Hasil untuk "Geophysics. Cosmic physics"

E. Y. H. Lippert, M. Morlighem, G. Cheng et al.

Abstract Calving is a critical factor in the dynamics of marine‐terminating glaciers, yet its long‐term behavior remains poorly understood. Existing models calibrate calving parameters with decadal observational periods and assume they remain constant, effectively overlooking shifts in external drivers like ice mélange. We investigate calving evolution from 1981 to 2021 using a centennial reconstruction of Kangerlussuaq Glacier and identify significant calving regime changes. Using the von Mises calving parameterization, we find that a change in the maximum tensile stress threshold precedes changes in ice mélange. This suggests that, while mélange may have a strong impact on calving rates on seasonal timescales, this effect does not persist over multi‐decadal timescales. Long‐term projections that account for variations in calving parameterization indicate that Kangerlussuaq Glacier will continue to retreat in most scenarios, with ice mass losses ranging from 220 to 1,090 Gt, equivalent to 0.61–3.01 mm of global sea level rise.

Fabiano Feleppa, Fabiano Feleppa, Elmo Benedetto et al.

Youdong Chen, Keren Dai, Ling Chang et al.

High-precision measurement in low-coherence areas remains challenging for multitemporal synthetic aperture radar interferometry (InSAR). For instance, over the regions covered by dense vegetation, InSAR merely provides sparse measurement points (MPs) due to high spatio-temporal decorrelation. To address this, our study proposes a coherence-enhanced multitemporal InSAR (CE-InSAR) approach to better monitor low-coherence landslide displacement in the radar line-of-sight (LOS) direction. The key ideas of CE-InSAR include the preprocessing feasibility assessment for obtaining the important predefined parameters for time series processing and coherence enhancement with the use of phase optimization for the C-band Sentinel-1 data stacks. To demonstrate the effectiveness of CE-InSAR, 85 scenes of Sentinel-1 images (2021–2023) covering the Tianxi landslide in Guangxi Province, China with an NDVI value greater than 0.5, were applied to retrieve the historical displacements and analyze the activity state. The InSAR measurements from both the presling and postsliding phases illustrated the significant advantages of CE-InSAR, with five more times of MPs both in a single landslide scale and regional scale, compared to small baseline subset interferometry (SBAS-InSAR). Furthermore, time series analysis considering rainfall factors, indicates CE-InSAR can detect the accelerated displacement of the Tianxi landslide prior to sliding, exhibiting a maximum LOS accumulative displacement of around 70 mm. Subsequently, the combined impacts of human activity and rainfall contributed to the landslide’s failure. Finally, the major uncertainties and limitations for the application of CE-InSAR were discussed, and the conclusions were summarized. In general, this research is valuable and useful for guiding landslide displacement monitoring characterized by low coherence using InSAR.

Ziyin Zhang, Jing Xu, Xiujuan Zhao et al.

Abstract Accurate PM2.5 and visibility predictions are essential for effective air quality management in central and eastern China. This study seeks to enhance the regional air quality numerical prediction system (RMAPS‐Chem) by integrating machine learning techniques and a dynamic ensemble algorithm to improve the accuracy of hourly PM2.5 and visibility forecasts across 309 cities in mainland China. Results demonstrate that machine learning methods significantly improve the accuracy of PM2.5 and visibility forecasts. For a 24‐hr lead time, the root mean square error (RMSE) is reduced by an average of 19% for PM2.5 and 30.2% for visibility, while the temporal correlation coefficient (TCC) increases by an average of 4.2% and 22.1%, respectively. Furthermore, we introduce a new ensemble forecasting algorithm, RCHEM‐AI, which capitalizes on dynamic RMSE and TCC weights based on machine learning predictions. RCHEM‐AI outperforms both RMAPS‐Chem and all individual machine learning members, reducing the average RMSE of PM2.5 (visibility) by 33.3% (39.3%) and increasing the average TCC by 16.4% (39.6%). Although the performance of machine learning and ensemble predictions declines with longer forecast time, the improvement in forecast accuracy remains substantial throughout the 1–10 days forecast period. By integrating RMAPS‐Chem, machine learning, and ensemble algorithms, this research provides a powerful tool for earlier and more accurate haze pollution predictions, thereby supporting more effective air pollution control and informed scientific decision‐making.

