Sheet Region Research Articles

Reconciled estimation of Antarctic ice sheet mass balance and contribution to global sea level change from 1996 to 2021

AbstractThe Antarctic Ice Sheet (AIS) has been losing ice mass and contributing to global sea level rise (GSLR). Given its mass that is enough to cause ∼58 m of GSLR, accurate estimation of mass balance trend is critical for AIS mass loss monitoring and sea level rise forecasting. Here, we present an improved approach to reconciled solutions of mass balance in AIS and its regions from multiple contributing solutions using the input-out, altimetric, and gravimetric methods. In comparison to previous methods, such as IMBIE 2018, this approach utilizes an adaptive data aggregation window to handle the heterogeneity of the contributing solutions, including the number of solutions, temporal distributions, uncertainties, and estimation techniques. We improved the regression-based method by using a two-step procedure that establishes ensembled solutions within each method (input-output, altimetry, or gravimetry) and then estimates the method-independent reconciled solutions. For the first time, 16 contributing solutions from 8 Chinese institutions are used to estimate the reconciled mass balance of AIS and its regions from 1996 to 2021. Our results show that AIS has lost a total ice mass of ∼3213±253 Gt during the period, an equivalent of ∼8.9±0.7 mm of GSLR. There is a sustained mass loss acceleration since 2006, from 88.1±3.6 Gt yr−1 during 1996–2005 to 130.7±8.4 Gt yr−1 during 2006–2013 and further to 157.0±9.0 Gt yr−1 during 2014–2021. The mass loss signal in the West Antarctica and Antarctic Peninsula is dominant and clearly presented in the reconciled estimation and contributing solutions, regardless of estimation methods used and fluctuation of surface mass balance. Uncertainty and challenges remain in mass balance estimation in East Antarctica. This reconciled estimation approach can be extended and applied for improved mass balance estimation in the Greenland Ice Sheet and mountain glacier regions.

Pressure Measurements and Video Observations Near and Inside Three EF2 Tornadoes

From the spring of 2016 through the spring of 2019, three EF2-rated tornadoes were sampled with in-situ tornado probes as part of the Pressure Acoustics Recordings Inside Tornadoes Experiment. The probe meteorological instrumentation resolved the temperature, humidity, and pressure-deficit characteristics near or inside all three tornadoes. Probe recorded pressure and visual observations during each tornado event show unique attributes, including multiple strong pressure irregularities before and just after the first EF2 tornado, a rotating bowl-shaped cloud feature located some distance ahead of the second EF2 tornado, independent of the tornado core and immediate inflow layer. Pressure measurements of the bowl feature reveal a brief pressure perturbation lasting roughly 4 s as it passed near or directly over the research team before the documentation of a 41 hPa pressure deficit. During the third EF2 near in-situ deployment, pressure trace observations also reveal pressure fluctuations ahead of the tornado core lasting some 65 s before the documentation of a 13 hPa pressure deficit. These pressure measurements and video observations are consistent in location with recent ultra-high-resolution simulations of the Streamwise Vorticity Current (SVC), or more precisely, the related Vertical Vorticity Sheet (VVS) and Pressure Deficit Lobe (PDL) regions. This paper describes the measured pressure deficit traces during three EF2 tornadoes near and in situ, augmented with brief, one-of-a-kind, near and in-situ video observations of a unique bowl feature, tornado inflow, corner-flow, and tornado core regions. The recorded data and instrumentation were analyzed; results are presented and discussed.

