line retreat rates into Nioghalvfjerdsfjorden. • During the Early Holocene thinning and retreat rates reached a maximum of 5.29 ma-1 and 613 ma-1 respectively. • Such rates are at the upper bounds of contemporary ice stream thinning and retreat rates in Greenland and Antarctica. [ABSTRACT FROM AUTHOR]

Observations of ice sheet stability in Antarctica in the past, during significantly warmer climatic periods than today, are hampered by a paucity of continental outcrops but they are essential if we are to test and more fully understand established concepts of ice sheet growth and decay and robustly predict Earth's future during rapid global warming. In this paper we use the unique terrestrial record preserved in the three most southerly volcanoes on Earth to reconstruct Antarctica's environmental landscape in the Transantarctic Mountains for three time slices (at 20.1, 19.31 and c. 17 Ma). We demonstrate that the East Antarctic Ice Sheet margin was highly dynamic and fluctuated greatly during the Early Miocene. The period included a much-reduced ice cover that left the southern Transantarctic Mountains virtually ice-free, although a few tidewater glaciers reached the shores of the Early Miocene Ross Sea (Sheridan Bluff; 20.1 Ma); and a substantially thicker, much more voluminous ice mass (represented by volcanism at Mount Early; 19.31 Ma). An intermediate stage of ice retreat is also indicated (at c. 17 Ma), when the East Antarctic Ice Sheet had again withdrawn to behind the Transantarctic Mountains. It is represented by a subglacial volcanic centre identified remotely by aerogeophysics and sampled only as glacial erratics. The associated ice cover at c. 17 Ma had a relatively low surface elevation but it was confluent with thin ice domes that covered the adjacent mountains. Although the ice margin probably did not extend down to the Ross Sea coast, several glaciers fed icebergs into the Ross Sea. The large ice sheet indicated by the Mount Early volcanic centre is the only known physical record of a significant glacial event that took place at 19.31 ± 0.32 Ma ('Mount Early glacial'). The records examined at the other two volcanic sites correspond to eruptions during periods of substantially reduced ice in Antarctica, of which that at 20.1 ± 0.4 Ma is the most remarkable ('Sheridan Bluff interglacial'). The causes of the extreme variations in ice sheet thickness and extent indicated are uncertain but they occurred during a period of rapidly fluctuating atmospheric CO 2 compositions. Although Milankovitch astronomical forcing probably also played a significant part, the results suggest that the East Antarctic Ice Sheet was highly susceptible to comparatively slight changes in CO 2 during the warm Early Miocene. • Transantarctic Mountains landscapes reconstructed using glaciovolcanic sequences for three time slices in the Early Miocene • Large, deep, unfrozen freshwater lake identified at 87°S and c. 2000 m elevation, not predicted by current modelling • Very large ice sheet recognized, more expanded than today, which overtopped the Transantarctic Mountains • Ross Sea margin of the East Antarctic Ice Sheet was highly dynamic between 20 and 17 Ma • Ice sheet margin was highly sensitive to comparatively small changes in CO 2 [ABSTRACT FROM AUTHOR]

Since Australia is the driest inhabited continent, it is a natural laboratory to study on a large scale dust, its composition, its sources, transport and geochemical composition. This is necessary as there has been a lack of appreciation of the diversity of the Australian regolith characterized by a great array of ages and compositions. This is particularly true of studies that examined the geochemistry of Australian dusts and links with potential deposition sites such as in Antarctica and comparison with South America. Hence, the first part of this paper provides an overview of the surficial geology of Australia with emphasis on regions from where dust can become deflated. A review follows on the investigations of significant dust transport and events in Australia. The second part of the paper provides a review of the sites of potential deflation of dust. It includes the study of different geomorphological sites of dust deflation, with a discussion on how dust particles can accumulate in regions linked to large playa lakes that are under the influence of groundwater below them. This is an important mode of dust deflation, a process of which had insufficiently been detailed before. The processes involving evaporative pumping are explained and several illustrations are provided to document those processes and location of dust deposits. Another region of importance to dust deflation consists of extensive alluvial plains and these are also documented, with an area in the upper reaches of the Darling River being now documented more fully. Finally, the inter-dunal corridors in large dune fields are also mentioned as a source of dust as previous studies already show. This second part ends with the description of the two main Potential Source Areas (PSA) of dust in Australia and these are the Kati Thanda-Lake Eyre region of central Australia, and the Darling Riverine Plain in the upper reaches of the Darling River. These two regions are important for their geochemical fingerprints for transcontinental studies, and supported by satellite imagery that identify dust plumes originating from these regions. The third part of the paper examines the geochemical composition of Australian PSAs by paying particular attention to Neodymium, Strontium and Lead isotopic ratios from both continents. We also suggest the possibility of combining Nd and Pb isotopes as a way of fingerprinting geochemically between different Australian regions, and for comparison with other continental PSAs. This part also reviews previous studies that aimed at geochemically fingerprinting the Australian regolith by referring also how these studies were applied to reconstruct past environmental conditions. [ABSTRACT FROM AUTHOR]

The Larsemann Hills and surrounding regions have been widely explored and studied from the year-round stations Progress (Russia), Zhongshan (China) and Bharati (India), and the seasonal-facility Law Base (Australia). The proximity of stations fosters scientific engagements and cooperation on the Antarctic continent. The first International Conference on Antarctic Research (ICAR) at Bharati in 2020 is one such example. The special issue (Parts 1 and 2) on Larsemann Hills is an outcome of the ICAR-2020. In addition, the BRICS working group on ocean and polar science and technology (OPST) provided an effective platform for strengthening scientific cooperation. Part 2 of the special issue compiles thirteen papers from diverse disciplines of Antarctic science. [ABSTRACT FROM AUTHOR]

• Aragonite cements in all sediment cores beneath New Harbor are analyzed. • Cement patterns indicate diverse brine-forming conditions in outlet glacial valleys. • Brine formation further illustrates how climate and ice sheets varied over time. • Guide to identify similar cryogenic processes elsewhere is provided. Cryogenic-brine precipitated carbonates (cryogenic-brine carbonates) have proven to be a valuable proxy for tracing the origin, nature, and distribution of Cenozoic brines that reside beneath McMurdo Sound (MMS) and adjacent McMurdo Dry Valleys (MDV), Antarctica. Of particular significance is the predominance of cryogenic-brine aragonite cements found in several stratigraphic sections in this region, reflecting the initial chemistry and conditions under which the brines formed. To fully explore this aspect, this paper presents a comprehensive examination of cryogenic-brine aragonite cements in all sediment cores recovered in New Harbor, an embayment that connects the MDV and MMS. Petrographic and isotopic analyses of the cements reveal a diverse range of brine-forming environments in the glacial outlet system during the middle Miocene Climatic Transition and the Early–Middle Pleistocene Transition. These environments span subglacial and ice-contact proglacial lakes to sub-ice-shelf fjords, occurring as cold-based, continent-sized Antarctic ice sheets expanded over the continental margin. Subsurface infiltration of the brines triggered almost instantaneous precipitation of aragonite cements below the sediment-water interface at low temperatures near 0 °C. Driven by the hydraulic gradient, the brines facilitated slow yet pervasive precipitation of an unusual form of aragonite characterized by coarse, blocky and poikilotopic morphologies—distinct from the typical acicular and fibrous aragonite dominating near-surface strata. The oxygen isotopic compositions of brines, as derived from aragonite precipitates, vary among different environments, displaying an increasing trend from ∼ –30 to –5 ‰ VSMOW toward MMS. The 18O depletion is primarily controlled by the availability of periodic saline water replenishment and the relative contribution of seawater versus meltwater during the cryoconcentration process. The ubiquity of brine-forming environments on the Antarctic continental margin suggests their potential existence during past ice ages, which may be identified by the presence of distinct cryogenic-aragonite cement patterns as documented in this study. [ABSTRACT FROM AUTHOR]

