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Satellite imagery reveals flowstripes on Foundation Ice Stream parallel to ice flow, and meandering features on the ice-shelf that cross-cut ice flow and are thought to be formed by water exiting a well-organised subglacial system. Here, ice-penetrating radar data show flow-parallel hard-bed landforms beneath the grounded ice, and channels incised upwards into the ice shelf beneath meandering surface channels. As the ice transitions to flotation, the ice shelf incorporates a corrugation resulting from the landforms. Radar reveals the presence of subglacial water alongside the landforms, indicating a well-organised drainage system in which water exits the ice sheet as a point source, mixes with cavity water and incises upwards into a corrugation peak, accentuating the corrugation downstream. Hard-bedded landforms influence both subglacial hydrology and ice-shelf structure and, as they are known to be widespread on formerly glaciated terrain, their influence on the ice-sheet-shelf transition could be more widespread than thought previously.

The flow of ice is temperature-dependent, but direct measurements of englacial temperature are sparse. The dielectric attenuation of radio waves through ice is also temperature-dependent, and radar sounding of ice sheets is sensitive to this attenuation. Here we estimate depth-averaged radar-attenuation rates within the Greenland Ice Sheet from airborne radar-sounding data and its associated radiostratigraphy. Using existing empirical relationships between temperature, chemistry, and radar attenuation, we then infer the depth-averaged englacial temperature. The dated radiostratigraphy permits a correction for the confounding effect of spatially varying ice chemistry. Where radar transects intersect boreholes, radar-inferred temperature is consistently higher than that measured directly. We attribute this discrepancy to the poorly recognized frequency dependence of the radar-attenuation rate and correct for this effect empirically, resulting in a robust relationship between radar-inferred and borehole-measured depth-averaged temperature. Radar-inferred englacial temperature is often lower than modern surface temperature and that of a steady state ice-sheet model, particularly in southern Greenland. This pattern suggests that past changes in surface boundary conditions (temperature and accumulation rate) affect the ice sheet's present temperature structure over a much larger area than previously recognized. This radar-inferred temperature structure provides a new constraint for thermomechanical models of the Greenland Ice Sheet.

To understand the effect of particulate contaminants on pavement skid resistance, the friction numbers of three surfaces under different pollution conditions (particle size, coverage fraction, and shape factor) were measured using a British Pendulum Tester (BPT). The results show that less than 45% coverage fraction of the particles above 0.3 mm even results in almost 50% friction loss at a low speed of 10 km/h. In this situation, the rougher surface has a stronger holding particles capacity. Moreover, the particle size determining the lowest friction level gradually increases as the surface roughness increases. The particle size of 1.18–2.36 mm is the most typical size range leading to a low friction level. In addition, the friction first drops sharply and then increases slowly with the coverage fraction increases, which also conforms to the Stribeck curve. The skid resistance of road surfaces covered with particles was tested. Effects of particle size, coverage fraction, and shape on friction were analysed. Potential hazard scenarios with particulate contaminants were discussed. [ABSTRACT FROM AUTHOR]

We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods--especially in Greenland and West Antarctica--and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year(-1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year(-1) to the rate of global sea-level rise.

Pavements skid resistance, especially in wet states, is an essential indicators of traffic safety. However, the existing testers cannot reflect actual road friction situations and oversimplify water's effect on texture and skid resistance. Therefore, this study compared a traditional British pendulum tester (BPT) with actual vehicle braking. A simplified water coverage simulation programme was proposed, and the BPT characterised the influence of different thin water films on skid resistance in the laboratory. Besides, several freshly constructed road sections (AC-13, SMA-13, and PAC-13) were tested with both BPT and vehicle braking during rainfall. The results showed that water film, even thin, is unfavourable for pavement skid resistance. The BPT results were inconsistent with that of the vehicle braking. Because the tribological properties characterised by BPT are provided by micro-texture and partly macro-texture within the rubber-texture interaction depth (0.1 mm). Larger texture depth and more tortuous and connected pores will offer pavements larger water capacity and higher water permeability, which is beneficial for alleviating braking distance reduction during rainfall. In general, an ideal skid resistance tester should consider characteristics within the rubber-texture contact depth and should consider braking conditions such as speed, water film thickness, drainage method, and slip rate. [ABSTRACT FROM AUTHOR]

