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Seasonal and interannual variabilities of sea-ice area in the Southern Ocean were examined using daily sea-ice concentration and ice velocity products for 2003–2019, derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) and AMSR2 data. This study quantified the contributions to changes in the sea-ice area due to sea-ice transport and local processes, including ice formation/melting and ice deformation. Regional differences in the processes of seasonal advance and retreat of sea ice were elucidated. In most regions, sea-ice area increases mainly due to new ice formation in the marginal ice zone during autumn and winter. However, in the Amundsen–Bellingshausen seas, ice melting occurs in the marginal ice zone, even during winter, and expansion of the ice cover is attributable mainly to off-ice transport. With regard to interannual variability, the maximum ice area for each year is highly correlated with increase of ice area attributable to the ice formation in the marginal ice zone. Revealed processes that controls sea-ice changes could help improve our understanding of the sea-ice response to climate change.

In order to improve the understanding of the dynamical deformation processes of sea ice in the seasonal ice zone (SIZ), measures to detect deformed ice were developed and validated using satellite L-band synthetic aperture radar (ScanSAR) images for the southern Sea of Okhotsk. To approach, sea ice was categorized into three ice types, typical of the sea ice in this region: nilas (thin level), pancake ice (thin rough), and deformed ice (thick rough), and then the measures to classify into these categories were developed using ALOS/Phased Array type L-band Synthetic Aperture Radar (PALSAR) as a function of backscatter coefficients at HH polarization ( $\sigma _{\text {HH}}^{0}$ ) and incidence angle ( $\theta _{i}$ ), based on the field observations. Comparative analysis confirmed that PALSAR can detect deformed ice more efficiently than RADARSAT-2 (C-band SAR). The temporal evolution of the area, judged as deformed ice from these measures, shows significant variability with both time and space, and deformed ice regions appear in relatively linear alignments with a width of a few tens of kilometers in the inner ice pack region, consistent with ice drift convergence. To confirm the results, PALSAR-2 images at HH and HV polarizations were examined as a function of $\theta _{i}$ , based on the four-year field observations in the same area. The results revealed that $\sigma _{\text {HH}}^{0}$ and $\sigma _{\text{HV}}^{0}$ are both subject to floe sizes as well as deformed ice, and $\sigma _{\text{HV}}^{0}$ is more sensitive. This indicates that care should be taken when applying these measures to the ice areas where significantly small floes are dominant like the marginal ice zone.

The lowest latitude sea ice in the world (excluding coastal freezing) is in the southern Sea of Okhotsk (south of 46°N), where it has significant impacts on freshwater input and primary production. This region is subject to climate change, and accordingly the monitoring of sea ice conditions is important. However, the interannual variability of the region’s sea ice is poorly understood due to its logistical challenges. Sea ice observations have been conducted in this region every winter for the period 1996-2020. The interannual variability of the ice conditions and the likely factors responsible for it were investigated using visual observations following the international ASPeCt protocol, combined with satellite SSM/I-SSMIS ice concentration data (1988-2020). AMSR-derived ice drift data sets and ERA5 meteorological reanalysis data sets were also analyzed to examine the effects of dynamic and thermodynamic processes. Our analysis revealed that 1) sea ice area in this region varies differently from that in the central and northern Sea of Okhotsk, where decreasing trends are reported, 2) sea ice volume has remarkable interannual variation and the peaks appeared much to more affected by dynamically deformed ice than freezing conditions, and 3) prominently deformed ice can be explained by taking shear components into account based on sea ice rheology. These results suggest the importance of including the proper sea ice rheology in numerical sea ice models to reproduce the realistic sea ice volume and deformation processes, and thereby the realistic primary production for all seasonal ice zones., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The 13th Symposium on Polar Science/Interdisciplinary sessions [IA] Arctic research, Thu. 17 Nov.

The 13th Symposium on Polar Science/Interdisciplinary sessions [IA] Arctic research, Thu. 17 Nov.

The aim of this study is to observe the spatial inhomogeneity of a rechargeable battery's electric conductivity distribution. Therefore, we have developed a system that uses the measurement results of a minute magnetic field that leaks from the cell to visualize, in real time, the cell's electric conductivity distribution. This system has a magnetic detection capability of 30 pT/Hz(0.5) (at 1 Hz); it measures the magnetic field distribution in the 240 x 240-mm range. This system has the ability to detect the 500-µA electric current that flows in a rechargeable battery 5 mm away from the sensor module. Because the magnetic signals are detected at the frequency synchronized with the alternating current flowing in the cell, this system is not affected by environmental magnetic field noise. Using this system, we have successfully visualized the short-circuit spot in a cell with significant self-discharge. Furthermore, we observe that the magnetic field distribution changes continually when the short circuit is being generated. The coordinate where the magnetic field distribution changed and the coordinate where metal precipitates were confirmed significant agreement.

