Antarctica Research Articles

Observed upper-ocean structure and seasonal production in the southern Kerguelen Plateau region, 1994-2021

In the Indian sector of the Southern Ocean, 80°E marks an important transition in ocean circulation between the greater Prydz Bay gyre to the west and the Australian Antarctic gyre to the east. Here, the submarine Kerguelen Plateau impedes the eastward flow of the Antarctic Circumpolar Current (ACC), topographically steering the flow. Enhanced biological productivity associated with the southern plateau supports an important marine ecosystem with many foraging marine predators. We collate ship-based hydrographic data on the vertical structure of the upper water column near 80°E from eight voyages spanning 1994 to 2021, from 58°S towards the Antarctic continent. The study aims to investigate the mixed layer oceanography, the implications for nutrient supply from deep to near-surface waters, and associated biological production. Our results show that the major oceanographic fronts are constrained within the narrow Princess Elizabeth Trough, between the southern Kerguelen Plateau and the Antarctic slope. Therefore, the Southern Boundary and the Southern ACC Front (SACCF) are often co-located, albeit with some interannual variability, with the location of the SACCF ranging from roughly 63°S to 65°S. The average depth of the seasonal mixed layer ranges from 34-49 m, typically deepening from south to north, in association with longer time since sea-ice melt. Below the mixed layer, Winter Water (WW) characteristics also vary across the observed latitudinal range; typically the temperature and thickness of the WW layer are inversely related, with warmer WW layers being thinner. Subsurface nitrate concentrations range from 20-40 µM, while silicate concentrations reach 100 µM. Nutrient drawdown is calculated based on mean concentrations in the mixed layer and WW layer, with drawdown values at individual stations reaching nearly 12 µM and 60 µM for nitrate and silicate, respectively, and a positive correlation between the two. Nutrient drawdown was higher in association with longer time since sea-ice melt and with thinner WW layers, while higher nitrate-based production was associated with deeper mixed layers. Observed relationships between upper water column characteristics and biological processes are discussed in terms of likely nutrient supply mechanisms and seasonal patterns of utilization.

Sustainability of regional Antarctic ice sheets under late Eocene seasonal atmospheric conditions

Abstract. The Eocene–Oligocene transition (EOT) is marked by a sudden δ18O excursion occurring in two distinct phases approximately 500 kyr apart. These phases signal a shift from the warm middle to late Eocene greenhouse climate to cooler conditions, with global surface air temperatures decreasing by 3–5 °C and the emergence of the first continent-wide Antarctic ice sheet (AIS). While ice sheet modelling suggests that ice sheet growth can be triggered by declining pCO2, it remains unclear how this transition was initiated, particularly the first growth phase that appears to be related to oceanic and atmospheric cooling rather than ice sheet growth. Recent climate model simulations of the late Eocene show improved accuracy but depict climatic conditions that are not conducive to the survival of incipient ice sheets throughout the summer season. This study therefore examines whether it is plausible to develop ice sheets of sufficient scale to trigger the feedback mechanisms required to disrupt the atmospheric regime above the Antarctic continent during warm and moist late Eocene summers and establish more favourable conditions for ice expansion. We aim to assess the sustainability of an incipient AIS under varying radiative, orbital and cryospheric forcing. To do so, we evaluate Community Earth System Model 1.0.5 simulations, using a 38 Ma geographical and topographical reconstruction, considering different radiative and orbital forcings. The climatic conditions prevailing during (and leading up to) the EOT can be characterised as extremely seasonal and monsoon-like, featuring a short yet intense summer period and contrasting cold winters. A narrow convergence zone with moist convection around the region with high sub-cloud equivalent potential temperature exhibits a ring-like structure, advecting moist surface air from the Southern Ocean in both summer and winter. This advection leads to high values of moist static energy and subsequent precipitation in coastal regions. Paradoxically, this atmospheric regime – particularly its coastal precipitation in winter – appears to be necessary for the sustenance of the moderately sized regional ice sheets we imposed on the continent, contrary to our assumption that these ice sheets would disrupt the atmospheric regime. This underscores a hysteresis effect for regional ice sheets on the Antarctic continent, suggesting the potential for a significant volume of ice on the continent without imminent full glaciation prior to the EOT.

