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The evolution and accumulation of snow cover are among the most important characteristics influencing Antarctica's climate and biotopes. The changes in Antarctica are also substantially impacting global climate change. Therefore, detailed monitoring of snow evolution is key to understanding such changes. One way to conduct this monitoring is by installing trail cameras in a particular region and then processing the captured information. This option is affordable, but has some drawbacks, such as the fully automatic solution for the extraction of snow height from these images is not feasible. Therefore, it still requires human intervention, manually correcting the inaccurately extracted information. In this paper, we present Antarstick, a tool for visual guidance of the user to potentially wrong values extracted from poor‐quality images and support for their interactive correction. This tool allows for much quicker and semi‐automated processing of snow height from time‐lapse photography. [ABSTRACT FROM AUTHOR]

The thickness of the Antarctic ice sheet is a crucial parameter for inferring glacier mass and its evolution process. In the literature, the gravity method has been proven to be one of the effective means for estimating ice sheet thickness. And it is a preferred approach when direct measurements are not available. However, few gravity inversion methods are valid in rugged terrain areas with undulating observation surfaces (UOSs). To solve this problem, this paper proposes an improved high-precision 3D density interface inversion method considering terrain and UOSs simultaneously. The proposed method utilizes airborne gravity data at their flight altitudes, instead of the continued data yield from the unstable downward continuation procedure. In addition, based on the undulating right rectangular prism model, the large reliefs of the terrain are included in the iterative inversion. The proposed method is verified on two synthetic examples and is successfully applied to real data in East Antarctica. [ABSTRACT FROM AUTHOR]

Rabies is one of the oldest viral diseases and it has been present on every continent except Antarctica. Within the U.S. human rabies cases are quite rare. In the eastern USA, raccoons are the main reservoir hosts and pet vaccination serves as an important barrier against human rabies exposure. In this paper, we develop a compartmental model for rabies transmission amongst raccoons and domestic pets. We find the disease-free equilibria, reproduction numbers for the raccoons and domestic pets. We also determine the vaccination coverage/rates, both for raccoons and pets, needed to achieve the elimination of rabies. [ABSTRACT FROM AUTHOR]

The Antarctic Digital Magnetic Anomaly Project is an international research effort to construct a magnetic map of the continent based on ground, satellite, marine, and aeromagnetic surveys. This paper reports the magnetic mapping of the shelf zone in the SE part of the Wilhelm Archipelago, West Antarctica, based on magnetic surveys conducted with Zodiac boats. A spectacular feature of this area is the strong magnetic anomaly of the Antarctic Peninsula (AP) batholith, which was the product of subduction-related Mesozoic–Cenozoic arc magmatism on the former margin of Western Gondwana. We constructed and analyzed a detailed magnetic map of magnetic field anomalies using field observations of rock exposures on the islands and magnetic properties of rocks from laboratory data. The oldest volcanic rocks of Jurassic to Lower Cretaceous age relate to N-NE trending bands of negative magnetic field. The largest feature in the study area is an Upper Cretaceous/Paleogene granodiorite complex that produces a positive magnetic anomaly. Many smaller anomalies are also present over gabbroid bodies of Cretaceous age. Two-dimensional magnetic modeling shows that heterogeneities in the upper crust may have magnetic susceptibilities in the range of 0.005–0.13 SI. Magnetic field anomalies also delineate an orthogonal system of tectonic faults, including the main NE fault along the Penola Strait (sub-parallel to the AP coastline) and four intersecting faults. These fault systems may be associated with different stages of continental margin evolution along the Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

Increasing snow accumulation over the Antarctic Ice Sheet may mitigate future sea level rise. However, current estimates of mitigation potential are poorly constrained due to limited records of past variability. We present an annually resolved reconstruction of Antarctic snow accumulation from 1801 to 2000 CE, employing a paleoclimate data assimilation methodology to integrate ice core records with a multi‐model ensemble of climate simulations. Our reconstruction correlates well with instrumental reanalysis, and we find that Antarctic accumulation rates increased over the 20th‐century, resulting in a modest amount (∼1 mm) of sea level mitigation. Mitigation is primarily driven by an accelerating trend since around 1970. Our results contrast with previous mitigation estimates of ∼10–12 mm; this discrepancy is due to poorly constrained baseline estimates of 19th‐century accumulation in East Antarctica. Our reconstruction suggests that the uncertainty of future sea level mitigation from increasing Antarctic accumulation has been underestimated. Plain Language Summary: Ice loss from Antarctica causes sea level to rise, but Antarctica can also mitigate sea level rise if snowfall on the continent increases faster than the ice loss. There is not currently a consensus on whether Antarctica will contribute to or mitigate sea level rise in the coming century, due to a lack of Antarctic snowfall records. In this paper, we merge information from ice core records with climate models to reconstruct annual Antarctic snowfall from 1801 to 2000. We find that snowfall on Antarctica increased during the 20th‐century, but only had a modest counteracting effect of 1 mm on sea level rise in the 20th‐century, much less than a previous estimate of 10 mm. The large discrepancy is due to uncertainty in East Antarctic accumulation in the 19th‐century. The potential for Antarctica to mitigate sea level is uncertain, affecting projections for future sea level rise. Key Points: Antarctic accumulation reconstruction using paleoclimate data assimilation finds modest (∼1 mm) 20th‐century sea level mitigationWe find similar 20th‐century trends to previous work; lower sea level mitigation (1 vs. 10 mm) is due to the 19th‐century baselineUncertainty in past East Antarctic accumulation limits confidence in future projections of Antarctic sea level mitigation [ABSTRACT FROM AUTHOR]

Antarctic seaweeds are vital components of polar marine ecosystems, playing a crucial role in nutrient cycling and supporting diverse life forms. The sulfur content in these organisms is particularly interesting due to its implication in biogeochemical processes and potential impacts on local and global environmental systems. In this study, we present a comprehensive characterization of seaweed collected in the Antarctic in terms of their total sulfur content and its distribution among different classes of species, including thiols, using various methods and high-sensitivity techniques. The data presented in this paper are unprecedented in the scientific literature. These methods allowed for the determination of total sulfur content and the distribution of sulfur compounds in different fractions, such as water-soluble and proteins, as well as the speciation of sulfur compounds in these fractions, providing valuable insights into the chemical composition of these unique marine organisms. Our results revealed that the total sulfur concentration in Antarctic seaweeds varied widely across different species, ranging from 5.5 to 56 g kg−1 dry weight. Furthermore, our investigation into the sulfur speciation revealed the presence of various sulfur compounds, including sulfate, and some thiols, which were quantified in all ten seaweed species evaluated. The concentration of these individual sulfur species also displayed considerable variability among the studied seaweeds. This study provides the first in-depth examination of total sulfur content and sulfur speciation in brown and red Antarctic seaweeds. [ABSTRACT FROM AUTHOR]

This paper aims to solve the limitations of traditional gravity physical property inversion methods such as insufficient depth resolution and difficulties in parameter selection, by proposing an improved 3D gravity inversion method based on deep learning. The deep learning network model is established using the fully convolutional U-net network. To enhance the generalization ability of the sample set, the large-scale training set and test set are generated by the random walk, based on the forward theory. Founded on the traditional loss function's definition, this paper introduces an improvement incorporating a physical constraint to measure the degree of data fitting between the predicted and the real gravity data. This improvement significantly boosted the accuracy of the deep learning inversion method, as verified through both a single model and an intricate combination model. Finally, we applied this improved inversion method to the gravity data from the Gamburtsev Subglacial Mountains in the interior of East Antarctica, obtaining a comprehensive 3D crustal density structure. The results provide new evidence for the presence of a dense crustal root situated beneath the central Gamburtsev Province near the Gamburtsev Suture. [ABSTRACT FROM AUTHOR]