Accurate description of sea ice velocity is necessary for improving the reproduction and prediction of high-latitude climate in modeling studies. In order to improve the simulated sea ice velocity field based on satellite-derived daily data, a set of sea ice dynamic parameters of the ocean–sea ice model was optimized with a Green’s function method, which uses linear combination of forward sensitivity operators for these parameters. An improved sea ice velocity field with 15–20% error reduction was obtained for both simulations with and without the data constraint of sea ice concentration. Moreover, dependencies of the sea ice dynamic parameters on background conditions were examined and linear dependency coefficients were also optimized by extending the above method. The sea ice velocity field was further improved for both free-drift and high-pressure regions with mean error reduction of about 25%. This resulted in decreases of surface salinities in the marginal ice zones, making them closer to observations. While the parameter adjustments as constants tended mainly to compensate influences of biases in surface forcing, the obtained dependencies were generally consistent with previous observational and theoretical studies and thus improved parameterizations of air–ice–ocean momentum exchange and ice pressure which are widely used in OGCMs. The enhanced ocean–sea ice initialization and parameterizations would be useful for operational seasonal prediction and climate prediction studies.

In summer 2018, thick sea ice blocked the mouth of the Amundsen Gulf (AG), Canada, obstructing shipping through the North-west Passage. This study analysed multi-year ice motion to investigate the source of this thick ice and the reasons for its unusual movement. For this purpose, a daily multi-year ice distribution product was generated by ice tracking using gridded daily sea-ice velocities (2003–2018) derived from the AMSR-E and AMSR-2 data. From autumn 2017 to summer 2018, the area of multi-year ice extended westward to the Beaufort Sea and then migrated towards the AG mouth. The primary cause of the unusual ice cover was anomalous AG-ward wind in September 2018. It is known that multi-year ice has become increasingly moveable over the past decades, as indicated by the increasing wind factor (i.e., ratio of ice-drift speed and wind speed), but the unusual ice motion in the summer of 2018 cannot be explainable by the wind factor alone. Accurately, predicting monthly wind and monitoring old thick ice will reduce the risk posed by thick Arctic sea ice to shipping.

This work presents the results of physical and biological investigations at 27 biogeochemical stations of early winter sea ice in the Ross Sea during the 2017 PIPERS cruise. Only two similar cruises occurred in the past, in 1995 and 1998. The year 2017 was a specific year, in that ice growth in the Central Ross Sea was considerably delayed, compared to previous years. These conditions resulted in lower ice thicknesses and Chl- a burdens, as compared to those observed during the previous cruises. It also resulted in a different structure of the sympagic algal community, unusually dominated by Phaeocystis rather than diatoms. Compared to autumn-winter sea ice in the Weddell Sea (AWECS cruise), the 2017 Ross Sea pack ice displayed similar thickness distribution, but much lower snow cover and therefore nearly no flooding conditions. It is shown that contrasted dynamics of autumnal-winter sea-ice growth between the Weddell Sea and the Ross Sea impacted the development of the sympagic community. Mean/median ice Chl- a concentrations were 3–5 times lower at PIPERS, and the community status there appeared to be more mature (decaying?), based on Phaeopigments/Chl- a ratios. These contrasts are discussed in the light of temporal and spatial differences between the two cruises., info:eu-repo/semantics/published