Limnological Characteristics of Inland, Glacial Lakes on the Horseshoe Island (Antarctica)

Antarctica is a continent with extreme climatic conditions, with many lakes and ponds with ecological status varying from ultra-oligotrophic to hypereutrophic. Horseshoe Island is situated in Marguerite Bay, in the western Antarctic Peninsula. In this research, we purpose to determine the limnological characteristics of four lakes on Horseshoe Island (Col 1, Col 2, Skua and Zano). Water samples were taken once (during the summer period) from one station in each of the lakes for chemical analysis. The Trophic State Index (TSI) was calculated based on Secchi depth, chlorophyll-a, and total phosphorus concentrations. Phytoplankton were sampled from the same stations, except for Lake Zano, because of the ice cover. Phytoplankton community indice (Q) was calculated. Total phosphorus concentration for Lake Col 1, Col 2, Skua and Zano were measured as 0.6, 0.65, 3.0, 4.6 mg/m3, respectively. Based on total phosphorus, these four lentic systems are oligotrophic. TSI values pointed out oligotrophy and mesotrophy in the lakes. Lake Skua was found to be excellent quality (0.59 mg/l) while Lake Col 1 (0.72 mg/l) and Lake Col 2 (0.68 mg/l) were found to be good quality according to total phytoplankton biomass. The ecological status of the lakes is prediction to be of medium quality based on cyanobacteria biomass. This may be due to the rapid increase of Cyanobacteria in the short summer period as well as nutrient enrichment. Based on the Q indice, Lake Skua (4.2) is of excellent quality, Lake Col 2 (4) is of good quality, and Lake Col 1 (2.73) is of moderate quality in ice-free period. Because these lakes are under stressors such as climatic pressure (duration of ice cover) and natural eutrophication processes, regular monitoring of the lakes on the Antarctic continent is recommended.

High vulnerability of the endemic Southern Ocean snail Neobuccinum eatoni (Buccinidae) to critical projected oceanographic changes

Climate change is projected to substantially alter the Southern Ocean’s physical and chemical properties, thereby impacting its marine ecosystems and species, particularly those in Antarctic and sub-Antarctic regions. This study focuses on Neobuccinum eatoni, a polar marine ‘true whelk’ endemic to these regions, utilizing 166 spatially independent occurrence data records to model potential distribution shifts under future climate scenarios. Employing Species Distribution Models (SDMs) on spatially cross-validated occurrences, we achieved high predictive accuracy, identifying "sea water salinity range" at mean bottom depth as the most significant predictor of habitat preferences. Additionally, dissolved iron (minimum), ocean temperature (range), and pH (long-term maximum) emerged as critical factors influencing the species’ modeled distribution. By 2050, future projections under the SSP2-4.5 scenario predict an eastward expansion, particularly in the Antarctic Peninsula, the Scotia Arc and the Weddell Sea, with an expansion in the latter region also predicted under the SSP5-8.5 scenario. However, in both scenarios, a reduction in habitat suitability is expected in certain sectors around the Antarctic continent and the Kerguelen Archipelago. By 2100, under the moderate emissions scenario (SSP2-4.5), the species is projected to move to deeper areas and lower latitudes, with notable expansions in the Weddell Sea and in the Southern Ocean surrounding the Kerguelen Archipelago. However, under the SSP5-8.5 scenario, expansion is projected in the Weddell Sea and reductions in Antarctic and subantarctic regions. This study highlights the critical influence of changing salinity on N. eatoni’s distribution, predicting a significant habitat reduction under high CO2 emissions scenarios (SSP5-8.5). The findings underscore the urgent need for focused research on the vulnerability of endemic marine invertebrates to develop effective conservation strategies in the face of rapid climatic changes.

Airborne microplastic pollution detected in the atmosphere of the South Shetland Islands in Antarctica.

