Forest tree species diversity plays a critical role in maintaining ecosystem resilience and function. However, large-scale assessments remain challenging due to the limitations of field-based and supervised remote sensing methods, which require costly training data and species-level labeling. In this study, we propose an unsupervised approach to estimating tree species diversity based solely on satellite imagery (Sentinel-2 or Landsat-8) acquired during the 2019 growing season. The method integrates vegetation indices (GNDVI, EVI, NDMI), self-organizing maps, and spectral clustering to derive the evenness index without the need for species classification. Validation against field data from over 10 000 hexagonal grid cells (10 square kilometers each) across Poland shows strong agreement, with Pearson’s <italic>r</italic> = 0.87 (Sentinel-2, <inline-formula><tex-math notation="LaTeX">$R^{2}$</tex-math></inline-formula> = 0.75) and <italic>r</italic> = 0.81 (Landsat-8, <inline-formula><tex-math notation="LaTeX">$R^{2}$</tex-math></inline-formula> = 0.66). Because the approach does not require ground-based training data, it can be directly integrated into operational forest monitoring frameworks, including national forest inventory programs. This scalable, label-free method enables the repeatable monitoring of tree species diversity at national and continental scales.
Abstract The irregularities of ionospheric plasma bubbles (EPBs) sequentially generated over wide longitudes are expected to share similar lifetime under normal conditions. In this study, we report a special case where the EPB irregularity lifetime over wide longitudes showed a quasi‐wavelike undulation pattern with wavelength of ∼3,000 km, that is, the lifetime of EPB irregularities sequentially generated at different longitudes experienced several gradually decreasing/increasing cycles. Irregularities with longer (shorter) lifetime corresponded to the EPBs with larger (smaller) development in latitude/altitude. Further observations revealed that smaller‐scale (hundred‐kilometer) and larger‐scale (thousand‐kilometer) waves may coexist at the bottomside of ionosphere around sunset. The former acted as the seeding source for EPB generation, whereas the latter superimposed on PRE and modulated EPB development in altitude over different longitudes, leading to the wavelike undulation morphology in irregularity lifetime ultimately. This study provides implications on how the complex wave structures influence EPB morphology over wide longitudes.
Spaceborne interferometric synthetic aperture radar (InSAR) has been extensively employed to detect surface displacements. However, the automatic extraction of locations and boundaries of active geohazards from surface displacement data remains a significant research challenge. In this study, we propose an improved spatial clustering method to automatically detect active geohazards in Lanzhou City, Gansu Province, China. First, we applied the general atmospheric correction online service for InSAR-assisted InSAR stacking technique to derive the annual surface deformation rate. Then, the C-index was employed to eliminate false deformation signals, and a spatial clustering method was used to delineate the boundaries of active geohazards efficiently. Subsequently, the geohazards were classified, and their spatial distribution characteristics were analyzed. Our results revealed that the annual surface deformation rates in Lanzhou city ranged from −176 to 74 mm/yr. The combination of ascending- and descending-track SAR images increased the observable area from 86.3% (ascending only) and 93.4% (descending only) to 96.8% . In addition, applying the C-index reduced misdetection probabilities by 14.4% and 10.9% for the ascending and descending tracks, respectively. Using the improved spatial clustering method, 775 active geohazards, including 331 active landslides and 444 land subsidence areas, were identified and mapped in Lanzhou City for the first time. Active landslides are predominantly located in the northern and southern hills of the urban area, while land subsidence mainly occurs in areas where hills have been excavated or flattened through land grading and leveling for urban development. The improved spatial clustering approach effectively and automatically extracts, classifies, and characterizes active geohazards, enabling rapid cataloging and providing essential data for geohazard management and risk assessment.
Anne Weit, Thierry Winiarski, Brice Mourier
et al.
Hydraulic structures such as dams have a direct or indirect influence on the hydro-sedimentary functioning of rivers. They can impact the sediment continuity of the river and can create a sediment imbalance with zones of sediment accumulation upstream and a lack of sediment downstream from the dam. Upstream deposits are a major issue for managers as they can impact the operation and/oraffect the safety of the structure and induce extra-flood hazards. Operators therefore seek to determine the physical characteristics of these deposits to determine their remobilization potential.Usually, these sediment deposits are described using bathymetric data, sonar images or samples (dredging, coring). For this study, new measurements from two geophysical methods (acoustic and electromagnetic) were used in addition to these current monitoring methods. The contribution of geophysical techniques is undeniable to improve the characterization of these deposits. These measurements make it possible to: i) define the internal structures of the sediments, ii) determine the spatial distribution of these structures over the entire development, iii) evaluate the volumes deposited when little bathymetric data is available on the reservoir. The coupling of these methods thus makes it possible to reconstruct the evolution and the structuring events of the sedimentary deposits. This approach provides complementary and important elements for managers in terms of exploitation and optimization of sedimentary deposits management scenarios.