Significance of Darcy–forchheimer Casson fluid flow past a non-permeable curved stretching sheet with the impacts of heat and mass transfer

Casson fluid flow based on a curved surface has been mathematically modeled using Brownian motion and the Darcy-Forchheimer equation of porosity. Similarity variables are applied to convert flow-anchored partial differential equations into basic ordinary differential equations. The MATLAB solver “bvp4c” is utilized to derive numerical responses for the problem under consideration. During the numerical approach, all parameters have been set to their values based on reviewed literatures and numerical solutions for all flow fields have been obtained against the concerned parameters. Additionally, a variety of graphs are created utilizing numerical extractions to discuss the results. The curvature parameter (K=1.5,2.5,3.5,4.5) results in an improvement in velocity distribution (f'η=1=0.32564,0.360142,0.378247,0.385401). The reason is that for higher values of the curvature parameter, the radius of a curved sheet decreases. Hence, a smaller region of sheet will be in contact, which produces a small amount of resistance towards fluid particles, so that the velocity profiles show an enhancement. Increasing inputs of Forchheimer number imply stronger inertial effects and it introduce an additional resistance to flow that's why fluid velocity decreased. Additionally, for a curved stretched sheet, a higher drag force is required compared to a flat plate because curved sheet has a larger surface area while flat plate has a minimal surface area in contact with the fluid.

What Drove the Carrington Event? An Analysis of Currents and Geospace Regions

AbstractThe 1859 Carrington event is the most intense geomagnetic storm in recorded history, and the literature provides numerous explanations for what drove the negative H perturbation on the Earth. There is debate on what dominated the event. Our analysis shows a combination of causes of similar orders of magnitude. Previous analyses generally rely upon the observed H perturbation at Colaba, India; historic newspaper reports; and empirical models. We expand the analysis using two Space Weather Modeling Framework simulations to examine what drove the event. We compute contributions from currents and geospace regions to the northward B field on Earth's surface, BN. We examine magnetospheric currents parallel and perpendicular to the local B field, ionospheric currents, and gap region field–aligned currents (FACs). We also evaluate contributions from the magnetosheath, near–Earth, and neutral sheet regions. A combination of currents and geospace regions significantly contribute to BN on the Earth's surface, changing as the storm evolves. At storm onset, magnetospheric currents and gap–region FACs dominate in the equatorial region. At auroral latitudes, gap–region FACs and ionospheric currents are the largest contributors. At storm peak, azimuthal magnetospheric currents and gap–region FACs dominate at equatorial latitudes. Gap–region FACs and ionospheric currents dominate in the auroral zone, down to mid‐latitudes. Both the magnetosheath and FACs contribute at storm peak, but are less significant than that from the near–Earth ring current. During recovery, the near–Earth ring current is the largest contributor at equatorial latitudes. Ionospheric currents and gap–region FACs dominate in the auroral zone.

ADGRL1 variants: From developmental and epileptic encephalopathy to genetic epilepsy with febrile seizures plus.

To expand the phenotypic spectrum of ADGRL1 and explore the correlation between epilepsy and the ADGRL1 genotype. We performed whole-exome sequencing in a cohort of 115 families (including 195 males and 150 females) with familial febrile seizure or epilepsy with unexplained aetiology. The damaging effects of variants was predicted using protein modelling and multiple in silico tools. All reported patients with ADGRL1 pathogenic variants were analysed. One new ADGRL1 variant (p.Pro753Leu) was identified in one family with genetic epilepsy with febrile seizures. Further analysis of 12 ADGRL1 variants in 16 patients revealed that six patients had epilepsy. Epilepsy types ranged from early-onset epileptic encephalopathy to genetic epilepsy with febrile seizures plus (GEFS+). All four variants associated with epilepsy were located in the non-helix or sheet region of ADGRL1. Three of the four epilepsy-associated variants were missense variants. Thus, all three variants located in the G-protein-coupled receptor autoproteolytic-inducing domain exhibited epilepsy. We found one new missense variant of ADGRL1 in one family with GEFS+. ADGRL1 may be a potential candidate or susceptibility gene for epilepsy. ADGRL1-associated epilepsy ranged from benign GEFS+ to severe epileptic encephalopathy; the genotypes and variant locations may help explain the phenotypic heterogeneity of patients with the ADGRL1 variant.