Plastic pollution has emerged as a growing environmental concern, affecting even the most remote regions of the planet as the Antarctic continent, endangering its ecosystem and contributing to climate change. In this context, a continuous atmospheric microplastics monitoring study was conducted at Carlini Argentine Antarctic Station located in the southwest of 25 de Mayo (King George) Island (South Shetlands). Passive samplers were installed at three locations throughout the station, chosen based on the intensity of human activity and proved to be effective in collecting atmospheric particles over a one-year study period. Micro-FTIR and micro-Raman spectroscopies were used to characterize the suspected microplastic particles. These techniques revealed a wide variety of plastic polymers compositions and industrial dyes associated with textile and plastic materials. Microfibers were found to be the predominant particle form, constituting approximately 80% of the particles detected at each sampling point. Semi-synthetic cotton, polyester, and polyamide were widely detected, along with other plastic compositions. Micro-Raman spectroscopy confirmed the presence of indigo blue, reactive blue 238, and copper phthalocyanine on both synthetic and semi-synthetic fibers, representing the first report of these types of anthropogenic pigments in the Antarctic atmosphere. The results suggest a significant role of short-range transport from local human activities; however, the potential influence of large-scale atmospheric patterns should also be evaluated. Our findings highlight the need to expand the monitoring network to additional scientific stations and remote regions with minimal human activity. Increasing the number of observational sites and conducting complementary studies on airborne dispersion will strengthen assessments of potential long-range pollution sources.

Lithospheric Structure and Strength Variations in Antarctica From Joint Modeling of Elevation, Geoid and Seismic Data

AbstractAntarctica is renowned for its ancient cratons, difficult‐to‐observe sutures and active continental rifts. Detailed lithospheric structure and strength estimates are crucial for understanding the potential distribution, long‐term geological evolution, and deformation patterns of this continent. The lithospheric structure of the Antarctic continent is investigated based on joint modeling of elevation and geoid data with the incorporation of seismic data and thermal constraints. Moreover, these results are used to infer the yield strength envelopes across Antarctica. The laterally variable lithospheric strength is finally generated by vertically integrating the above envelopes. Our results show that the variations in the depth of the lithosphere‐asthenosphere boundary (LAB) are analogous to the variations in the integrated lithospheric strength; these parameters vary from 60 to 220 km and from 0.5 × 1013 Pa m to 4.5 × 1013 Pa m, respectively. Several regions of East Antarctica exhibit thick and strong lithospheric mantle, suggesting the presence of scattered cratonic blocks. In contrast, a thin and weak lithosphere is observed in the tectonically active West Antarctica and East Antarctic orogenic belts. Generally, our new LAB model correlates well with previous estimates, but there is a significant inconsistency beneath the Gamburtsev Subglacial Mountains, where a shallow LAB (∼120 km), high Moho temperature, and low strength (<1.0 × 1013 Pa m) are estimated. We speculate that this anomaly may be similar to the thinned lithosphere in Dronning Maud Land and reflects the removal of the mantle lithosphere during or after the orogenesis associated with the assembly of the Gondwana supercontinent.

Alteration of the gut microbiota changes during the one-year Antarctic deployment in a group of Chinese Han population

BackgroundIt is common knowledge that people’s intestinal microbiota is significantly influenced by the external environment. Although the Antarctic continent has been discovered for nearly 200 years, it is still unclear how this environment affects the human intestinal microbiota, especially that of the Chinese Han population.MethodsTwelve explorers underwent a one-year Antarctic deployment from December 2017 to December 2018. The gut microbiota and clinical indexes at five time points, including two months (T1), five months (T2), eight months (T3), 11 months (T4) of residence in Antarctica and 7 months after returning to China (T5), were investigated.ResultsThe intestinal microbiota of the participants was changed after one-year Antarctic deployment even after they left Antarctica. For the microbiota tested after returning to China (T5), the amount of Citrobacter, Akkermansia and conditional pathogens such as Escherichia-Shigella increased significantly (P < 0.05). The concentration of the major biochemical indicators in the serum exhibited an increasing trend before T3, and decreased significantly at T4. When tested again at T5, most of the serum concentrations increased, only 5-hydroxytryptamine was significantly decreased. Spearman correlation analysis showed the change in the relative abundance of Anaerotruncus was negatively associated with the changes in the concentration of total thyroxine, alanine transaminase, γ-glutamyl transpeptidase, serum cystatin C and apolipoprotein A1. The relative abundance change in Citrobacter was positively associated with the change in the concentration of uric acid.ConclusionBy objectively analyzing the influence of the Antarctic environment on the change of intestinal microbiota, we were able to provide theoretical support for subsequent Antarctic related research.