Antarctica is one of the most susceptible regions to climate change on Earth. Rising ocean temperatures, glacier melting, and disruptions of marine ecosystems make this polar region a focus of research on ecosystem transformation associated with ongoing climate change. Within the Antarctic ecosystem, diatoms, a key group of phytoplankton at the base of the marine food web, play a crucial role in maintaining marine ecosystem balance and functioning. Conventionally, fossil diatom assemblages have been investigated in marine sediment records to reconstruct paleoenvironmental conditions and understand climate change patterns of Antarctica. Recently, the application of ancient DNA techniques to ocean sediments (sedimentary ancient DNA, sed aDNA) has provided new insights into diatom community responses to environmental change over geological time scales. One benefit of sed aDNA analysis is that this technique can detect fragile diatom species that do not preserve well and are thus difficult to study via traditional microscopy techniques. In this paper, we review the importance of diatoms as indicators of Antarctic paleoenvironmental change, the novel use of diatom sed aDNA to assist Antarctic paleoenvironmental reconstruction, and the challenges and promises of using the sed aDNA approach. We propose that Fragilariopsis cylindrus , an extant polar diatom species, is an ideal model organism to study adaptation patterns of diatoms to changing climate due to its ecological success through time and the availability of whole-genome information for this species. Novel genetic information obtainable from ancient F. cylindrus, as well as other diatoms, will help us to better predict the evolutionary and adaptive dynamics of this important group of primary producers in the climatically vulnerable Antarctic region. • Climate change in Antarctica and the need to study this polar region. • Diatoms in Antarctic ecosystem and their role as paleoenvironmental indicators. • Using the novel technique of sedimentary ancient DNA (sed aDNA) in Antarctica. • Fragilariopsis cylindrus to study adaptation and evolution of diatoms in Antarctica. [ABSTRACT FROM AUTHOR]

GNSS networks in Antarctica are a fundamental tool to define actual crustal displacements due to geological and geophysical processes and to constrain the glacial isostatic models (GIA). A large network devoted to the detection and monitoring of crustal deformations in the Northern Victoria Land (Victoria Land Network for DEFormation control – VLNDEF), was monumented during the 1999–2000 and 2000–2001 field campaigns, as part of Italian National Program for Antarctic Research and surveyed periodically during the Southern summer seasons. In this paper, GPS observations of VLNDEF collected over a more than 15-year span, together with various selected POLENET sites and more than 70 IGS stations, were processed with Bernese Software, using a classical double difference approach. A solution was obtained combining NEQs by means of ADDNEQ2/FODITS tools embedded in Bernese Software. All the Antarctic sites were kept free and a subset of 50 IGS stations were used to frame VLNDEF into ITRF2008. New evidence provided by analysis of GPS time series for the VLNDEF network is presented; also displacements along the vertical component are compared with the recently published GIA models. The absolute velocities indicate an overall displacement of the northern Victoria Land region along the south-east direction (Ve = 10.6 mm/yr, Vn = −11.5 mm/yr) and an average uplift rate of Vu = 0.5 mm/yr. Two GIA models have been analyzed: ICE-6G_C-VM5a proposed by Argus et al. (2014), Peltier et al. (2015) and W12A_v1 by Whitehouse et al. (2012a,b). Up rates, predicted over the VLNDEF sites by the mentioned GIA models, have been extracted and compared with those observed. A preliminary comparison with GPS-derived vertical rates shows that the Victoria Land ICE-6G_C-VM5 and W12A_v1 GIA models predict overestimated uplift rates of 0.7 and 0.9 mm/yr weighted mean residuals respectively. The mean horizontal relative motions within the Victoria Land (VL) area are in most cases negligible, while only a few points exhibit horizontal velocities greater than the confidence level. Such a residual horizontal velocity field could represent some of the tectonic characteristics affecting VL, characterized by block faulting, tilting along NE striking and SE dipping extensional faults. Uplift rates, highlighted in the present paper depict a well defined spatial pattern in the investigated areas. Northward, all sites show a general positive trend up to 2.3 mm/yr. In the central and southern areas small negative trends (up to −1.3 mm/yr) were detected in the vertical displacements. Only the site VL06, located atop the Mt. Melbourne volcano, does not concord with such a general reading, as it is representative of the volcanic complex’s evolution. Observed and predicted uplift rates increase westward (inland) where the ice-load increases. The same behavior is predicted southward by the GIA models; whereas GPS values decrease toward the south pole, due to the movements of a few sites reflecting the neotectonic phenomena acting in the Victoria Land region. [ABSTRACT FROM AUTHOR]

Autonomous sondes are used to study the Antarctic subglacial environment, yet they risk of being frozen in ice due to heating failure. To recover an accidently frozen sonde this paper describes a concept for a hot-water rescue ice drilling system. A special hot-water drill tool was designed to drill downward along the cable/sonde and melt surrounding ice. Theoretical estimation indicated the power system needed to provide hot water at a flow rate of 25 L/min and a pressure of more than 4.2 MPa to release the sonde at ice depth of 500 m. Laboratory testing and field testing near the Chinese Zhongshan Station in Antarctica demonstrated rationality of the concept. Potential risks were estimated and corresponding solutions presented. The hot-water rescue ice drilling system mentioned in the paper provides a safety guarantee for subglacial lake successful exploration, furthermore supports more ideas for future ice sheet exploration. [ABSTRACT FROM AUTHOR]

Neutron monitors have been the premier ground-based instruments for monitoring the near-Earth cosmic ray flux for more than 70 years. It is essential to continue with such measurements in order to extend this unique long-term time series. Moreover, with the recent interest of the aviation industry to space weather effects, and especially the radiation risk posed by solar energetic particles and galactic cosmic rays, it is vital to extend the current neutron monitor network in order to provide near-real-time measurements to the space weather community. In this paper we discuss a new electronics system that was retrofitted to the SANAE neutron monitor in Antarctica. We present initial results from this system, featuring very high temporal resolution and discuss the techniques applied to the data analysis. Based on these successful upgrades, we are confident that this system can be used to rejuvenate the aligning neutron monitor network, and even possibly to revive some of the decommissioned instruments. [ABSTRACT FROM AUTHOR]