A mechanism for reconciling the synchronisation of Heinrich events and Dansgaard-Oeschger cycles

The evolution of the northern hemispheric climate during the last glacial period was beset by quasi-episodic iceberg discharge events from the Laurentide ice sheet, known as Heinrich events (HEs). The paleo record places most HEs into the cold stadial of the Dansgaard-Oeschger cycle. However, not every Dansgaard-Oeschger cycle is associated with a HE, revealing a complex interplay between the two modes of glacial variability. Here, using a coupled ice sheet-solid earth model, we introduce a mechanism that explains the synchronicity of HEs and Dansgaard-Oeschger cycles. Unlike earlier studies, our mechanism does not require a trigger during the stadial. Instead, the atmospheric warming signal during the interstadial of the Dansgaard-Oeschger cycle causes enhanced ice stream thickening that leads to the HE during the late interstadial. We demonstrate that this mechanism reproduces the key HE characteristics and provides an explanation for synchronous HEs from different regions of the Laurentide ice sheet.

Study of the effect of cavitation flow patterns in diesel injector nozzles on near-field spray atomization characteristics using a LES-VOF method

The spray atomization process plays a critical role in achieving high efficiency and reducing emissions in internal combustion engines. The fuel injection atomization process, especially the spray primary atomization process, is significantly influenced by turbulent flow and cavitation phenomena within the nozzle. In this study, based on the coupled large eddy simulation(LES) and a volume-of-fluid (VOF)method, the effects of four typical nozzle internal flow patterns on the spray primary breakup in the near-nozzle region were investigated. To realize this objective, the generation of four distinct flow patterns was accomplished through the design and construction of corresponding nozzle structures: (1) nearly single-phase flow in a tapered-orifice nozzle with low orifice location, (2) strong geometry-induced sheet cavitation flow with sheet region extending to the nozzle orifice exit in a normal cylindrical orifice, (3) vortex-induced string cavitation flow in a tapered-orifice nozzle with relative high orifice location, and (4) geometry-induced sheet cavitation is partially suppressed while it is enhanced in the orifice region close to exit in a convergent-divergent orifice. The numerical results unequivocally reveal that the initial atomization of the spray exhibits remarkable efficacy in the case of the conventional cylindrical nozzle, characterized by internal regions of substantial sheet cavitation, despite a relatively minimal flow discharge coefficient. Conversely, the normal tapered-orifice nozzle, lacking significant cavitation, demonstrates a larger flow discharge coefficient, yet its initial atomization performance is notably suboptimal.It is worth noting that the appropriate vortex-induced cavitation in the nozzle can correspond a higher flow rate with a thin string-type cavitation and simultaneously a better spray atomization quality with a strong vortex flow. Also it is concluded that a convergent-divergent nozzle with appropriate transition location can achieve strong atomization .

Enhancing automatic inspection and characterization of carbon fiber composites through hyperspectral diffuse reflection analysis and k-means clustering

Numerous industries utilize carbon fiber composites (CFC) for their exceptional strength-to-weight ratio and stiffness. However, inherent manufacturing defects such as voids and delamination can undermine the material’s structural integrity and performance. This study introduces an advanced imaging technique employing hyperspectral imaging (HSI) to effectively detect and characterize flaws within CFC materials. HSI provides high-resolution spectral data, enabling precise analysis of material properties. Initial observations indicate a distinctive peak variability in dispersed reflectance spanning 440 nm to 600 nm for both pristine surfaces and defective regions of CFC sheets. The proposed methodology entails the automated characterization of CFC through a combination of HSI and an advanced clustering technique, k-means clustering (k-mc). The application of k-mc facilitates rapid and accurate categorization of defect locations. Statistical analysis reveals mean and standard deviation (SD) values of 0.34 and 0.33, respectively, for normal CFC surfaces, compared to 0.43 and 0.29 for cracked CFC sections. These discernible variations enable precise differentiation between defect-free and defective CFC specimens. By employing spectral signatures at 445 nm, 546 nm, and 585 nm as optical markers, the study accurately measures fracture penetration depths. Implementation of this approach generates 3D-resolved images, offering a comprehensive visualization of CFC imperfections. The proposed methodology presents a more automated and objective strategy for defect identification and categorization. This unique approach holds significant potential for industrial applications, particularly in scenarios necessitating efficient and precise evaluation of numerous CFC components.

