Polar Science最新文献

In this article, we identify what herders in Fennoscandia and northwestern Russia see as critical conditions and events in the annual reindeer herding cycle. Indigenous Sámi and Yamal reindeer herders identify eight seasons, each of which has crucial importance in its own way. Differences in perception between Fennoscandian and northwestern Russian reindeer herders about good and bad seasonal conditions are based on the degree of climatic and geographic variation, herd control and the variety of simultaneous pressures on pastures. The scope and speed of ongoing climate change in the Arctic will profoundly modify these conditions, and consequently shape critical events and outcomes in reindeer herding. The resulting challenges need to be assessed in the context of social and economic dynamics. Reindeer herders throughout Fennoscandia and Russia are concerned about future prospects of their livelihood. To adapt to climate change and develop new strategies, reindeer herders must have access to pastures; they must retain their mobility and flexibility; and their participation in land-use decisions must be endorsed.

Diving patterns of air-breathing predators were monitored from three moored subsurface upward-looking echosounders. Complete and partial dive profiles were visible on active acoustic records as echoes that started and/or returned to the surface. Dive metrics: maximum dive depths, durations, and wiggle count were measured and angles, distances, and velocities, were calculated at each site. Dive shapes ‘U’, ‘V’ and ‘W’ were derived using the number of wiggles and the percentage of dive bottom time. Dive profiles were classified into four types with type 1 dives being short in total duration and distance, low velocities, small angles, shallow, and linked to ‘U’ and ‘W’ shapes. Type 2 dives were short in distance, had low velocities, shallow depths, and were linked to ‘V’ dives. Dive types 3 and 4 had higher velocities, larger angles, longer total durations, and were deeper than types 1 and 2. Observed dive types could correspond to travelling, exploring, and foraging predator behaviors. Significant predator-prey overlaps occurred with predator dive profile counts correlated with krill aggregation thickness, density, and depth. This study demonstrates the utility of using stationary active acoustics to identify predator dive profiles with a simultaneous characterization of the potential prey field.

This study presented an extended time series of ice production in Antarctic coastal polynyas for 20 years of 2002–21 using high spatial resolution satellite data from passive microwave sensors: the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2). For this, we reconstructed the previously presented thin ice thickness algorithms and re-estimated ice production by replacing atmospheric input data for the heat flux calculations with the newly released ECMWF Reanalysis v5 (ERA5). The consistency of ice production between AMSR-E and AMSR2, whose operation periods do not overlap, was confirmed from comparisons with ice production by the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS) with relatively coarse spatial resolution. The open ocean area, which cannot be detected from the thin ice thickness algorithm, was defined using sea-ice concentration (SIC) from AMSR-E and AMSR2. The satellite derived SIC has been suggested to be underestimated in the new thin ice (polynya) area. The effect of the underestimation on the ice production estimation was evaluated. The underestimation of SIC from three major algorithms was also investigated from comparisons with the thin ice thickness presented in this study. The coastal polynya dataset covering 20 years with the higher spatial resolution presented in this study is vital for climate-change-related studies.

Although temperature plays a crucial role in governing seed reproduction in High Arctic plants, little is known about the germination response of these plants to climate warming. We conducted a germination experiment to examine the thermal germination characteristics of three common High Arctic plant species in Svalbard: Dryas octopetala, Oxyria digyna, and Salix polaris. We exposed the seeds to two temperature regimes: gradually increasing and decreasing temperatures between 4 and 15 °C. Additionally, we measured the ground surface temperatures at the study site. All three High Arctic plant species exhibited no specific temperature requirements for germination, with minimum germination temperatures falling within the range of 4–8 °C. Based on the ground surface temperature data, the period during which the weekly average ground surface temperature exceeded this minimum germination temperature range (period available for germination) spanned from mid-June to mid-August. By simulating a warming scenario of 2 and 4 °C, we estimated that the onset of the period available for germination would advance by 1–2 and 2–3 weeks, respectively. Furthermore, our results suggest the possibility of autumn germination in the High Arctic region under future warming conditions.

A three-dimensional numerical model based on the smoothed particle hydrodynamics (SPH) method is utilized to model such interactions. The effects from air and water are well captured using suitable force components and without explicit inclusion of air and water phases. This reduces the four-phase SPH model into a two-phase model, significantly reducing computational costs and potentially enabling the use of this model for large-scale simulations. This study includes two simulation domain size. The results show that the remained oil slick in the icy domain is completely depend on properties of different crude oils and current velocity. Then we performed a numerical experiment to study the effects of different ice parameters (e.g., ice concentration, floe shape) on the drift of fresh and weathered oil. Ice fields with the size of 750 m $\times$ 1350 m are used in the experiment. The ice concentration varies between 30%, 50% and 70%. Quadrilateral and circular ice floes, in addition to real-shape floes digitize from an aerial image are all used in the experiment. Oil spills of 1257 $m^3$ are released in the open water and later drift into the ice under the influence of steady current of 50 $\frac{\mathrm{cm}}{s}$. The type of spilled crude oil varies from fresh Troll B, Troll B 250 °C, and Troll B 250 °C and 75%emuls. The behavior of oil spills while crossing through the ice infested area are investigated by measuring the thickness of crude oil, the average and maximum distance traveled by crude oil.