Slope correction is important to improve the accuracy of satellite radar elevation measurements by mitigating the slope-induced error (SE), especially over uneven ground surfaces. Although several slope correction methods have been proposed, guidance in the form of stepwise algorithm on how to implement these methods in processing radar altimetric data at the coding level, and the differences among these methods need to be presented and discussed systematically. In this paper, three existing types of slope correction methods—the direct method (DM), intermediate method (IM), and relocation method (RM, further divided into RM1 and RM2)—are described in detail. In addition, their main differences and features for various scientific applications are analyzed. We conduct a systematic experiment with CryoSat-2 Low Resolution Mode (LRM) data in a physically stable area around Dome Argus in East Antarctica, where in-situ measurements were available for comparison. The slope correction is implemented separately using the three methods, with the latest high-accuracy Reference Elevation Model of Antarctica (REMA) as the a-priori topography model. The bias and precision of the slope-corrected CryoSat-2 data results from the RM2 is −0.18 ± 0.86 m based on the comparison with the field Global Navigation Satellite System (GNSS) data. The results from the RM2 indicate higher precision compared to those from the RM1. According to the correlation analysis of the slope-corrected CryoSat-2 data results (RM1 and RM2), the bias enlarges and the precision becomes worse when the surface slope increases from 0 to 0.85°. After a comprehensively comparative analysis, we find that the results from the RM1 and RM2 are superior in precision (0.93 m and 0.86 m) with respect to the GNSS data. The relatively low precision (1.22 m) from the IM is due to the potential error from the a-priori digital elevation model (DEM). The DM has the lowest precision (2.66 m). Another experiment over rough topography in West Antarctica is carried out for comparison, especially between the RM1 (precision of 15.27 m) and RM2 (precision of 16.25 m). In general, the RM is recommended for the SE elimination among the three methods. Moreover, the RM2 is firstly considered over smooth topography due to the superior performance in bias and precision, while the RM1 is more suggested over the rough topography because of the slightly smaller bias and better precision. The IM relies much on the accuracy of the a-prior DEM and is not usually recommended, because of the strict requirement in the sampling time between the radar altimetry data and the a-priori DEM to avoid any surface change over time. [ABSTRACT FROM AUTHOR]

The knowledge of polychlorinated naphthalenes (PCNs) in the Antarctic atmosphere is quite limited compared to the Arctic. PCNs are a global concern because of their PBT characteristics (i.e., persistent, bioaccumulative, and toxic) and severe and often deadly biological effects on people and other animals. Therefore, the present study used a passive air sampling method to conduct long-term air monitoring of PCNs for almost a decade from 2013 to 2022, specifically on Fildes Peninsula, situated on King George Island, located in West Antarctica. The median sum of mono-CNs to octa-CN concentration (∑ 75 PCNs) in the Antarctic atmosphere was 12.4 pg/m3. In terms of homologues, mono-CNs to tri-CNs predominated. Among these, the prevalent congeners observed were PCN-1 and PCN-2, originating from mono-CNs, followed by PCN-5/7 from di-CNs, and PCN-24/14 from tri-CNs, respectively. Between 2013 and 2022, the total levels of PCNs were found to have decreased approximately fourfold. Ratio analyses and principal component analysis (PCA) showed that the long-range atmospheric transport and combustion-related sources as the potential PCN sources in the study area. This paper provides the most up-to-date temporal trend analysis of PCNs in the Antarctic continent and is the first to document all 75 congeners (mono-CNs to octa-CN homologue groups). [Display omitted] • This is the first study to report all 75 PCN congeners from the Antarctic continent. • A decreasing temporal trend was observed from 2013 to 2022. • The mono-CNs to tri-CNs consist of the dominating homologues group. • LRAT and combustion-related sources were the primary sources of the study area. [ABSTRACT FROM AUTHOR]

• The natural variability of directly observed soil thermal conductivity was low. • Soil moisture can explain at least 50 % of soil thermal conductivity variability. • The effect of soil thermal conductivity on active layer thickness was insignificant. • Active layer thickness negatively correlates with soil moisture. The knowledge of soil thermal properties is important for determining how a soil will behave under changing climate conditions, especially in the sensitive environment of permafrost affected soils. This paper represents the first complex study of the interplay between the different parameters affecting soil thermal conductivity of soils in Antarctica. Antarctic Peninsula is currently the most rapidly warming region of the whole Antarctica, with predictions of this warming to continue in the upcoming decades. This study focuses on James Ross Island, where the Abernethy Flats automatic weather station is located in a lowland area with semi-arid climate. Air and ground temperature, soil heat flux and soil moisture during the thawing season were monitored on this site from 2015 to 2023. Moreover, two approaches to determining soil thermal conductivity were compared – laboratory measurements and calculation from field data. During this period, mean annual temperatures have increased dramatically for both air (from −6.9 °C in 2015/2016 to −3.8 °C in 2022/2023) and ground (from −6.5 °C to −3.2 °C), same as active layer thickness (from 68 cm to 95 cm). Average soil thermal conductivity for the thawing period reached values between 0.49 and 0.74 W/m.K−1 based on field data. Statistically significant relationships were found between the seasonal means of volumetric water content and several other parameters – soil thermal conductivity (r = 0.91), thawing degree days (r = −0.87) and active layer thickness (r = −0.88). Although wetter soils generally have a higher conductivity, the increase in temperature exhibits a much stronger control over the active layer thickening, also contributing to the overall drying of the upper part of the soil profile. [ABSTRACT FROM AUTHOR]

• Role of periglacial regions in mercury (Hg) cycling in the Antarctic coastal zone. • Spatial variability of Hg and MeHg concentrations in soil of ice-free areas. • Study confirms link between weathering of rocks and the Hg concentration in soil. • Presence of animals, e.g. penguins and seals, impacts the concentration of Hg in soil. • OM is a key factor affecting Hg distribution across Antarctic terrestrial ecosystems. The Antarctic plays a critical role in global mercury cycling as both a sink of Hg and, in response to rapid global warming, an emerging source of Hg through its release from thawing permafrost and recessing glaciers. At the present time, Antarctica and surrounding areas have little mercury contamination in comparison to other regions of the world. Understanding the sources and transformations of Hg in the Antarctic will be particularly important in predicting the role of a changing environment in the mercury cycle as emissions and global climate change. Study samples were collected at 12 stations, categorized into three groups based on the human or animal presence and flora. Sampling took place in December 2018 and January 2019, and soil and parent rock samples were collected and analyzed for total mercury concentration and its fractions using atomic absorption spectroscopy. Bedrock samples collected on the coast of Admiralty Bay were found to have low organic matter content, while soil samples from the west shore of the bay had a high variability of organic matter content, ranging from 3 % to 41 %. The concentration of total mercury in bedrock ranged from 2.1 ng/g to 15.0 ng/g, and in soil samples, the total mercury concentration ranged from 4.7 ng/g to 143.1 ng/g. This paper reviews current knowledge of Hg cycling in the Antarctic, including its sources, fate, and effects on the ecosystem. The implications of climate change for Hg cycling in the region are also discussed, highlighting the need for continued research to better understand the potential impacts of Hg contamination in the Antarctic. [ABSTRACT FROM AUTHOR]