The case for a Framework for UnderStanding Ice-Ocean iNteractions (FUSION) in the Antarctic-Southern Ocean system

We are in a period of rapidly accelerating change across the Antarctic continent and Southern Ocean, with land ice loss leading to sea level rise and multiple other climate impacts. The ice-ocean interactions that dominate the current ice loss signal are a key underdeveloped area of knowledge. The paucity of direct and continuous observations leads to high uncertainty in the glaciological, oceanographic and atmospheric fields required to constrain ice-ocean interactions, and there is a lack of standardised protocols for reconciling observations across different platforms and technologies and modelled outputs. Funding to support observational campaigns is under increasing pressure, including for long-term, internationally coordinated monitoring plans for the Antarctic continent and Southern Ocean. In this Practice Bridge article, we outline research priorities highlighted by the international ice-ocean community and propose the development of a Framework for UnderStanding Ice-Ocean iNteractions (FUSION), using a combined observational-modelling approach, to address these issues. Finally, we propose an implementation plan for putting FUSION into practice by focusing first on an essential variable in ice-ocean interactions: ocean-driven ice shelf melt.

Biotechnological potential in agriculture of soil Antarctic microorganisms revealed by omics approach.

The biotechnological potential for agricultural applications in the soil in the thawing process on Whalers Bay, Deception Island, Antarctica was evaluated using a metagenomic approach through high-throughput sequencing. Approximately 22.70% of the sequences were affiliated to the phyla of the Bacteria dominion, followed by 0.26% to the Eukarya. Proteobacteria (Bacteria) and Ascomycota (Fungi) were the most abundant phyla. Thirty-two and thirty-six bacterial and fungal genera associated with agricultural biotechnological applications were observed. Streptomyces and Pythium were the most abundant genera related to the Bacteria and Oomycota, respectively. The main agricultural application associated with bacteria was nitrogen affixation; in contrast for fungi, was associated with phytopathogenic capabilities. The present study showed the need to use metagenomic technology to understand the dynamics and possible metabolic pathways associated with the microbial communities present in the soil sample in the process of thawing recovered from the Antarctic continent, which presented potential application in processes of agro-industrial interest.

ALBATROSS: Advancing Southern Ocean tide modelling with high resolution and enhanced bathymetry

The knowledge of bathymetry and ocean tides plays a pivotal role at the crossroads of various scientific fields, especially in the Polar regions. Its significance extends to ocean circulation modeling and understanding the coupled dynamical response of the ocean, sea-ice and ice-sheet systems. In the Southern Ocean, conventional satellite altimetry measurements are rare below the 66° parallel. Hydrodynamic models are thus useful tools to provide spatially continuous information about ocean tides. However, the accuracy of ocean tide models around the Antarctic continent is currently limited by the quality of bathymetry. Recent reprocessing of decade-long CryoSat-2 data has facilitated a new computation of bathymetry around Antarctica, bringing innovative information on bathymetry gradients. This, combined with new compilations of bathymetry, ice draft, coastline, and grounding line datasets in ice-shelf regions, allows improving models and knowledge of ocean tides in the Southern Ocean. We developed a new high-resolution tidal model that implements the improved bathymetry data and includes data assimilation of satellite-altimetry tidal retrievals computed from CryoSat-2, filling the gap between the 66°S-limited coverage of the TOPEX-Jason suite missions and the Antarctic coast. Comparisons with tidal estimates derived from tide gauge measurements showed very good consistencies with an RMSE of 3 cm.

Deep-sea benthic hydroids (Cnidaria, Hydrozoa) from Antarctic submarine ridges off the Ross Sea (Antarctica)