Surface solar radiation (SSR) is an essential factor in the flow of surface energy, enabling accurate capturing of long-term climate change and understanding of the energy balance of Earth's atmosphere system. However, the long-term trend estimation of SSR is subject to significant uncertainties due to the temporal inhomogeneity and the uneven spatial distribution of in situ observations. This paper develops an observational integrated and homogenized global terrestrial (except for Antarctica) station SSR dataset (SSRIH station) by integrating all available SSR observations, including the existing homogenized SSR results. The series is then interpolated in order to obtain a 5 ∘ × 5 ∘ resolution gridded dataset (SSRIH grid). On this basis, we further reconstruct a long-term (1955–2018) global land (except for Antarctica) SSR anomaly dataset with a 5 ∘ × 2.5 ∘ resolution (SSRIH 20CR) by training improved partial convolutional neural network deep-learning methods based on 20th Century Reanalysis version 3 (20CRv3). Based on this, we analysed the global land- (except for Antarctica) and regional-scale SSR trends and spatiotemporal variations. The reconstruction results reflect the distribution of SSR anomalies and have high reliability in filling and reconstructing the missing values. At the global land (except for Antarctica) scale, the decreasing trend of the SSRIH 20CR (- 1.276 ± 0.205 W m -2 per decade) is smaller than the trend of the SSRIH grid (- 1.776 ± 0.230 W m -2 per decade) from 1955 to 1991. The trend of the SSRIH 20CR (0.697 ± 0.359 W m -2 per decade) from 1991 to 2018 is also marginally lower than that of the SSRIH grid (0.851 ± 0.410 W m -2 per decade). At the regional scale, the difference between the SSRIH 20CR and SSRIH grid is more significant in years and areas with insufficient coverage. Asia, Africa, Europe and North America cause the global dimming of the SSRIH 20CR , while Europe and North America drive the global brightening of the SSRIH 20CR. Spatial sampling inadequacies have largely contributed to a bias in the long-term variation of global and regional SSR. This paper's homogenized gridded dataset and the Artificial Intelligence reconstruction gridded dataset (Jiao and Li, 2023) are both available at 10.6084/m9.figshare.21625079.v1. [ABSTRACT FROM AUTHOR]

Objectives: Reconstruction of ice flow velocity on the Antarctic Ice Sheet plays a critical role in estimating mass balance and contribution to global sea level rise. However, due to the low availability of optical satellite images before the 1990s, the time span of image pairs ranges from several years to more than ten years, leading to velocity overestimations. In this study, we correct the overestimated ice flow velocity based on the Lagrangian framework. After correction, we analyze the distribution of the overestimation values in the East Antarctic Ice Sheet (EAIS) according to the space and magnitude. Methods: We formulate a set of correction rules, including filtering points of ice flow velocity before correction and whether to retain results after correction. As a transition zone between grounded ice and ice shelf, ice flow velocity near the grounding line is one of the most important parameters of the ice sheet mass balance. In this paper, the overestimations of ice flow velocity are mainly studied from three aspects: First from different regions including inland region, grounding region and ice shelf region, then from different ocean sectors including Weddell Sea, West Indian Ocean, East Indian Ocean and Ross Sea, finally from different glaciers/ice shelves. Results: The average overestimation of ice flow velocity in EAIS is about 28 m/a. Both the grounding and ice shelf regions have larger overestimations than the inland region. The peak correction appears at ±25 km near the grounding line, and the maximum correction exceeds 300 m/a. As for ocean sectors, the overestimation of velocity is the largest in the East Indian Ocean. The average corrections of the Holmes Glacier, Ninnis Glacier, Publications Ice Shelf, and Totten Glacier in this sector exceed 50 m/a, much larger than that of EAIS. Conclusions: This paper shows that only a very small proportion of ice velocity points can meet the correction rules. The points show differences in regional distribution and they are concentrated mainly in the fast-flowing areas such as glaciers and ice shelves. Especially at the grounding zone and ice front areas of ice shelves, the ice flow velocity can be greatly overestimated. By analyzing the corrections and ice flow velocities in different ocean sectors, we found that the spatial acceleration trend of velocity in the East Indian Ocean is obvious and may be related to the interaction between the ocean and the ice shelves. The distribution of corrections varies among different ice shelves and glaciers. For example, Amery Ice Shelf has a larger correction at the confluence of three upstream glaciers, while Shirase Glacier has a larger correction in the inland region. The correction results in this paper have been applied to historical ice flow velocity products for East Antarctica from 1960s to 1980s. The overestimation correction of ice velocity is important for reducing the uncertainty in estimation and forecasting the contribution of Antarctic mass loss to the global sea level rise. [ABSTRACT FROM AUTHOR]

This paper presents a weakly supervised machine learning method, which we call DAS-N2N, for suppressing strong random noise in distributed acoustic sensing (DAS) recordings. DAS-N2N requires no manually produced labels (i.e. pre-determined examples of clean event signals or sections of noise) for training and aims to map random noise processes to a chosen summary statistic, such as the distribution mean, median or mode, whilst retaining the true underlying signal. This is achieved by splicing (joining together) two fibres hosted within a single optical cable, recording two noisy copies of the same underlying signal corrupted by different independent realizations of random observational noise. A deep learning model can then be trained using only these two noisy copies of the data to produce a near fully denoised copy. Once the model is trained, only noisy data from a single fibre is required. Using a data set from a DAS array deployed on the surface of the Rutford Ice Stream in Antarctica, we demonstrate that DAS-N2N greatly suppresses incoherent noise and enhances the signal-to-noise ratios (SNR) of natural microseismic icequake events. We further show that this approach is inherently more efficient and effective than standard stop/pass band and white noise (e.g. Wiener) filtering routines, as well as a comparable self-supervised learning method based on masking individual DAS channels. Our preferred model for this task is lightweight, processing 30 s of data recorded at a sampling frequency of 1000 Hz over 985 channels (approximately 1 km of fibre) in <1 s. Due to the high noise levels in DAS recordings, efficient data-driven denoising methods, such as DAS-N2N, will prove essential to time-critical DAS earthquake detection, particularly in the case of microseismic monitoring. [ABSTRACT FROM AUTHOR]

The widespread perception of New Zealand is of a group of remote islands dominated by reptiles and birds, with no native mammals except a few bats. In fact, the islands themselves are only part of a wider New Zealand Region which includes a large section of Antarctica. In total, the New Zealand Region has at least 63 recognised taxa (species, subspecies and distinguishable clades) of living native mammals, only six of which are bats. The rest comprise a large and vigorous assemblage of 57 native marine mammals (9 pinnipeds and 48 cetaceans), protected from human knowledge until only a few centuries ago by their extreme isolation in the southwestern Pacific Ocean. Even after humans first began to colonise the New Zealand archipelago in about 1280 AD, most of the native marine mammals remained unfamiliar because they are seldom seen from the shore. This paper describes the huge contrast between the history and biogeography of the tiny fauna of New Zealand's native land mammals versus the richly diverse and little-known assemblage of marine mammals. [ABSTRACT FROM AUTHOR]

The bryophytes are the second largest group of land plants and are represented by three lineages: Marchantyophyta (liverworts), Anthocerotophyta (hornworts), and Bryophyta (mosses). They occupy a wide variety of habitats, from deserts to Antarctica, and exercise great ecological importance. These facts and their wide use in traditional medicine raise the question of what is known about moss chemistry. This paper gathered studies from the last 52 years about the compounds identified in mosses, aiming to address the following questions: Are mosses chemically under-studied? How many families, genera, and species of mosses have been chemically studied? Which continent and countries have been responsible for the majority of these studies? A literature search was performed in major scientific databases, using a combination of keywords. A total of 199 papers were compiled, of which 45% were published during the last decade. Only a small percentage of moss species has been studied, mostly from Europe and Asia. Dicranales and Hypnales are the most studied orders. In general, fatty acids and flavonoids are the most commonly reported classes of compounds. Biflavonoids and triflavonoids are detected mainly in derived clades of mosses, while coumarins are most reported for basal groups. Akthough only a small percentage of moss species has been chemically studied, most of these studies were published in the last decade—there has been a 135% increase in the number of reported compounds in the last 13 years. The emergence of new equipment, which can produce high-resolution spectra with small amounts of sample, combined with bioinformatics tools, has undoubtedly contributed to the increase of chemical investigation of mosses. Also, advances in the identification and phylogenetics of moss groups are contributing to a better understanding of them generally, which should lead also to increased study of moss chemistry. [ABSTRACT FROM AUTHOR]