This paper examines the hydration/dehydration behaviour of geosynthetic clay liner (GCL) under polar conditions for four simulated conditions experienced at Australia's Casey Station in Antarctica: (a) hydration during summer, (b) dehydration during a winter-summer cycle, (c) hydration through a fine Antarctic soil, and (d) hydration through a coarse Antarctic soil. Hydration during the summer is found to occur if there is direct contact with the water table. In contrast, the low relative humidity of the environment tends to dehydrate the GCL along a path that depends on the field conditions the GCL is exposed to. Hydration from either fine or coarse Antarctica soil is function of the original gravimetric water content of the subgrade soil and its grain size distribution as well as the low relative humidity prevailing in Antarctica. [ABSTRACT FROM AUTHOR]

Interplanetary human missions to Mars and beyond will suppose a very demanding physical and psychological environment for future astronauts. Isolation, confinement, hypoxia or hypercapnia in a less pressurized atmosphere, darkness and other factors are expected to endanger a mission's success, directly influencing human performance. In order to study the effects of such environmental conditions on human beings, the SIMSKILL Experiment aims to investigate how spacecraft piloting performance decays over time by deploying a Soyuz flight simulator on the Antarctic research stations Halley VI and Concordia, which feature similar living conditions as those of a space mission, leading eventually to muscular atrophy, loss of cognitive capacities, and reduction of psycho-motor skills. This paper offers an analysis on the recorded data from the scientific campaigns in Antarctica, compared to those of the subjects in a control group in Stuttgart, Germany. An overall total of 69 subjects and more than one thousand approach and docking flights to the ISS performed in a Soyuz-TMA simulator have been analysed using a performance assessment methodology. The post-processed simulation dataset allows to recognize collective trends and find which are the essential parameters that affect the pilot's skill evolution. The results obtained from this analysis show how the influence of isolation, confinement and hypoxia in Antarctica is crucial to understand how differences in performance appear between subjects. The significance of the obtained results has been proven by means of statistical models, which show that a one-month training refreshing delivers satisfactory performance for a docking simulation, whereas a frequency of 3 months follows to a loss of piloting reliability. Moreover, the effect of isolation and hypoxia aggravates the loss of flight performance. • Use of a Soyuz space flight simulator for the analysis of flight performance. • International Space Station approach and docking procedures prove to be an optimal testbed for human performance analysis. • Antarctic isolation and confinement conditions cause a degradation on spacecraft piloting performance. • Training intervals of three months show a decrease on flight performance and reliability. • The hypoxic environment at the Concordia Station exacerbates the decay of piloting skills. [ABSTRACT FROM AUTHOR]

The generation of a truly global DEM with enhanced accuracy, resolution and coverage was the main objective of the TanDEM-X mission. The mission is innovative for many reasons and as a result an abundance of research about its technology has been published so far. This paper aims to fill the literature gap between the scientific use of the TerraSAR-X and TanDEM-X data and the practical use of the final TanDEM-X DEM. A review of the DEM is performed over non trivial areas of the globe, some of which are test sites of international scientific societies. LIDAR data and DSMs are used as reference elevation information and other widely used global DEMs are employed. The visual inspection and the accuracy analysis over 14 sites in Europe, USA and Antarctica show the clear superiority of the TanDEM-X DEM in the family of global DEMs, regardless of the latitude, the terrain type and the land cover. The TanDEM-X DEM is more morphologically detailed than the AW3D30, the ASTER and the SRTM global DEMs, which agrees with its much finer pixel spacing. It is also more complete than the other global DEMs, especially over the polar test sites. The accuracy analysis shows that the TanDEM-X DEM is more accurate than the other global DEMs with RMSEs ranging from 1.0 to 8.7 m, while the RMSEs of the AW3D30, the ASTER, the 1 arcsec SRTM and the 3 arcsec SRTM range from 2.6 to 49.0 m, from 8.3 to 80.2 m, from 3.0 to 8.7 m and from 7.3 to 20.5 m, respectively. The accuracy analysis also shows that the TanDEM-X DEM has better geolocation accuracy, and the application of the computed 3D bias with respect to the reference data leaves the RMSE practically unaffected. All in all, it seems that the TanDEM-X DEM paves the way for a new generation of global DEMs and re-introduces SAR as a state-of-the art technology for global topographic, and other, applications. [ABSTRACT FROM AUTHOR]

The total electron content (TEC) is a key parameter that is used to understand the effects of ionosphere on satellite-based navigation and communication signals. The ionosphere at polar is highly dynamic and acts as a major sink for the solar-terrestrial energy transfer processes, different magnetospheric and space weather events. Especially in Antarctica, the observation is still sparse due to a limited number of stations. In this paper, the study of ionosphere variability over Bharati station (69.41° S, 76.19° E), an Indian Antarctic research base at Larsemann Hills, was carried out. During the geomagnetically quiet conditions, the Bharati station is located outside of auroral oval but towards the poleward of auroral oval. The variation of ionosphere for diurnal, seasonal, and solar activity was studied using the TEC data for the years 2010–2022 which covers the solar cycle 24. The TEC diurnal pattern is strong even during polar days and nights with a peak at local noon. The seasonal variability was distinctly observed with about 50% increase in TEC during equinoctial months compared to summer months during high solar active year 2014. However, during low solar active year there is a marginal increase of TEC in equinoxes compared to summer. [ABSTRACT FROM AUTHOR]

Surface roughness is an important parameter in deriving energy balance over the polar ice-sheets and glaciers. In Antarctica, roughness appears as snow patches and is affected by wind transport. It is also influenced by snowfall, snowdrifts, snowmelt, and snow grain size. In this paper, we derive surface roughness using a laser distometer. The roughness measurements were collected during the 32nd Indian Scientific Expedition to Antarctica 2013 (ISEA-32). After removal of all the possible error sources, it is found that around the Indian Antarctic station Bharati (69.41°S, 76.18°E), roughness is in the range of 0.7–1.2 cm. Snowfall and wind introduce fluctuations in surface roughness measurements. Measurements around Maitri (70.76°S, 11.73°E) showed that different ice surfaces have different values of roughness (0.6–1.4 cm), with the minimum roughness in the interior ice sheet surrounded by hummocks. Sastrugi patterns were also captured in the analysis. Backscattering signatures from RADARSAT-2 imagery were examined in conjunction with the roughness measurements. [ABSTRACT FROM AUTHOR]

