Polar Science最新文献

The geomagnetic field focuses onto the polar regions near the auroral oval, which the Larsemann Hills are in proximity to. Solar disturbances cause instabilities in the geomagnetic field and the associated electrically-charged particle (plasma) population, which translate into waves that propagate along geomagnetic field lines towards the Earths polar regions. As the waves enter the electrically charged upper atmosphere (ionosphere) they convert to a mode that propagates parallel to the Earth's surface in a waveguide. Hence, energy from outer space is distributed into the polar atmosphere, particularly near the auroral oval. A series of winter vehicle traverses in the Larsemann-Vestfold region deployed and operated a sensor array, with international co-operation, to measure and characterise the waveguide for the first time at polar latitudes. The directions of areas of origin for the plasma waves and propagation properties could be assessed using the array, not previously possible at permanent stations. Similar waves from sources equatorward of the auroral oval have been recently observed by new radar techniques, which could also be employed at high-latitudes, where the waves have recently been shown to affect the lower atmosphere.

The crustal structure in terms of crustal thickness, shear wave velocities and Poisson's ratio plays a crucial role in understanding and/or deciphering the tectonic setting and its evolution. The receiver function analysis, H–K stacking and inversion techniques are the widely used tools to determine these parameters. In the present study, the data obtained from the first-ever established broadband seismological observatory at Larsemann Hills, East Antarctica has been utilized for the P receiver function (PRF) analysis and H–K stacking to decipher the crustal thickness, Poisson's ratio and the intra-crustal layer. Further, the obtained PRFs were inverted using Bayesian inversion to get the crustal structure. The results obtained from H–K analysis reveal a crustal thickness of ∼37.9 km and the corresponding Poisson's ratio is 0.19. The inversion technique also yielded consistent results, indicating a Moho depth of ∼37 km with a velocity jump from 4.1 km/s to 4.6 km/s and an intra-crustal layer at around 16 km with a velocity jump from 3.95 km/s to 4.06 km/s. It indicates a Poisson's ratio of 0.20. These findings suggest that the crust beneath the Larsemann Hills is felsic in nature and has high crustal shear wave velocity. Further, the variation in the crustal thickness along the coast of the Princess Elizabeth Land (PEL) region, ranging from 37.9 km to 36 km with the intra-crustal layer variation from 16 km to 13 km distinguishes the Neoproterozoic Larsemann Hills from the Archean-Mesoproterozoic Vestfold Hills.

The Indian Antarctic program, a multi-disciplinary and multi-institutional program initiated in 1981 with the first expedition to Antarctica, has been instrumental in advancing our understanding of Antarctic meteorology and its global climate implications. This study focuses on the latest meteorological characteristics of newly established research base Bharati aiming to unravel the climate dynamics of Bharati station in East Antarctica. The meteorological data for the period December 2014 to December 2022 have been analysed in present study. We observed the highest maximum temperature of 9.9 °C on January 5, 2018, and the lowest minimum temperature of −40.3 °C on September 6, 2016. The monthly mean temperature exhibits pronounced seasonal variation, with a summer maximum of approximately 0 °C in December and January, and a winter minimum of about −19 °C from May to September. While the eight-year observations are not sufficient for studying long-term trends, we identify a slight increasing tendency in temperature at Bharati. In addition to temperature, we examined the characteristics of pressure, relative humidity, precipitation, wind, and blizzards. The analysis reveals a negative correlation between the Southern Annular Mode (SAM) and temperature and pressure at Bharati. Station experiences predominantly easterly and northeasterly winds. The upper air data were obtained using radiosonde and ozonesonde ascents, enhancing our understanding of the atmospheric conditions in the region. These results provide important knowledge about the weather in Bharati and how it relates to the Southern Annular Mode. Understanding this helps us comprehend how East Antarctica weather influences global climate patterns.

Wilson's storm-petrel (Oceanites oceanicus, family Oceanitidae, order Procellariiformes) breeds in rock cavities along the ice-free coastline of Antarctica, a habitat susceptible to environmental change and human disturbance. Despite extensive presence, high numbers and wide-ranging movement, there are taxonomic ambiguities surrounding species' phylogenetic positioning and data gaps for most parts of its range. In this study, we provide support to the phylogenetic status of family Oceanitidae through new genetic datasets and modern analytical approaches. We generated mitochondrial cytochrome b gene sequences from samples collected from east Antarctica's ice-free regions. Reconstructed trees obtained using Bayesian and maximum likelihood models show Oceanitidae as a monophyletic group where Hydrobatidae (northern storm-petrels) appeared as a basal group to the order Procellariiformes. Phylogeographic network analysis resulted in seven distinct haplotypes with strong genetic differentiation (F_ST > 0.99) between east Antarctic and sub-Antarctic populations. Our study provides one of the first genetic datasets on Wilson's storm-petrel populations in east Antarctica. It serves as a baseline to undertake rigorous investigations into species' population structure, genetic connectivity and demographic responses to human-mediated changes in the austral environment.