Antarctica is of great importance in terms of global warming, the sustainability of resources, and the conservation of biodiversity. However, due to 99.66% of the continent being covered in ice and snow, geological research and geoscientific study in Antarctica face huge challenges. Geophysical surveys play a crucial role in enhancing comprehension of the fundamental structure of Antarctica. This study used bibliometric analysis to analyze citation data retrieved from the Web of Science for the period from 1982 to 2022 with geophysical research on Antarctica as the topic. According to the analysis results, the amount of Antarctic geophysical research has been steadily growing over the past four decades as related research countries/regions have become increasingly invested in issues pertaining to global warming and sustainability, and international cooperation is in sight. Moreover, based on keyword clustering and an analysis of highly cited papers, six popular research topics have been identified: Antarctic ice sheet instability and sea level change, Southern Ocean and Sea Ice, tectonic activity of the West Antarctic rift system, the paleocontinental rift and reorganization, magmatism and volcanism, and subglacial lakes and subglacial hydrology. This paper provides a detailed overview of these popular research topics and discusses the applications and advantages of the geophysical methods used in each field. Finally, based on keywords regarding abrupt changes, we identify and examine the thematic evolution of the nexus over three consecutive sub-periods (i.e., 1990–1995, 1996–2005, and 2006–2022). The relevance of using geophysics to support numerous and diverse scientific activities in Antarctica becomes very clear after analyzing this set of scientific publications, as is the importance of using multiple geophysical methods (satellite, airborne, surface, and borehole technology) to revolutionize the acquisition of new data in greater detail from inaccessible or hard-to-reach areas. Many of the advances that they have enabled be seen in the Antarctic terrestrial areas (detailed mapping of the geological structures of West and East Antarctica), ice, and snow (tracking glaciers and sea ice, along with the depth and features of ice sheets). These valuable results help identify potential future research opportunities in the field of Antarctic geophysical research and aid academic professionals in keeping up with recent advances. [ABSTRACT FROM AUTHOR]

The NASA Atmospheric Tomography Mission (ATom) completed four seasonal deployments (August 2016, February 2017, October 2017, May 2018), each with regular 0.2–12 km profiling by transecting the remote Pacific Ocean and Atlantic Ocean basins. Additional data were also acquired for the Southern Ocean, the Arctic basin, and two flights over Antarctica. ATom in situ measurements provide a near-complete chemical characterization of the ∼ 140 000 10 s (80 m by 2 km) air parcels measured along the flight path. This paper presents the Modeling Data Stream (MDS), a continuous gap-filled record of the 10 s parcels containing the chemical species needed to initialize a gas-phase chemistry model for the budgets of tropospheric ozone and methane. Global 3D models have been used to calculate the Reactivity Data Stream (RDS), which is comprised of the chemical reactivities (production and loss) for methane, ozone, and carbon monoxide, through 24 h integration of the 10 s parcels. These parcels accurately sample tropospheric heterogeneity and allow us to partially deconstruct the spatial scales and variability that define tropospheric chemistry from composition to reactions. This paper provides a first look at and analysis of the up-to-date MDS and RDS data including all four deployments (Prather et al., 2023, 10.7280/D1B12H). ATom's regular profiling of the ocean basins allows for weighted averages to build probability densities for the key species and reactivities presented here. These statistics provide climatological metrics for global chemistry models, e.g., the large-scale pattern of ozone and methane loss in the lower troposphere and the more sporadic hotspots of ozone production in the upper troposphere. The profiling curtains of reactivity also identify meteorologically variable and hence deployment-specific hotspots of photochemical activity. Added calculations of the sensitivities of the production and loss terms relative to each species emphasize the few dominant species that control the ozone and methane budgets and whose statistical patterns should be key model–measurement metrics. From the sensitivities, we also derive linearized lifetimes of ozone and methane on a parcel-by-parcel basis and average over the basins, providing an observational basis for these previously model-only diagnostics. We had found that most model differences in the ozone and methane budgets are caused by the models calculating different climatologies for the key species such as O 3 , CO, H 2 O, NO x , CH 4 , and T , and thus these ATom measurements make a substantial contribution to the understanding of model differences and even identifying model errors in global tropospheric chemistry. [ABSTRACT FROM AUTHOR]

Surface solar radiation (SSR) is an essential factor in the flow of surface energy, enabling accurate capturing of long-term climate change and understanding the energy balance of Earth's atmosphere system. However, the long-term trend estimation of SSR is subjected to significant uncertainties due to the temporal inhomogeneity and the uneven spatial distribution of the in-situ observations. This paper develops an observational integrated and homogenized global-terrestrial (except for Antarctica)) stational SSR dataset (SSRIHstation) by integrating all available SSR observations, including the existing homogenized SSR results. The series are then interpolated in order to obtain a 5°×5° resolution gridded dataset (SSRIHgrid). On this basis, we further reconstruct a long-term (1955-2018) global land (except for Antarctica) SSR anomalies dataset with a 5°×2.5° resolution (SSRIH20CR) by training improved partial convolutional neural network deep learning methods based on the reanalysis 20CRv3. Based on this, we analysed the global land (except for Antarctica)/regional scale SSR trends and spatiotemporal variations: the reconstruction results reflect the distribution of SSR anomalies and have high reliability in filling and reconstructing the missing values. At the global land (except for Antarctica) scale, the decreasing trend of the SSRIH20CR (-1.276±0.205 W/m2 per decade) is slightly smaller than the trend of the SSRIHgrid (- 1.776±0.230 W/m2 per decade) from 1955 to 1991. The trend of SSRIH20CR (0.697±0.359 W/m2 per decade) from 1991 to 2018 is also marginally lower than that of the SSRIHgrid (0.851±0.410 W/m2 per decade). At the regional scale, the difference between the SSRIH20CR and SSRIHgrid is more significant in years and areas with insufficient coverage. Asia, Africa, Europe and North America cause the global dimming of the SSRIH20CR, while Europe and North America drive the global brightening of the SSRIH20CR. Spatial sampling inadequacies have largely contributed to a bias in the long-term variation of global/regional SSR. This paper's homogenized gridded dataset and the Artificial Intelligence reconstruction gridded dataset (Jiao and Li, 2023) are all available at. [ABSTRACT FROM AUTHOR]

The NASA Atmospheric Tomography (ATom) Mission completed four seasonal deployments (August 2016, February 2017, October 2017, May 2018), each with regular 0.2-12 km profiling through transecting the remote Pacific and Atlantic Ocean basins. Additional data are acquired also for the Southern Ocean and Artic basin, as well as two flights over Antarctica. ATom in situ measurements provide a near-complete chemical characterization of the ~140,000 10-second (80 m by 2 km) air parcels measured along the flight path. This paper presents the Modeling Data Stream (MDS), a continuous gap-filled record of the 10-s parcels containing the chemical species needed to initialize a gas-phase chemistry model for the budgets of tropospheric ozone and methane. Global 3D models have been used to calculate the Reactivity Data Stream RDS), which is comprised of the chemical reactivities (production and loss) for methane, ozone, and carbon monoxide, through 24-hour integration of the 10-s parcels. These parcels accurately sample tropospheric heterogeneity and allow us to partially deconstruct the spatial scales and variability that defines tropospheric chemistry from composition to reactions. This paper provides a first look and analysis of the up-to-date MDS and RDS data including all four deployments (Prather et al., 2023, doi: 10.7280/D1B12H). ATom's regular profiling of the ocean basins allows for weighted averages to build probability densities for key species and reactivities presented here. These statistics provide climatological metrics for global chemistry models, for example, the large-scale pattern of ozone and methane loss in the lower troposphere, and the more sporadic hot spots of ozone production in the upper troposphere. The profiling curtains of reactivity also identify meteorologically variable and hence deploymentspecific hot spots of photochemical activity. Added calculations of the sensitivities of the production and loss terms relative to each species emphasize the few dominant species that control the ozone and methane budgets, and whose statistical patterns should be key model-measurement metrics. From the sensitivities, we also derive linearized lifetimes of ozone and methane on a parcel-by-parcel basis and average over the basins, providing an observational basis for these previously model-only diagnostics. We had found that most model differences in the ozone and methane budgets are caused by the models calculating different climatologies for the key species such as O3, CO, H2O, NOx, CH4 plus T, and thus these ATom measurements provide a substantial contribution to the understanding of model differences and even identifying model errors in global tropospheric chemistry. [ABSTRACT FROM AUTHOR]

As the climate warms, the grounded ice sheet and floating ice shelves surrounding Antarctica are melting and releasing additional freshwater into the Southern Ocean. Nonetheless, almost all existing coupled climate models have fixed ice sheets and lack the physics required to represent the dominant sources of Antarctic melt. These missing ice dynamics represent a key uncertainty that is typically unaccounted for in current global climate change projections. Previous modelling studies that have imposed additional Antarctic meltwater have demonstrated regional impacts on Southern Ocean stratification, circulation, and sea ice, as well as remote changes in atmospheric circulation, tropical precipitation, and global temperature. However, these previous studies have used widely varying rates of freshwater forcing, have been conducted using different climate models and configurations, and have reached differing conclusions on the magnitude of meltwater–climate feedbacks. The Southern Ocean Freshwater Input from Antarctica (SOFIA) initiative brings together a team of scientists to quantify the climate system response to Antarctic meltwater input along with key aspects of the uncertainty. In this paper, we summarize the state of knowledge on meltwater discharge from the Antarctic ice sheet and ice shelves to the Southern Ocean and explain the scientific objectives of our initiative. We propose a series of coupled and ocean–sea ice model experiments, including idealized meltwater experiments, historical experiments with observationally consistent meltwater input, and future scenarios driven by meltwater inputs derived from stand-alone ice sheet models. Through coordinating a multi-model ensemble of simulations using a common experimental design, open data archiving, and facilitating scientific collaboration, SOFIA aims to move the community toward better constraining our understanding of the climate system response to Antarctic melt. [ABSTRACT FROM AUTHOR]