Subglacial processes influence the large-scale behaviour of glaciers and determine the geological processes that occur at the ice-substrate interface. In this paper we focus on subglacial deformation beneath a cold-based glacier resting on permafrost. We ask what are the drivers of subglacial permafrost deformation, how is strain distributed beneath glaciers with a permafrost substrate, how is strain transmitted from the glacier into the substrate, and how is deformed permafrost incorporated into the basal zone of the glacier? To address these questions a tunnel excavated in the margin of Wright Lower Glacier in the McMurdo Dry Valleys, Antarctica to observe the structure of the basal zone and bed of the glacier and to monitor basal ice deformation over a period of 4 years. The tunnel revealed a stacked sequence of stratified debris-bearing and clean ice layers, and thick rafts of frozen sediment. Isotopic and gas analyses reveal that despite the low local temperature of the basal ice (−18.5 °C), liquid water has played an important role in the formation of this basal sequence. The rafts of frozen sediment contain well preserved sedimentary structures and algae layers that show the material has been entrained from the underlying permafrost. Deformation measurements made with a combination of displacement transducers, strain arrays, and plumb-lines show that strain and motion within the basal zone are heterogeneous and that strain is transmitted through the permafrozen sediment and into intra-sediment ice layers. The distribution of strain in the basal zone produces a compound velocity profile resembling the deformation patterns inferred from deformation structures in Pleistocene permafrost and also resembles profiles associated with subglacial sediment deformation driven by hydrogeological processes. We conclude that ice-rich permafrost is readily deformed by glaciers and that there is no clear boundary between basal ice and deforming permafrost. [ABSTRACT FROM AUTHOR]

Soils and landforms of Nelson Island remain one of the least studied in the South Shetlands Archipelago, despite that it is one of the oldest ice-free areas and is strongly vegetated. In this paper, we examine the main processes and factors of soil formation at Harmony Point and the relation of soils to landforms, vegetation and lithology. To achieve the goals, 26 pedons were collected and studied from a 4 km2 ice-free area at Harmony Point (S62°18′; W059°10′) on the southern area of Nelson Island (Maritime Antarctica). The soils were sampled on all representative local landforms, including three levels of uplifted marine terraces up to cryoplanated plateau, waterlogged depressions, rock felsenmeer, debris slopes and patterned ground, and a paraglacial border of the ice cap (270 m a.s.l). Sampling along the cryoplanated plateau was carried out along a gradient extending inland from the margins of the Ice Cap; and sampling of the marine terraces was performed along a chronosequence under varying bird-nesting influence and age. The main pedogenetic processes observed in this area are marked phosphatization, melanization from the accumulation of organic matter, and cryoturbation. Soil development varies from weakly developed, shallow, stony and cryoturbated to well-developed and organic-rich, phosphate soils with colors ranging from grayish to brown. The mineralogical composition of the clay fraction contains secondary minerals, indicating the active role of chemical weathering. Ornithogenic soils have mature phosphate minerals such as vivianite and taranakite, as well as poorly crystalline leucophosphite. Intensively cryoturbated soils are underlain by permafrost and are classified as Typic Haploturbels; polygonal soils are widespread on the cryoplanated plateau. Areas without permafrost were classified as Typic Gelorthents. Phosphatization is a dominant soil-forming process in this area and is associated with past and present-day guano accumulation by bird nesting and has led to the the development of deeper Ornithogenic Haplorthels. The ornithogenic soils occur at different topographic levels on the cryplanated platform and marine terraces. High P concentrations can be used as a proxy of the past nesting birds' activities, with far-reaching implications, especially with regards to vegetation growth and microbial activity and diversity. • In Harmony Point the soils and the landforms are related. • The main soil-forming processes are cryoturbation, humification and phosphatization. • Solifluction, cryoplanation, frost heave, and thermokarst occur in the landscape. • The landforms and vegetation are associated to the water and bird distribution. [ABSTRACT FROM AUTHOR]

Values are the core of human when it comes to decision making. In the context of Antarctica, the study of Antarctic values helps to direct the future development in policy formulation related to the continent. The research on value perception in Malaysia has been quite recent and is focusing on young citizens in secondary schools and within the university campus. This paper aims to share the results of research conducted nationwide among the working adults in the state capital cities. Specifically, it aims to identify the influence of Malaysia's scientific involvement on the awareness and values perceived by the urban citizens in Malaysia. Data was collected using a questionnaire survey in all the state capital cities. The analysis results reveal that, the scientific research and publicity of these scientific activities in Antarctica in local media has a significant influence on the awareness and values perceived among the respondents. These include scientific and environmental values. The authors conclude that the recommendations to strengthen the existing awareness programs by focusing on the target audience and to setup media and information centre and coordinating body must be backed by enhancing the existing science communication quality and incorporating the element at all programs. [ABSTRACT FROM AUTHOR]

This paper presents the observations and characterization of Cloud-to-Ground (CG) lightning activity in Western Antarctica in a region that covers the Amundsen/Bellingshausen Sea (ABS), the Antarctic Peninsula (AP) and the Weddell Sea (WS). Lightning data have been collected by a lightning detector (Boltek LD-350) and an atmospheric electric field mill (EFM-100) sensors deployed at the Carlini Base on the Antarctic Peninsula (CARL: 62.23oS, 58.63oW). The flash rate and flash multiplicity were analysed for three different seasons within a 1,000 km range, starting at the end of summer (February 2017) and ending in winter (July 2017). Three storm days for each month (within the 1,000 km radius from the LD sensor) with three composite active thunderstorms (labelled as Storm region A, B, and C) for each day have been selected from a collection of storm days between February and July 2017. A total of 355,899 flashes have been recorded with 156,190 Positive CG and 199,709 Negative CG flashes from these 54 thunderstorms. In total, Positive CG flash counts made up around 43.9% of the total detected CG flashes. Most of the Positive CG flashes (>80%) had only 1 or 2 strokes with a maximum number of 5. For Negative CG flashes, the average multiplicity and the maximum multiple stroke were 1.2 and 16 respectively. Most CG flashes were detected during the summer and fall months. Positive CG flashes were prevalent in Western Antarctic storms even during the winter. The mean, median and range of the ratio of Positive CG to Negative CG flashes were 0.7, 0.718 and 0.217–1.279, respectively. • Flash rate and stroke multiplicity for CG flashes of 54 thunderstorms are examined. • Positive CG constituted 43.9% of the total detected flashes in the Western Antarctica region. • Most Positive CG flashes had only 1 or 2 strokes with a maximum of 5 strokes. • Most of the CG flashes were detected during the summer and fall between February and April 2017. • Abstract. [ABSTRACT FROM AUTHOR]