Net evolution of subglacial sediment transport in the Quebec–Labrador sector of the Laurentide Ice Sheet

The Laurentide Ice Sheet's (LIS) interior had a dynamic polythermal base, but the spatiotemporal variations of subglacial processes related to ice divide migration and other transient changes remain largely unknown, limiting our understanding of regional glacial dynamics. Previous studies focused on the regional glacial landform record, while ice sheet models lacked detailed parameterization within these regions, leading to an overestimation of cold-based subglacial conditions' extent and duration. In this study, glacial sediment dispersal patterns as identified by heavy minerals, clasts, and multivariate statistics of till matrix geochemistry were used to assess ice sheet dynamics within the Quebec–Labrador sector of the LIS. The earliest ice-flow phase produced and transported till across the study area (>175 km). However, major oxide data from till matrix geochemistry show a correlation with underlying bedrock, and this relationship is relatively common in areas of thin till cover and resistant bedrock lithologies. These results suggest a switch from an early phase of widespread erosion and long, sustained sediment transport to one of more limited erosion, perhaps abrasion dominant and shorter transport. Till compositional data and related dispersal patterns add supporting evidence to earlier ice sheet reconstructions based on ice-flow indicators and 10Be data together suggesting a transition from widespread uniform warm-based conditions during the earliest ice flow, followed by the development of an ice divide, its migration, and more sporadic warm-based conditions. Consequently, a thorough understanding of ice-flow history is essential for ice sheet modelling and future mineral exploration programs in inner ice sheet regions of the LIS.

Kinetic Modeling of Ionospheric Outflows in Pressure Cooker Environments

AbstractPlasma escape from the high‐latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to the magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. A new fully kinetic and semi‐kinetic model, KAOS (Kinetic model of Auroral ion OutflowS), is constructed from first principles which traces large numbers of individual O+ ion macro‐particles along curved magnetic field lines, using a guiding‐center approximation, in order to facilitate calculation of ion distribution functions and moments. Particle forces include mirror and parallel electric field forces, a self‐consistent ambipolar electric field, and a parameterized source of ion cyclotron resonance wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady‐state ion density altitude profile and Maxwellian velocity distribution and particle trajectories are advanced via a direct simulation Monte Carlo scheme. This outlines the implementation of the kinetic outflow model, demonstrates the model's ability to achieve near‐hydrostatic equilibrium necessary for simulation spin‐up, and investigates L‐shell dependent wave heating and pressure cookers scenarios. This paper illustrates the model initialization process and numerical investigations of L‐shell dependent outflows and pressure cooker environments and serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere.

Research on dynamic deformation behaviors of laser driving metal sheet precision forming

Laser shock forming (LSF) is an advanced sheet forming technology. With the aid of forming die, it can realize sheet precise forming, and has extensive application prospects in aeronautic and electronics industries. In the paper, a two-dimensional axial symmetric numerical model of SUS304 stainless steel is established. Finite element method is utilized to explore the dynamic deformation behaviors of the laser-driving sheet impacted by the forming die. The results show that the node velocity of metal sheet increases in an oscillatory manner during initial stage and then it starts to bulge. After collision with die cavity bottom, the central region of metal sheet jumps up reversely, and experiences repeating damped vibration. The metal sheet gradually exhausts the obtained kinetic energy from the shock wave, and the flat sheet is finally shaped into the geometrical shape of die cavity. The sheet forming precision can be improved by way of increasing laser shock pressure. The corresponding experiments are also carried out to verify the predicted results. The applied method and gained results can provide a reference for theoretical research and parameters optimization in LSF.