Climate warming is the driving force behind the mass change of glaciers, resulting in their thinning and retreat. These changes could result in the formation of glacial lakes across the Himalayan landscape, posing a risk of glacial lake outburst flood (GLOF) hazards, causing enormous damage to the natural environment, human property, and lives. The present study demonstrates a semi-automated tool named 'Himalayan Glacier Thickness Mapper' (HIGTHIM), a Python script based on the ArcPy module. The tool provides the glacier's ice thickness, bed topography, location of the potential lake, and lake volume. It utilizes the laminar flow equation to model ice thickness by applying the surface velocity and slope. We used HIGTHIM in the Sutlej and Beas basins for 132 glaciers covering an area of 618 km² in the Western Himalaya for this investigation. The results indicate 118 potential lake sites covering a total area of 16 km² and a volume of 269 × 10⁶ m³. The information provided by the HIGTHIM tool will be useful in understanding the formation and progression of future glacial lakes caused by deglaciation. Such data is required for the scientific community to perform dynamic modelling of outburst scenarios, hydrological modelling, and risk mitigation from GLOF.

The article presents a two-dimensional three-layer non-stationary thermodynamic model allowing to calculate the annual variation (thermodynamic evolution) of the ice ridge using external meteorological and hydrological parameters as well as the information on the initial ice ridge porosity. For the test model simulation, the results of the study of morphometric characteristics of the ice ridge carried out in May-June 2011 and in April 2012 at « North Pole −38» and «North Pole −39» drifting stations were used. These studies were conducted using electric thermal drilling with computer recording of the penetration rate. Boreholes were drilled along the cross-section of the ridge crest at 0.5 m intervals. Cross-sectional profiles of ice ridge are illustrated. Applying the proposed model, it was possible to adequately reproduce the observed evolutionary changes in the main morphometric parameters (sail height, keel depth, thickness of the consolidated layer) of the investigated ice ridge.

This research note presents a report documenting a rare phenomenon observed in Sanionia uncinata (Hedw.) Loeske, entailing the presence of sporophytes across eight distinct locations on King George Island, Antarctica. Additionally, it briefly explores the potential correlation between regional warming air temperatures, water availability, and the emergence of these structures, suggesting their utility as indicators of climate change. Given that S. uncinata is recognized as a hygrophilic moss species typically found in well-hydrated environments, our hypothesis posits that the unprecedented development of substantial sporophyte numbers might be a consequence of rapid regional warming in the vicinity of the Antarctic Peninsula. Further investigations are essential to elucidate the potential interplay between shifting climate patterns and the observed proliferation of Sanionia uncinata sporophytes, thereby contributing to a more comprehensive understanding of their ecological responses to environmental fluctuations.

During geomagnetic quiet conditions, Indian Antarctic stations are considered to be located outside the auroral oval: Maitri (CGM coordinates: 63.3°S, 54.2°E) is equatorward and Bharati (CGM coordinates: 74.8°S, 98.4°E) is poleward of the auroral oval. Simultaneous observations of magnetic field variations at these two locations for 10-years (2013–2022) provide an opportunity to study quiet-time magnetic field patterns, if any. Geomagnetic quiet days with ΣKp ≤ 3 are selected, during which the lower values of solar wind and interplanetary parameters are also confirmed. Maitri station exhibits clear southern hemispheric solar quiet (Sq) type of magnetic field variation on geomagnetic quiet days in all seasons, indicating the influence of ionospheric dynamo due to thermospheric winds. Interestingly, Bharati station also displays regular and systematic magnetic field variations in all three components. The D-component at Bharati exhibits very strong variation at early morning hours (7–8 MLT), which is ∼2–4 times stronger than that of H-component, driving strong equatorward/northward currents during all seasons. Both stations show annual type of seasonal variation with peak amplitude during summer and least during winter. The schematic illustration of global and polar Sqs proposed here explains the results obtained through 10-years’ statistical study.

During the Austral summer of 2022, a study was conducted to investigate the physical properties of six lakes in the Larsemann Hills, East Antarctica. The lake water column's key properties, viz. temperature, salinity, density, fluorescence, and depth, were examined using a CTD profiler to establish a high-resolution description of their variations and identify the factors influencing intra and inter-lake variations. The results indicated that the shallow lakes LH14, LH04, and Discussion were well mixed. Lakes LH04 and LH14 on Stornes were affected by salinity, likely sea spray. In contrast, the deeper lakes, namely Nella, Cameron and Progress, were primarily driven by temperature and density dynamics. The hydrological characteristics of Cameron and Progress were notably impacted by their proximity to the ice sheet, while Nella was influenced by the presence of a partial lake ice cover. The lake depth, geographical location and presence of ice cover in the catchment significantly influenced temperature and salinity variations within the lakes. Deep lakes may be more sensitive to changes in temperature and density as compared to shallow lakes and could potentially affect other physical lake parameters. This baseline information is a valuable reference for future investigations on these lakes and similar environments.