Here we summarize the motivation and issues surrounding the responses of ice sheets and sea level to past climate warming as part of the PALeo constraints on SEA level rise (PALSEA) working group. Papers in this special issue of Quaternary Science Reviews focus on the timescale of glaciations during the late Pliocene, the magnitude of ice-sheet fluctuations and volume leading up to and during the last glacial maximum, the timing and persistence of ice-sheet impacts on deglacial and future relative sea-level change, and relative sea-level change during peak interglacial climate. A more dynamic cryosphere is noted under both late Pliocene and last glacial cycle climate conditions, while relative sea-level changes during the last deglaciation appear to correspond closely with individual ice-sheet deglaciation. Lastly, relative sea-level change during peak interglacial conditions may have fluctuated by as much as a meter, although the sources of such variability (Greenland, Antarctica or elsewhere) remain elusive. [ABSTRACT FROM AUTHOR]

The Antarctic Peninsula (AP) constitutes the warmest region of Antarctica, although 98% of the surface is still covered by glaciers. The region shows contrasting geographic and climatic properties, which have conditioned past and present glacial activity. This paper constitutes a review of the spatial and temporal patterns of paraglacial activity across the AP bridging the geomorphological and ecological perspectives. The number and extent of ice-free environments has increased since the Last Glacial Maximum, particularly during the Early Holocene and the 20th century. Following deglaciation, the redefinition of coastlines and the uplift of landmasses proceeded differently in the three sectors of AP, with maximum uplift in the western sector (40 m a.s.l.), the minimum on the north (20.4 m a.s.l.), and intermediate in the eastern sector (30 m). There are also differences in the levels of raised beaches, with the highest complexity in the northern AP (5–7 levels) and the lowest in the eastern AP (3 levels). The transition from glacial to periglacial conditions (paraglacial stage) also differed greatly between the three sectors, with the absence of rock glaciers in the western sector, the development almost exclusively of glacier-derived rock glaciers in the eastern AP, and the majority of talus-derived rock glaciers in the northern AP. The development of protalus lobes, block streams and other periglacial features was highly dependent on the cold/warm based character of individual glaciers; this characteristic determines the existence or absence of permafrost following deglaciation which, in turn, conditions the type and intensity of geomorphic processes in newly exposed ice-free areas. More recently, following the post-1950s regional warming, there have still been important differences between the three sectors in the development of paraglacial environments. Permafrost degradation has occurred in newly exposed areas, accelerating mass wasting and sediment redistribution and changing hydrological processes, especially in the northern and western AP, while sudden glacial outburst flooding has occurred in the eastern AP. The most apparent major ecological response to this recent warming is greening due to vegetation expansion, which is more evident where paraglacial and periglacial processes are less intense. The accurate characterization of the different paraglacial responses existing in the AP enables a better understanding of future environmental responses in this climatically sensitive region, where climate models forecast significant environmental change for during forthcoming decades. [ABSTRACT FROM AUTHOR]

Abstract ISRO's SCATSAT-1 is a miniature satellite which serves as a continuity mission to the bygone Oceansat-2. Three important parameters from SCATSAT-1 are made available through the Meteorological & Oceanographic Satellite Data Archival Centre (MOSDAC), Space Applications Centre-ISRO. They are the backscattering coefficient (σ 0), incidence angle normalized backscattering coefficient or the gamma naught (γ 0) and the scatterometer noise-derived brightness temperature (T b). In this paper, an attempt has been made to use the initially available SCATSAT-1 data in native resolution of 25 km as well as the enhanced resolution at 0.225° to explore the Larsen C ice-shelf, West Antarctica during the recent calving event of 2017. Moreover, a preliminary study on the plausible melt conditions over the shelf is reported. [ABSTRACT FROM AUTHOR]

Abstract Constraining Antarctic ice sheet evolution provides a way to validate numerical ice sheet models that aid predictions of sea-level rise. In this paper we collate cosmogenic exposure ages from exposed nunataks in Antarctica that have been used, or have the potential to be used, to constrain rates of thinning of the Antarctic Ice Sheets since the Last Glacial Maximum. We undertake quality control of the data and adopt a Bayesian approach to outlier detection. Past thinning rates are modelled by Monte Carlo linear regression analysis. We present thinning rates from 23 sites across Antarctica. The resulting data set is the first Antarctic-wide collation of past ice sheet thinning rates and provides an empirical starting point for future model-data comparisons. Palaeo-thinning rates are spatially variable with high rates appearing to correlate to areas of contemporary rapid changes. On centennial timescales past thinning rates are comparable to modern day observations implying that modern day thinning has the potential to persist for centuries in numerous parts of Antarctica. The onset of abrupt thinning from all sites post-dates Meltwater Pulse 1A suggesting that its source region(s) are distal to areas where exposure age constraints on ice surface geometry exist. Highlights • Exposure ages that constrain ice sheet thickness collated from an online database. • Thinning rates are reconstructed from 23 sites across Antarctica. • Palaeo-thinning rates are comparable to modern observations. • Wide-spread thinning during the Holocene, but after Meltwater Pulse 1A. [ABSTRACT FROM AUTHOR]

Abstract Pointing calibration and sub-reflector focusing are an important task of antenna measurement, which significantly contributes to the observational performance of a radio telescope. According to the requirements on the pointing accuracy and defocusing gain loss of the 5 m Dome A Terahertz Explorer (DATE5), this paper has derived the requirements of signal-to-noise ratio for the pointing and sub-reflector focusing calibration observations, and selected several astronomical radio sources suitable for the pointing and focusing calibrations at the terahertz waveband in Antarctica, which include planets and ultra-compact HII regions. The effects of the atmospheric absorption and the source angular diameter on the accuracy of calibration measurements are analyzed. Simulations show that when the telescope operates in Antarctica, these sources can provide sufficient flux densities for verifying the pre-established pointing model and focusing model. [ABSTRACT FROM AUTHOR]

Abstract: The Weddell Sea Embayment (WSE) sector of the Antarctic ice sheet has been suggested as a potential source for a period of rapid sea-level rise – Meltwater Pulse 1a, a 20m rise in ∼500 years. Previous modelling attempts have predicted an extensive grounding line advance in the WSE, to the continental shelf break, leading to a large equivalent sea-level contribution for the sector. A range of recent field evidence suggests that the ice sheet elevation change in the WSE at the Last Glacial Maximum (LGM) is less than previously thought. This paper describes and discusses an ice flow modelling derived reconstruction of the LGM ice sheet in the WSE, constrained by the recent field evidence. The ice flow model reconstructions suggest that an ice sheet consistent with the field evidence does not support grounding line advance to the continental shelf break. A range of modelled ice sheet surfaces are instead produced, with different grounding line locations derived from a novel grounding line advance scheme. The ice sheet reconstructions which best fit the field constraints lead to a range of equivalent eustatic sea-level estimates between approximately 1.4 and 3m for this sector. This paper describes the modelling procedure in detail, considers the assumptions and limitations associated with the modelling approach, and how the uncertainty may impact on the eustatic sea-level equivalent results for the WSE. [Copyright &y& Elsevier]