AbstractKnowledge of benthic hydroids inhabiting the Antarctic continental shelf waters, particularly of relatively well-studied areas, has increased in recent years. This has allowed us to recognise them as one of the main and most characteristic zoological groups of the Antarctic benthos. However, little is known about the hydroids dwelling on the continental slope or in deeper waters, let alone about those inhabiting the seafloor far away from the Antarctic continent, despite the Southern Ocean extending significantly northwards. This study contributes to reducing that knowledge gap by studying material collected from a series of deep-sea ridges north of the Ross Sea, from which hydrozoans have never been reported. Twelve species, including Halecium divergens sp. nov., have been found and studied. Except for Turritopsis sp., belonging to the Anthoathecata family Oceaniidae, all species belong to Leptothecata, in particular to the families Campanulariidae, Haleciidae, Lafoeidae, Phylactothecidae, Sertularellidae, and Symplectoscyphidae. Lafoeidae is the most represented family with four species. Sertularella pseudovervoorti and Filellum liberum are found for the second time. The discovery of Symplectoscyphus frondosus, a species previously considered endemic to the shelf and slope of the eastern Ross Sea, significantly extends its known northern distribution limit. Tulpa diverticulata and the genus Tulpa are reported in Antarctic waters for the first time. The lower limit of the bathymetric range for several species has been extended. Despite being well within Antarctic waters, the studied area hosts a very distinctive fauna, markedly different from the typical Antarctic benthic hydroid fauna. Its endemisms, the presence of species unknown in the Antarctic region and the absence of representatives of the most characteristic Antarctic genera account for its originality.

Endophytic Bacterial Biofilm-Formers Associated with Antarctic Vascular Plants.

Deschampsia antarctica and Colobantus quitensis are the only two vascular plants colonized on the Antarctic continent, which is usually exposed to extreme environments. Endophytic bacteria residing within plant tissues can exhibit diverse adaptations that contribute to their ecological success and potential benefits for their plant hosts. This study aimed to characterize 12 endophytic bacterial strains isolated from these plants, focusing on their ecological adaptations and functional roles like plant growth promotion, antifungal activities, tolerance to salt and low-carbon environments, wide temperature range, and biofilm formation. Using 16S rRNA sequencing, we identified several strains, including novel species like Hafnia and Agreia. Many strains exhibited nitrogen-fixing ability, phosphate solubilization, ammonia, and IAA production, potentially benefiting their hosts. Additionally, halotolerance and carbon oligotrophy were also shown by studied bacteria. While some Antarctic bacteria remain strictly psychrophilic, others demonstrate a remarkable ability to tolerate a wider range of temperatures, suggesting that they have acquired mechanisms to cope with fluctuations in environmental temperature and developed adaptations to survive in intermediate hosts like mammals and/or birds. Such adaptations and high plasticity of metabolism of Antarctic endophytic bacteria provide a foundation for research and development of new promising products or mechanisms for use in agriculture and technology.

The Southern Ocean marine ice record of the early historical, circum-Antarctic voyages of Cook and Bellingshausen

Abstract. The circumnavigations of Cook (second voyage, 1772–1775) and Bellingshausen (1819–1821) were attempts to find any great southern land mass poleward of ∼ 50° S and consequently involved sailing for three or two summers, respectively, in polar latitudes around Antarctica. Extensive sea ice eventually blocked each voyage's southern probes, although Bellingshausen, unknowingly at the time, saw the Antarctic continent. However, these attempts meant sea ice and iceberg records from the early historical period were collected nearly simultaneously from around much of Antarctica. Here, these records are extracted from journals, analysed, and compared to each other and the modern satellite record of both forms of marine ice. They generally show an early historical period with a more northerly record of both forms of marine ice than normal for today, but to a geographically varying degree. However, the early historical period in the Pacific sector of the Southern Ocean saw marine ice generally within the range of modern observations for the same time of year, but the Weddell Sea and Indian Ocean marine ice, particularly on Cook's voyage, then extended several degrees further north than in today's extreme ice years.

Low prevalence of microplastic contamination in the bottom sediments and deep-sea waters of the Bransfield strait, Antarctica

Despite the remoteness of the Antarctic continent and Southern Ocean, microplastic (MPs) contamination has been evidenced in recent years. However, the deep-sea compartments of the Southern Ocean are yet to be investigated. In the present study, we conducted a baseline MP assessment of the deep-sea waters and bottom sediments of the Bransfield Strait, Antarctica. A low abundance of suspected MPs was found. The average MP abundances in bottom sediments and water samples were 0.09 MP/g (range of 0–0.2 MP/g) and 7.00 MP/L (range of 0–16 MP/L), respectively. The majority of the particles were fibers identified as cellulose, although polyethylene terephthalate (PET) and polyacrylonitrile (PAN) was also detected. These results suggest low MP contamination levels in the Southern Ocean's deepest environmental compartments. However, future studies must aim to investigate the smallest MP fractions and, if possible, nanoplastic (<1 μm) contamination in these remote compartments.

