ALBERT

Description: Warm Deep Water intrusion over the Antarctic continental shelves threatens the Antarctic ice-sheet stability by enhancing the basal melting of ice shelves. In East Antarctica, the Antarctic Slope Current (ASC), along with the Antarctic Slope Front (ASF), acts as a potential vorticity barrier to prevent the warm modified Circumpolar Deep Water (mCDW) from ventilating the cold and fresh shelf. However, mCDW onshore transport is still observed within certain shelf regions, such as submarine troughs running perpendicular to the continental shelf. This study focuses on the dynamic mechanisms governing mCDW intrusion within a submarine trough over the fresh shelf regions, East Antarctica. Based on an idealized eddy-resolving coupled ocean-ice shelf model, two high resolution process-oriented numerical experiments are conducted to reveal the mechanisms responsible for the mCDW onshore transport. Three dynamic mechanisms governing cross-slope mCDW intrusion are identified: 1) the bottom pressure torque, 2) the topography beta spiral, and 3) the topography Rossby waves. These three mechanisms simultaneously govern the mCDW intrusion together. The bottom pressure torque plays a leading role in driving the time-mean onshore flow whose vertical structure is determined by the topography beta spiral, while the topography Rossby waves contribute to the high-frequency oscillations in the onshore volume and heat transport. The simulated spatial distribution and seasonality of mCDW intrusion qualitatively coincide with the observed mCDW intrusion over fresh shelf regions, East Antarctica. Both the topography beta spiral and the ASC play an important role in governing the seasonality of mCDW intrusion.

Description: The rapid convergence of PPP-RTK depends on the ionospheric correction including the accuracy and prior information. However, the traditional grid-based ionospheric model often uses fixed ionospheric prior information without taking into account the spatiotemporal diversity of the ionosphere, thus weakening the performance of PPP-RTK and limiting its application scenarios. In this study, a self-validation grid-based ionospheric model is proposed to improve the performance of PPP-RTK. A grid-based slant ionospheric model adapted to multi-scale networks is developed first with the careful consideration of receiver DCBs. Additionally, the ionosphere residuals obtained by self-validation of each reference station are assigned to the regional area based on distance and time, providing more reasonable ionospheric prior information for PPP-RTK. Then, PPP-RTK can achieve fast convergence with more reasonable ionospheric prior information. Experiments conducted under different ionospheric conditions demonstrate that the modified model significantly improves both the positioning accuracy and convergence time of PPP-RTK. During the ionosphere calm period, the average convergence time is reduced from 15.4s to 4.1s and the positioning accuracy is improved by 29.96% compared with the traditional grid model. Furthermore, during the ionosphere active period, the positioning accuracy is improved from (0.08, 0.10, 0.39) m to (0.05, 0.04, 0.12) m, with the improvement of 37.50%, 60.00%, 69.23% in the east, north and up directions, respectively.

Description: Earth’s climate experienced a major reorganization across the mid-Pleistocene transition (MPT) from 1.25 to 0.6 million years ago (Ma), when the dominant climate periodicity transitioned from 41-thousand years (kyr) to around 100-kyr. The MPT occurred without a concomitant shift in the orbital forcing rhythm, so it is related to internal climate dynamics rather than external astronomical forcing. Here, we investigate Asian climate dynamics associated with two extreme glacial loess coarsening events at the onset and middle of the MPT by combining new and existing grain size and magnetic susceptibility records from the Chinese Loess Plateau (CLP) spanning the last 1.6 Ma. We find that the two extreme glacial events were marked by a combination of intensified and expanded Asian aridity, winter monsoon strengthening, and distinct coarsening of loess layers L15 and L9-1 across the CLP. These two glacial intensifications coincided with notable Northern Hemisphere glacial ice sheet expansion at 1.25 and 0.9 Ma when the 100-kyr initiated and intensified. By integrating observations, land-sea correlations, and model simulations, we propose that these anomalously dry and windy Asian glacials were probably driven by an amplified terrestrial climate response to the coincident Northern Hemisphere ice sheet expansion. The shift from a 41-kyr to 100-kyr orbital periodicity across the MPT also occurred in our monsoon records, which reflect Northern Hemisphere ice sheet control on orbital-scale Asian climate variability, not just on extreme glacial Asian climate events at 1.25 and 0.9 Ma. Our study supports a close relationship between Asia-interior and global climate changes.

