Hasil untuk "Geophysics. Cosmic physics"

Ming Tong, Shenghua Fan, Jiu Jiang et al.

Recently, detectors based on deep learning have boosted the state-of-the-art of application on ship detection in synthetic aperture radar (SAR) images. However, constructing discriminative feature from scattering of background and distinguishing contour of ship precisely still present challenging subject to the inherent scattering mechanism of SAR. In this article, a dual-branch detection framework with perception of scattering characteristic and geometric contour is introduced to deal with the problem. First, a scattering characteristic perception branch is proposed to fit the scattering distribution of SAR ship through conditional diffusion model, which introduces learnable scattering feature. Second, a convex contour perception branch is designed as two-stage coarse-to-fine pipeline to delimit the irregular boundary of ship by learning scattering key points. Finally, a cross-token integration module following Bayesian framework is introduced to couple features of scattering and texture adaptively to learn construction of discriminative feature. Furthermore, comprehensive experiments on three authoritative SAR datasets for oriented ship detection demonstrate the effectiveness of proposed method.

Jie Li, Chenbo Yang, Chengyong Zhu et al.

Lodging, a major agricultural issue, significantly compromises the yield, stability, and quality of oilseed crops, particularly rapeseed (Brassica napus L.). Real-time monitoring and accurate assessment of lodging are critical for precise yield estimation and the development of lodging-resistant varieties. However, traditional methods for quantifying lodging rates, which rely on manual measurements of lodged plant proportions, are often labor-intensive and prone to inaccuracies, limiting their utility in large-scale breeding programs. This article provides an indirect method for lodging assessment by simplifying the lodging issue to the enumeration of upright plants. First, we use a deep learning model for plant counting from Unmanned aerial vehicle (UAV) imagery in plot level. A novel CMRNet model is developed for upright plants counting and localization, leveraging a hybrid CNN-Mamba backbone network. The model synergizes local feature extraction via CNN with the global modeling strengths of the Mamba state space model, yielding semantically rich features while significantly enhancing computational efficiency and inference speed. Then, we created a new Upright Rapeseed Center Point (URCP) dataset using high-altitude UAV remote sensing orthoimages, encompassing rapeseed fields at various maturity stages and lodging degrees. Training and validation of CMRNet on the URCP dataset yielded exceptional performance metrics, with mean absolute error (MAE) of 5.70, relative root mean square error (rrMSE) of 8.08, and coefficient of determination (R<inline-formula><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>) of 0.9220. These results significantly outperformed existing TasselNetV2, RapeNet, and RPNet models. The number of parameters in our model is only 7.94 M, which is lower than SOTA counting networks. In addition, we also verified the robustness on different rape materials in two years, 2023 and 2025, and the R<inline-formula><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> were all above 0.8, indicating that the model should cope with different field conditions.

Chae‐Woo Jun, Yoshizumi Miyoshi, Tomoaki Hori et al.

Abstract This study demonstrates the influence of electromagnetic ion cyclotron (EMIC) rising‐tone emissions on relativistic electrons in the inner magnetosphere using data obtained from the Van Allen Probes and Arase satellites. We find that the intense EMIC rising‐tone emissions occur during the increase in the solar wind pressures, creating favorable conditions for triggering nonlinear wave growth. The strong flux drop‐out of relativistic electrons in the parallel directions of the magnetic field, with energies of 0.2–4 MeV, was associated with the wave activity. We calculated the nonlinear triggering conditions and the minimum resonant energy of relativistic electrons interaction with EMIC waves, based on our observations. We conclude that EMIC rising‐tone emissions contribute not only to the rapid loss of MeV electrons through EMIC wave‐particle interactions while extending the resonance energy to a few MeV by broadening bandwidth via nonlinear wave growth but also to interactions with sub‐MeV electrons through the nonresonant effect.

Ziyu Wang, Weiqing Zhao, Sen Cao et al.