Bridging the Gap Between Experimental and Natural Fabrics: Modeling Ice Stream Fabric Evolution and its Comparison With Ice‐Core Data

AbstractFabrics, also known as textures or crystallographic preferred orientations, reveal information about the deformation history of the flow of polycrystalline materials, including glacial ice, olivine in the mantle, and feldspar and quartz in the crust. Ice fabrics can have an order‐of‐magnitude effect on the ease of flow in ice sheets. However, due to the choice of ice core drill site locations, the outputs of fabric models have mostly been compared to observations from the least dynamic regions of the ice sheet (ice divides). Recently, fabric data from an active ice stream have become available from ice cores drilled at the East Greenland Ice‐core Project (EGRIP). In this work, we present a novel approach that combines satellite‐derived velocity data with the fabric evolution model SpecCAF, a continuum model based on dominant dislocation creep. We directly compare model output to ice‐core observations from EGRIP, allowing us to examine the quantitative predictions of calibrated fabric models alongside those of active ice streams for the first time. As the model is calibrated against laboratory experiments, it provides a surrogate to compare the evolution of fabrics under laboratory and natural conditions. The predictions show good qualitative agreement with the observed fabric patterns and orientations, suggesting that a fabric between a girdle and horizontal maximum, orientated perpendicular to the flow direction, is the characteristic ice stream fabric. A discrepancy in fabric strength is attributed to the lower strain rates of ice sheets compared to laboratory experiments, revealing a significant strain‐rate dependence in the processes controlling fabric evolution.

A cellular selection identifies elongated flavodoxins that support electron transfer to sulfite reductase.

Flavodoxins (Flds) mediate the flux of electrons between oxidoreductases in diverse metabolic pathways. To investigate whether Flds can support electron transfer to a sulfite reductase (SIR) that evolved to couple with a ferredoxin, we evaluated the ability of Flds to transfer electrons from a ferredoxin-NADP reductase (FNR) to a ferredoxin-dependent SIR using growth complementation of an Escherichia coli strain with a sulfur metabolism defect. We show that Flds from cyanobacteria complement this growth defect when coexpressed with an FNR and an SIR that evolved to couple with a plant ferredoxin. When we evaluated the effect of peptide insertion on Fld-mediated electron transfer, we observed a sensitivity to insertions within regions predicted to be proximal to the cofactor and partner binding sites, while a high insertion tolerance was detected within loops distal from the cofactor and within regions of helices and sheets that are proximal to those loops. Bioinformatic analysis showed that natural Fld sequence variability predicts a large fraction of the motifs that tolerate insertion of the octapeptide SGRPGSLS. These results represent the first evidence that Flds can support electron transfer to assimilatory SIRs, and they suggest that the pattern of insertion tolerance is influenced by interactions with oxidoreductase partners.

Parametrization of Energetic Ion and Electron Fluxes in the Near‐Earth Magnetotail

AbstractThe near‐Earth plasma sheet region is the main source of energetic (tens to hundreds keV) ion and electron populations transported by convection and injections into the inner magnetosphere. Energetic ions from the plasma sheet contribute to the ring current, whereas energetic electrons contribute to the radiation belt seed population for further acceleration to relativistic energies. Near‐Earth plasma sheet energetic fluxes have been traditionally used to set boundary conditions for radiation belt and ring current models. This study provides an empirical parametrization for ∼75 keV flux intensity as a function of the geomagnetic activity index auroral electrojet and the equatorial magnetic field Bz. Such parametrization includes the dynamic magnetic field configuration in the near‐Earth plasma sheet and may be merged with empirical magnetic field models. We also provide models extending this parametrization to the [20, 300] keV of electron energy range and [75, 300] keV of ion energy range. The parametrization is developed based on THEMIS and Geostationary Operational Environmental Satellite measurements, and verified by comparison with MMS measurements in the near‐Earth plasma sheet. This parametrization incorporates meso‐scale transient flux variations associated with Bz perturbations into ring current and radiation belt simulations.