Chen Shi, Anna Tenerani, Antonio Franco Rappazzo et al.

Numerical simulations have been an increasingly important tool in space physics. Here, we introduce an open-source three-dimensional compressible Hall-Magnetohydrodynamic (MHD) simulation code LAPS (UCLA-Pseudo-Spectral, https://github.com/chenshihelio/LAPS). The code adopts a pseudo-spectral method based on Fourier Transform to evaluate spatial derivatives, and third-order explicit Runge-Kutta method for time advancement. It is parallelized using Message-Passing-Interface (MPI) with a “pencil” parallelization strategy and has very high scalability. The Expanding-Box-Model is implemented to incorporate spherical expansion effects of the solar wind. We carry out test simulations based on four classic (Hall)-MHD processes, namely, 1) incompressible Hall-MHD waves, 2) incompressible tearing mode instability, 3) Orszag-Tang vortex, and 4) parametric decay instability. The test results agree perfectly with theory predictions and results of previous studies. Given all its features, LAPS is a powerful tool for large-scale simulations of solar wind turbulence as well as other MHD and Hall-MHD processes happening in space.

L. Hoffmann, R. Spang

Abstract. The tropopause layer plays a key role in manifold processes in atmospheric chemistry and physics. Here we compare the representation and characteristics of the lapse rate tropopause according to the definition of the World Meteorological Organization (WMO) as estimated from European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data. Our study is based on ten-year records (2009 to 2018) of ECMWF's state-of-the-art reanalysis ERA5 and its predecessor ERA-Interim. The intercomparison reveals notable differences between ERA5 and ERA-Interim tropopause data, in particular on small spatiotemporal scales. The monthly mean differences of ERA5 minus ERA-Interim tropopause heights vary between −300 m at the transition from the tropics to the extratropics (near 30° S and 30° N) to 150 m around the equator. Mean tropopause temperatures are mostly lower in ERA5 than in ERA-Interim, with a maximum difference of up to −1.5 K in the tropics. Monthly standard deviations of tropopause heights of ERA5 are up to 350 m or 60 % larger than for ERA-Interim. Monthly standard deviations of tropopause temperatures of ERA5 exceed those of ERA-Interim by up to 1.5 K or 30 %. The occurrence frequencies of double tropopause events in ERA5 exceed those of ERA-Interim by up to 25 percentage points at mid latitudes. We attribute the differences between the ERA5 and ERA-Interim tropopause data and the larger, more realistic variability of ERA5 to improved spatiotemporal resolution and better representation of geophysical processes in the forecast model as well as improvements in the data assimilation scheme and the utilization of additional observations in ERA5. The improved spatiotemporal resolution of ERA5 allows for a better representation of mesoscale features, in particular of gravity waves, which affect the temperature profiles in the upper troposphere and lower stratosphere and thus the tropopause height estimates. We evaluated the quality of the ERA5 and ERA-Interim reanalysis tropopause data by comparisons with COSMIC and MetOp Global Positioning System (GPS) satellite observations as well as high-resolution radiosonde profiles. The comparison indicates an uncertainty of the first tropopause for ERA5 (ERA-Interim) of about ±150 m to ±200 m (±250 m) based on radiosonde data and ±120 m to ±150 m (±170 to ±200 m) based on the coarser resolution GPS data at different latitudes. Consequently, ERA5 will provide more accurate information than ERA-Interim for future tropopause-related studies.

Riccardo Pagliarello, Riccardo Pagliarello, Elisabetta Bennici et al.