Abstract This study investigates the intricate dynamics of nutrient transport and stratification in Lake Biwa, highlighting the significant impact of river inflows on water quality. Utilizing a validated three-dimensional flow field model and ecosystem model including a bottom sediment model, the analysis revealed that nutrient concentrations, specifically NH₄⁺, NO₂⁻, NO₃⁻, and PO₄3⁻, exhibited pronounced seasonal variations. In the RN_double scenario, NH₄⁺ and NO₂⁻ concentrations demonstrated a slight increase of 0.1 µg/L, respectively, while NO₃⁻ concentrations rose by 0.05–0.10 µg/L in response to precipitation changes. Conversely, in the RN_half scenario, NH₄⁺ and NO₂⁻ concentrations decreased, with NO₃⁻ seeing a more substantial decline of approximately 0.1 µg/L, attributed to reduced precipitation. PO₄3⁻ levels exhibited a maximum decrease of 0.03 µg/L from summer to autumn. Furthermore, simulations limiting nutrient inflows indicated a modest reduction in concentrations: NH₄⁺ decreased by approximately 0.03 µg/L during summer, and NO₂⁻ decreased by around 0.05 µg/L from spring to summer. The results suggest that while immediate improvements in dissolved oxygen levels are limited, effective long-term nutrient management could stabilize oxygen concentrations and improve overall water quality. These findings underscore the necessity for comprehensive water management strategies to mitigate eutrophication effects and support the ecological health of Lake Biwa.
These notes summarize the lectures about "Cosmic-ray propagation in extragalactic space and secondary messengers", focusing in particular on the interactions of cosmic-ray particles with the background photons in the Universe, including nuclear species heavier than hydrogen, and on the analytical computation of the expected cosmic-ray fluxes at Earth. The lectures were held at the Course 208 of the International School of Physics "Enrico Fermi" on "Foundations of Cosmic-Ray Astrophysics", in Varenna (Como, Italy) from June 23rd to June 29th, 2022. These notes are complementary to the content of the lectures held by Pasquale Dario Serpico at the same school.
Regularization is critical for solving ill-posed geophysical inverse problems. Explicit regularization is often used, but there are opportunities to explore the implicit regularization effects that are inherent in a Neural Network structure. Researchers have discovered that the Convolutional Neural Network (CNN) architecture inherently enforces a regularization that is advantageous for addressing diverse inverse problems in computer vision, including de-noising and in-painting. In this study, we examine the applicability of this implicit regularization to geophysical inversions. The CNN maps an arbitrary vector to the model space. The predicted subsurface model is then fed into a forward numerical simulation to generate corresponding predicted measurements. Subsequently, the objective function value is computed by comparing these predicted measurements with the observed measurements. The backpropagation algorithm is employed to update the trainable parameters of the CNN during the inversion. Note that the CNN in our proposed method does not require training before the inversion, rather, the CNN weights are estimated in the inversion process, hence this is a test-time learning (TTL) approach. In this study, we choose to focus on the Direct Current (DC) resistivity inverse problem, which is representative of typical Tikhonov-style geophysical inversions (e.g. gravity, electromagnetic, etc.), to test our hypothesis. The experimental results demonstrate that the implicit regularization can be useful in some DC resistivity inversions. We also provide a discussion of the potential sources of this implicit regularization introduced from the CNN architecture and discuss some practical guides for applying the proposed method to other geophysical methods.