The Gamma-Ray Pulsar Phenomenology in View of 3D Kinetic Global Magnetosphere Models

We develop kinetic plasma models of pulsar magnetospheres with magnetic-field-line-dependent plasma injection that reveal the importance of various magnetosphere regions in regulating the γ-ray emission. We set different particle injection rates for the so-called open, closed, and separatrix zones. Moderate particle injection rates in open and closed zones ensure a global field structure close to the force-free structure, while the dissipation occurs mainly in and around the equatorial current sheet. The particles that are injected into the separatrix zone affect the particle populations that enter the equatorial current sheet region, and therefore the corresponding accelerating electric fields, particle energies, the spectral cutoff energy, and γ-ray efficiency. The separatrix zone models reproduce the recently discovered fundamental plane of γ-ray pulsars consistent with curvature radiation emission, the γ-ray light-curve shapes, and the radio-lag versus peak-separation correlation reported in the Fermi second pulsar catalog. The model beaming factors indicate that the pulsar total γ-ray luminosities listed in the Fermi catalogs are overestimations of the actual ones. We find that the radiation reaction limited regime starts ceasing to govern the high-energy emission for . Our results also indicate that toward high magnetic inclination angles, the Y point around the rotational equator migrates well inside the light cylinder, sparking additional peaks in the γ-ray pulse profiles. We find that an equivalent enhanced particle injection beyond the Y point strengthens these features, making the model γ-ray light curves inconsistent with those observed.

Was there a nonglacial episode in the western Hudson Bay Lowland during Marine Isotope Stage 3?

AbstractEstablishing the timing of glacial and nonglacial intervals in the core regions of the Laurentide Ice Sheet (LIS) is essential to constrain ice-sheet configuration at times of globally reduced ice volume, such as during Marine Isotope Stage (MIS) 3 (~57–29 ka). Hudson Bay Lowland (HBL) deglaciation, at the centre of the LIS, has been inferred at MIS 3 based on near-infinite wood radiocarbon ages and limited luminescence ages. To better constrain the age of the penultimate deglaciation of the western HBL, this study initially identified the youngest intertill nonglacial sediments, based on extensive fieldwork and till characterization. Next, vetted radiocarbon ages were combined with revised stratigraphy to show that five previously identified “MIS 3” sites were likely deposited during an earlier ice-free period. Finally, new optical ages targeting the youngest intertill nonglacial bed at three localities yielded ages ranging from 166 to 146 ka; all older than MIS 3. These ages indicate that the penultimate deglaciation of the western HBL likely occurred during MIS 5e. This interpretation better explains accompanying paleobotanic data sets that indicate vegetation similar to vegetation existing under present interglacial conditions. Currently no firm evidence exists in the terrestrial stratigraphic record for the deglaciation of the western HBL during MIS 3.

Stability analysis of radiative-magnetive Ag −MoS 2/water hybrid nanofluid flow due to a permeable exponential surface with variable thermal conductivity, mass diffusivity and binary chemical reaction: an entropy generation

ABSTRACT This investigation concentrated on the /water hybrid nanofluid to solve the problem of heat-mass transmission across a permeable stretching/contracting sheet with the impacts of radiant heat and inclined magnetic force field. Here, we additionally take into account hybrid nanofluids with variable thermal conductivity, variable mass diffusivity, Joule dissipation, binary chemical reactions with velocity, and thermal and solutal slip conditions. Before being numerically solved by the MATLAB function bvp4c, the controlling PDE is converted into nonlinear coupled ordinary differential equations by appropriate similarity transformation. The findings also point to the presence of dual solutions in the stretching/contracting sheet region for a given value of the mass suction parameter, with stable upper branch solution and unstable lower branch solution. As a result of the velocity and temperature gradients, the entropy generation equation is constructed. The effects of the selected parameters are discussed and visually displayed for the velocity, temperature, concentration, skin friction coefficient, local Nusselt number, and Sherwood number. Due to some selected flow parameters, the pattern of entropy formation and assessment of the Bejan number are anticipated. Furthermore, it is discovered that when the volume percentage of nanoparticles increases, the Sherwood number decreases, and the skin friction coefficient increases with the rate of heat transmission. The Bejan number and entropy generation rate both increase with the volume proportion of nanoparticles and the radiant heat parameter, according to the visual simulations created using the present model.