Antarctic sea ice kinematics plays a crucial role in shaping the Southern Ocean climate and ecosystems. Satellite passive-microwave-derived sea ice motion data have been used widely for studying sea ice motion and deformation, and they provide daily global coverage at a relatively low spatial resolution (in the order of 60 km × 60 km). In the Arctic, several validated datasets of satellite observations are available and used to study sea ice kinematics, but far fewer validation studies exist for the Antarctic. Here, we compare the widely used passive-microwave-derived Antarctic sea ice motion product by Kimura et al. (2013) with buoy-derived velocities and interpret the effects of satellite observational configuration on the representation of Antarctic sea ice kinematics. We identify two issues in the Kimura et al. (2013) product: (i) errors in two large triangular areas within the eastern Weddell Sea and western Amundsen Sea relating to an error in the input satellite data composite and (ii) a more subtle error relating to invalid assumptions for the average sensing time of each pixel. Upon rectification of these, performance of the daily composite sea ice motion product is found to be a function of latitude, relating to the number of satellite swaths incorporated (more swaths further south as tracks converge) and the heterogeneity of the underlying satellite signal (brightness temperature here). Daily sea ice motion vectors calculated using ascending- and descending-only satellite tracks (with a true ∼ 24 h timescale) are compared with the widely used combined product (ascending and descending tracks combined together, with an inherent ∼ 39 h timescale). This comparison reveals that kinematic parameters derived from the shorter-timescale velocity datasets are higher in magnitude than the combined dataset, indicating a high degree of sensitivity to observation timescale. We conclude that the new generation of “swath-to-swath” (S2S) sea ice velocity datasets, encompassing a range of observational timescales, is necessary to advance future research into sea ice kinematics.

We report three-dimensional pressure-field-temperature phase diagrams of ${\mathrm{Yb}}_{2}{\mathrm{Pd}}_{2}\mathrm{Sn}$ and ${\mathrm{Yb}}_{2}{({\mathrm{Pd}}_{0.9}{\mathrm{Ni}}_{0.1})}_{2}\mathrm{Sn}$ that are constructed from electrical resistivity measurements. In ${\mathrm{Yb}}_{2}{\mathrm{Pd}}_{2}\mathrm{Sn}$, which is known to be a pressure-induced antiferromagnet, we found an unexpected magnetic-field-induced phase at a higher field than the antiferromagnetic (AFM) phase under pressure. A non-Fermi-liquid (NFL) behavior characterized by ${T}^{3/2}$ dependence of the resistivity is observed along the AFM phase boundary, indicating the existence of the quantum critical line. As the AFM and field-induced phases approach each other with increasing pressure, the NFL behavior is more pronounced. ${\mathrm{Yb}}_{2}{({\mathrm{Pd}}_{0.9}{\mathrm{Ni}}_{0.1})}_{2}\mathrm{Sn}$ is known to be an antiferromagnet at ambient pressure. We also found a field-induced phase under pressure. Although the temperature-pressure phase diagram of ${\mathrm{Yb}}_{2}{({\mathrm{Pd}}_{0.9}{\mathrm{Ni}}_{0.1})}_{2}\mathrm{Sn}$ corresponds to that of ${\mathrm{Yb}}_{2}{\mathrm{Pd}}_{2}\mathrm{Sn}$ shifted by 1.7 GPa, the field-induced phase does not separate from the AFM phase. Furthermore, the NFL behavior is less pronounced than ${\mathrm{Yb}}_{2}{\mathrm{Pd}}_{2}\mathrm{Sn}$. The Ni substitution for Pd not only acts as a chemical pressure but also produces other effects for the magnetism and its criticality.

Antarctic sea ice kinematic plays a crucial role in shaping the polar climate and ecosystems. Satellite passive microwave-derived sea ice motion data have been used widely for studying sea ice motion and deformation processes, and provide daily, global coverage at a relatively low spatial-resolution (in the order of 60 × 60 km). In the Arctic, several validated data sets of satellite observations are available and used to study sea ice kinematics, but far fewer validation studies exist for the Antarctic. Here, we compare the widely-used passive microwave-derived Antarctic sea ice motion product by Kimura et al. (2013) with buoy-derived velocities, and interpret the effects of satellite observational configuration on the representation of Antarctic sea ice kinematics. We identify two issues in the Kimura et al. (2013) product: (i) errors in two large triangular areas within the eastern Weddell Sea and western Amundsen Sea relating to an error in the input satellite data composite, and (ii) a more subtle error relating to invalid assumptions for the average sensing time of each pixel. Upon rectification of these, performance of the daily composite sea ice motion product is found to be a function of latitude, relating to the number of satellite swaths incorporated (more swaths further south as tracks converge), and the heterogeneity of the underlying satellite signal (brightness temperature here). Daily sea ice motion vectors calculated using ascending- and descending-only satellite tracks (with a true ~24 h time-scale) are compared with the widely-used combined product (ascending and descending tracks combined together, with an inherent ~39 h time-scale). This comparison reveals that kinematic parameters derived from the shorter time-scale velocity datasets are higher in magnitude than the combined dataset, indicating a high degree of sensitivity to observation time-scale. We conclude that the new generation of “swath-to-swath” (S2S) sea ice velocity datasets, encompassing a range of observational time scales, is necessary to advance future research into sea ice kinematics.