Abstract China has made extensive afforestation efforts over the past 40 years. However, ecosystem models simulate only modest vegetation enhancement, creating a significant disparity between documented reforestation efforts and model‐based simulations. This fundamental mismatch remains largely unexplored. Here, we conducted a comprehensive analysis using diverse observation data to identify the determinant within Dynamic Global Vegetation Models (DGVMs) that underestimates vegetation growth in China. By developing a high‐resolution forest cover change data set, we found that LUH2‐GCB, the common land use input for DGVMs, causes models to underestimate afforestation. With a neighborhood comparison analysis, we quantitively demonstrated the predominant role of underestimated afforestation in lowering leaf area index (LAI) trends. Overall, DGVMs underestimated China's afforestation area by an average of 26.88%, leading to a 29.46% underestimation in LAI increase. Our findings confirm a significant greening trend in China and highlight the need for improved land use data representation in DGVMs.

Yangyang Liao, Kelly H. Liu, Stephen S. Gao

Abstract To provide constraints on the formation mechanisms of intracontinental volcanisms and intriguing lithospheric thickness variations in the East Sayan Mountains and surrounding areas, we stack P‐to‐s receiver functions to image the 410‐km and 660‐km discontinuities. Mantle transition zone (MTZ) thickening observed in a continuous area is attributable to ancient slab remnants, and Cenozoic volcanisms in the peripheral area can be explained by slab dehydration. The thinning of the MTZ in the Tuva‐Mongolian Massif can be explained by mantle upwelling branches induced by slab subduction. Our results reveal an approximately circular area in the MTZ that is significantly thicker than usual, suggesting the presence of detached mantle lithosphere in the form of a lithospheric drip extending to the MTZ. The presence of the drip is consistent with geochemical and lithospheric thickness observations, and the drip could be triggered by passage of a mantle plume currently located beneath western Lake Baikal.

Jing Ling, Hongsheng Zhang, Rui Liu et al.

Accurate and timely monitoring of functional urban impervious surfaces (FUISs), such as ports, roads, and buildings, is essential yet challenging for complex coastal cities due to their cloudy weather and diverse land surfaces. Synthetic aperture radar (SAR) provides unique all-weather observation capabilities for prompt and regular urban mapping. However, SAR scattering information is limited to distinguish impervious surfaces with similar scattering responses but different functions. This study develops a scattering&#x2013;compactness fusion network (SCFN), which integrates SAR polarimetric scattering and object compactness characteristics for enhanced FUIS recognition. Central to our approach is the scattering object compactness index, which is specifically designed to capture the distinct spatial patterns and compactness of scattering objects and complement their intrinsic scattering signatures. The dual-branch SCFN concurrently extracts and fuses object-scale scattering and compactness features using tailored network architectures. Experiments on <italic>L</italic>-band and <italic>C</italic>-band fully polarimetric ALOS-2 and GF-3 data in Hong Kong, as well as <italic>L</italic>-band dual-polarized ALOS-2 data, are undertaken to verify SCFN&#x0027;s effectiveness, achieving up to 8&#x0025; improvement in the overall FUIS classification accuracy over baselines. The transferability of SCFN is further validated using fully polarimetric ALOS-2 data in Shenzhen, where consistent performance improvements are observed. The successful application of SCFN in both coastal cities highlights the potential of joint scattering&#x2013;compactness modeling for advanced SAR-based urban mapping and its robustness across different urban landscapes.