Introduction: Methods for production of fresh, health food are needed in view of long-term, deep-space manned missions. To this end, crops tailored for better performance under non-terrestrial conditions may be obtained by the exploitation of biochemical patterns related to specialized metabolites known to confer protection against environmental challenges and to be beneficial to human health.Methods: In this work, for the first time, MicroTom plants have been engineered specifically for agrospace applications to express PhAN4, a MYB-like transcription factor able to regulate the biosynthesis of anthocyanins that influence tomato genes possibly involved in agrospace-relevant functions. Results:PhAN4 engineering underpinned the genetic background of the dwarf tomato MicroTom while maintaining yield and photosynthetic capacity. PhAN4 expression resulted in the accumulation of anthocyanins and polyphenols, a differential carotenoid profile, increased antioxidant scavenging capacities of fruits compared to the original genotype. Improved ability to counteract ROS generation and to preserve plant protein folding after ex-vivo gamma irradiation was observed.Discussion: These results highlights that the manipulation of specific metabolic pathways is a promising approach to design novel candidate varieties for agrospace applications.

Hariom Sogarwal, P. Shukla

The particle showers produced in the atmosphere due to the interactions of primary cosmic particles require a thorough understanding in the backdrop of searches for rare interactions. In this work, we made a comprehensive study of air shower simulations using various combinations of hadronic models and particle transport code of the CORSIKA package. The primary proton and helium distributions are taken as power law which are scaled to match the measured flux in balloon and satellite-based experiments at the top of atmosphere. The shower simulation includes production, transport and decays of secondaries up to the ground level. In this study, we focus on the bulk of the spectra and particles which is computationally intensive and hence parallel processing of events is done on computer cluster. We provide a way to normalize the simulation results to be compared with the ground-based measurements namely, single and multiple muon yields and their charge ratios as a function of zenith angle and momentum. This provides a basis for comparisons among the six model combinations used in this study and the differences are outlined. Most of the hadronic models in CORSIKA produce the bulk ground based measurements fairly well. We use one of the best model combinations to quantitatively predict the absolute and relative yields of various particles at ground level as well as their correlations with primaries and with each other. The leptonic ratios are obtained as a function of energy and zenith angle which are important inputs for the neutrino oscillation physics.

B. Barone, R. M. Letelier, K. H. Rubin et al.

Abstract The largest submarine volcanic eruption of this century led to a dramatic phytoplankton bloom north of the island of Tongatapu, in the Kingdom of Tonga. In the absence of shipboard observations, we reconstructed the dynamics of this event by using a suite of satellite observations. Two independent bio‐optical approaches confirmed that the phytoplankton bloom was a robust observation and not an optical artifact due to volcanogenic material. Furthermore, the timing, size, and position of the phytoplankton bloom suggest that plankton growth was primarily stimulated by nutrients released from volcanic ash rather than by nutrients upwelled through submarine volcanic activity. The appearance of a large region with high chlorophyll a concentrations <48 hr after the largest eruptive phase indicates a fast ecosystem response to nutrient fertilization. However, net phytoplankton growth probably initiated before the main eruption, when weaker volcanism had already fertilized the ocean.

Anett Blischke, Bryndís Brandsdóttir, Martyn S. Stoker et al.

Abstract Volcanostratigraphic and igneous province mapping of the Jan Mayen microcontinent (JMMC) and Iceland Plateau Rift (IPR) region have provided new insight into the development of rift systems during breakup processes. The microcontinent's formation involved two breakup events associated with seven distinct tectono‐magmatic phases (∼63–21 Ma), resulting in a fan‐shaped JMMC‐IPR igneous domain. Primary structural trends and anomalous magmatic activity guided initial opening (∼63–56 Ma) along a SE‐NW trend from the European margin and along a WNW‐ESE trend from East Greenland. The eastern margin of the microcontinent formed during the first breakup (∼55–53 Ma), with voluminous subaerial volcanism and emplacement of multiple sets of SSW–NNE‐aligned seaward‐dipping reflector sequences. The more gradual, second breakup (∼52–23 Ma) consisted of four northwestward migrating IPR (I–IV) rift zones along the microcontinent's southern and western margins. IPR I and II (∼52–36 Ma) migrated obliquely into East Greenland, interlinked via segments of the Iceland‐Faroe Fracture Zone, in overlapping sub‐aerial and sub‐surface igneous formations. IPR III and IV (∼35–23 Ma) formed a wide igneous domain south and west of the microcontinent, accompanied by uplift, regional tilting, and erosion as the area moved closer to the Iceland hotspot. The proto‐Kolbeinsey Ridge formed at ∼22–21 Ma and connected to the Reykjanes Ridge via the Northwest Iceland Rift Zone, near the center of the hotspot. Eastward rift transfers, toward the proto‐Iceland hotspot, commenced at ∼15 Ma, marking the initiation of segmented rift zones comparable to present‐day Iceland.