The annular structure of Antarctic oscillation (AAO) is a research hotpot, but its asymmetry receives less attention. In this paper, the self‐organizing map method is employed to cluster the AAO patterns into symmetric and asymmetric modes in austral autumn. The asymmetry is mainly reflected in the Pacific‐Atlantic sector, and the AAO evolves toward asymmetric positive polarity, with the most pronounced asymmetry in May. Originating from near Australia, the asymmetry indicates a zonal wave train in the Pacific‐Atlantic sector. Both modeled and observed results demonstrate that the sea surface temperature anomaly in the equatorial western Pacific stimulates a local meridional circulation anomaly and induces anomalous Rossby wave sources near Australia subsequently. An anomalous wave train propagating toward the Antarctic Peninsula is formed, and the associated geopotential anomaly enhances the asymmetry of AAO. Asymmetric AAO is conducive to the Antarctic dipole, which modulates the air temperature and sea ice anomalies around Antarctica. Plain Language Summary: The zonal symmetry of the Antarctic oscillation (AAO; also named southern annular mode) is well known to researchers, while the zonal asymmetry has received less attention. We use a clustering method to cluster the AAO modes in austral autumn into symmetric modes and asymmetric modes. The asymmetry of AAO is mainly reflected in the Pacific‐Atlantic sector. The results show that the AAO mode evolves to a positive asymmetric mode, and the asymmetry is most obvious in May. Both simulations and observations suggest that this asymmetry stems from sea surface temperature anomaly in the equatorial western Pacific that stimulates an anomalous local meridional circulation near Australia, and in turn triggers an anomalous wave train propagating toward the Antarctic Peninsula. The associated geopotential anomalies enhance the asymmetry of AAO. The asymmetric AAO favors the Antarctic dipole, regulating the air temperature and sea ice anomalies around Antarctica. Key Points: Via a cluster method, we obtained the zonal asymmetric Antarctic oscillation (AAO) mode, and analyzed its trend and preferred monthThe source of its asymmetry is from the sea surface temperature anomaly in the tropical western PacificThe asymmetric AAO mode has a vital influence on the Antarctic dipole [ABSTRACT FROM AUTHOR]

Orbital precession has been linked to glacial cycles and the atmospheric carbon dioxide (CO2) concentration, yet the direct impact of precession on the carbon cycle is not well understood. We analyze output from an Earth system model configured under different orbital parameters to isolate the impact of precession on air‐sea CO2 flux in the Southern Ocean—a component of the global carbon cycle that is thought to play a key role on past atmospheric CO2 variations. Here, we demonstrate that periods of high precession are coincident with anomalous CO2 outgassing from the Southern Ocean. Under high precession, we find a poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2 along the core of the Antarctic Circumpolar Current. These results suggest that orbital precession may have played an important role in driving changes in atmospheric CO2. Plain Language Summary: Over the past one million years, Earth has experienced several glacial and interglacial periods. As a glacial period is ending, carbon in the atmosphere can rise by up to 50%. The cause for this change is currently unknown, but most theories suggest that this carbon is released from the deep ocean into the atmosphere. The Southern Ocean surrounding Antarctica is the location of a lot of carbon outgassing from the deep ocean into the atmosphere, so it could be responsible for some of this change in atmospheric carbon. One of Earth's orbital cycles, precession, has been shown to change circulation in the Southern Ocean, that can affect how much carbon is carried from the deep ocean to the surface and released into the atmosphere. This paper uses simulations of a climate model to show that high precession corresponds to a 20% increase in the release of carbon from the Southern Ocean into the atmosphere. These findings suggest that precession could have affected changes in past atmospheric carbon concentrations. Key Points: Increased insolation during austral summer due to orbital precession shifts the southern westerlies polewardPoleward shifted westerlies enhance CO2 outgassing due to increased turbulent exchange and vertical transport of carbon‐rich watersEnhanced transport of carbon‐rich waters is driven by a deepening of the overturning circulation in response to poleward shifted winds [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 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]

The science enabled by the deep and high‐cadence survey that will be performed by the Vera Rubin Observatory has led to an increase of survey and follow‐up capabilities around the world. The infrared, has however, not match this growth due to the challenges caused by the atmospheric and the cost of large detector arrays. In this paper, we present solutions to resolve these challenges and a path toward an Antarctic observatory capable matching the volumetric speed of the Vera Rubin Observatory survey in the infrared k‐band. We will detail the current state of infrared survey telescopes, demonstrate the benefits of Antarctic high‐plateau for such observations, and show some of the development made in detector technologies to make large detector arrays a reality for such application. [ABSTRACT FROM AUTHOR]

This is one of the first papers to study the ionospheric effects of two solar eclipses that occurred in South America and Antarctica under geomagnetic activity in different seasons (summer and autumn) and their impact on the equatorial ionization anomaly (EIA). The changes in total electron content (TEC) during the 15 February 2018 and 30 April 2022 partial solar eclipses will be analyzed. The study is based on more than 390 GPS stations, Swarm-A, and DMSP F18 satellite measurements, such as TEC, electron density, and electron temperature. The ionospheric behaviors over the two-fifth days on both sides of each eclipse were used as a reference for estimating TEC changes. Regional TEC maps were created for the analysis. Background TEC levels were significantly higher during the 2022 eclipse than during the 2018 eclipse because ionospheric levels depend on solar index parameters. On the days of the 2018 and 2022 eclipses, the ionospheric enhancement was noticeable due to levels of geomagnetic activity. Although geomagnetic forcing impacted the ionosphere, both eclipses had evident depletions under the penumbra, wherein differential vertical TEC (DVTEC) reached values <−40%. The duration of the ionospheric effects persisted after 24 UT. Also, while a noticeable TEC depletion (DVTEC ∼−50%) of the southern EIA crest was observed during the 2018 eclipse (hemisphere summer), an evident TEC enhancement (DVTEC > 30%) at the same crest was seen during the eclipse of 2022 (hemisphere autumn). Swarm-A and DMSP F18 satellite measurements and analysis of other solar eclipses in the sector under quiet conditions supported the ionospheric behavior. [ABSTRACT FROM AUTHOR]

Satellite data have revealed that the Greenland and Antarctic Ice Sheets are changing rapidly due to warming air and ocean temperatures. Crucially, Earth Observations can now be used to measure ice sheet mass balance at the continental scale, which can help reduce uncertainties in the ice sheets' past, present, and future contributions to global mean sea level. The launch of satellite missions dedicated to the polar regions led to great progress towards a better assessment of the state of the ice sheets, which, in combination with ice sheet models, have furthered our understanding of the physical processes leading to changes in the ice sheets' properties. There is now a three-decade-long satellite record of Antarctica and Greenland mass changes, and new satellite missions are planned to both continue this record and further develop our observational capabilities, which is critical as the ice sheets remain the most uncertain component of future sea-level rise. In this paper, we review the mechanisms leading to ice sheets' mass changes and describe the state of the art of the satellite techniques used to monitor Greenland's and Antarctica's mass balance, providing an overview of the contributions of Earth Observations to our knowledge of these vast and remote regions. [ABSTRACT FROM AUTHOR]

The solar corona is the outer layer of the Sun's atmosphere. The brightness of the solar corona is a million times lower than that of the solar disk. The Earth's sky brightness itself is high enough to cover the coronal signal during ground-based observations. For this reason, the study of sky characteristics plays a fundamental role in observing the solar corona. To date, the only place with the sky characteristics that allow continuous coronagraphic measurements from Earth is at the MLO (Mauna Loa Observatory; Hawaii, ≈ 3400 m above sea level). This paper shows the results obtained as part of the "Extreme Solar Coronagraphy Antarctic Program Experiment" (ESCAPE) at Concordia Base, Antarctica (Dome C plateau-coord.: 75∘06′ S, 123∘20′ E, ≈ 3300 m above sea level) during the 37th campaign and gives a summary of all the sky-brightness measurements obtained from this site (34th and 35th campaigns). Dome C is confirmed to be a coronagraphic site with a sky brightness of about 1 × 10 − 6 B ⊙ . For the first time, it was also possible to detect a coronal signal and to compare it with what was measured by the COronal Solar Magnetism Observatory (COSMO) K-coronagraph (K-Cor) at the MLO. All these results were obtained by using a micropolarizer camera mounted within a coronagraph designed for Antarctic environments. [ABSTRACT FROM AUTHOR]