L. Lomidze, D. Knudsen, M. Shepherd et al.

The terrestrial ionosphere displays significant equinoctial asymmetry despite the upper atmosphere receiving similar levels of solar ionization energy at a given location and local time in March and September during similar solar activity conditions. This intriguing feature is not well understood or modeled, particularly in the upper ionosphere, and causes of the asymmetry are not fully established and quantified. Yet, their study is important to provide better insights into the atmosphere‐ionosphere coupling processes. Analysis of Langmuir probe data from ESA's Swarm B satellite at ∼525 km altitude reveals that the daytime electron density is larger for all latitudes during the March equinox than during the September equinox, while the electron temperature shows an inverted asymmetry except at low latitudes. Simultaneously obtained neutral density data from Swarm GPS accelerations indicate that the thermosphere is denser during the March equinox. The asymmetry seen by Swarm electron density observations is also present in electron densities obtained using GPS radio occultation measurements from the COSMIC satellites. Simulations were performed using physics‐based ionosphere models (SAMI3, WACCM‐X, and TIE‐GCM) to determine their ability to produce the observed asymmetry, understand the generation mechanism(s), and establish the relative role of physical drivers. Results produced by TIE‐GCM are closest to the observations when seasonally varying eddy diffusivity is considered in the model. The asymmetry produced by other models is noticeably weaker. Modeling of the asymmetry by SAMI3 driven with the TIE‐GCM neutral atmosphere shows that both neutral density and winds play a critical role, but the density has a greater effect.

Rui Chen, Xinliang Gao, Quanming Lu et al.

Abstract Electron cyclotron harmonic (ECH) waves are one of the most common plasma waves in the Earth's magnetosphere, and they are considered to be excited by the electron loss‐cone distributions near the magnetic equator. Using the Magnetospheric Multiscale data, we report an unusual event of ECH waves at L = ∼12.4 and MLT = ∼16.0 hr, where the ECH waves are locally excited inside non‐propagating magnetic oscillations, that is, mirror mode structures. The observation reveals that the mirror mode structures are generated by anisotropic ions (Ti⊥/Ti∥ ∼ 1.3 – 1.7), and electron mirror loss‐cone distributions are formed due to the magnetic configuration of the mirror mode structures. Combing with the linear instability analysis, we confirm that the ECH waves are locally excited by the electron mirror loss‐cone distributions inside the mirror mode structures. Therefore, we propose that the mirror mode structures provide another potential source region for ECH waves in the Earth's magnetosphere.

Shishun Wang, Liao Chang

Abstract The Ocean Drilling Program Leg 158 drill holes from the Trans‐Atlantic Geotraverse hydrothermal field are investigated to understand the rock magnetic signatures of hydrothermal mineralization. A composite columnar section has been constructed through hole correlation to understand the stratigraphic variation of magnetomineralogy within the stockwork. Isothermal remanent magnetization components unmixing, first‐order reversal curve diagrams, low‐temperature magnetic signatures, and electron microscopic analyses disclose magnetic minerals of disparate occurrences related to predominating hydrothermal mineralization reactions in three broad zones: For basaltic basements, serpentinization of olivine phenocrysts during preliminary hydrothermal alteration produces magnetite, in addition to primary titanomagnetite; Chloritized and silicified zone samples contain relict titanomagnetite and exsolved magnetite that survived hydrothermal dissolution; Anhydrite and sulfide zone samples are dominated by magnetite and hematite, likely from oxidation of polymetallic sulfides due to exposure in oxidative seafloor environments during drilling. Our findings suggest that seafloor oxidation potentially modifies the magnetic properties of polymetallic sulfides in hydrothermal deposits, which applies to magnetic tomography of sophisticated subseafloor vent structures and prospecting seafloor massive sulfides (SMS) deposits therein. Meanwhile, we alert future deep‐sea mining that drilling may promote physicochemical alteration of SMS deposits, causing environmental risks. The established magnetic signatures ultimately contribute to understanding the in situ geological preservation of SMS deposits and optimizing exploitation procedures in the future.

