AlbaNova

We present TOAD v1.0 (Tipping and Other Abrupt events Detector), an open-source Python framework for the systematic detection and analysis of abrupt shifts in gridded Earth system data. TOAD provides a user-oriented workflow that combines grid-level shift detection with spatio-temporal clustering to identify domains where abrupt change co-occurs. An optional ensemble consensus step then identifies spatial patterns that are robust across ensemble members, models, variables, or method configurations, and quantifies associated statistics. The framework is method-agnostic, allowing different detection and clustering algorithms to be compared within a reproducible analysis pipeline. TOAD serves as an introspection tool for exploratory analysis of abrupt change across scales and addresses key questions in tipping-point research by identifying where such changes occur and providing first-order information on when they emerge along a time or forcing trajectory. The framework supports coordinated analyses in large model ensembles and intercomparison projects, such as TIPMIP and CMIP.

Solar flares are complex phenomena driven by the release of magnetic energy, but a large energy reservoir is not sufficient to determine their eruptive potential; the magnetic topology and plasma dynamics play a key role. We investigated the thermodynamic and magnetic properties of the solar atmosphere during the rise, peak, and decay phases of a C5.1-class flare and filament eruption in active region NOAA 12561 on 2016 July 7 to understand the origin and atmospheric response of this event. High spatial and spectral resolution spectropolarimetric observations of the chromospheric Ca II 8542 Å line and nearby photospheric lines were obtained with the TRIPPEL-SP spectropolarimeter at the Swedish 1-m Solar Telescope. Using nonlocal thermodynamic equilibrium (NLTE) inversions and non-force-free field (NFFF) magnetic extrapolations, we followed the event’s evolution from its precursor to its decay. Before the flare, our analysis reveals a complex, sheared magnetic topology with a high free energy content (∼2 × 10 30 erg). In this precursor phase, we detected persistent localized heating (temperature increase of ∼2000 K) with strong downflows (∼10–20 km s −1 ) deep in the atmosphere. This heating was co-spatial with a bald-patch region, suggesting that low-altitude magnetic reconnection could destabilize the filament of the region. The flare’s rise phase was marked by the filament’s eruption, with a total speed greater than ∼70 km s −1 , when combining inversions and plane-of-sky motions. Following the eruption, the free energy decreased by ∼30% as post-flare loops formed, connecting the flare ribbons and channeling the released energy into the lower atmosphere. The flare ribbons exhibited significant heating to ∼8500 K and downflows up to ∼10 km s −1 , consistent with energy deposition along reconnected loops.

Abstract Social norms play a pivotal role in sustainability transitions by shaping human behavior and influencing responses to challenges such as climate change and natural resource management. They can facilitate or impede collective action. Although simulation models help to explore norm dynamics, modeling approaches remain scattered and lack synthesis specific to social-ecological systems. This systematic review aims to map existing computational approaches to modeling social norms within social-ecological systems, identifying trends, gaps and implications for research and policy. We conducted a systematic search of Web of Science and Scopus (search date: 15 November 2024), screened abstracts using validated large language models, and selected 153 relevant studies for analysis. Key aspects analyzed included publication trends, thematic focus, modeling methods, spatial scale, empirical data used behavioral theory incorporation and norm representation. Publications increased over 25 years, with most studies originating from Europe and North America. Two dominant themes emerged: common-pool resource management and individual consumption behavior. Agent-based and evolutionary game-theoretic models prevail, but many omit explicit behavioral theories beyond rational choice theory. Models are mostly local or regional in scale and theoretical in nature and often lack empirical data for the quantification of the social norm modeled. Norms are generally modeled on an observation base, meaning that the majority of models include norms based on what others do. Interactions between norm types and dynamic norm signaling remain under-explored. To strengthen social-ecological modeling and its policy relevance, future work should enhance geographic diversity, integrate behavioral theories more deeply and develop models that capture dynamically signaled norms in order to advance our understanding of human–environment interactions and sustainability transitions.

Abstract We present a time-resolved joint Swift–Fermi spectral study of GRB 241030A ( z = 1.411) that cleanly isolates the synchrotron origin of its prompt emission and favors a matter-dominated internal-shock scenario. The light curve shows two episodes separated by a quiescent gap. Episode 1 (0–45 s) is well described by a single power law with photon index ≃ –3/2, consistent with the fast-cooling synchrotron slope below the peak. Episode 2 (100–200 s) exhibits two robust spectral breaks: a low-energy break at E b ∼ 2–3 keV that remains nearly constant in time, and a spectral peak E p that tracks the flux within pulses but steps down between them. The photon indices below and above E b cluster around −2/3 and −3/2, respectively, as expected for fast-cooling synchrotron emission. The burst displays an unusually small (consistent with zero) spectral lag across Fermi Gamma-ray Burst Monitor bands. At later times (≳230 s), the spectrum softens toward ∼–2.7, as expected when the observing band lies above both ν m and ν c . These behaviors are difficult to reconcile with a globally magnetized outflow with a decaying field, which naturally produces hard-to-soft E p evolution, growing ν c , and appreciable lags. By contrast, internal shocks with a roughly steady effective magnetic field and a time-variable minimum electron Lorentz factor (equivalently, for example, a varying fraction of accelerated electrons) simultaneously account for: (1) the stable E b ; (2) the intensity-tracking yet stepped-down E p ; (3) the canonical −2/3 and −3/2 slopes; and (4) the near-zero lag.