The Antarctic Continent: a geostrategic interest of the Colombian State

The purpose of this research article is to determine the geostrategic relevance for the Colombian State, reflected in policies, research and institutional architecture that covers the Antarctic continent. The argumentation and analysis are supported by primary and secondary sources, which allow visualizing the characteristics, conditions, contributions and projection of Colombia in the Antarctic Treaty System. As a working hypothesis, Colombia has identified Antarctica as part of a geostrategic interest -from a humanistic and investigative perspective- and has deployed a series of institutional efforts in the last 30 years to approach the understanding of the region. As conclusions, there is a clear oceanic, aerial, cyberspace, space, climatic and biological connection between Colombia, represented in public institutions -such as the Foreign Ministry and the Military Forces- and educational institutions -such as universities and research centers- and the Antarctica, inserting it in this way as a geostrategic interest of the country

Legacy and novel contaminants in surface sediments of Admiralty Bay, Antarctica Peninsula

Despite being one of the most remote areas on the planet, the Antarctic continent is subject to anthropogenic influences. The presence of various groups of contaminants, including persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs), has been documented in the region over the past decades. However, a significant knowledge gap remains regarding the detection of new pollutants, such as emerging contaminants (ECs), in Antarctic coastal environments. This study analyzed the occurrence and levels of selected POPs, PAHs, ECs in surface sediments from Admiralty Bay, Antarctica Peninsula. Non-target screening was employed to identify potential novel contaminants in the region. Samples (n = 17) were extracted using an accelerated solvent extraction (ASE) system and instrumental analyses were performed using gas chromatography coupled to a triple-quadrupole mass spectrometer (GC/MS-MS). Regarding regulated contaminants, concentrations of Σ5PCBs ranged from <LOD to 0.5 ng g−1, while Σ16PAHs ranged from 2.6 to 617.4 ng g−1. These compounds were predominant in the Martel inlet, suggesting influences of local input sources, especially for PAHs. ECs were detected in some sites of the Ezcurra and Martel inlets, especially nearby the Brazilian and Polish research stations. The UV filters homosalate (0.3 to 251.3 ng g−1) and octocrylene (0.7 to 93.8 ng g−1) were the most abundant EC, followed by TPP (0.1 to 87.4 ng g−1) and galaxolide (0.2 to 55.0 ng g−1). Applying non-target analysis, phthalates, and the fragrance OTNE (octahydro-tetramethyl-naphthalenyl-ethanone) were identified for the first time in Antarctic sediments. The data highlights the contribution of human activities in the region, possibly through wastewater effluents. This study provides data on the current levels of PAHs and POPs in the region, which are steadily decreasing over the years.

Borderscape Antarctica: The uncanny geographical imaginaries of Terra Australis Incognita

The harsh beauty of the Antarctic continent has always fascinated explorers, scientists, policymakers, and global audiences alike. From the 18th century onwards, national expeditions competed to discover and claim Terra AustralisIncognita, the fantastical Great Southern Land believed to be located in the southern Asia-Pacific. This article investigates the worldmaking potential of Antarctica as an uncanny borderscape where humans confront the familiar yet otherworldly ice. I argue this encounter produces a double-sided imaginary of Antarctica as a geography of exception – both as a utopian world elevated above the everyday politics that dominates international relations elsewhere and as a dystopian world where monsters and madness lurk just beneath the icy surface. This double-sided imaginary enabled diplomatic agreement at the 1959 Washington Conference that froze competing sovereignty claims and preserved Antarctica as a frozen laboratory for collaborative science. At the same time, it inspires fears of a potentially thawed Antarctica as a place of horror where alien forces threaten to overwhelm human rationality. Drawing on primary accounts of exploration, archival material, and science and speculative fiction, my intertextual analysis demonstrates how this imaginary was created, represented, and reproduced to create utopian and dystopian visions of our collective planetary future.