John C. Foster, Philip J. Erickson

Nonlinear processes are involved in both the growth of VLF chorus waves and the energization of radiation belt electrons trapped in the wave potential. Nonlinear theory has led to analytic formulae describing both these processes. To investigate these processes, observations from the Van Allen Probes twin spacecraft provide simultaneous in situ information on VLF chorus waves, radiation belt and injected electrons, and local plasma parameters. We combine the theoretical treatment summarized by Omura (2021) with these in situ observations to investigate the characteristics and effects of nonlinear radiation belt processes at the off-equatorial location of the spacecraft observations. We show the smooth phase transition between initial subpackets of chorus wave elements, conducive to extended trapping and enhancement of resonant electrons. The structure of the chorus wave element changes as it propagates away from the equator. Frequency dispersion due to the variation of parallel wave group velocity with frequency contributes to the chorus waveform frequency sweep rate observed at an off-equatorial location. Nonlinear damping at the local value of ½ fce progressively erodes wave amplitude at frequencies above ½ fceEQ. We examine the important dependencies of the nonlinear inhomogeneity factor on the time rate of change of the wave frequency and the field-aligned gradient of the magnetic field and discuss their implication for the energization of trapped non-relativistic and MeV electrons. The 0.5–2% energy gain we find for 3–6 MeV seed electrons indicates that prompt local acceleration of highly relativistic and ultra-relativistic radiation belt electrons can take place directly through their nonlinear interaction with an individual VLF chorus wave element.

Abdul Malek

Kepler’s Laws of planetary motion (following the Copernican revolution in cosmology), according to Leibniz and his follower Hegel, for the first-time in history discovered the keys to what Hegel called the absolute mechanics mediated by dialectical laws, which drives the celestial bodies, in opposition to finite mechanics in terrestrial Nature developed by mathematical and empirical sciences, but that are of very limited scope. Newton wrongly extended and imposed finite mechanics on the absolute mechanics of the cosmic bodies in the form of his Law of one-sided Universal Gravitational Attraction, by distorting and misrepresenting Kepler’s profound laws and in opposition to Leibniz’s more appropriate “Radial Planetary Orbital Equation”. The still-prevailing error by Newton (notwithstanding his well known manipulation of science for selfish ends), not only shows the limitation of mathematical idealism and prejudice driven modern cosmology in the form of Einstein’s theories of relativity; but also, have made gaining positive knowledge of the cosmos an impossibility and has impaired social/historical development of humanity by reinforcing decadent ruling ideas. Hegel’s Naturphilosophie is not only a protest against the misrepresentation of Kepler’s Laws in particular; his Enzyklopädie der Philosophischem Wissenschaften is the negation and the direct rebuttal of Newtonian physics and Philosophiæ Naturalis Principia Mathematica, in general. Modern natural science ignores Leibniz and Hegel at its own peril! Kepler’s phenomenological laws of planetary motion and the dialectical insights of Leibnitz and Hegel opens the way for gaining positive knowledge of the dynamics, structure and the evolution of the cosmic bodies and other cosmic phenomena; without invoking mysteries and dark/black cosmic entities, which has been the pabulum of official astrophysics and cosmology so far.

Yi Ling, Yuxuan Liu, Sai Wang et al.

The Large High Altitude Air Shower Observatory (LHAASO) has reported the measurement of photons with high energy up to 1.42 PeV from 12 gamma-ray sources. We are concerned with the implications of LHAASO data on the fate of Lorenz symmetry at such high energy level, thus we consider the interaction of the gamma ray with those photons in cosmic microwave background (CMB), and compute the optical depth, the mean free path as well as the survival probability for photons from all these gamma-ray sources. Employing the threshold value predicted by the standard special relativity, it is found that the lowest survival probability for observed gamma ray photons is about 0.60, which is a fairly high value and implies that abundant photons with energy above the threshold value may reach the Earth without Lorentz symmetry violation. We conclude that it is still far to argue that the Lorentz symmetry would be violated due to the present observations from LHAASO. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