Contemporary archaeology brings a unique perspective from which to critically think about Antarctic Treaty System conservation policies and practices concerning material things. The paper begins by highlighting how they have relied on several underlying assumptions, which we summarise as the 'wilderness' and 'heritage' principles. It then discusses how these policies and practices have often led to non‐sustainable or non‐inclusive outcomes. In particular, the application of the wilderness and heritage principles to environmental conservation has, on the one hand, reinforced the dominant images and narratives of Antarctica, selectively neglecting and erasing diverse human and non‐human stories, and on the other hand, led to human–thing entanglements that are currently difficult to overcome. The paper's conclusions encourage readers to envision more inclusive and sustainable conservation models by challenging the assumptions underlying current policies and practices. [ABSTRACT FROM AUTHOR]

This paper explores whether a central plank of the Antarctic Treaty System (ATS) – the science criterion – is threatened by anthropogenic climate change. It begins by situating the origins of the ATS within the context of the International Geophysical Year (IGY), and the privileged position that science obtained within first the IGY and later the ATS. This extends to science functioning as the dominant currency through which states may ascend to the level of consultative parties (CPs), the highest level of authority within the ATS. Within this model Antarctica functions as a laboratory, a metaphor with a long history in Antarctica, reinforced by the Madrid Protocol and its strong focus on maintaining environmental boundaries and by a perception that Antarctica otherwise plays a minimal role in global affairs. Much of the research in Antarctica focuses on climate change and indeed has been important in establishing its scope and magnitude. But climate change also threatens both Antarctica itself and – by extension – the many low‐lying areas of the world that would be affected by rising sea levels caused by melting Antarctic ice. Given Antarctica may no longer be so removed from the rest of the world, is this sufficient reason to revisit the centrality of science to legitimate participation in Antarctic governance? The paper considers alternatives to the current system, including assigning authority within the ATS to states affected by climate change. It concludes that while the science criterion remains viable, it rests on a moral as well as practical foundation that could be undermined if the right to authority over Antarctica remains disconnected from the actions that cause changes to the continent. Science is the privileged currency for participating in Antarctic governance. Anthropogenic climate change threatens this by reframing Antarctica as a conduit through which harms flow rather than an isolated laboratory. Consequently the moral bases for the place of science in Antarctic governance should be re‐examined. [ABSTRACT FROM AUTHOR]

In this paper, we study the problem of extracting trends from time series data involving missing values. In particular, we investigate a general class of procedures that impute the missing data and then extract trends using seasonal-trend decomposition based on loess (STL), where loess stands for locally weighted smoothing, a popular tool for describing the regression relationship between two variables by a smooth curve. We refer to them as the imputation-STL procedures. Two results are obtained in this paper. First, we settle a theoretical issue, namely the connection between imputation error and the overall error from estimating the trend. Specifically, we derive the bounds for the overall error in terms of the imputation error. This subsequently facilitates the error analysis of any imputation-STL procedure and justifies its use in practice. Second, we investigate loess-STL, a particular imputation-STL procedure with the imputation also being performed using loess. Through both theoretical arguments and simulation results, we show that loess-STL has the capacity of handling a high proportion of missing data and providing reliable trend estimates if the underlying trend is smooth and the missing data are dispersed over the time series. In addition to mathematical derivations and simulation study, we apply our loess-STL procedure to profile radiosonde records of upper air temperature at 22 Antarctic research stations covering the past 50 years. For purpose of illustration, we present in this paper only the results for Novolazaravskaja station which has temperature records with more than 8.4% dispersed missing values at 8 pressure levels from October/1969 to March/2011. [ABSTRACT FROM AUTHOR]

This is the first comprehensive review of marine mammal records from the Haswell archipelago (Davis Sea, East Antarctica), collected in 1912-2016. The goal of the review is to provide baseline ecological and faunal information on the marine mammals during the historical period (species diversity and status). Eight marine mammal species were recorded within the survey area. Ross seals (Ommatophoca rossii) and sei whales (Balaenoptera borealis) were seen very rarely. Killer whales (Orcinus orca), southern elephant seals (Mirounga leonina) and leopard seals (Hydrurga leptonyx) appeared rarely and few in numbers. Crabeater seals (Lobodon carcinophaga) were rare in general but common during the rare seasons of early fast ice breaking. Weddell seals (Leptonychotes weddellii) were common year-round. Antarctic minke whales (Balaenoptera bonaerensis) were seasonally common. Weddell seals and Antarctic minke whales were recorded annually. Only Weddell seals were found year-round. Leopard seals were seasonal residents, the remaining species were seasonal visitors in the area. The archipelago is an annual breeding site for Weddell seals (up to 10 pups per breeding season). Rare breeding of crabeater seals is possible. The information presented in this paper was obtained mostly through random observations and few historical records. During the long-term monitoring, a single agreed-upon data collection protocol was not used. As a result, the status of each marine mammal species in this paper should be regarded as preliminary. The review represents a basis for the development of further research programs. A unified protocol for the year-round registration of marine mammals under the conditions of the Mirny Station for the program for monitoring the biota of the Haswell archipelago is proposed. [ABSTRACT FROM AUTHOR]

Antarctic mapping with satellite images is an important basic task for polar environmental monitoring. Since the first Chinese marine satellite was launched in 2002, China has formed three series of more than 10 marine satellites in orbit. As global operational monitoring satellites of ocean color series, HY-1C and HY-1D have good coverage characteristics and imaging performance in polar regions, and they provide an effective tool for Antarctic monitoring and mapping. In this paper, Antarctic images acquired by the HY-1 satellite Coastal Zone Imager (CZI) sensor were used to study color matching in the mosaic process. According to the CZI characteristics for Antarctic imaging, experiments were carried out on the illuminance nonuniformity of a single image and color registration of multiple images. A gray-level segmentation color-matching method is proposed to solve the problem of image overstretching in the Antarctic image color-matching process. The results and statistical analysis show that the proposed method can effectively eliminate the color deviation between HY-1 Antarctic images, and the mosaic results have a good effect. [ABSTRACT FROM AUTHOR]

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

A chain of magnetometers has been placed in Antarctica for comparisons with magnetic field measurements taken in the Northern Hemisphere. The locations were chosen to be on magnetic field lines that connect to magnetometers on the western coast of Greenland, despite the difficulty of reaching and working at such remote locations. We report on some basic comparisons of the similarities and differences in the conjugate measurements. Our results presented here confirm that the conjugate sites do have very similar (symmetric) magnetic perturbations in a handful of cases, as expected. Sign reversals are required for two components in order to obtain this agreement, which is not commonly known. More frequently, a strong Y component of the Interplanetary Magnetic Field (IMF) breaks the symmetry, as well as the unequal conductivities in the opposite hemispheres, as shown in two examples. In one event the IMF Y component reversed signs twice within 2 hours, while the magnetometer chains were approaching local noon. This switch provided an opportunity to observe the effects at the conjugate locations and to measure time lags. It was found that the magnetic fields at the most poleward sites started to respond to the sudden IMF reversals 20 min after the IMF reaches the bow shock, a measure of the time it takes for the electromagnetic signal to travel to the magnetopause, and then along magnetic field lines to the polar ionospheres. An additional 9–14 min is required for the magnetic perturbations to complete their transition. Plain Language Summary: Space science research has long relied on magnetometer measurements in the Northern Hemisphere to detect and observe the flow of currents in the ionosphere and magnetosphere. In the past few years it has become possible to acquire magnetic field measurements in the southern polar region as well, as a result of the placement of a chain of magnetometer stations in a remote part of Antarctica. Each of these magnetometers were placed where the Earth's magnetic field connects to an existing magnetometer in the Northern Hemisphere, on the western coast of Greenland. The locations follow a roughly north‐south meridian in geomagnetic coordinates. These "conjugate" magnetometer chains are useful for observing the similarities and differences between the ionospheric currents flowing in opposite hemispheres as a result of the solar wind's interaction with the Earth's magnetosphere. This paper presents results showing how the inter‐hemispheric measurements are very similar in some cases, but only if the signs of two of the vector components are reversed. In other cases the magnetic fields in the two polar hemispheres are different, mainly due to the summer‐winter differences in conductivity. The conjugate measurement will be useful for future space science research. Key Points: Magnetic field measurements are obtained from magnetic conjugate points in both hemispheresUnder optimal conditions the conjugate magnetic fields are very similar, with signs reversed on two components due to coordinate geometriesMore often the fields differ due to different seasonal conductivities and asymmetrical driving by the magnetic field in the solar wind [ABSTRACT FROM AUTHOR]