After more than a century of discovering cosmic rays, a comprehensive description of their origin, propagation, and composition still eludes us. One of the difficulties is that these particles interact with magnetic fields; therefore, their directional information is distorted as they travel. In addition, as cosmic rays (CRs) propagate in the Galaxy, they can be affected by magnetic structures that temporarily trap them and cause their trajectories to display chaotic behavior, therefore modifying the simple diffusion scenario. Here, we examine the effects of chaos and trapping on the TeV CR anisotropy. Concretely, we develop a new method to study the chaotic behavior of CRs. This work is based on the heliospheric effects since they can be remarkably significant for this anisotropy. Specifically, how the distinct heliospheric structures can affect chaos levels. We model the heliosphere as a coherent magnetic structure given by a static magnetic bottle and the presence of temporal magnetic perturbations. This configuration is used to describe the draping of the local interstellar magnetic field lines around the heliosphere and the effects of magnetic field reversals induced by the solar cycles. In this work, we explore the possibility that particle trajectories may develop chaotic behavior while traversing and being temporarily trapped in this heliospheric-inspired toy model and its potential consequences on the CR arrival distribution. It was found that the level of chaos in a trajectory is linked to the time the particles remain trapped in the system. This relation is described by a power law that could prove to be inherently characteristic of the system. Also, the arrival distribution maps show areas where the different chaotic behaviors are present, which can constitute a source of time-variability in the CR maps and can prove critical in understanding the anisotropy on Earth.
1) Since the outer electron radiation belt is lost on occasion, the radiation belt needs seed electrons to rebuild. 2) The clear candidate for that seed population is energetic substorm-injected electrons in the dipolar magnetosphere. 3) The energetic substorm-injected electrons in the dipole come from the suprathermal electron population in the magnetotail plasma sheet, delivered by substorms. Scenario (1)–3) begs the question: Where do these magnetotail suprathermal electrons come from? We are hypothesizing that one source (perhaps the dominant source) is the energetic field-aligned electron strahl in the solar wind, which are electrons fresh from the solar corona.
Currently, thermospheric species densities and temperatures between ∼100 and 200 km are not known to the accuracy needed to fully characterize how the thermosphere transitions from a well-mixed atmosphere to a diffusively separated atmosphere with zero temperature gradient. This greatly inhibits scientific discovery attainable from either models or observations in this region, especially the understanding of mechanisms that drive thermosphere and ionospheric variability from space weather to climatological time scales. The purpose of this paper is to highlight the importance and critical need for new, global, height-resolved neutral composition (O, O2, N2) and temperature measurements in the new ignorosphere: the 100–200 km region of the thermosphere. We conclude with observation recommendations and requirements for new comprehensive composition and temperature measurements in the 100–200 km altitude region that would lead to significant advances in thermosphere-ionosphere science, space weather, and space climate.
The deposition of wax on pipelines causes problems that affect the oil production rate and the facilities. Several preventive and control measures were employed to manage this problem. However, there is no single technique that is hundred per cent effective for different fields. Therefore, this article provides new interpretation of the associated risk of the problem – such as the impact of ethical and professionalism on wax deposition. In a nutshell, this paper sheds more-light on the need for the implementation of sound engineering practices during pipeline design, construction, and operations to improve wax deposition risks, thereby reduces the associated remediation costs. The laboratory case study revealed that crude oil properties (WAT, PPT, API), standard operating conditions and procedures must be accurate and continuously updated throughout the production life cycle. The results showed that maintaining crude oil temperature above wax appearance temperature (30°C) and at a relatively high flow rate particularly within the turbulent flow region (7, 9 and 11 l/min) provides a safe and uninterrupted production of waxy crude oil (δwax ≈ 0 mm).
<p>Ensemble simulation of the atmospheric general
circulation at altitudes up to the lower thermosphere is performed using the
3-D nonlinear mechanistic numerical model MUAM. The residual mean meridional
circulation (RMC), which is the superposition of the mean Eulerian and
wave-induced eddy components, is calculated for the boreal winter. Changes
in the vertical and meridional RMC velocity components are analysed at
different stages of a simulated composite sudden stratospheric warming (SSW)
event averaged over 19 model runs. The simulation results show a general
decrease in RMC velocity components up to 30 % during and after SSW in the
mesosphere and lower thermosphere of the Northern Hemisphere. There are also
increases in the downward and northward velocities at altitudes of 20–50 km at
the northern polar latitudes during SSW. Associated vertical transport and
adiabatic heating can contribute to warming the stratosphere and downward
shifting of the stratopause during the composite SSW. The residual mean and
eddy mass fluxes are calculated for different SSW stages. It is shown that
before the SSW, planetary wave activity creates wave-induced eddy
circulation cells in the northern upper stratosphere, which are directed
upwards at middle latitudes, northward at high latitudes and downwards near
the North Pole. These cells increase heat transport and adiabatic heating in
the polar region. During SSW, the region of upward eddy vertical velocity is
shifted to high latitudes, but the velocity is still downward near the North
Pole. After SSW, upward eddy-induced fluxes span the entire polar region,
producing upward transport and adiabatic cooling of the stratosphere and
providing the return of the stratopause to higher altitudes. The obtained
statistically significant results on the evolution of RMC and eddy
circulation at different SSW stages at altitudes up to the lower
thermosphere can be useful for a better understanding the mechanisms of planetary
wave impacts on the mean flow and for the diagnostics of the transport of
conservative tracers in the atmosphere.</p>
Luis A. Anchordoqui, Akitaka Ariga, Tomoko Ariga
et al.