Rocío E. Gallardo Jara , Matías C. Ghiglione, Lisandro Rojas Galliani

The evolutionary history of the Austral Magallanes has been object of several studies both in Chile and Argentina, due to its importance as hydrocarbon and gas producer. In the evolution of southern South America, a stage of intracratonic rifting development between the Middle-Late Jurassic has been recognized in a wide part of southern Patagonia that generated an extensional basin (Rocas Verdes basin). Following the creation of a synrift fault system the basins evolved towards an Early Cretaceous postrift sag stage that deposits a thick pelitic succession in a marine shelf environment, constituting these deposits in the main reservoir and source rock for the oil plays. During the middle-Late Cretaceous in the entire Austral Patagonian region took a place a compressional regime over the east and south margin of southernmost South America. Product of Andean growth in this sector were produced a magmatic arc, a Basement domain and fold-and-thrust belt, and a foreland basin related to flexural loading. Since the Neogene to Recent, the Fueguian Andes were affected by transpressive tectonics related to the opening of the Drake Passage. This contribution is a review, and pretend to account the stratigraphic and the structural evolution of the basin of the southernmost Patagonia and its fold-and-thrust belt associated, summarized in a regional stratigraphic correlations for Late Jurassic–Quaternary rock units throughout the southern Austral-Magallanes basin. However, new ideas and interpretation are presented supported by new information at the regional level, using a north-to-south direction seismic-line reflection, well-log data and their regional correlation. The tectonic evolution of the studied depocenters is related to structural phases recognized in the Patagonian-Fueguian Andes and the Burdwood bank, constituting their southern active boundary. These depocenters migrated to the east in the southern Patagonian Andes and towards the north and east in Tierra del Fuego and Malvinas. The thrust advance is evidenced by discordances within the basin fill that coalesce towards the external depocenter and depositional bulge, characteristic geometric stacking patterns and configuration of clinoforms. These key surfaces enabled the definition of four evolutionary stages: Foreland I (Coniacian (?) - Maastrichtian), Foreland II (early-middle Paleocene – middle Eocene), Foreland III (early-middle Eocene - Oligocene) and Foreland IV (early Miocene - Pliocene).

J. Goswami, J. MacDougall

Devendra Lal was an Indian nuclear physicist who began his career studying particle physics while a student at the Tata Institute of Fundamental Research (TIFR) in Bombay, using tracks in nuclear emulsions to study cosmic ray particles and their interactions. He soon moved on to the search for radionuclides produced in the atmosphere by cosmic ray bombardment, independently (with colleagues) discovering radioisotopes of Be, P and Si and using them as geophysical tracers for atmospheric, meteorological and oceanographic processes. His career revolved principally around multiple aspects of cosmic rays, employing theory and experiment to examine their flux, chemical composition and energy spectrum, both at present and in the past through (for example) studies of particle tracks in the minerals of meteorites and lunar samples. He played a major role in developing approaches for the use of terrestrial cosmic-ray-produced isotopes as dating tools and tracers for a wide range of Earth processes, from biological cycles in the ocean to landscape evolution and ice ablation in the Antarctic. At various stages of his career Lal was professor at TIFR and led the geophysics group there, was professor and director of the Physical Research Laboratory in Ahmedabad, India, and was professor at the Scripps Institution of Oceanography, University of California San Diego. He was elected fellow of numerous scientific organizations and academies internationally, and was the recipient of many scientific awards and prizes.

L. Kuzmichev, I. Astapov, P. Bezyazykov et al.

A. Kounine

The Alpha Magnetic Spectrometer (AMS) is a 15-nation project on the International Space Station (ISS). Following a 16-year period of construction and testing and a precursor flight on the Space Shuttle in 1998, AMS was installed on the ISS on May 19, 2011. AMS is a precision particle physics magnetic spectrometer. Since its installation on the ISS, it has collected more than 140 billion cosmic rays. Precision measurements by AMS of the fluxes of cosmic ray positrons, electrons, antiprotons, protons and light nuclei as well as their ratios show several unexpected and intriguing features. The new AMS results on the positron flux reveal a new source of high energy positrons. Surprisingly, in this rigidity range the spectral indices of cosmic ray nuclei experience progressive hardening over the rigidity interval of few hundred GV. AMS continues studies of complex antimatter candidates with stringent detector verification and collection of additional data.