Description: Most arcs show systematic temporal and spatial variations in magmatism with clear shifts in igneous rock compositions between those of the magmatic front (MF) and those in the backarc (BA). It is unclear if similar magmatic polarity is seen for extensional continental arcs. Herein, we use geochemical and isotopic characteristics coupled with zircon U‐Pb geochronology to identify the different magmatic style of the Iran convergent margin, an extensional system that evolved over 100 Myr. Our new and compiled U‐Pb ages indicate that major magmatic episodes for the NE Iran BA occurred at 110–80, 75–50, 50–35, 35–20, and 15–10 Ma. In contrast to NE Iran BA magmatic episodes, compiled data from MF display two main magmatic episodes at 95–75 and 55–5 Ma, indicating more continuous magmatism for the MF than for the BA. We show that Paleogene Iran serves as a useful example of a continental arc under extension. Our data also suggest that there is not a clear relationship between the subduction velocity of Neotethyan Ocean beneath Iran and magmatic activity in Iran. Our results imply that the isotopic compositions of Iran BA igneous rocks do not directly correspond to the changes in tectonic processes or geodynamics, but other parameters such as the composition of lithosphere and melt source(s) should be considered. In addition, changes in subduction zone dynamics and contractional versus extensional tectonic regimes influenced the composition of MF and BA magmatic rocks. These controls diminished the geochemical and isotopic variations between the magmatic front and backarc.

Description: This study presents a general framework, namely, Sparse Spatiotemporal System Discovery (S3d⁠), for discovering dynamical models given by Partial Differential Equations (PDEs) from spatiotemporal data. S3d is built on the recent development of sparse Bayesian learning, which enforces sparsity in the estimated PDEs. This approach enables a balance between model complexity and fitting error with theoretical guarantees. The proposed framework integrates Bayesian inference and a sparse priori distribution with the sparse regression method. It also introduces a principled iterative re-weighted algorithm to select dominant features in PDEs and solve for the sparse coefficients. We have demonstrated the discovery of the complex Ginzburg–Landau equation from a traveling-wave convection experiment, as well as several other PDEs, including the important cases of Navier–Stokes and sine-Gordon equations, from simulated data.

Description: We demonstrate an indirect, rather than direct, role of quasi-resonant amplification of planetary waves in a summer weather extreme. We find that there was an interplay between a persistent, amplified large-scale atmospheric circulation state and soil moisture feedbacks as a precursor for the June 2021 Pacific Northwest “Heat Dome” event. An extended resonant planetary wave configuration prior to the event created an antecedent soil moisture deficit that amplified lower atmospheric warming through strong nonlinear soil moisture feedbacks, favoring this unprecedented heat event.

Description: Accelerating the construction of ecological civilization in the industrial field and guiding the transformation of industry toward a green direction have become a national development strategy. Promoting the coordinated development of energy-intensive industries such as steel, cement, and power is a key breakthrough in achieving the green transformation of various industries. This study has designed a steel–cement–power polygeneration system with the collaborative utilization of solid waste resources as the ecological link point. Four scenarios, including business-as-usual, optimization of product structure, low-carbon technology application, and policy advancement (PAD), were established to assess the overall energy-saving and emissions reduction potential of the steel–cement–power polygeneration system from 2015 to 2050. The results show that product structure adjustment and industrial symbiosis have a significant impact on energy saving and emission reduction of key industries. In 2050, the total energy consumption and carbon emissions of the polygeneration system could reach 38,697.64 PJ and 3766.73 Mt CO2. Based on the scenario analysis, the production and use of solid waste in the polygeneration system and the economic benefits are also discussed. Under the PAD scenario, by 2050, the proportion of fly ash as cement raw material will increase to 41%, while the supply of blast furnace slag may be insufficient, and the comprehensive utilization of solid waste can bring economic benefits of 238.32 billion Yuan to the system.

Description: The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union’s chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment. We propose two innovative hazard indicators, termed cumulative toxicity equivalents (CTE) and persistent toxicity equivalents (PTE). Together they are intended to replace existing PBT indicators and can also accommodate the emerging concept of PMT (where M stands for mobility). The proposed “toxicity equivalents” can be measured with high throughput in vitro bioassays. CTE refers to the toxic effects measured directly in any given sample, including single chemicals, substitution products, or mixtures. PTE is the equivalent measure of cumulative toxicity equivalents measured after simulated environmental degradation of the sample. With an appropriate panel of animal-free or alternative in vitro bioassays, CTE and PTE comprise key environmental and human health hazard indicators. CTE and PTE do not require analytical identification of transformation products and mixture components but instead prompt two key questions: is the chemical or mixture toxic, and is this toxicity persistent or can it be attenuated by environmental degradation? Taken together, the proposed hazard indicators CTE and PTE have the potential to integrate P, B/M and T assessment into one high-throughput experimental workflow that sidesteps the need for analytical measurements and will support the Chemicals Strategy for Sustainability of the European Union.

Description: A correction to this paper has been published: 10.1140/epjc/s10052-021-09344-w