We report electrical transport properties and electronic structure of a nonmagnetic metal ${\mathrm{Cu}}_{2}\mathrm{Sb}$ single crystal. ${\mathrm{Cu}}_{2}\mathrm{Sb}$ was found to be a compensated metal with high carrier density $\ensuremath{\sim}{10}^{22}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$ and high carrier mobility $\ensuremath{\ge}{10}^{3}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}/\mathrm{Vs}$ for both electron and hole carriers. The current-in-plane magnetoresistance at 2 K and 9 T was 730%, while the current-perpendicular-to-plane magnetoresistance at 2 K and 9 T was 2700% without the saturation. Angle-resolved photoemission spectroscopy throughout the three-dimensional (3D) bulk Brillouin zone signified a quasi-two-dimensional (2D) electron pocket axially centered along the M-A line and a 3D hole pocket at the \ensuremath{\Gamma} point, in accordance with the electron-hole compensated nature. The presence of quasi-2D open Fermi surface, in line with the first-principles band-structure calculations, is likely responsible for the observed nonsaturating current-in-plane magnetoresistance. The present result lays the foundation for realizing large magnetoresistance via Fermiology engineering in compensated metals.

Climate change alters the extent and structure of sea-ice environments, which affects how they function as a habitat for polar species. Identifying sea-ice characteristics that serve as indicators of habitat quality will be crucial to the monitoring and management of climate change impacts. In the Southern Ocean, Antarctic krill is a key prey species and fishery target. Krill larvae depend upon sea-ice habitats to survive the winter and recruit to the population in spring. Existing observations of sea-ice characteristics lack sufficient spatiotemporal coverage to quantify which ones contribute to favourable overwintering habitat, leading to uncertainties in how current and future changes in sea ice affect krill populations. Here, we derive regional-scale indices of annual krill recruitment spanning 35 years across the southwest Atlantic. To develop meaningful indicators of sea-ice habitat, we selected variables from a high-resolution sea-ice model that are hypothesized as relevant for larval habitat use. The resulting correlations between recruitment and sea-ice indicators vary by region and show remote connections to sea ice that correspond with established theories of larval transport. Through an improved representation of sea-ice habitat quality, as compared with using more traditional satellite-derived variables such as sea-ice extent and duration, we highlight plausible regions of overwintering habitat. Our findings improve current understanding of how krill are likely responding to changing sea ice and support emerging views that larval habitat use is complex. Furthermore, regional variation in larval dependence on sea ice may provide pockets of resilience to change for the broader krill population.

Metallic anti-ThCr

Antarctic Bottom Water (AABW) supplies the lower limb of the global overturning circulation, ventilates the abyssal ocean and sequesters heat and carbon on multidecadal to millennial timescales. AABW originates on the Antarctic continental shelf, where strong winter cooling and brine released during sea ice formation produce Dense Shelf Water, which sinks to the deep ocean. The salinity, density and volume of AABW have decreased over the last 50 years, with the most marked changes observed in the Ross Sea. These changes have been attributed to increased melting of the Antarctic Ice Sheet. Here we use in situ observations to document a recovery in the salinity, density and thickness (that is, depth range) of AABW formed in the Ross Sea, with properties in 2018–2019 similar to those observed in the 1990s. The recovery was caused by increased sea ice formation on the continental shelf. Increased sea ice formation was triggered by anomalous wind forcing associated with the unusual combination of positive Southern Annular Mode and extreme El Nino conditions between 2015 and 2018. Our study highlights the sensitivity of AABW formation to remote forcing and shows that climate anomalies can drive episodic increases in local sea ice formation that counter the tendency for increased ice-sheet melt to reduce AABW formation. Interacting atmospheric circulation patterns are responsible for a recent reversal of a decades-long decline in deepwater formation on the Antarctic shelf, according to an analysis of in situ and remote sensing data from the Ross Sea.