Abstract. Large-scale, nonlinear, abrupt, and potentially irreversible transitions in major Earth-system components are becoming increasingly likely under human pressures, with far-reaching consequences for ecosystems, climate stability, and human societies. Yet detecting and comparing such transitions across Earth System Model ensembles remains fragmented and inconsistent, hindering systematic assessment of tipping-point risks. Here we present the first release of the Tipping and Other Abrupt events Detector (TOAD v1.0), an open-source, user-oriented Python framework for detecting abrupt changes in gridded Earth-system data. TOAD implements a modular three-stage pipeline consisting of 1) grid-level abrupt shift detection, 2) spatio-temporal clustering of co-occurring changes, and 3) consensus synthesis to identify statistically robust regions across ensemble members, variables, models, or methodological configurations and quantifies agreement in transition timing. The framework addresses key practical challenges of large-scale spatio-temporal clustering on geographic grids and provides diagnostic statistics and visualisation tools. Detection, clustering, and synthesis algorithms can be flexibly exchanged, supporting systematic method comparison and extensibility. TOAD functions as a data-introspection tool that reveals potentially tipping-relevant dynamics across spatial and temporal scales for subsequent, process-based analysis. We apply TOAD to a synthetic benchmark, domain models of the Antarctic Ice Sheet and the global terrestrial biosphere, and a global Earth System Model ensemble of the North Atlantic Subpolar Gyre. Together, these demonstrations illustrate TOAD's applicability across diverse systems and establish a structured foundation for investigating where and when potentially tipping-relevant changes occur and for quantifying associated uncertainties, supporting coordinated assessment efforts such as the Tipping Points Modelling Intercomparison Project (TIPMIP).

The fine structures of the solar chromosphere, driven by photospheric motions, play a crucial role in the dynamics of solar magnetic fields. Many such structures have already been identified, such as fibrils, filament feet, and arch filament systems. Nevertheless, high-resolution observations show a wealth of structures whose nature remains elusive. We observed a puzzling, unprecedented chromospheric fibril singularity in the close vicinity of a blow-out solar jet and a flaring loop. We aim to understand the magnetic nature of this singularity and the cause of its activity using coordinated high-resolution, multi-wavelength observations. We aligned datasets from Solar Orbiter, SST, IRIS, and SDO. We re-projected the Solar Orbiter datasets to match the perspective of the Earth-based instruments and performed potential field extrapolations from Solar Orbiter/PHI data. We analysed the spatial and temporal evolution of the plasma structures and their link with the surface magnetic field. This led us to derive a model and scenario for the observed structures, which we explain in a general schematic representation. We have discovered a new feature: a singularity in the chromospheric fibril pattern. It forms in a weak magnetic-field corridor between two flux concentrations of equal sign, at the base of a vertically inverted-Y-shaped field-line pattern. In this specific case, some activity develops along the structure: first, a flaring loop at one end, and second, a blow-out jet at the other end, where a coronal null point was present and associated with a chromospheric saddle point located on the fibril singularity. The observations suggest that both active phenomena are initiated by converging photospheric moat flows that exert pressure on this fibril singularity.

ABSTRACT We present photometric and spectroscopic studies of two core-collapse supernovae (SNe) 2008aq and 2019gaf in the optical wavelengths. Light curve and spectral sequence of both the SNe are similar to those of other Type IIb SNe. The pre-maximum spectrum of SN 2008aq showed prominent H $\alpha$ lines, the He lines started appearing in the near maximum spectrum. The near maximum spectrum of SN 2019gaf shows shallow H $\alpha$ absorption and He lines with almost similar strength. Both the SNe show transition from hydrogen-dominated spectra to helium-dominated spectra within a month after maximum brightness. The velocity evolution of SN 2008aq matches well with those of other well-studied Type IIb SNe, while SN 2019gaf shows higher velocities. Close to maximum light, the H $\alpha$ and He i line velocities of SN 2019gaf are $\sim$ 2000 and $\sim$ 4000 km s$^{-1}$ higher than other well-studied Type IIb SNe. Semi-analytical modelling indicates SN 2019gaf to be a more energetic explosion with a smaller ejecta mass than SN 2008aq. The zero-age main-sequence (ZAMS) mass of the progenitor estimated using the nebular spectra of SN 2008aq ranges between 13 and 20 M$_\odot$, while for SN 2019gaf, the inferred ZAMS mass is between 13 and 25 M$_\odot$. The [O i] to [Ca ii] lines flux ratio favours a less massive progenitor star in a binary system for both the SNe.

