North Pole Research Articles

Radar Sounding Reveals Common Evolutionary History Between the North Polar Layered Deposits and an Outlier Ice Deposit on Mars

AbstractMars' polar ice deposits are thought to preserve a record of climate throughout their evolution. In addition to the large north polar layered deposits (NPLD) at Mars' north pole, smaller ice deposits are preserved in craters nearby. These outlying deposits were potentially formed by the same mechanisms that drive NPLD formation, or may represent more local mechanisms. Distinguishing between these possibilities would help elucidate the spatial homogeneity of Martian climate processes. Here, we analyzed SHARAD radar depth profiles from 34 locations across the NPLD and 5 locations within the Korolev crater ice deposit using Fourier transform analysis and dynamic time warping to quantitatively assess the similarity between the internal layered stratigraphy of the two deposits. We identify broad stratigraphic similarities between the Korolev deposit and the NPLD, suggesting they likely formed due to the same climate forcing mechanism, with local variability also observed across the NPLD.

Snapshot of a Paleoarchean seafloor: Evidence from 3.43-3.35 Ga Strelley Pool chert-pebble conglomerate for deposition, silicification, and erosion of hydrothermal greenalite-apatite precipitates

Some of the oldest, well-preserved exhalative sedimentary rocks (ferruginous cherts and jaspilites) occur in volcanic-dominated Paleoarchean sequences in the northern Pilbara Craton, Australia. Jaspilites contain fine-grained hematite particles that have been interpreted to have formed following seawater oxidation of vent-derived Fe2+(aq) by photoautotrophs. However, recent studies suggest that most of the iron in the jaspilites was originally deposited as Fe(II)-rich silicates such as greenalite, sparking renewed debate about how iron was precipitated in the early oceans. Here we show that rounded clasts of dusty ferruginous chert in basal conglomerates of the 3.43–3.35 Ga Strelley Pool Formation, North Pole Dome, Pilbara Craton, Australia, contain abundant nanoparticles of greenalite and apatite that are texturally, mineralogically and chemically near-identical to occurrences in Neoarchean banded iron formations in the Hamersley Group, Australia. Hematite where present occurs in trace amounts and its distribution along the edges of clasts implies that at least some of the hematite formed during weathering. The greenalite-rich clasts display a pronounced positive shale-normalized Eu anomaly, small positive Y anomaly and lack a positive La anomaly, features typical of Paleoarchean exhalites. The co-occurrence of greenalite- and apatite-rich chert-pebbles with clasts of hydrothermal black chert and silicified felsic volcaniclastic sedimentary rocks points to a volcanically active provenance with vigorous hydrothermal activity, consistent with derivation from the underlying 3.43 Ga Panorama Formation. We argue that the greenalite and apatite nanoparticles precipitated during mixing between hydrothermal vent fluids and anoxic seawater and were silicified on the seafloor. The round to oval shape of the chert clasts indicates that the silica cement had recrystallized prior to erosion, consistent with the presence of polygonal shrinkage structures in the dusty chert clasts. Our findings imply that greenalite, contrary to recent suggestions, not only formed in Paleoarchean seawater, but was also stable during deposition, diagenesis, and resedimentation. The precipitation and non-dissolution of apatite nanoparticles in Paleoarchean seawater points to elevated phosphate concentrations, whereas the absence of primary hematite is consistent with models advocating a role for abiotic iron deposition during the Archean.

Mars' North Polar Spiral Trough Migration Paths as Revealed Through 3D Radar Mapping