R. Ghara, G. Mellema, S. Zaroubi

One of the explanations for the recent EDGES-LOW band 21 cm measurements of a strong absorption signal around 80 MHz is the presence of an excess radio background to the Cosmic Microwave Background (CMB). Such excess can be produced by the decay of unstable particles into small mass dark photons which have a non-zero mixing angle with electromagnetism. We use the EDGES-LOW band measurements to derive joint constraints on the properties of the early galaxies and the parameters of such a particle physics model for the excess radio background. A Bayesian analysis shows that a high star formation efficiency and X-ray emission of 4–7 × 1048 erg per solar mass in stars are required along with a suppression of star formation in halos with virial temperatures ≲ 2 × 104 K. The same analysis also suggests a 68 percent credible intervals for the mass of the decaying dark matter particles, it's lifetime, dark photon mass and the mixing angle of the dark and ordinary photon oscillation of [10-3.5, 10-2.4] eV, [101.1, 102.7] × 13.8 Gyr, [10-12.2, 10-10] eV and [10-7, 10-5.6] respectively. This implies an excess radio background which is ≈ 5.7 times stronger than the CMB around 80 MHz. This value is a factor ∼ 3 higher than the previous predictions which used a simplified model for the 21 cm signal.

Xingyu Tuo, Yin Zhang, Yulin Huang et al.

It is greatly significant to achieve radar forward-looking region imaging. Due to the limitation of phase ambiguity and small Doppler gradient in forward-looking region, synthetic aperture radar and Doppler beam sharpening cannot work for forward-looking imaging, while real aperture radar (RAR) has arbitrary imaging geometry. Nevertheless, restricted by the antenna aperture, azimuth resolution of RAR is coarse, super-resolution technology is required to improve its azimuth resolution. Exploiting the sparse prior information of the target, the super-resolution problem can be transformed into an <inline-formula><tex-math notation="LaTeX">$L_1$</tex-math></inline-formula> norm minimization problem mathematically. Iterative reweighted algorithm can effectively solve the <inline-formula><tex-math notation="LaTeX">$L_1$</tex-math></inline-formula> norm minimization problem by replacing <inline-formula><tex-math notation="LaTeX">$L_1$</tex-math></inline-formula> norm with reweighted <inline-formula><tex-math notation="LaTeX">$L_2$</tex-math></inline-formula> norm and computing the weight in each iteration. However, it suffers from a large computational load due to the repeated multiplications and inversions of large matrices. In this article, a fast azimuth super-resolution imaging method of RAR based on iterative reweighted least squares (IRLS) with linear sketching (LS) was proposed to achieve fast super-resolution imaging of RAR. The LS theory is employed to compress echo matrix and antenna measurement matrix into much smaller matrices via multiplying them by an embedded matrix. Then, the IRLS solver was utilized to address the reconstructed objective function. Much of the expensive computation can then be performed on the smaller matrices, thereby accelerating the algorithm. Simulations and experimental data prove that the proposed algorithm can offer a time complexity reduction without loss of imaging performance.