The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF's physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.
Abstract The Quaternary Big Pine (BP) volcanic field in eastern California is notable for the occurrence of mantle xenoliths in several flows. This points to rapid ascent of basalt through the crust and precludes prolonged storage in a crustal reservoir. In this study, the hypothesis of phenocryst growth during ascent is tested for several basalts (13–7 wt% MgO) and shown to be viable. Phenocrysts of olivine and clinopyroxene frequently display diffusion‐limited growth textures, and clinopyroxene compositions are consistent with polybaric crystallization. When the most Mg‐rich olivine in each sample is paired with the whole‐rock composition, resulting Fe2+‐MgKD(olivine‐melt) values (0.31–0.36) match those calculated from literature models (0.32–0.36). Application of a Mg‐ and a Ni‐based olivine‐melt thermometer from the literature, both calibrated on the same experimental data set, leads to two sets of temperatures that vary linearly with whole‐rock MgO wt%. Because the Ni thermometer is independent of water content, it provides the actual temperature at the onset of olivine crystallization (1247–1097°C), whereas the Mg thermometer gives the temperature under anhydrous conditions and thus allows ΔT (=TMg − TNi = depression of liquidus due to water) to be obtained. The average ΔT for all samples is ~59°C, which is consistent with analyzed water contents of 1.5–3.0 wt% in olivine‐hosted melt inclusions from the literature. Because the application of olivine‐melt thermometry/hygrometry at the liquidus only requires microprobe analyses of olivine combined with whole‐rock compositions, it can be used to obtain large global data sets of the temperature and water contents of basalts from different tectonic settings.
In this paper a new Geophysical gravimetry approach is presented, which is based on satellite imagery in remote sensing. The method uses a satellite image, together with a set of points in the image the gravity values of which are known. Template-based spheroidal spline method of interpolation is used to constitute a system of equations to find the values of gravity at other points in the image. A real case study is presented for the Qom region in Iran. Values of gravity are determined from the Landsat satellite image for this region, using 9 points in the image whose gravity values are known. Reference ellipsoid gravity values, which are based on coefficients derived from satellite gravimetry, are computed for this region, as well. Comparison between gravity values derived from Landsat image and those from reference ellipsoid shows that the standard deviation of the results is around 6.71 milli Gal, with the maximum of differences being 35 milli Gal.
The NA61/SHINE experiment at the SPS accelerator at CERN is a unique facility for the study of hadronic interactions at fixed target energies. The data collected with NA61/SHINE is relevant for a broad range of topics in cosmic-ray physics including ultrahigh-energy air showers and the production of secondary nuclei and anti-particles in the Galaxy. Here we present an update of the measurement of the momentum spectra of anti-protons produced in $π^-$+C interactions at 158 and 350 GeV/c and discuss their relevance for the understanding of muons in air showers initiated by ultrahigh-energy cosmic rays. Furthermore, we report the first results from a three-day pilot run aimed at investigating the capability of our experiment to measure nuclear fragmentation cross sections for the understanding of the propagation of cosmic rays in the Galaxy. We present a preliminary measurement of the production cross section of Boron in C+p interactions at 13.5 AGeV/c and discuss prospects for future data taking to provide the comprehensive and accurate reaction database of nuclear fragmentation needed in the era of high-precision measurements of Galactic cosmic rays.
Within the frame of the ANR-funded CANTARE-Alsace project, we have undertaken a multi-scale and multidisciplinary approach to increase our knowledge of the transition zone between the sedimentary cover and the basement and provide fundamental knowledge for the assessment of its geothermal potential. In this paper, we report out the results of a study performed on an exhumed transition zone in the Ringelbach area in the Vosges Mountains, on the flank of the Rhine graben. In this analogue of a deeply buried transition zone of the Rhine Graben, a thin layer of Triassic sandstones is still present on the top of the fractured and altered granitic basement providing the opportunity to study in-situ the physical properties of this transition zone. In this paper, we focused on electrical and acoustic properties of the transition zone as they are the main physical parameters usually assessed with the help of geophysical methods during the exploration phase of a geothermal project.