Recently, miniaturization and three-dimensional integration for improving the performance of electric devices have been accelerated, and smaller storage batteries with higher energy density and shrinked electric components have been more required. Therefore, failure analysis technologies targeted for these cutting-edged devices should be developed for increasing production yields and reducing product accidents. In mass production processes, pre-shipment inspections are performed on the core parts of electronic devices. In the case of electronic parts, energization check is adopted, and in the case of storage batteries, voltage drop, that is called to be an aging test, is checked. However, many cases have been reported in which products, that have passed the inspection, cause accidents. One of the typical causes of failures related about electronic components is internal electric-short caused by foreign matters mixed into the insulation or whiskers accidentally generated from the electrodes and wiring. Similarly, storage batteries also accidentally have internal short circuits due to foreign matter contaminations and dendrite formation at the electrodes. The internal short-circuited points of electronic components and storage batteries are identified by X-ray imaging method. However, it is difficult to acquire the contrast due to the lack of the dynamic range required for visualization of short-circuited parts because the wirings and insulation areas between electrodes have been significantly miniaturized. In addition, short circuits between wirings on the surface of electronic circuit boards have been visualized by thermography, although it is difficult to apply electronic components with multi-layered electrodes. Then we have focused on the relationship between the electric current distribution inside the devices and the magnetic field generated from it and spread toward outside, we have succeeded in deriving the analysis solution of the inverse problem for the first time. Combining this novel theory and a highly-sensitive magnetic field detection based on quantum effect, we have developed a subsurface electric current imaging system capable of detecting electric short-circuited points in the deep region. In this study, we discuss about the details of the theory about the analytical solution of the inverse problem and the visualization system, and show some results of failure analysis for actual electronic components and storage batteries. [1] Yuki Mima, Noriaki Oyabu, Takeshi Inao, Noriaki Kimura, Kenjiro Kimura, “Failure analysis of electric circuit board by high resolution magnetic field microscopy” Proceedings of IEEE CPMT Symposium Japan, pp.257-260, 2013. [2] Kenjiro Kimura, Yuki Mima, Noriaki Kimura, “Local electric current reconstruction theory for nondestructive inspection inside battery cell using magnetic field measurement”, Subsurface Imaging Science & Technology, 1, 1, pp.1-16, 2017. [3] Shogo Suzuki, Hideaki Okada, Kai Yabumoto, Seiju Matsuda, Yuki Mima, Noriaki Kimura, and Kenjiro Kimura, “Non-destructive visualization of short circuits in lithium-ion batteries by a magnetic field imaging system”, Japanese Journal of Applied Physics, Vol 60, No 5, pp.056502-1-4, 2021.

With the rapid spread of electric vehicles and hybrid vehicles in recent years, the energy density of lithium-ion batteries, which are the power sources of them, tends to increase.This means that the risk of ignition is further increased as represented by some fire accident case of an EV vehicle that had taken long time to extinguish, and thus eventually makes the requirement of safety management in the battery manufacturing process be expected stricter.To prevent ignition due to internal short circuit of battery, and eliminate a short-life battery product, we have been developing a technology to non-destructively visualize the self-discharged part inside the storage battery. In this technology, on the first, electric current is applied to the battery from external power source, and the leakage magnetic field that generated due to the internal electric current in the battery is sensed on outside of the battery. Next, the electric current density distribution inside the battery can be reconstructed and visualized three-dimensionally by using the spatial distribution of the measured magnetic field as the boundary condition and solving the inverse problem analytically. To measure leakage magnetic field with high sensitivity, it is necessary to take steps against disturbances as like DC magnetic field derived from magnetism or magnetic materials (often Ni is used for the collector foil), and AC magnetic fields generated from external circuits. In this method, two steps are used in combination for detection sensitivity of the pico-tesla order; (1) An AC current is applied to the battery, and the AC magnetic field generated in synchronization is phase-detected. (2) Install a small coil near the sensor and generate a DC cancel magnetic field by feedback control. By this method, it is possible to detect only the AC magnetic field corresponding to the applied current with high sensitivity in the linear operating region of the magnetic sensor. In actual detection of the leakage magnetic field, a DC voltage that balances with the output voltage of the battery is applied to the AC output of the AC current source connected to the battery so that the SOC of the storage battery is kept constant voltage. In addition to the above, the frequency of the AC output is usually set to 10 Hz or less to avoid the shielding effects of electrodes and the metallic package of the battery.By these steps and scanning two-dimensional of magnetic sensors or using a sensor array in which magnetic sensors are arranged two-dimensionally, the spatial distribution of the two-dimensional magnetic field outside the storage battery can be obtained. Since the sensor detects only one direction component of magnetic field, changing the direction of the sensor by 90 ° is needed. On data processing, some realistic structural assumptions are required to solve the inverse problem. (1) Defining that the plane parallel to the storage battery electrode plane is the XY plane, the Z component of the magnetic field vector is zero around the battery, and only X component and Y component remains as magnetic field vector components generated from internal current of the battery. (2) The thickness of the battery is sufficiently smaller than the size of the battery in the plane direction, that is, the three-dimensional current in the battery is confined in the thin two-dimensional plane. In the first step of the reconstruction, under the fact of (1), Laplace's equation is analytically solved in the "free space from the measurement surface to just above the electrode surface in the battery, without a magnetic source", and derive the two-dimensional magnetic field distribution directly above the electrode surface. In the next step, it is possible to obtain a three-dimensional current distribution inside the battery by analytically solving the Poisson-type equation and the electric current continuity equation under the realistic structural assumption of (2) with first calculation result as the boundary condition. In the presentation, we will introduce in detail the experiment and data processing for identifying the self-discharge point with this technology, including examples of visualizing the magnetic field distribution and current density distribution inside a battery after aging test.