AbstractWe present observations and maps of Mars' northern polar spiral trough migration paths (TMPs) as revealed through the 3D SHARAD (Shallow Radar) data volume, identify patterns of TMP morphology, and provide interpretations and implications of these TMPs on past climate. This data set provides additional spatial context over traditional 2D data as it allows for radargrams to be taken perpendicular to each trough strike, which minimizes distortion of migration paths due to oblique viewing geometry. Here, we present an expanded survey of trough migration and analysis of surface troughs across the north polar layered deposits. We corroborate many previous observations of trough migration such as: the general poleward and stratigraphically upward migration from the TMP initiation point; the broadly similar depth of trough initiation across the cap; regional variability in TMP morphology; and the presence of buried promontories. Our results support the presence of two generations of troughs, though we cannot confirm that the oldest generation originated deeper than ∼600 m beneath the current surface, as previously reported. Two generations of troughs suggest that climate conditions favorable for initiation of trough migration have occurred at least twice. Trough initiation occurring only in the upper ∼600 m suggests that troughs are relatively recent features in the polar cap, developing after the formation of ∼half the current cap height. The mapped TMPs provide insight into the consistency of Mars' climate during the accumulation of the past few hundred meters of ice by recording the boundary of erosion and accumulation of ice at the troughs.

Weakly nonlinear shape oscillations of viscoelastic drops

Axisymmetric shape oscillations of a viscoelastic drop in a vacuum are studied by a weakly nonlinear analysis. The two-lobed initial drop deformation mode is studied. The Oldroyd-B model is used for characterizing the drop liquid rheological behaviour. The equations of motion and the solutions up to second order are developed, where elastic effects appear. Solutions of the characteristic equation are validated against the decay rate and frequency of damped shape oscillations of polymer solution drops in an acoustic levitator. The theory shows enhancing or dampening of the nonlinear behaviour and enhanced mode coupling, as compared with the Newtonian case. The study reveals an excess time in the prolate shape and a frequency change, together with a quasi-periodicity of the oscillations. The Fourier power spectra of traces of the drop north pole position in time show mode coupling as a nonlinear effect. At moderate stress-relaxation Deborah number, the resultant drop motion for large Ohnesorge number, suggesting aperiodic drop behaviour, may nonetheless be oscillatory, where the drop elasticity is owing to the liquid bulk elasticity instead of surface tension. A method is developed to predict the oscillatory or aperiodic behaviour of a drop of a given size from a rheologically characterized viscoelastic Oldroyd-B liquid.

Optical edge-to-screw singularity state conversions

Optical singularity states, which significantly affect propagation properties of light in free space or optical medium, can be geometrically classified into screw and edge types. These different types of singularity states do not exhibit direct connection, being decoupled from each other in the absence of external perturbations. Here we demonstrate a novel optical process in which a higher-order edge singularity state initially nested in the propagating Gaussian light field gradually involves into a screw singularity with a new-born topological charge determined by order of the edge state. The considered edge state comprises an equal superposition of oppositely charged vortex and antivortex modes. We theoretically and experimentally realize this edge-to-screw conversion process by introducing intrinsic vortex–antivortex interaction. We also present a geometrical representation for mapping this dynamical process, based on the higher-order orbital Poincaré sphere. Within this framework, the edge-to-screw conversion is explained by a mapping of state evolution from the equator to the north or south pole of the Poincaré sphere. Our demonstration provides a novel approach for manipulating singularity state by the intrinsic vortex–antivortex interactions. The presented phenomenon can be also generalized to other wave systems such as matter wave, water wave, and acoustic wave.

Holographic Einstein ring of a charged Rastall AdS black hole with bulk electromagnetic field* *Supported by the National Natural Science Foundation of China (11675140, 11705005, 12375043), the Innovation and Development Joint Foundation of Chongqing Natural Science Foundation (CSTB2022NSCQ-LZX0021), and the Basic Research Project of Science and Technology Committee of Chongqing (CSTB2023NSCQ-MSX0324)

We study the Einstein images of a charged Rastall AdS black hole (BH) within the fabric of AdS/CFT correspondence. Considering the holographic setup, we analyze the amplitude of the total response function for various values of model parameters. With an increase in parameter λ and temperature T, the amplitude of the response function decreases, while it increases with an increase in electric charge e and chemical potential μ. The influence of frequency ω also plays an important role in the bulk field, as it is found that decreasing ω leads to an increase in the periods of the waves, which means that the amplitude of the response function also depends on the wave source. The relation between T and the inverse of the horizon for various values of parameter λ is interpreted under fixed values of other involved parameters. These, in turn, affect the behavior of the response function and the Einstein ring, which may be used to differentiate the present study from previous ones. We construct the holographic images of the BH in bulk via a special optical system. The results show that the Einstein ring always appears with concentric stripes at the position of the north pole, and this ring transforms into a luminosity-deformed ring or bright light spot when the distant observer lies away from the north pole. Finally, we discuss the influence of the associated parameters on the Einstein ring radius, which is consistent with wave optics.