S. Ra, D. Kim, C. Lee et al.

Center for Underground Physics (CUP) at Institute for Basic Science (IBS) has been operating the COSINE-100 for WIMP search and the AMoRE (Advanced Mo based Rare process Experiment) for neutrinoless double beta decay search. Both experiments are using ultra-pure scintillating crystals at the underground facility to avoid the cosmic muon background. In order to grow the ultra-pure crystals, the raw materials are purified and their radioactive levels are measured using ICP-MS and HPGe. A clean-room facility has been constructed to avoid external contaminations during the crystal treatment procedure after the growth. We present the current status of the crystal growth facility and discuss further about next levels for the ultra-pure crystal production in near future.

I. Astapov, P. Bezyazeekov, V. Boreyko et al.

Abstract The TAIGA experiment in the Tunka valley near Lake Baikal is planning an extension with new TAIGA-Muon scintillation detector stations. The main purpose of TAIGA is gamma-ray astronomy in the TeV to PeV energy range and cosmic ray physics. The purpose of the Taiga-Muon detectors is to measure the muon component of air showers for improving cosmic ray composition measurements as well as gamma–hadron separation above 100 TeV. Monte Carlo simulations of the experiment are done with the software packages CORSIKA and GEANT4. Extensive air showers of primary particles in the energy range 100–3000 TeV are created with CORSIKA. The trigger efficiency is calculated and used for optimization. The suppression factor of hadronic showers versus electromagnetic showers is studied, leading to an optimum depth of soil absorber (2 m), at the lowest energy range. Data on the identification efficiency for primary gamma-quanta and proton events are presented as well as the suppression factor.

Abstract. New particle formation (NPF) is known to be an important source of atmospheric particles that impacts air quality, hydrological cycle, and climate. Although laboratory measurements indicate that ammonia enhances NPF, the physicochemical processes underlying the observed effect of ammonia on NPF are yet to be understood. Here we present a comprehensive kinetically based H2SO4–H2O–NH3 ternary ion-mediated nucleation (TIMN) model that is based on the thermodynamic data derived from both quantum-chemical calculations and laboratory measurements. NH3 was found to reduce nucleation barriers for neutral, positively charged, and negatively charged clusters differently, due to large differences in the binding strength of NH3, H2O, and H2SO4 to small clusters of different charging states. The model reveals the general favor of nucleation of negative ions, followed by nucleation on positive ions and neutral nucleation, for which higher NH3 concentrations are needed, in excellent agreement with Cosmics Leaving OUtdoor Droplets (CLOUD) measurements. The TIMN model explicitly resolves dependences of nucleation rates on all the key controlling parameters and captures the absolute values of nucleation rates as well as the dependence of TIMN rates on concentrations of NH3 and H2SO4, ionization rates, temperature, and relative humidity observed in the well-controlled CLOUD measurements well. The kinetic model offers physicochemical insights into the ternary nucleation process and provides a physics-based approach to calculate TIMN rates under a wide range of atmospheric conditions.

G. Blazey, J. Colston, A. Dyshkant et al.

Abstract Results of radiation tests of Hamamatsu 2.0 × 2.0 mm 2 through-silicon-via (S13360-2050VE) multi-pixel photon counters, or MPPCs, are presented (Hamamatsu, 0000). Distinct sets of eight MPPCs were exposed to four different 1 MeV neutron equivalent doses of 200 MeV protons. Measurements of the breakdown voltage, gain and noise rates at different bias overvoltages, photoelectron thresholds, and LED illumination levels were taken before and after irradiation. No significant deterioration in performance was observed for breakdown voltage, gain, and response. Noise rates increased significantly with irradiation. These studies were undertaken in the context of MPPC requirements for the Cosmic Ray Veto detector of the Mu2e experiment at the Fermi National Accelerator Laboratory.