Metallic anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth) with Bi square nets show superconductivity while insulating La$_2$O$_2$Bi shows high hole mobility, by expanding the c-axis length through oxygen intercalation. In this study, alkaline earth metal oxides (CaO, SrO, and BaO) were co-sintered with La$_2$O$_2$Bi. CaO and BaO served as oxygen intercalants without incorporation of Ca and Ba in La$_2$O$_2$Bi. On the other hand, SrO served as not only oxygen intercalant but also hole dopant via Sr substitution with La in La$_2$O$_2$Bi. The oxygen intercalation and hole doping resulted in expansion of the c-axis length, contributing to improved electrical conduction. In addition, the hole mobility was enhanced up to 150 cm$^2$V$^{-1}$s$^{-1}$ in La$_2$O$_2$Bi, which almost doubles the mobility in previous study.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 3 Dec.

The 11th Symposium on Polar Science/Special session: [S] Accelerating Arctic research: Recent progress and future prospect of Arctic research, Tue. 1 Dec.

This paper examines the temporal and spatial change in the characteristics of sea-ice motion in the Arctic. Ice motion is generally expressed by a motion at a constant ratio (wind factor) of wind speed, with a certain angle (turning angle) from the wind direction, and ocean currents. This study aimed to reveal the recent changes of the wind factor and turning angle using satellite observation data. We first prepared a daily ice-velocity data set from data for 2003–2017 collected by the satellite microwave sensor Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and its successor, AMSR2. Monthly values of the wind factor and turning angle were calculated by a least squares technique, based on the linear relationship between sea-ice velocity and geostrophic wind velocity. The daily variation of sea-ice motion was strongly correlated with that of the wind. The wind factor and turning angle changed regionally, seasonally and interannually. With regard to long-term trends, the wind factor has increased in almost all areas of the Arctic. However, the trend of increase stopped around 2010, especially around the central Arctic.

The 11th Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Poster presentations, Mon. 16 Nov. - Fri. 18 Dec.

To develop a high-density and long-life lithium-ion battery, a technology is needed that allows non-destructive visualization of the spatial distribution of deteriorated parts after cycle test. In the present study, we measured the distribution of the magnetic field leaking from the lithium-ion battery during its operation. Based on the measurement results, we evaluated the current density distribution inside a battery using the electric current reconstruction process. With respect to the changes in an internal state of the lithium-ion battery associated with cycle deterioration, we successfully visualized the spatial changes in the conductivity distribution inside the lithium-ion battery., 11 pages, 5 figures, letter