Guillermo E. Ojeda, Jorge O. Chiesa, Daniel H. Gómez

Asociado a la margen derecha del río Desaguadero, colector principal de los cursos fluviales que drenan el piedemonte de la región andina central, y la zona de interacción con el piedemonte distal mendocino, se disponen destacadas acumulaciones arenosas eólicas que han recibido escasa atención hasta la fecha. Durante investigaciones recientes se ha determinado que estos depósitos se pueden diferenciar en relación a una variedad de geoformas eólicas tales como dunas lunetas, dunas longitudinales y mantos arenosos. En conjunto, estas unidades eólicas se disponen estratigráficamente sobre la Fm. Arco del Desaguadero, sucesión fluvio-lacustre desarrollada entre el Pleistoceno superior y el Holoceno superior. Los depósitos eólicos más antiguos forman dunas lunetas de hasta 14 m de altura, y se los asocia a la deflación de arenas desde las costas occidentales de lagunas temporales vinculadas a inundaciones del río Desaguadero. En base a dataciones numéricas realizadas sobre restos de conchillas de gasterópodos, se asignan estas dunas al Optimo Cálido Medieval. Posteriormente, durante el deterioro climático vinculado a la Pequeña Edad de Hielo, se desarrollaron dunas longitudinales y mantos arenosos con aportes sedimentarios provenientes de la llanura aluvial del río Desaguadero y de la removilización de arenas de las dunas lunetas previamente formadas. Se distinguen además dunas lunetas de menor envergadura asociadas a depresiones de deflación y encharcamiento temporal y extensos mantos arenosos de escaso espesor (menores en general a los 50 cm), generados por sedimentación eólica y posterior removilización por la escorrentía superficial, cuyo desarrollo se estima habrían comenzado también durante este último periodo. La disposición espacial de las dunas lunetas y las dunas longitudinales permiten establecer paleovientos provenientes del Este y Sureste.

D. Green, Alexander K. Ridgway

The baryon acoustic oscillations (BAO) provide an important bridge between the early universe and the expansion history at late times. While the BAO has primarily been used as a standard ruler, it also encodes recombination era physics, as demonstrated by a recent measurement of the neutrino-induced phase shift in the BAO feature. In principle, these measurements offer a novel window into physics at the time of baryon decoupling. However, our analytic understanding of the BAO feature is limited, particularly for the range of Fourier modes measured in surveys. As a result, it is unclear what the BAO phase teaches us about the early universe beyond what is already known from the cosmic microwave background (CMB). In this paper, we provide a more complete (semi-)analytic treatment of the BAO on observationally relevant scales. In particular, we compute corrections to the frequency and phase of the BAO feature that arise from higher order effects which occur in the tight coupling regime and during baryon decoupling. The total phase shift we find is comparable to a few percent shift in the BAO scale (frequency) and thus relevant in current data. Our results include an improved analytic calculation of the neutrino induced phase shift template that is in close agreement with the numerically determined template used in measurements of the CMB and BAO.

D. Smith, D. Besson, C. Deaconu et al.

The balloon-borne ANITA [1] experiment is designed to detect ultra-high energy neutrinos via radio emissions produced by in-ice showers. Although initially purposed for interactions within the Antarctic ice sheet, ANITA also demonstrated the ability to self-trigger on radio emissions from ultra-high energy charged cosmic rays [2] (CR) interacting in the Earth's atmosphere. For showers produced above the Antarctic ice sheet, reflection of the down-coming radio signals at the Antarctic surface should result in a polarity inversion prior to subsequent observation at the ∼35–40 km altitude ANITA gondola. Based on data taken during the ANITA-1 and ANITA-3 flights, ANITA published two anomalous instances of upcoming cosmic-rays with measured polarity opposite the remaining sample of ∼50 UHECR signals [3, 4]. The steep observed upwards incidence angles (25–30 degrees relative to the horizontal) require non-Standard Model physics if these events are due to in-ice neutrino interactions, as the Standard Model cross-section would otherwise prohibit neutrinos from penetrating the long required chord of Earth. Shoemaker et al. [5] posit that glaciological effects may explain the steep observed anomalous events. We herein consider the scenarios offered by Shoemaker et al. and find them to be disfavored by extant ANITA and HiCal experimental data. We note that the recent report of four additional near-horizon anomalous ANITA-4 events [6], at >3σ significance, are incompatible with their model, which requires significant signal transmission into the ice.