The British pendulum tester (BPT) provides a method to measure the skid resistance of pavement, which possesses both theoretical and practical engineering significance. This article aims to establish a numerical hysteresis friction model for BPT to reproduce the dynamic motion of the slider and estimate the pavement friction based on surface texture roughness, rubber viscoelasticity property and contact characteristics. The analytical hysteresis friction model was introduced based on one of the modern rubber friction theories. As an input parameter of this model, the average penetration depth of rubber was calculated based on the interfacial separation assumption. A numerical model was established by combining the geometric and motion characteristics of BPT. To validate the model, the self-affine characteristics of texture from four types of asphalt pavement were analysed; simultaneously, the storage and the loss modulus of rubber slider at various frequencies were obtained using the Zener constitutive model. As a result, the velocity of the slider decreases gradually with the dynamic fluctuation of the friction coefficient. A significant linear correlation was found between the predicted values and the measured data. This numerical friction model performs some potential for friction estimation. However, more conditions need considering for the improvement and practicability of the model. [ABSTRACT FROM AUTHOR]

Ice formation on concrete surfaces significantly challenges productivity, economic growth, and safety in diverse industrial sectors. Superhydrophobic coatings represent an effective solution to delay ice formation, although their functionality deteriorates under repeated freeze–thaw cycles. To address this issue, carbon nanotubes (CNTs) are frequently employed due to their exceptional photothermal conversion and mechanical properties, which contribute to extending the sustainability of the superhydrophobic coatings. However, the chemical inertness of CNTs often necessitates complex reactions to modify their functionalization. In this study, we have invented a simple method involving the sequential growth of silica on the surface of CNTs and the hydrophobic modification of the silica surface to enhance CNT functionality. These CNTs/SiO2 functionalized nanoparticles were then incorporated into an epoxy resin using a simple spray technique, resulting in a superhydrophobic and photothermal coating on concrete. To fine-tune the coating's properties, we explored the effects of varying the doping levels of the nanoparticles on the surface morphology, roughness, and wettability of the CNT/SiO2-EP coatings. The optimal level of hydrophobicity was achieved by doping the coatings with 300 mg of functionalized nanoparticles, yielding an impressive contact angle of 159.6°. The integration of functionalized nanoparticles into the epoxy matrix not only enhances hydrophobicity but also improves mechanical robustness and abrasion resistance by creating multiscale surface roughness. Additionally, the coating exhibits outstanding chemical stability even under extreme conditions. One of the most significant advantages of these coatings is their ability to extend the ice nucleation time significantly. This effect is primarily attributed to the superior superhydrophobicity of the nanoparticles and the remarkable photothermal conversion capability of the CNTs. Upon exposure to Xenon lamp radiation, the ice droplets rapidly melt, underscoring the impressive performance of these coatings in preventing ice formation. [ABSTRACT FROM AUTHOR]

Few ice cores from the Amundsen Sea and Bellingshausen Sea sectors of the West Antarctic Ice Sheet (WAIS) extend back in time further than a few hundred years. The WAIS is believed to be susceptible to collapse as a result of anthropogenic climate change and may have at least partially collapsed during the Last Interglacial (LIG) period. Understanding the stability of the WAIS during warm periods such as the LIG and Holocene is important. As part of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project, the British Antarctic Survey's (BAS) Rapid Access Isotope Drill (RAID) was deployed in 2020 on Sherman Island in the Abbot Ice Shelf, West Antarctica. We drilled a 323 m deep borehole, with discrete samples of ice chippings collected that cover the entire depth range of the drilled ice. The samples were analysed for stable water isotope composition and major ion content at BAS from 2020–2022. Using annual layer counting of chemical records, volcanic horizon identification and ice modelling, an age scale for the record of 1724 discrete samples is presented. The Sherman Island ice record extends back to greater than 1240 years, providing the oldest, continuous ice-derived palaeoclimate records in the coastal Amundsen and Bellingshausen Sea sectors to date. We demonstrate the potential for recovery of a complete Holocene climate record from Sherman Island in the future and confidence in the ability of RAID samples to contain sufficiently resolved records for meaningful climatic interpretation. [ABSTRACT FROM AUTHOR]