In this study, satellite-derived observations of sea ice concentration, drift, and thickness are combined to provide a climatology and inter-annual monthly variability of the sea ice volume budget over the growth season for the CryoSat-2 period Octobre 2010 to April 2019. This allows the first wintertime observational decomposition of the dynamic (advection and divergence) and thermodynamic drivers of ice volume change.Dynamic and thermodynamic processes will be separated by applying similar methods to Holland and Kwok (2012), which decomposed the governing equation of ice concentration, C:[1] ∂C/∂t + ∇.(uC) = f_C - rwhere u is ice drift motion, f_C is thermodynamic freezing or melting, and r is the concentration change from mass-conserving mechanical ice redistribution processes which convert ice area to ice thickness, such as ridging and rafting. ∂C/∂t represents ice intensification and ∇.(uC) represents ice flux divergence, the dynamic contribution to ice concentration.Equation 1 can be rearranged and the dynamic contribution, ∇.(uC), expanded to show the contributions from advection, (-u.∇C) and divergence, (-C∇.u), determining four terms:[2] ∂C/∂t = -u.∇C - C∇.u + f - rThe governing equation of the volume budget is of the same form but combines the thickness and concentration data:[3] ∂Ch/∂t = -u.∇Ch - Ch∇.u + f_Chwhere h is the thickness of the ice and the resulting product of the two datasets, Ch, is the effective thickness. If Ch were to be multiplied by the grid cell area this would give the volume, V. It is not necessary to take this step because the area remains constant and does not influence the relative values of the terms. However, when deriving an Arctic-wide climatology spatial integration across the grid cell areas is required. Ridging is taken into account by effective thickness change, therefore, it is not included in the calculations.The method is replicated using model simulations from the Centre for Climate Observation and Modelling (CPOM)-modified Los Alamos sea-ice model (CICE), providing a test of the model’s ability to calculate the volume budgets but also identifying unrealistic growth regimes in the CryoSat-2 observational datasets. Sensitivity to several observational datasets is performed to provide an estimated uncertainty of the budget calculations.The observational results show ice gain in the central Arctic is dominated by ice freezing with contributions from convergence. Divergence at the coastlines of the Arctic form an ice sink where freezing generates new ice. Advection is shown to drive ice equatorward and induce melting at the ice edge where ice becomes thermodynamically unstable. The dynamic components are found to grow in influence throughout the growth season.The 2016/17 winter growth season budget shows reduced thermodynamic intensification and stronger dynamic tendencies which may be in response to thin initial ice and an exceptionally warm winter. Compared to the observed volume budget, the CICE model displays similar patterns of thermodynamic freezing, however, dynamic components in the central Arctic are significantly reduced whilst they are over-amplified at the ice edge.

We report a series of layered superconductors, anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth), composed of electrically conductive Bi square nets and magnetic insulating $RE_2$O$_2$ layers. The superconductivity was induced by separating Bi square nets as a result of excess oxygen incorporation, irrespective of the presence of magnetic ordering in $RE_2$O$_2$ layers. Intriguingly, the transition temperature of all $RE_2$O$_2$Bi including nonmagnetic Y$_2$O$_2$Bi was approximately scaled by the unit cell tetragonality ($c$/$a$), implying a key role of relative separation of the Bi square nets to induce the superconductivity.

We report a series of layered superconductors, anti-ThCr

A rectenna, standing for a rectifying antenna, is an apparatus which generates d.c. electricity from electric fluctuations. It is expected to realize wireless power transmission as well as energy harvesting from environmental radio waves. To realize such rectification, devices that are made up of internal atomic asymmetry such as an asymmetric junction have been necessary so far. Here we report a material that spontaneously generates electricity by rectifying environmental fluctuations without using atomic asymmetry. The sample is a common superconductor without lowered crystalline symmetry, but, just by putting it in an asymmetric magnetic environment, it turns into a rectifier and starts generating electricity. Superconducting vortex strings only annihilate and nucleate at surfaces, and this allows the bulk electrons to feel surface fluctuations in an asymmetric environment: a vortex rectenna. The rectification and generation can be switched on and off with only a slight change in temperature or external magnetic fields., Devices that generate electricity from electric fluctuations are promising for wireless power transmission as well as energy harvesting from environmental radio waves. Here the authors report the electric power generation from environmental fluctuations by using superconducting vortex strings in MoGe/YIG bilayer system.

We have performed angle-resolved photoemission spectroscopy of AlB2 which is isostructural to high-temperature superconductor MgB2. Using soft-x-ray photons, we accurately determined the three-dimensional bulk band structure and found a highly anisotropic Dirac-cone band at the K point in the bulk hexagonal Brillouin zone. This band disperses downward on approaching the H point while keeping its degeneracy at the Dirac point, producing a characteristic Dirac nodal line along the KH line. We also found that the band structure of AlB2 is regarded as a heavily electron-doped version of MgB2 and is therefore well suited for fully visualizing the predicted Dirac nodal line. The present results suggest that (Al,Mg)B2 system is a promising platform for studying the interplay among Dirac nodal line, carrier doping, and possible topological superconducting properties., 6 pages, 3 figures