Abstract: The Xth SCAR International Biology Symposium was held under the theme of “Antarctic Biology in the 21st Century—Advances in and beyond IPY—“ at the Conference Hall, Hokkaido University, between July 26 and 31, 2009. A total of 113 oral presentations and 122 poster presentations were given under six sub-themes. This special issue was edited by six guest editors under the Editor-in-Chief of “Polar Science”, in accordance with the editorial system of “Polar Science” and contains one overview paper and five review papers and 18 research papers. [Copyright &y& Elsevier]

The Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT) took place over the timer period of 15 November to 31 December in the year 2000. The study location was the Amundsen Scott Station in Antarctica. ISCAT 2000 defines the second phase of a program designed to explore tropospheric chemistry in Antarctica. As in 1998, the 2000 ISCAT study revealed a strong oxidizing environment at South Pole (SP). During the 2000 investigation, however, the suite of measurements was greatly expanded. These new measurements established the recycling of reactive nitrogen as a critical component of this unique environment. This paper first presents the historical background leading up to the ISCAT 2000 observations; then it focuses on providing a summary of the year 2000 results and contrasts these with those recorded during 1998. Important developments made during the 2000 study included the recording of SP data for several species being emitted from the snowpack. These included NO, H2O2 and CH2O. In this context, eddy-diffusion flux measurements provided the first quantitative estimates of the SP NO and NOx snow-to-atmosphere fluxes. This study also revealed that HNO3 and HO2NO2 were major sink species for HOx and NOx radicals. And, it identified the critical factors responsible for SP NO levels exceeding those at other polar sites by nearly an order of magnitude. Finally, it reports on the levels of gas phase sulfur species and provides evidence indicating that the absence of DMS at SP is most likely due to its greatly shorten chemical lifetime in the near vicinity of the plateau. It is proposed that this is due to the influence of NO on the distribution of OH in the lower free troposphere over a region that extends well beyond the plateau itself. Details related to each of the above findings plus others can be found in the 11 accompanying Special Issue papers. [Copyright &y& Elsevier]

Ice streams are corridors of fast ice flow (ca. 0.8 km/year) within an ice sheet and are responsible for discharging the majority of the ice and sediment within them. Consequently, like the arteries in our body, their behaviour and stability is essential to the well being of an ice sheet. Ice streams may either be constrained by topography (topographic ice streams) or by areas of slow moving ice (pure ice streams). The latter show spatial and temporal patterns of variability that may indicate a potential for instability and are therefore of particular interest. Today, pure ice streams are largely restricted to the Siple Coast of Antarctica and these ice streams have been extensively investigated over the last 20 years. This paper provides an introduction to this substantial body of research and describes the morphology, dynamics, and temporal behaviour of these contemporary ice streams, before exploring the basal conditions that exist beneath them and the mechanisms that drive the fast flow within them. The paper concludes by reviewing the potential of ice streams as unstable elements within ice sheets that may impact on the Earth''s dynamic system. [Copyright &y& Elsevier]

This paper introduces the complete image of the Weddell Sea Anomaly, observed with the over-the-ocean ionospheric total electron content (TEC) values obtained from the TOPEX satellite data with an almost unlimited coverage over the oceans, the first time according to the literature; and investigates its development. With a series of TOPEX TEC maps, this paper demonstrates the diurnal variations of both the night-time and the day-time Weddell Sea Anomaly, which appeared as a night-time TEC enhancement and as a day-time TEC depletion, during the near sunspot maximum period of 1998 and 1999 investigated. Several TOPEX passes, plotted in geomagnetic latitudes, are also presented to demonstrate the longitudinal variations of the Weddell Sea Anomaly, and also to show other ionospheric features appearing such as the southern-hemisphere mid-latitude day-time and night-time trough, the northern-hemisphere mid-latitude night-time trough and the equatorial anomaly. This paper demonstrates how large the anomaly is in reality situated west of the Faraday ionosonde station over the Bellinghausen Sea and not over the Weddell Sea that is east of Faraday. Thus the correct name should be Bellinghausen Sea Anomaly. Based upon the review paper of Dudeney and Piggott (1978), the development of the Weddell Sea Anomaly is explained with the combined effects of solar ultraviolet radiation and thermospheric neutral winds. [Copyright &y& Elsevier]

This paper describes the experimental modelling procedure and results to evaluate the snowdrift characteristics surrounding the research station of the South African National Antarctic Expedition, SANAE IV. For this purpose a 1:25 scale model of the research station was constructed and mounted on a large flat snow covered area in the vicinity of the base. The wind profiles of the prevailing winds were measured with a 6-m wind mast positioned near the base model and the characteristic surface roughness and shear velocity functions were derived and analysed. Snow buildup was measured behind the scale model as well as the existing research station and a comparison was evaluated between the two, based on a similarity analysis. The similarity analysis method and results are presented in this paper. It is found that the surface roughness and shear velocity functions derived from the wind velocity data compares favourably with available results in literature for similar measurements of wind profiles in drifting snow conditions. From these results an inner law velocity relationship is established with additional parameters to account for the effects of surface roughness and saltating snow. It is further shown that the scaling parameters employed for the snowdrift modelling provide acceptable results when applied to outdoors modelling of snowdrifting. [Copyright &y& Elsevier]

>98% of Antarctica is covered by ice sheet with an average thickness of 2126 m. The maximum thickness is 4897 m. Several scientific deep-drilling expeditions are being conducted in Antarctica, including studies on the evolution of Earth's paleoclimate, searches for microbiological life inhabiting deep ice, estimates of Antarctic geothermal heat flux, and observations of subglacial environments. Such operations are complicated by extremely harsh environments; thus, special purpose-built drilling equipment and technology have been designed, and conventional drilling rigs have been heavily modified. Electrothermal and electromechanical drills are suspended on cables if continuous core sampling is required, and hot-water drilling systems for non-core boring are routinely used to drill deep boreholes in the Antarctic ice. The depth of the deepest hole was 3769.3 m at the Vostok Station. Projects with cable-suspended drills require a long time to complete. Hot-water drilling systems are much faster but are very heavy and bulky and consume a large amount of power. To develop lighter and energy-efficient drilling technologies, ice-drilling communities are continuously investigating innovative ice-drilling systems. This paper summarizes the current state of knowledge with respect to the design and performance of various tools and drills for deep drilling in Antarctic ice and presents prospects for improving existing drilling methods and developing new ones. [ABSTRACT FROM AUTHOR]