Spatial and temporal variability of 21st century sea level changes

SUMMARY Mass loss from polar ice sheets is becoming the dominant contributor to current sea level changes, as well as one of the largest sources of uncertainty in sea level projections. The spatial pattern of sea level change is sensitive to the geometry of ice sheet mass changes, and local sea level changes can deviate from the global mean sea level change due to gravitational, Earth rotational and deformational (GRD) effects. The pattern of GRD sea level change associated with the melting of an ice sheet is often considered to remain relatively constant in time outside the vicinity of the ice sheet. For example, in the sea level projections from the most recent IPCC sixth assessment report (AR6), the geometry of ice sheet mass loss was treated as constant during the 21st century. However, ice sheet simulations predict that the geometry of ice mass changes across a given ice sheet and the relative mass loss from each ice sheet will vary during the coming century, producing patters of global sea level changes that are spatiotemporally variable. We adopt a sea level model that includes GRD effects and shoreline migration to calculate time-varying sea level patterns associated with projections of the Greenland and Antarctic Ice Sheets during the coming century. We find that in some cases, sea level changes can be substantially amplified above the global mean early in the century, with this amplification diminishing by 2100. We explain these differences by calculating the contributions of Earth rotation as well as gravitational and deformational effects to the projected sea level changes separately. We find in one case, for example, that ice gain on the Antarctic Peninsula can cause an amplification of up to 2.9 times the global mean sea level equivalent along South American coastlines due to positive interference of GRD effects. To explore the uncertainty introduced by differences in predicted ice mass geometry, we predict the sea level changes following end-member mass loss scenarios for various regions of the Antarctic Ice Sheet from the ISMIP6 model ensemblely, and find that sea level amplification above the global mean sea level equivalent differ by up to 1.9 times between different ice mass projections along global coastlines outside of Greenland and Antarctica. This work suggests that assessments of future sea level hazard should consider not only the integrated mass changes of ice sheets, but also temporal variations in the geometry of the ice mass changes across the ice sheets. As well, this study highlights the importance of constraining the relative timing of ice mass changes between the Greenland and Antarctic Ice Sheets.

High-sensitivity strain sensor with micron-scale imitation dumbbell structure based on differential temperature self-compensation

A micron-sized dumbbell-like -MZI structure has been developed using hydroxide flame melt taper and arc fusion discharge, with the dumbbell rod region prepared by melt taper drawing and the dumbbell sheet region prepared by arc fusion discharge. This structure has a sensitive light intensity response in the sensing field due to a double-order mode-field coupled excitation region. The geometrical parameters of the dumbbell-like system are optimized theoretically, and the feasibility of the microstructure to achieve high strain sensing sensitivity is analyzed. Experimental results show that the microstructure has a high strain sensing sensitivity of ∼ 0.074 dB/µε and a consistent temperature sensing sensitivity over the entire monitoring wavelength range. Therefore, a light intensity-dependent temperature self-compensation calculation is proposed to achieve a uniform light intensity-strain response for each characteristic peak in the monitored wavelength domain. Since the device has a significant advantage in light intensity modulation and is not affected by polarization light perturbations, it can be used as an alternative light intensity modulation device in optical communication networks and laser research. It can also be used as a probe for medical diagnostic testing based on its enhanced evanescent field properties.

How changing the height of the Antarctic ice sheet affects global climate: a mid-Pliocene case study

Abstract. Warming-induced topographic changes of the East Antarctic ice sheet (EAIS) during the Pliocene warm period could have a significant influence on the climate. However, how large changes in the EAIS height could theoretically affect global climate have yet to be studied. Here, the influence of possible height changes of the EAIS on climate over the East Antarctic ice sheet region versus the rest of the globe is investigated through numerical climate modeling using the Pliocene as a test case. As expected, the investigation reveals that the reduction of ice sheet height leads to a warmer and wetter East Antarctica. However, unintuitively, both the surface air temperature and the sea surface temperature decrease over the rest of the globe. These temperature changes result from the higher air pressure over Antarctica and the corresponding lower air pressure over extra-Antarctic regions with the reduction of EAIS height. This topography effect is further confirmed by energy balance analyses. These findings could provide insights into future climate change caused by warming-induced height reduction of the Antarctic ice sheet.