Glaciers fluctuations are an indicator of changes in natural circulation mechanisms in the ‘glaciation–ocean–atmosphere’ system of the Southern Hemisphere. To assess the dynamics of the movement of shelf and outlet Antarctic glaciers, remote sensing methods are mainly used including unmanned aerial surveys. This article discusses methods for assessing the movement of the Dålk Glacier (Ingrid Christensen Coast, East Antarctica) using digital surface models (DSMs) and orthomosaics derived from data of multi-temporal unmanned aerial surveys. We estimated the dynamics of the Dålk Glacier over three weeks in January–February 2017 and over two years from January 2017 to January 2019. To study short-term displacements, a pseudo-parallax method was applied. Biennial displacements of the glacier were estimated by a visual comparison of orthomosaics. During three weeks of the 2017 austral summer, the average velocity of the actively moving part of the glacier was 1.3 m/day. At the same time, the average displacement of the central part of the Dålk Glacier was 423 m over two years, that is, the average velocity was about 0.6 m/day. Our results can serve as a basis for glaciological studies, monitoring, and prediction of fluctuations in hard-to-reach areas of outlet glaciers in Antarctica.

Petrology, geothermobarometry, and phase equilibrium modelling of garnetiferous felsic gneiss from Grovnes peninsula in the Larsemann Hills of Prydz Bay, East Antarctica provide pristine evidence for the preservation of high-grade metamorphic imprint in the area. The metamorphic evolution of the sample is demonstrated by the development of the assemblage Grt+Bt+Melt+Pl+Sill+Kfs+Qtz+Ilm at peak metamorphic conditions of ∼790 °C and ∼7.5 kbar, which subsequently underwent retrogression and cooling to lower P-T conditions along a clockwise path. Texturally constrained chemical dating of monazites constrain the timing of peak metamorphism and garnet formation at ∼575 Ma, whereas the apatite U–Pb ages constrain cooling ages at ∼518 Ma. The clockwise P˗T˗t trajectory of the studied samples, together with the Ediacaran-Cambrian metamorphic/cooling ages demonstrate the long-lived nature of metamorphism in Prydz Bay, which is ascribed to collisional tectonism prevalent during the final stages of the assembly of East Gondwana supercontinent. Similar results from adjacent continental fragments including Sri Lanka, Eastern Ghats Belt, Madagascar, and South India suggest their coeval metamorphic evolution during the East African orogeny.

In the Larsemann Hills, three countries – Russia, China, and India – maintain year-round stations, while Australia operates a summer facility. These countries engage in diverse scientific research in the Larsemann Hills and the surrounding areas. The unprecedented cooperation resulted in the International Conference on Antarctic Research (ICAR) at Bharati station in 2020. Additionally, the BRICS working group on ocean and polar science and technology (OPST) has played a crucial role in fostering scientific engagements. This first volume of the special issue compiles twenty-five research findings based on data collected in the region, including presentations from ICAR-2020. Beyond showcasing international cooperation, the special issue also commemorates a decade of the Bharati station’s presence in the Larsemann Hills.

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

Antarctica, the southernmost continent on Earth, is a harsh and remote place with an extreme climate. Despite its challenges, the continent has become a significant site for scientific research, particularly in the fields of earth sciences, glaciology, environmental science, atmospheric sciences, meteorology, palaeoclimatology, and biology. As a signatory to the Antarctic Treaty, India has actively pursued scientific research on the continent since 1981. The Indian Antarctic Program has conducted research, provided logistical support, and monitored environmental activities in Antarctica for over four decades. Science is a currency in Antarctica, and international collaboration is the route to progress. This article explores India's efforts, particularly those of the Ministry of Earth Sciences, Government of India, and the National Centre for Polar and Ocean Research, in fostering international collaboration in Antarctica.

Antarctica harbours a wide range of extreme and diverse ecological niches that support diverse group of microorganisms, making it important to investigate the microbial diversity of this pristine environment. The current study focuses on the diversity and distribution of fungi in diverse environmental niches like exposed soil, accumulated snow, deep sea, and lake sediments in the Larsemann Hills, Antarctica. Ascomycota (61.7%) was the most dominating phylum followed by Basidiomycota (31.1%), Chytridiomycota (5.7%) and Rozellomycota (1.4%). The families Camptobasidiaceae (23.1%), Cladosporiaceae (15.3%), Kriegeriaceae (8.2%), Mycosphaerellaceae (6.8%) and Helotiaceae (6.2%), while at the genus level Glaciozyma (24.8%), Cladosporium (16.8%), Phenoliferia (8.8%), Acrodontium (8%), and Aspergillus (5.4%) were highly prevalent. Interestingly, Austroplaca genus which is mostly indigenous to polar regions was exclusively detected in the accumulated snow sediments. Among the four heterogenous environments analyzed, lake sediments were shown to have a higher number of amplicon sequence variants (ASVs) than the other environments.