We discuss the requirements, concepts, simulations, implementation, and calibration of two dual Fabry-Perot (FPI)-based imaging spectropolarimeters, CRISP and CHROMIS, at the Swedish 1-m Solar Telescope, and CRISP2, which is under construction. These instruments are optimised for a large field of view and high cadence at the expense of a moderate spectral resolution, and use a combination of a high-resolution and a low-resolution etalon together with an order-sorting prefilter to define the bandpass. The overall design is made robust and stable by tailoring the low-resolution etalon reflectivity to accommodate expected cavity errors from both etalons, by using a compact optical design that eliminates the need for folding mirrors, and enclosing the entire system within a single container sealed by lenses. By using a telecentric design based on lenses rather than mirrors, image degradation by the FPI system is negligible, as shown in a previous publication, and the throughput of the system is maximised. The initial alignment, and maintaining that alignment over time, is greatly simplified. Moreover, the telecentric design allows the full calibration and/or modelling of essential system parameters to be carried out without interfering with the optical set-up or the cameras. We also discuss briefly the polarimeters developed for CRISP and CHROMIS. The high performance of CRISP and CHROMIS has been demonstrated in an earlier publication through measurements of the granulation contrast and comparisons with similar measurements simultaneously made through broadband continuum filters. Here, we focus on the aspects of the design that are central to enabling high performance and robustness, but also discuss the calibration and processing of the data, and use a few examples of processed data to demonstrate the achievable image and data quality. We put forward a proposal for a similar conceptual design for the European Solar Telescope and conclude by discussing potential problems of the proposed approach to designs of this type. Some aspects of these FPI systems may also be of interest outside the solar community.

Abstract. Understanding Earth resilience—the capacity of the Earth system to absorb and regenerate from perturbations—is key to assessing risks from anthropogenic pressures and sustaining a safe operating space for humanity within planetary boundaries. Classical resilience indicators are designed for autonomous systems with fixed attractors, but the Earth system is fundamentally non-autonomous and out of equilibrium, calling for new ways of defining and quantifying resilience. Here, we introduce a path-resilience approach that assesses how perturbations deviate from and return to a reference trajectory of a conceptual climate model replicating the glacial-interglacial cycles of the Late Pleistocene. We generate two types of perturbation ensembles: a stochastic ensemble and a single-event ensemble, and compute two complementary metrics: the Reference Adherence Ratio (RAR)—defined as the fraction of stochastic trajectories that remain within a narrow band around the unperturbed trajectory—and return time—defined as the time a single perturbed trajectory takes to return to the reference path. Together, these metrics reveal strong temporal variation in resilience across the glacial-interglacial cycles. We find that RAR increases markedly during deglaciations and peaks in interglacial periods, while return times generally shorten as the system approaches interglacial conditions—indicating that certain phases of the cycles act as convergence zones and potential anchors of Earth system stability. As the Earth system departs from such stable interglacial regimes under ongoing anthropogenic forcing, understanding the resilience of these trajectories—and what it may take to return to them—becomes increasingly important. These results highlight that resilience in non-autonomous systems is inherently path-dependent and illustrate a promising first step toward its quantification. Further research is needed to develop more general resilience indicators suitable for complex, forced dynamical systems.

ABSTRACT We present a multiwavelength analysis of the fast X-ray transient EP241021a, discovered by the Wide-field X-ray Telescope aboard the Einstein Probe satellite on 2024 October 21. The event was not detected in gamma-rays. Follow-up observations from $\sim$1.5 to 100 d post-trigger were obtained across X-ray, ultraviolet, optical, near-infrared, and radio bands with ground- and space-based facilities. The redshift is constrained to $z = 0.7485$ from prominent optical spectral features. The optical light curve shows complex evolution: an initial $\sim t^{-0.7}$ decay, followed by a rapid re-brightening peaking at day 7.7 with $\sim t^{-1.7}$ decay, and a third phase peaking near day 19 with $\sim t^{-1.3}$ decay. The spectral energy distribution (SED) and its temporal evolution are consistent with a mix of non-thermal and thermal components. Early optical-to-X-ray spectral indices agree with optically thin synchrotron emission, while steepening of the optical SED after $\sim$20 d indicates either a shift in emission mechanism or the emergence of an additional component. Although broad-lined absorption features are absent, comparisons with Type Ic-BL supernovae suggest an SN contribution at late times, suggesting a collapsar origin for EP241021a. The likely SN in EP241021a appears to require an additional energy source beyond $^{56}$Ni decay. These results support the view that some fast X-ray transients detected by the Einstein Probe arise from massive stellar explosions.