Climatology of the open–closed boundary using ULF wave observations from South Pole, McMurdo, and distributed Antarctic AGOs

It has been shown that a proxy determination of the magnetospheric open–closed magnetic field line boundary (OCB) location can be made by examining the ultra-low-frequency (ULF) wave power in magnetometer data, with particular interest in the Pc5 ULF waves with periods of 3–10 min. In this study, we present a climatology of such Pc5 ULF waves using ground-based magnetometer data from the South Pole Station (SPA), McMurdo (MCM) station, and the Automatic Geophysical Observatories (AGOs) located across the Antarctic continent, to infer OCB behavior and variability during geomagnetically quiet times (i.e., Ap &amp;lt; 30 nT). For each season [i.e., austral fall (20 February 2017–20 April 2017), austral winter (20 May 2017–20 July 2017), austral spring (20 August 2017–20 October 2017), and austral summer (20 November 2017–20 January 2018)], north–south (i.e., H-component) magnetic field line residual power–spectral density (PSD) measurements taken during geomagnetically quiet periods within a 60-day window centered at the austral solstice/equinox are averaged in 10-min temporal bins to form the climatology at each station. These residual PSDs thus enable the analysis of Pc5 activity (and lower period “long-band” oscillations) and, thus, OCB location/variability as a function of season and magnetic latitude. The dawn and dusk transitions across the OCB are analyzed, with a discussion of dawn and dusk variability during nominally quiet geomagnetic periods. In addition, latitudinal dependencies of the OCB and peak Pc5 periods at each station are discussed, along with the empirical Tsyganenko model comparisons to our site measurements.

A satellite-derived baseline of photosynthetic life across Antarctica

Terrestrial vegetation communities across Antarctica are characteristically sparse, presenting a challenge for mapping their occurrence using remote sensing at the continent scale. At present there is no continent-wide baseline record of Antarctic vegetation, and large-scale area estimates remain unquantified. With local vegetation distribution shifts now apparent and further predicted in response to environmental change across Antarctica, it is critical to establish a baseline to document these changes. Here we present a 10 m-resolution map of photosynthetic life in terrestrial and cryospheric habitats across the entire Antarctic continent, maritime archipelagos and islands south of 60° S. Using Sentinel-2 imagery (2017–2023) and spectral indices, we detected terrestrial green vegetation (vascular plants, bryophytes, green algae) and lichens across ice-free areas, and cryospheric green snow algae across coastal snowpacks. The detected vegetation occupies a total area of 44.2 km2, with over half contained in the South Shetland Islands, altogether contributing just 0.12% of the total ice-free area included in the analysis. Due to methodological constraints, dark-coloured lichens and cyanobacterial mats were excluded from the study. This vegetation map improves the geospatial data available for vegetation across Antarctica, and provides a tool for future conservation planning and large-scale biogeographic assessments.

Unravelling spatiotemporal patterns in global sea surface temperatures with dynamic mode decomposition

AbstractExtracting global sea surface temperature (SST) patterns is essential for understanding climate variability in both regional and global perspective. Traditional methods, limited by assumptions of orthogonality, hinder our ability to fully capture the dynamics of global SST, particularly in the complex Pacific basin. This study introduces dynamic mode decomposition (DMD), a powerful method from fluid dynamics, to extract global SST patterns since 1900. Our analysis shows that DMD successfully captures well‐known patterns like global warming and the Atlantic Multidecadal Oscillation (AMO). More importantly, it reveals three Pacific SST modes that are spatially non‐orthogonal but exhibit distinct characteristics. Spectral analysis shows that these Pacific modes have distinct periodicities: Pacific Multi‐decadal Mode (PMDM, ~50 years), Quasi‐decadal Mode (PQDM, 8–16 years) and Interannual Mode (PIAM, 2–8 years). This highlights DMD's strength in not only capturing known patterns but also separating modes with similar spatial features but unique dynamics. Further analysis reveals significant differences in their impacts on global air temperature. During positive phases, all three modes induce tropical warming, with PIAM exerting the strongest influence and PMDM the weakest. In the Northern Hemisphere, both PQDM and PIAM drive mid‐latitude cooling and high‐latitude warming, with a more pronounced effect from PQDM. PMDM, in contrast, triggers widespread cooling across the Northern extratropics. In the Southern Hemisphere, PMDM's influence on temperature exhibits a distinct latitudinal banding pattern. PIAM and PQDM, on the other hand, exhibit a regionalized impact, primarily concentrated in the Amundsen and Ross Seas, with PQDM's influence extending to the Antarctic continent.