Abstract—This paper presents numerous new data on the geochemical composition of olivine, clinopyroxene, and leucite phenocrysts, as well as spinel inclusions in olivine and quench glass from lamproites of Gaussberg volcano (East Antarctica). Most of the olivine phenocrysts in the Gaussberg lamproites are high Mg varieties (Fo89–91) with elevated Ni contents (up to 4900 ppm) and high Ni/Co ratios. According to data of about 320 clinopyroxene analyses, two groups of diopsidic phenocrysts have been established. Group I consists mainly of high-Mg varieties (Mg#>80), while group II clinopyroxenes are less magnesian (Mg# 52–80). The main difference between the clinopyroxenes of the two groups is the elevated contents of Al2O3, FeO and reduced TiO2, Cr2O3, and NiO in the compositions of group II compared to group I, as well as different contents of trace elements, which may reflect their crystallization from different types of primary melts. According to the study of ~550 grains of leucite phenocrysts in the Gaussberg lamproites, it was shown that they correspond to the ideal stoichiometry of leucite K[AlSi2O6] and are enriched in Na2O (0.05–0.35 wt %), but depleted in K2O (19.9–20.9 wt %) compared to leucites from lamproites of other provinces. The BaO content reaches 0.3 wt %, SrO –0.04 wt %. The iron content in most leucite phenocrysts varies within 0.7–1.2 wt % Fe2O3, but some grains have the low Fe2O3 contents (<0.5 wt %). In leucite microlites of the groundmass and rims of phenocrysts, the Fe2O3 content can reach 2.4 wt %, which may indicate more oxidized conditions at lava eruption. Based on the study of natural samples, existing experimental data and numerical models, the order and conditions of crystallization of the Gaussberg lamproites were obtained. Crystallization proceeded in the following order: chromian spinel → chromian spinel + olivine → olivine + leucite (± chromian spinel) → olivine + leucite + clinopyroxene (± chromian spinel). The near-liquidus assemblage represented by high-Mg olivine phenocrysts with inclusions of Cr-spinel was formed in the temperature range from 1180 to 1250°C. Further crystallization of the melt with the formation of an association of olivine+leucite+clinopyroxene phenocrysts could occur at pressures below 2 GPa and temperatures of 1070–1180°C, corresponding to the presence of water in the magmatic system. Estimates of the redox conditions of crystallization of lamproites obtained using different oxybarometers vary in a wide range from QFM-0.5 to QFM+2.3. The elevated Ni contents in liquidus olivines of Gaussberg indicate the high nickel contents in the source. It is shown that the formation of ultra-alkaline magmas in the Gaussberg volcano area is likely related to melting of the continental lithosphere, which was heterogeneous and included both the peridotite mantle and hydrous pyroxenite fragments. [ABSTRACT FROM AUTHOR]

Observations of ocean-driven grounding-line retreat in the Amundsen Sea Embayment in Antarctica raise the question of an imminent collapse of the West Antarctic Ice Sheet. Here we analyse the committed evolution of Antarctic grounding lines under the present-day climate. To this aim, we first calibrate a sub-shelf melt parameterization, which is derived from an ocean box model, with observed and modelled melt sensitivities to ocean temperature changes, making it suitable for present-day simulations and future sea level projections. Using the new calibration, we run an ensemble of historical simulations from 1850 to 2015 with a state-of-the-art ice sheet model to create model instances of possible present-day ice sheet configurations. Then, we extend the simulations for another 10 000 years to investigate their evolution under constant present-day climate forcing and bathymetry. We test for reversibility of grounding-line movement in the case that large-scale retreat occurs. In the Amundsen Sea Embayment we find irreversible retreat of the Thwaites Glacier for all our parameter combinations and irreversible retreat of the Pine Island Glacier for some admissible parameter combinations. Importantly, an irreversible collapse in the Amundsen Sea Embayment sector is initiated at the earliest between 300 and 500 years in our simulations and is not inevitable yet – as also shown in our companion paper Part 1,. In other words, the region has not tipped yet. With the assumption of constant present-day climate, the collapse evolves on millennial timescales, with a maximum rate of 0.9 mma-1 sea-level-equivalent ice volume loss. The contribution to sea level by 2300 is limited to 8 cm with a maximum rate of 0.4 mma-1 sea-level-equivalent ice volume loss. Furthermore, when allowing ice shelves to regrow to their present geometry, we find that large-scale grounding-line retreat into marine basins upstream of the Filchner–Ronne Ice Shelf and the western Siple Coast is reversible. Other grounding lines remain close to their current positions in all configurations under present-day climate. [ABSTRACT FROM AUTHOR]

Theoretical and numerical work has shown that under certain circumstances grounding lines of marine-type ice sheets can enter phases of irreversible advance and retreat driven by the marine ice sheet instability (MISI). Instances of such irreversible retreat have been found in several simulations of the Antarctic Ice Sheet. However, it has not been assessed whether the Antarctic grounding lines are already undergoing MISI in their current position. Here, we conduct a systematic numerical stability analysis using three state-of-the-art ice sheet models: Úa, Elmer/Ice, and the Parallel Ice Sheet Model (PISM). For the first two models, we construct steady-state initial configurations whereby the simulated grounding lines remain at the observed present-day positions through time. The third model, PISM, uses a spin-up procedure and historical forcing such that its transient state is close to the observed one. To assess the stability of these simulated states, we apply short-term perturbations to submarine melting. Our results show that the grounding lines around Antarctica migrate slightly away from their initial position while the perturbation is applied, and they revert once the perturbation is removed. This indicates that present-day retreat of Antarctic grounding lines is not yet irreversible or self-sustained. However, our accompanying paper (Part 2,) shows that if the grounding lines retreated further inland, under present-day climate forcing, it may lead to the eventual irreversible collapse of some marine regions of West Antarctica. [ABSTRACT FROM AUTHOR]

Solid precipitation measurements in Antarctica are crucial as snowfall represents the main water input term for the polar cap, and its probable increase in the coming century can mitigate sea-level rise caused by global warming. This paper presents 7 years of Micro Rain Radar (Metek MRR-2) data at the Dumont d'Urville station in coastal Adélie Land, East Antarctica. Statistics are calculated on 3 radar variables (equivalent reflectivity, mean Doppler velocity and signal-to-noise ratio) to outline the main characteristics of the radar dataset. Seasonal and interannual variabilities are also investigated, but no significant temporal trends are detected except for the seasonal mean Doppler velocity which is higher in summer and lower in winter. We then use the snowfall rate (S) data from a colocated snow-gauge to estimate the MRR precipitation profile from the radar equivalent reflectivity (Ze) through a locally derived Ze-S relation. We find the relation Ze = 43.3 S0.88. The processing method used to obtain this relation, data quality and uncertainty considerations are discussed in the manuscript. In order to give an example of application of the dataset, a brief statistical comparison of the MRR precipitation rate along the vertical with model data from the ERA5 reanalysis and the LMDZ climate model is performed, and notably shows that models underestimate heavy precipitation events. [ABSTRACT FROM AUTHOR]

Large-ensemble modelling has become an increasingly popular approach to studying the mean climate and the climate system's internal variability in response to external forcing. Here we present the Royal Netherlands Meteorological Institute (KNMI) Large Ensemble Time Slice (KNMI–LENTIS): a new large ensemble produced with the re-tuned version of the global climate model EC-Earth3. The ensemble consists of two distinct time slices of 10 years each: a present-day time slice and a +2 K warmer future time slice relative to the present day. The initial conditions for the ensemble members are generated with a combination of micro- and macro-perturbations. The 10-year length of a single time slice is assumed to be too short to show a significant forced climate change signal, and the ensemble size of 1600 years (160 × 10 years) is assumed to be sufficient to sample the full distribution of climate variability. The time slice approach makes it possible to study extreme events on sub-daily timescales as well as events that span multiple years such as multi-year droughts and preconditioned compound events. KNMI–LENTIS is therefore uniquely suited to study internal variability and extreme events both at a given climate state and resulting from forced changes due to external radiative forcing. A unique feature of this ensemble is the high temporal output frequency of the surface water balance and surface energy balance variables, which are stored in 3-hourly intervals, allowing for detailed studies into extreme events. The large ensemble is particularly geared towards research in the land–atmosphere domain. EC-Earth3 has a considerable warm bias in the Southern Ocean and over Antarctica. Hence, users of KNMI–LENTIS are advised to make in-depth comparisons with observational or reanalysis data, especially if their studies focus on ocean processes, on locations in the Southern Hemisphere, or on teleconnections involving both hemispheres. In this paper, we will give some examples to demonstrate the added value of KNMI–LENTIS for extreme- and compound-event research and for climate-impact modelling. [ABSTRACT FROM AUTHOR]