Iceberg ploughmarks and glacial lineations on Jan Mayen Ridge: Evidence for past iceberg and possible ice-shelf grounding in deep water

Jan Mayen Ridge, south of the isolated island of Jan Mayen (71°N 8°W), is located strategically near the centre of the Polar North Atlantic and surrounded by deep-water seas. Examination of about 4,100 km2 of multibeam bathymetric data allowed identification of 1700 chaotic seafloor depressions at 300–1000 m modern water depth and two sets of lineations at 400–600 m and 750–900 m deep. The chaotic depressions are interpreted as ploughmarks produced as iceberg keels impinged on a sedimentary seafloor. The deepest ploughmarks reach 1010 m depth. Multi-keel ploughmarks indicate the presence of tabular icebergs of minimum widths 0.5–2.3 km. Ploughmark orientations were W/E and SW/NE on the northern and southern ridge, respectively, suggesting that deep-keeled icebergs drifting across Jan Mayen Ridge were probably calved mainly from short floating tongues at the margins of full-glacial Greenland ice streams. The mapped seafloor lineations are morphologically similar to mega-scale glacial lineations and flutes formed by soft-sediment deformation beneath active ice. They are interpreted to indicate the possible grounding of glacier ice on Jan Mayen Ridge. Their W-E orientation precludes ice flow from a full-glacial Jan Mayen ice cap. A possible interpretation is that they may represent grounding of a large floating ice shelf probably fed by ice from the Greenland Ice Sheet during one of the very large pre-Weichselian glaciations of the Quaternary. Whereas these lineations at 70°N do not provide direct evidence for a huge ice-shelf complex flowing southwards from the Arctic Ocean, the general climatic conditions required to form and maintain large ice shelves suggest that the development of an Arctic Ocean ice shelf at some point during Quaternary full-glacials remains a possibility.

Atmosphere circulation patterns synchronize pan-Arctic glacier melt and permafrost thaw

The Arctic is changing rapidly due to the amplification of global temperature trends, causing profound impacts on the ice sheet in Greenland, glaciers, frozen ground, ecosystems, and societies. Here, we focus on impacts that atmospheric circulation causes in addition to the climate warming trends. We combine time series of glacier mass balance from temporal satellite gravimetry measurements (GRACE/GRACE-FO; 2002–2023), active layer thickness in permafrost areas from ESA’s Climate Change Initiative remote sensing and modelling product (2003–2019), and field measurements of the Circumpolar Active Layer Monitoring Network (2002–2023). Despite regional and system-related complexities, we identify robust covariations between these observations, which vary asynchronously between neighbouring regions and synchronously in regions antipodal to the North Pole. We reveal a close connection with dominant modes of atmosphere circulation, controlling about 75% of the common pan-Arctic impact variability (2002–2022), also affecting the Greenland Ice Sheet. We emphasize that it is necessary to consider such atmospheric driving patterns when projecting impacts, particularly caused by extremes, in an increasingly warmer Arctic.

Sea ice mass balance during the MOSAiC drift experiment: Results from manual ice and snow thickness gauges