This paper reports zircon U–Pb geochronology, whole-rock chemistry and Sr–Nd–Hf isotopic data of intermediate-acid intrusive rocks from the Gerlache Strait area, Antarctic Peninsula. These intrusive rocks can be divided into three groups. Group #1 has an emplacement age of ca. 117 Ma, and is further subdivided according to K 2 O contents into High-K (HKS) and Low-K (LKS) Subgroups. The HKS monzogranites are weakly peraluminous, and yield ε Hf ( t ) and ε Nd ( t ) values of +0.9 to +2.3 and +0.1 to +2.3, respectively, with corresponding model Nd ages (T DM Nd ) of 766–471 Ma, indicating that they were derived from the partial melting of dominantly early Neoproterozoic to early Paleozoic juvenile basaltic materials with minor involvement of sediments. In contrast, the LKS granodioritic magma was derived from partial melting of early Paleozoic juvenile basaltic materials with ε Hf ( t ) and ε Nd ( t ) values of +10.3 to +12.5 and +5.4 to +5.5, respectively, and corresponding T DM Nd ages of 548–500 Ma. Group #2 consists of granite porphyry that formed at ca. 82 Ma and is characterized by positive values of ε Hf ( t ) (+5.1 to +8.1) and ε Nd ( t ) (+1.9 to +3.1) with weakly peraluminous chemistry and corresponding T DM Nd ages of 712–548 Ma, suggesting that it was generated from partial melting of dominantly Neoproterozoic juvenile basaltic materials with minor involvement of sediments. Group #3 comprises dioritic–granodioritic rocks that were emplaced at ca. 62–54 Ma. These rocks have Mg# values of 39–46, and ε Hf ( t ) and ε Nd ( t ) values of +6.7 to +12.2 and +3.6 to +7.2, respectively, with corresponding T DM Nd ages of 529–307 Ma, indicating that they were derived from partial melting of Paleozoic juvenile basaltic materials with minor injection of mantle materials. Spatially, the lithology of these plutons roughly changes from acid to intermediate from east to west, concomitant with increasing ε Hf ( t ) and ε Nd ( t ) values and decreasing initial 87 Sr/ 86 Sr ratios and T DM Nd ages. This trend reflects changes in source characteristics from a Gondwana affinity to a juvenile crust affinity. Overall, the southeast-to-northwest migration of magmatism in the northern Antarctic Peninsula since the Mesozoic may have been related to retreating subduction of the paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

Many telescopes are deployed in Antarctica as it offers excellent astronomical observation conditions. However, because Antarctica’s environment is harsh to humans, remote operation of telescope is necessary for observation. Furthermore, communication to devices in Antarctica through satellite link with low bandwidth and high latency limits the effectiveness of remote observation. This paper introduces a web service framework for remote astronomical observation in Antarctica. The framework is based on Python Tornado. RTS2-HTTPD and REDIS are used as the access interface to the telescope control system in Antarctica. The web service provides real-time updates through WebSocket. To improve user experience and control effectiveness under the poor satellite link condition, an agent server is deployed in the mainland to synchronize the Antarctic server’s data and send it to domestic users in China. The agent server will forward the request of domestic users to the Antarctic master server. The web service was deployed and tested on Bright Star Survey Telescope (BSST) in Antarctica. Results show that the service meets the demands of real-time, multiuser remote observation and domestic users have a better experience of remote operation. [ABSTRACT FROM AUTHOR]

This paper analyses the suitability of seas and the attractiveness of shores for the construction of submarine power interconnections. Water depth and distance between shores are considered to assess the suitability of seas, while potential for electricity consumption (estimated through population size and density) and potential for power generation from renewable energy sources are taken into account to evaluate shore favourability. Scores are attributed to these variables by using four classes of suitability. Individual scores are added to map the overall suitability of seas and shores for building submarine power interconnections. It is found that more than 20% of the global surface of seas and more than 40% of the global shore length are highly favourable. Most of the submarine power interconnections built so far are located in these highly favourable areas, confirming the validity of the presented methodology. Accordingly, the study offers a useful tool for planning submarine power interconnections, which play an increasingly important role in ongoing energy transitions. • First time an estimation of suitability of seas and shores for building submarine power interconnections is done at the global scale. • More than 20% of the global surface of seas and more than 40% of the global shore length are highly favourable. • All major landmasses of the World (except Antarctica) are interlinked at high levels of suitability. • Most of the submarine power interconnections built so far are located in these highly favourable areas. [ABSTRACT FROM AUTHOR]

Atmospheric seeing is one of the most important parameters for evaluating and monitoring an astronomical site. Moreover, being able to predict the seeing in advance can guide observing decisions and significantly improve the efficiency of telescopes. However, it is not always easy to obtain long-term and continuous seeing measurements from a standard instrument such as differential image motion monitor (DIMM), especially for those unattended observatories with challenging environments such as Dome A, Antarctica. In this paper, we present a novel machine learning-based framework for estimating and predicting seeing at a height of 8 m at Dome A, Antarctica, using only the data from a multi-layer automated weather station (AWS). In comparison with DIMM data, our estimate has a root mean square error (RMSE) of 0.18 arcsec, and the RMSE of predictions 20 min in the future is 0.12 arcsec for the seeing range from 0 to 2.2 arcsec. Compared with the persistence, where the forecast is the same as the last data point, our framework reduces the RMSE by 37 per cent. Our method predicts the seeing within a second of computing time, making it suitable for real-time telescope scheduling. [ABSTRACT FROM AUTHOR]

This paper uses conservation of marine living resources in the Arctic and Antarctica as case-studies to examine the implications of a rising China to the future governance of the polar regions. It first discusses China's positions regarding international fisheries law in the polar waters, more specifically in negotiations of 2018 Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean (CAO Agreement), and CCAMLR's process of establishing the Southern Ocean marine protected areas (MPAs). The paper then engages with norm dynamics literature on international relations to analyse what norms China promotes and resists, as well as the motives behind China's dilemma between norm-promotion versus norm-resistance. It concludes with some predictions about China's future positions in polar governance. [ABSTRACT FROM AUTHOR]

The preliminary results obtained in the first environmental radiation dosimetry campaign performed in the Antarctic region are presented. This experiment is carried out in the framework of CORA (COsmic Rays in Antarctica) Project, a collaboration between Argentine and Italian institutions. After a feasibility study performed in the Antarctic summer 2013, a new campaign has been carried out, started in March 2015, to measure various components of cosmic ray induced secondary atmospheric radiation at the Argentine Marambio Base (Antarctica; 196 m a.s.l., 64°13′ S, 56°43′ W). Due to a very few dosimetric data available in literature at high southern latitudes, accurate measurements are performed by using a set of different active and passive detectors. Special attention is dedicated to measure the neutron ambient dose equivalent in different energy ranges, by using an active detector, the Atomtex Rem Counter, for neutron energy between 0.025 eV–14 MeV and a set of passive bubble dosimeters, sensitive to thermal neutrons and neutrons in the energy range 100 keV–20 MeV. The results obtained in the first six months of measurements for X and γ radiation and for low and intermediate energy neutrons (E n ≤ 20 MeV) are presented in this paper and show that at high latitude, also at sea level and at distance from the South Magnetic Pole, the ambient dose equivalent is significant, in particular for the high contribution of neutron component. This involves that at higher altitude (i.e. Antarctic Plateau, over 3000 m a.s.l.) the yearly ambient dose equivalent could be higher than the limit of 1 mSv recommended for general public by the International Commission on Radiological Protection (ICRP). [ABSTRACT FROM AUTHOR]