This paper presents work using a machine learning model to diagnose Antarctic blowing snow (BLSN) properties with the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), data. We adopt the random forest classifier for BLSN identification and the random forest regressor for BLSN optical depth and height diagnosis. BLSN properties observed from the Cloud--Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used as the truth for training the model. Using MERRA-2 fields such as snow age, surface elevation and pressure, temperature, specific humidity, and temperature gradient at the 2-m level, and wind speed at the 10-m level as input, reasonable results are achieved. Hourly blowing snow property diagnostics are generated with the trained model. Using 2010 as an example, it is shown that the Antarctic BLSN frequency is much higher over East than West Antarctica. High-frequency months are from April to September, during which BLSN frequency exceeds 20% over East Antarctica. For May 2010, the BLSN snow frequency in the region is as high as 37%. Due to the suppression by strong surface-based inversions, larger values of BLSN height and optical depth are usually limited to the coastal regions, wherein the strength of surface-based inversions is weaker. [ABSTRACT FROM AUTHOR]

Abstract—The paper discusses the spatial distribution of the main parameters of primary production in the Bransfield Strait in the austral summer. The integrated primary production in the strait varied from 435 to 741 mgC m–2 day–1. The share of primary production in the total production of phyto- and bacterioplankton in the upper 10 m layer was 82–91%. Potential photosynthetic capacity (Fv/Fm) was high within the euphotic layer (0.418–0.749) throughout the area. The production parameters in the two main water masses in the strait did not differ. Photosynthetic efficiency (the ratio of the assimilation number and the relative electron transport rate, AN/rETR) varied in different subregions of the study area by almost six times. [ABSTRACT FROM AUTHOR]

During the recent four decades since 1980, a series of modern climate satellites were launched, allowing for the measurement and record-keeping of multiple climate parameters, especially over the polar regions where traditional observations are difficult to obtain. China has been actively engaging in polar expeditions. Many observations were conducted during this period, accompanied by improved Earth climate models, leading to a series of insightful understandings concerning Arctic and Antarctic climate changes. Here, we review the recent progress China has made concerning Arctic and Antarctic climate change research over the past decade. The Arctic temperature increase is much higher than the global-mean warming rate, associated with a rapid decline in sea ice, a phenomenon called the Arctic Amplification. The Antarctic climate changes showed a zonally asymmetric pattern over the past four decades, with most of the fastest changes occurring over West Antarctica and the Antarctic Peninsula. The Arctic and Antarctic climate changes were driven by anthropogenic greenhouse gas emissions and ozone loss, while tropical-polar teleconnections play important roles in driving the regional climate changes and extreme events over the polar regions. Polar climate changes may also feedback to the entire Earth climate system. The adjustment of the circulation in both the troposphere and the stratosphere contributed to the interactions between the polar climate changes and lower latitudes. Climate change has also driven rapid Arctic and Southern ocean acidification. Chinese researchers have made a series of advances in understanding these processes, as reviewed in this paper. [ABSTRACT FROM AUTHOR]

This paper formulates the cosmic ray--driven electron- induced reaction as a universal mechanism to provide a quantitative understanding of global ozone depletion. Based on a proposed electrostatic bonding mechanism for charge- induced adsorption of molecules on surfaces and on the measured dissociative electron transfer (DET) cross sections of ozone- depleting substances (ODSs) adsorbed on ice, an analytical equation is derived to give atmospheric chlorine atom concentration: ... where Φe is the prehydrated electron ... flux produced by cosmic ray ionization on atmospheric particle surfaces, ... is the surface coverage of an ODS, and ... is the ODS's effective DET coefficient that is the product of the DET cross section, the lifetimes of surface-trapped ... and ..., and the particle surface area density. With concentrations of ODSs as the sole variable, our calculated results of time-series ozone depletion rates in global regions in the 1960s, 1980s, and 2000s show generally good agreement with observations, particularly with ground- based ozonesonde data and satellite-measured data over Antarctica and with satellite data in a narrow altitude band at 13 to 20 km of the tropics. Good agreements with satellite data in the Arctic and midlatitudes are also found. A previously unreported effect of denitrification on ozone loss is found and expressed quantitatively. But this equation overestimates tropospheric ozone loss at northern midlatitudes and the Arctic, likely due to increased ozone production by the halogen chemistry in polluted regions. The results render confidence in applying the equation to achieve a quantitative understanding of global ozone depletion. [ABSTRACT FROM AUTHOR]

The Antarctic Marine Protection Area (AMPA) has always been a global benchmark in the field of High Sea's protection. It is committed to maintain the ecological health of the Southern Ocean through the implementation of the Marine Protection Areas (MPAs) proposals and the promotion of related work. However, due to the dynamic nature of the marine environment and the time lag of the protection effect, the actual effect and promotion status of marine reserves, which have been widely applied and planned in Antarctica, are still difficult to be quantified in the context of the lack of long-term monitoring data and a complete evaluation system. In this paper, the international research status on AMP As issues in recent years was integrated and explored. Based on open access and published reports and data from the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the game between science and policy in the process of advancing AMP As issues was analyzed and presented from multiple perspectives, such as the planning efficiency, scientific basis, the demand for MPA in the planned area, the monitoring and evaluation of the protected areas, the consideration of the rational utilization of marine living resources and the management particularity of Antarctic resource governance issues. The results show that, although the Antarctic ocean protection is unmatched in the field of international waters protection, the results of longitudinal comparison indicate the development is still in its infancy, the difficulties, such as the slow process of planning, insufficient scientific evidence, difficult coordination of the interests between countries, weak mechanism of research and monitoring, controversial protection requirement and effects, needs to be overcome. It is suggested that future work should focus on the linkage between scientific data and marine governance policies, and the improvement of research and monitoring plans, so as to meet the diverse demands of different agents, to explore efficient and scientific management strategies and resource regulation modes. [ABSTRACT FROM AUTHOR]

This paper continues the work of Kang and Larsson Theoretical and Applied Climatology 116:537–548 (2014) What is the link between temperature and carbon dioxide levels? A Granger causality analysis based on ice core data. Theoretical and Applied Climatology 116:537-548, by adding methane to the study of causality between temperature and carbon dioxide. The data used goes 800,000 years back in time which is possible due to it being extracted from ice cores located at Dome C in Antarctica. First we use linear interpolation to make the three data sets equidistant to be able to employ statistical methods. We adjust for a deterministic trend and find the best model fit to be an autoregressive model with lag two and a piecewise quadratic trend. By employing multivariate Granger causality tests we find strong evidence that temperature, carbon dioxide and methane all Granger cause each other in both directions i.e. carbon dioxide Granger causes temperature and temperature Granger causes carbon dioxide, etc. This is in accordance with the findings of Kang and Larsson, with the extension that we can add methane to establish a trivariate feedback system between temperature, carbon dioxide and methane. [ABSTRACT FROM AUTHOR]

Amber is a fossilized tree resin that ranges in age from the Carboniferous to the Cenozoic. It occurs globally from the Arctic to Antarctica. As the resin petrifies and turns into amber, it can enclose and preserve other materials. Amber with inclusions can help reconstruct past biodiversity and ecosystems. Some amber contains fossils representing the oldest and most detailed records of critical evolutionary traits or markers. Inclusions can even capture behavioral indicators previously only observed in extant organisms. Evidence of insect pollination of flowering plants and dragonfly mating behavior appears in amber, as does the morphological specialization of insects, indicating sociality and social parasitism. Dating amber deposits can help calibrate evolutionary events and inform reconstructions of past ecosystems. While the direct dating of amber remains impossible, age constraints on most amber deposits are based on correlations or relative dating, methods that come with significant uncertainties. This study discusses two cases using 40Ar/39Ar and U–Pb geochronologic methods to constrain the ages of amber deposits in China and the paleo-ecosystems they record. This paper also summarizes how radio-isotopic dating and other techniques combined with the analysis of inclusions in amber can help elucidate biogeography and the dynamic relationship between life and the physical environment. [ABSTRACT FROM AUTHOR]