Precise measurements of Arctic sea ice mass balance are necessary to understand the rapidly changing sea ice cover and its representation in climate models. During the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, we made repeat point measurements of snow and ice thickness on primarily level first- and second-year ice (FYI, SYI) using ablation stakes and ice thickness gauges. This technique enabled us to distinguish surface and bottom (basal) melt and characterize the importance of oceanic versus atmospheric forcing. We also evaluated the time series of ice growth and melt in the context of other MOSAiC observations and historical mass balance observations from the Surface Heat Budget of the Arctic (SHEBA) campaign and the North Pole Environmental Observatory (NPEO). Despite similar freezing degree days, average ice growth at MOSAiC was greater on FYI (1.67 m) and SYI (1.23 m) than at SHEBA (1.45 m, 0.53 m), due in part to initially thinner ice and snow conditions on MOSAiC. Our estimates of effective snow thermal conductivity, which agree with SHEBA results and other MOSAiC observations, are unlikely to explain the difference. On MOSAiC, FYI grew more and faster than SYI, demonstrating a feedback loop that acts to increase ice production after multi-year ice loss. Surface melt on MOSAiC (mean of 0.50 m) was greater than at NPEO (0.18 m), with considerable spatial variability that correlated with surface albedo variability. Basal melt was relatively small (mean of 0.12 m), and higher than NPEO observations (0.07 m). Finally, we present observations showing that false bottoms reduced basal melt rates in some FYI cases, in agreement with other observations at MOSAiC. These detailed mass balance observations will allow further investigation into connections between the carefully observed surface energy budget, ocean heat fluxes, sea ice, and ecosystem at MOSAiC and during other campaigns.

The Transpolar Drift current: an ocean-ice-wind complex in rotating, spherical coordinates

Starting from the governing equations for a viscous, incompressible fluid, written in a rotating, spherical coordinate system that is valid at the North Pole, the thin-shell approximation is invoked. No further approximations are needed in the derivation of the system of asymptotic equations used here. Suitable stress conditions on the upper and lower surfaces of the ice are described, leading to the construction of a solution for the Transpolar Drift current. This involves the specification of a suitable geostrophic flow, combined with an Ekman component. Then, via the stress conditions across the ice at the surface, a solution for the motion of the ice, and for the associated wind blowing over it, are obtained. In addition, the model adopted here provides a prediction for the reduction in ice thickness along the Transpolar Drift current as it passes through the Fram Strait. The formulation that we present allows considerable freedom in the choices of the various elements of the flow; the model chosen for the physical properties of the ice is particularly significant. All these aspects are discussed critically, and it is shown that many avenues for future investigation have been opened.

Current Status and Trends of Low-Temperature Steel Used in Polar Regions.

The desire to explore the natural resources and geopolitical patterns of the North and South Poles has significantly increased the interest of experts and researchers in the development and utilization of the polar regions. In this article, we comprehensively analyzed the current state of the development of polar low-temperature steel around the world. We highlighted the challenges that must be addressed in the ongoing development efforts and summarized the expected future trends in this field. The main theme of this article involves the challenges encountered in polar environments primarily caused by the low-temperature toughness and seawater corrosion of marine steel.

StraitFlux – precise computations of water strait fluxes on various modeling grids

Abstract. Oceanic transports shape the global climate, but the evaluation and validation of this key quantity based on reanalysis and model data are complicated by the distortion of the used curvilinear ocean model grids towards their displaced north poles. Combined with the large number of different grid types, this has made the exact calculation of oceanic transports a challenging and time-consuming task. Use of data interpolated to standard latitude/longitude grids is not an option, since transports computed from interpolated velocity fields are not mass-consistent. We present two methods for transport calculations on grids with variously shifted north poles, different orientations, and different Arakawa partitions. The first method calculates net transports through arbitrary sections using line integrals, while the second method generates cross sections of the vertical–horizontal planes of these sections using vector projection algorithms. Apart from the input data on the original model grids, the user only needs to specify the start and endpoints of the required section to get the net transports (for the first method) and their cross sections (for the second method). Integration of the cross sections along their depth and horizontal extent yields net transports in very good quantitative agreement with the line integration method. This allows us to calculate oceanic fluxes through almost arbitrary sections to compare them with observed oceanic volume and energy transports at available sections, such as the RAPID array or at Fram Strait and other Arctic gateways, or to compare them amongst reanalyses and to model integrations from the Coupled Model Intercomparison Projects (CMIPs). We implemented our methods in a Python package called StraitFlux. This paper represents its scientific documentation and demonstrates its application on outputs of multiple CMIP6 models and several ocean reanalyses. We also analyze the robustness and computational performance of the tools, as well as the uncertainties in the results. The package is available on GitHub and Zenodo and can be installed using pypi.

Dynamics of holographic images of scalar-tensor-vector gravity-AdS black holes* *Supported by the National Natural Science Foundation of China (11675140, 11705005, 12375043), the Innovation and Development Joint Foundation of Chongqing Natural Science Foundation (CSTB2022NSCQ-LZX0021), and the Basic Research Project of Science and Technology Committee of Chongqing (CSTB2023NSCQ-MSX0324).

Using AdS/CFT correspondence, we analyze the holographic Einstein images via the response function of the complex scalar field as a probe wave on an AdS Schwarzschild scalar-tensor-vector gravity (STVG) black hole (BH). We find that the amplitude of the response function decreases with increasing values of coupling parameter α and increases with decreasing temperature T. The frequency ω of the wave source also plays a significant role in wave periods; as we increase the values of ω, the periods of waves decrease, indicating that the total response function closely depends on the wave source. Further, we investigate the optical appearance of the holographic images of the BH in bulk. We found that the holographic ring always appears with surrounding concentric stripes when the observer is located at the north pole, and an extremely bright ring appears when the observer is at the position of the photon sphere of the BH. This ring changes into a luminosity-deformed ring or a bright light spot as the observational angle changes. The corresponding brightness profiles show that the luminosity of the ring decreases and the shadow radius increases with increasing values of α. The relation between temperature T and the inverse of the horizon is discussed; T is small at the beginning of the horizon and then increases as the horizon radius increases. This effect can be used to distinguish the STVG BH solution from other BH solutions. Moreover, these significant features are also reflected in the Einstein ring and corresponding brightness profiles. In addition, we compare the results obtained by wave optics and geometric optics, which align well, implying that the holographic scheme adopted in this study is valid.

Макромасштабные экспериментальные исследования ледовых сжатий в Северном Ледовитом океане в период первого дрейфа ледостойкой самоходной платформы «Северный полюс» в составе полярной дрейфующей станции «Северный полюс-41» в 2022—2023 гг.

The nipping problem is of scientific and practical interest from the perspective of the strategy for the development of ice shipbuilding and shipping in Russian Arctic, and is fundamental in studying the very nature of the phenomenon. It is possible to solve the tasks within the framework of the problem only by the contact research method during a long stay of a specialized vessel in drifting ice. The review article presents descriptions of the experimental and analytical studies carried out on the issue during the first year of operation of the drifting station “North Pole-41”, organized on the ice-resistant self-propelled platform “North Pole”.

Development of low‐torque‐ripple motor with high rotational speed to downsize electrical systems

AbstractElectrification is progressing across different fields such as automobiles and construction machinery. Motors for electric systems are required to be compact and achieve high power density. In this study, we developed a small motor with rotation speed of 22,000 r/min by reducing stress concentration. Each pole has three magnets in the circumferential direction, and the magnets are arranged in a U‐shape. The magnet insert slots are comprised of expanded flux barriers on the inner diameter side and a guide‐less structure. The magnet slots reduce stress concentration. Additionally, the rotor has two dents on the outer diameter surface and expanded flux barriers on the outer diameter side. The dents have different shapes between the North (N) and South (S) poles. The structures reduce the torque ripple.

Coupled bulk and interfacial transport of surfactants governs the settling of a drop towards a wall

Surfactant-like impurities are omnipresent in multiphase emulsions and may substantially affect the motion of small droplets by altering their interfacial properties. Usually these surfactants are soluble in the bulk and undergo adsorption–desorption onto the interface which modifies their surface concentration and hence their overall influence on droplet motion. Yet, the impact of the bulk solubility and transport of surfactants on droplet dynamics, especially in the presence of bounding walls, remains poorly understood. As such, in this article, we assess the impact of bulk soluble surfactants on the settling of a spherical drop towards a plane wall. We consider coupled bulk and interfacial transport of surfactants, mediated by adsorption–desorption processes and construct a semi-analytical framework for arbitrary values of ‘bulk interaction parameter’, which dictates the strength of adsorption–desorption kinetics compared with bulk diffusion. Our results indicate that while mass exchange between the bulk and the interface can remobilize the drop, a finite bulk diffusion rate restricts this process and therefore slows down the drop. This also results in bulk concentration depletion near the south pole and accumulation near the north pole, the extent of which becomes strongly asymmetric with an enhanced intensity of depletion, as the drop approaches the wall. Presence of the wall and bulk solubility are found to aid each other towards remobilizing the drop by aptly modifying the interfacial concentration. Our results may provide fundamental insights into the kinetics of surfactant-laden drops, with potential applications in food and pharmaceutical industries, separation processes, etc.