In studying the mass balance of polar ice sheets, fluctuations in firn density near the surface is a major uncertainty. In this paper, we explore these variations at locations on the Greenland Ice Sheet and at the Dome C location in Antarctica. Borehole in situ measurements, snow radar echoes, microwave brightness temperatures, and modeling results from the Community Firn Model (CFM) are used. It is shown that firn density profiles can be represented using three processes: "long-scale" and "short-scale" density variations and "refrozen layers". Consistency with this description is observed in the dynamic range of airborne 0.5–2 GHz brightness temperatures and snow radar echo peaks in measurements performed in Greenland in 2017. Based on these insights, a new analytical partially coherent model is implemented to explain the microwave brightness temperatures using the three-scale description of the firn. Short- and long-scale firn processes are modeled as a 3D continuous random medium with finite vertical and horizontal correlation lengths as opposed to past 1D randomly layered medium descriptions. Refrozen layers are described as deterministic sheets with planar interfaces, with the number of refrozen-layer interfaces determined by radar observations. Firn density and correlation length parameters used in forward modeling to match measured 0.5–2 GHz brightness temperatures in Greenland show consistency with similar parameters in CFM predictions. Model predictions also are in good agreement with multi-angle 1.4 GHz vertically and horizontally polarized brightness temperature measured by the Soil Moisture and Ocean Salinity (SMOS) satellite at Dome C, Antarctica. This work shows that co-located active and passive microwave measurements can be used to infer polar firn properties that can be compared with predictions of the CFM. In particular, 0.5–2 GHz brightness temperature measurements are shown to be sensitive to long-scale firn density fluctuations with density standard deviations in the range of 0.01–0.06 gcm-3 and vertical correlation lengths of 6–20 cm. [ABSTRACT FROM AUTHOR]

Antarctic coastal polynyas produce dense shelf water, a primary source of Antarctic Bottom Water that contributes to the global overturning circulation. This paper investigates Antarctic dense water formation in the high-resolution version of the Energy Exascale Earth System Model (E3SM-HR). The model is able to reproduce the main Antarctic coastal polynyas, although the polynyas are smaller in area compared to observations. E3SM-HR also simulates several occurrences of open-ocean polynyas (OOPs) in the Weddell Sea at a higher rate than what the last 50 years of the satellite sea ice observational record suggests, but similarly to other high-resolution Earth system model simulations. Furthermore, the densest water masses in the model are formed within the OOPs rather than on the continental shelf as is typically observed. Biases related to the lack of dense water formation on the continental shelf are associated with overly strong atmospheric polar easterlies, which lead to a strong Antarctic Slope Front and too little exchange between on- and off-continental shelf water masses. Strong polar easterlies also produce excessive southward Ekman transport, causing a build-up of sea ice over the continental shelf and enhanced ice melting in the summer season. This, in turn, produces water masses on the continental shelf that are overly fresh and less dense relative to observations. Our results indicate that high resolution alone is insufficient for models to properly reproduce Antarctic dense water; the large-scale polar atmospheric circulation around Antarctica must also be accurately simulated. [ABSTRACT FROM AUTHOR]

This paper introduces a unique multiyear dataset and the monitoring capability of the PANDA automatic weather station network, which includes 11 automatic weather stations (AWSs) across the Prydz Bay–Amery Ice Shelf–Dome A area from the coast to the summit of the East Antarctic Ice Sheet. The ∼ 1460 km transect from Zhongshan to Panda S follows roughly along ∼ 77 ∘ E longitude and covers all geographic units of East Antarctica. Initial inland observations, near the coast, started in the 1996/97 austral summer. All AWSs in this network measure air temperature, relative humidity, air pressure, wind speed and wind direction at 1 h intervals, and some of them can also measure firn temperature and shortwave/longwave radiation. Data are relayed in near real time via the Argos system. The data quality is generally very reliable, and the data have been used widely. In this paper, we firstly present a detailed overview of the AWSs, including the sensor characteristics, installation procedure, data quality control protocol and the basic analysis of each variable. We then give an example of a short-term atmospheric event that shows the monitoring capacity of the PANDA AWS network. This dataset, which is publicly available, is planned to be updated on a near-real-time basis and should be valuable for climate change estimation, extreme weather events diagnosis, data assimilation, weather forecasting, etc. The dataset is available at 10.11888/Atmos.tpdc.272721 (Ding et al., 2022b). [ABSTRACT FROM AUTHOR]

Sea ice elevation is crucial in the characterization of three‐dimensional (3D) sea ice patterns, providing physical insights to advance sea ice dynamic models. Moreover, how sea ice elevation may be related to the ocean geophysical environment is still a significant knowledge gap, especially in Antarctica. A radar theory relating electromagnetic scattering mechanisms to sea ice elevation over old and deformed rough ice has been reported in a prior companion paper. This follow‐up paper presents the validated model function and synthetic aperture radar (SAR)‐retrieved sea ice elevations based on the field data acquired during the Operation IceBridge and TanDEM‐X Antarctic Science Campaign. A high‐resolution sea ice digital elevation model (DEM) is generated extensively over a 19 × 450 km sector in the Western Weddell Sea, achieving a good accuracy with a low root‐mean‐square error of 0.23 m. From the SAR‐retrieved sea ice DEM, 3D sea ice patterns including roughness height, auto‐correlation lengths, correlation ellipticity, and orientation angles are calculated over the old and deformed rough sea ice. The 3D sea ice patterns give a comprehensive characterization of sea ice topography in the Western Weddell Sea and show the potential to be used for understanding sea ice formation processes in the Antarctic. Plain Language Summary: Sea ice elevation provides essential information on characterizing sea ice features in three dimensions (3D) and relates to the ocean geophysical environment in the Antarctic. Synthetic aperture radar (SAR) provides a novel capability to characterize sea ice in 3D over a large coverage area across the ocean surface regardless of weather and darkness. This paper presents a method to retrieve sea ice elevations based on SAR imagery. A high‐resolution map of sea ice elevation for old and rough ice is generated extensively over a wide sector in the Western Weddell Sea. Numerous sea ice 3D features are derived from the sea ice elevation map and show potential to provide geophysical insights into sea ice formation processes in the Antarctic. Key Points: A sea ice digital elevation model (DEM) is derived from satellite radar data and validated over old and rough sea ice in the Weddell SeaThree‐dimensional (3D) sea ice patterns are calculated from the sea ice DEM, and are quantitatively analyzed with bathymetrySea ice DEM helps advance the understanding of sea ice processes and facilitates applications such as ship navigation in ice‐covered waters [ABSTRACT FROM AUTHOR]

This paper introduces a unique multiyear dataset and the monitoring capability of the PANDA automatic weather station network which includes eleven automatic weather stations (AWS) across Prydz Bay-Amery Ice Shelf-dome area from the coast to the summit of the East Antarctica ice sheet. The ~1460 km transect from Zhongshan to Panda S station follows roughly along ~77° E longitude and covers all geographic and climatic units of East Antarctica. Initial inland observation, near the coast, started in the 1996/1997 austral summer. All AWSs in this network measure air temperature, relative humidity, air pressure, wind speed and wind direction at 1-hour intervals, and some of them can also measure firn temperature and shortwave/longwave radiation. Data are relayed in near real-time via the ARGOS system. Data quality is generally very reliable and the data have been used widely. In this paper, we firstly present a detailed overview of the AWSs, including the sensor characteristics, installation procedure, data quality control protocol, and the basic analysis of each variable. We then give an example of a short-term atmospheric event that shows the monitoring capacity of the network. This dataset, which is publicly available, is planned to be updated on a near-real time and should be valuable for climate change estimation, extreme weather events diagnosis, data assimilation, weather forecasting, etc. The dataset is available at https://doi.org/10.11888/Atmos.tpdc.272721 (Ding et al., 2022). [ABSTRACT FROM AUTHOR]

The effect of global warming on the southern polar regions necessitates careful monitoring of glacier deformations and their movements, as well as an understanding of atmospheric physics. For this purpose, the yearly movements of UNAVCO stations-South Pole Station (AMU2) (winter-summer) and other stations in the South Pole region have been observed in this paper for about a fifteen-year period (2006–2021). In addition, the area differences of the Antarctic continent due to seasonal changes (winter-summer) between 1980 and 2021 were investigated in this study. Moreover, the height values of the stations on the Antarctic continent were observed seasonally. The subglacial lakes in the Antarctic continent cause the differences in the height values as a result of the seasonal changes. A decrease in sea ice of 0.91 million km² for the winter season and 0.55 million km² for the summer season during a 41-year period has been determined for four sectors of the Antarctic continent. The temperature changes on the Antarctic continent in the summer and winter seasons (2005–2022) were also evaluated in this paper. Air temperature increases was apparent especially in the Antarctic Peninsula, East Antarctic and West Antarctic coasts. The Weddell Sea and the Amundsen Sea regions have had the most sea ice loss, each with 1.24 million km². On the other hand, it can be observed that the East Antarctic sector has expanded by 0.32 million km². [ABSTRACT FROM AUTHOR]