Stereographic compactification and affine bi-Lipschitz homeomorphisms

Abstract Let $\sigma _q \,:\,{{\mathbb{R}}^q} \to{\textbf{S}}^q\setminus N_q$ be the inverse of the stereographic projection with center the north pole $N_q$ . Let $W_i$ be a closed subset of ${\mathbb{R}}^{q_i}$ , for $i=1,2$ . Let $\Phi \,:\,W_1 \to W_2$ be a bi-Lipschitz homeomorphism. The main result states that the homeomorphism $\sigma _{q_2}\circ \Phi \circ \sigma _{q_1}^{-1}$ is a bi-Lipschitz homeomorphism, extending bi-Lipschitz-ly at $N_{q_1}$ with value $N_{q_2}$ whenever $W_1$ is unbounded. As two straightforward applications in the polynomially bounded o-minimal context over the real numbers, we obtain for free a version at infinity of: (1) Sampaio’s tangent cone result and (2) links preserving re-parametrization of definable bi-Lipschitz homeomorphisms of Valette.

Holographic study on Einstein ring for a charged black hole in conformal gravity

Under the help of AdS/CFT correspondence, the Einstein ring of a charged black hole in conformal gravity has been studied. As an alternative to standard Einstein’s theory, the conformal gravity is both renormalizable and unitary. And such conformal theory can naturally solve some troublesome problems in physics, such as the quantum gravity problem, the dark matter problem and so on. Considering the conformal gravity has many advantages, therefore in this paper, we study Einstein ring and the effect of gravity-related parameters c0, temperature T and chemical potential u on such Einstein ring in the conformal gravity through the holographic method. Explicitly, imposing an oscillating Gauss source on one side of the AdS boundary which propagates in the bulk, the response functions are derived on the other side of the boundary. Given the proposed wave optics system, the Einstein rings are observed as expected. All these results reveal that when the observer locates at the north pole, there always exists the Einstein ring and surrounding concentric stripes. And such ring becomes into a luminosity-deformed ring or light spot while the observer departs away from the north pole. We also investigate the effect of temperature T, chemical potential u and gravity-related parameters c0 on the ring radius. We find the ring radius increases with the decrease of the temperature, increase of the chemical potential, and increase of the gravity-related parameters respectively. And more, in conformal gravity, because the charge does not appear in the metric but is given by the constraint relation, the chemical potential affects the radius of the ring differently compared with that in Einstein’s gravity. To check the results in the framework of holography, we investigate the ingoing angle of photon at the photon ring via geometric optics and find it is consistent with the angle of Einstein ring obtained via holography.

Global Ecology and Geography of Gender Equality.

Proximal socio-economic drivers of gender equality tend to obscure its remote ecological origins. General systems theory predicts that the greater annual variability in daylength, temperature, and daily precipitation at higher latitudes requires greater psychosocial flexibility. We extend this prediction to gender equality as a likely consequence. Accordingly, for 87 pre-industrial societies after 1500 CE, we find more gender equality in more variable habitats, and that this link is mediated by greater subsistence flexibility-foraging rather than raising plants and animals. Mutatis mutandis, these ecological predictors of global gender equality replicate in 175 modern countries after 2000 CE. Gender equality was, and still is, lowest around the Equator, higher toward the North and South Poles, and invariant in east-west direction. The geographical positioning of gender equality in pre-industrial times can predict over 40% of the opposite north-south gradients of gender equality in the opposite Northern and Southern Hemispheres today.

Geomorphology of craters located at Mercury’s north pole

Geomorphology of craters located at Mercury’s north pole