R. Holanda, G. Pordeus-da-Silva, S. Pereira

An accurate determination of the Hubble constant remains a puzzle in observational cosmology. The possibility of a new physics has emerged with a significant tension between the current expansion rate of our Universe measured from the cosmic microwave background by the Planck satellite and from local methods. In this paper, new tight estimates on this parameter are obtained by considering two data sets from galaxy distribution observations: galaxy cluster gas mass fractions and baryon acoustic oscillation measurements. Priors from the Big Bang nucleosynthesis (BBN) were also considered. By considering the flat ΛCDM and XCDM models, and the non-flat ΛCDM model, our main results are: H0=65.9+1.5−1.5 km s−1 Mpc−1, H0=65.9+4.4−4.0 km s−1 Mpc−1 and H0=64.3+ 4.5− 4.4 km s−1 Mpc−1 in 2σ c.l., respectively. These estimates are in full agreement with the Planck satellite results. Our analyses in these cosmological scenarios also support a negative value for the deceleration parameter at least in 3σ c.l. .

V. Domcke, Yohei Ema, K. Mukaida

Particle production in strong electromagnetic fields is a recurring theme in solid state physics, heavy ion collisions, early universe cosmology and formal quantum field theory. In this paper we discuss the Dirac equation in a background of parallel electric and magnetic fields. We review the Schwinger particle production rate, clarify the emergence of the chiral anomaly equation and compute the induced current of charged fermions. We distinguish the contributions from non-perturbative particle production, from the running of the gauge coupling constant and from non-linearities in the effective QED Lagrangian, and clarify how these contributions arise within a single framework. We apply these results to axion inflation. A Chern-Simons coupling between the pseudoscalar particle driving cosmic inflaton and an abelian gauge group induces a dual production of gauge fields and charged fermions. We show that the resulting scalar and gravitational wave power spectra strongly depend on the fermion mass.

G. Zherebtsov

The paper discusses the importance of the problem of adverse effects of cosmic processes and phenomena (space weather factors) on the ground engineering and technical infrastructure, space-born radio-electronic facilities, etc. It examines the state of the experimental base for research in solar, atmosphere, and near-Earth space physics in Russia and abroad. The necessity of creating new-generation instruments, developed using advanced engineering solutions and technologies, is justified. The complex of the main facilities and instruments of the National Heliogeophysical Complex of the Russian Academy of Sciences is analyzed. The main scientific directions of basic research and applied problems are formulated.

R.S. Ysmagul, А.Е. Nurgeldina

The article deals with integral equations that are widely used in various sections of physics (theory of waves on the surface of liquids, quantum mechanics, problems of spectroscopy, crystallography, acoustics, analysis and diagnostics of plasma, etc.), Geophysics (problems of gravimetry, kinematic problems of seismics), mechanics (vibrations of structures), etc. When the physics introduced aftereffect, it is not enough ordinary differential equations or partial differential equations, otherwise the initial data would determine the future state. To take into account the continuous sequence of previous States, we need to use integral and integro-differential equations, where the sign of the integral appears functions of parameters that characterize the system, which depend on time for some period preceding the moment under consideration. In this article we have considered the solution of Fredholm integral equations of the second kind by the method of successive approximations and the method of iterated nuclei.

K. Belotsky, E. Esipova, Airat Kamaletdinov et al.

Here, we briefly review possible indirect effects of dark matter (DM) of the universe. It includes effects in cosmic rays (CR): first of all, the positron excess at [Formula: see text]500[Formula: see text]GeV and possible electron–positron excess at 1–1.5[Formula: see text]TeV. We tell that the main and least model-dependent constraint on such possible interpretation of CR effects goes from gamma-ray background. Even ordinary [Formula: see text] mode of DM decay or annihilation produces prompt photons (FSR) so much that it leads to contradiction with data on cosmic gamma-rays. We present our attempts to possibly avoid gamma-ray constraint. They concern with peculiarities of both space distribution of DM and their physics. The latter involves complications of decay/annihilation modes of DM, modifications of Lagrangian of DM-ordinary matter interaction and inclusion of mode with identical fermions in final state. In this way, no possibilities to suppress were found except, possibly, the mode with identical fermions. While the case of spatial distribution variation allows achieving consistency between different data. Also, we consider stable form of DM which can interact with baryons. We show which constraint such DM candidate can get from the damping effect in plasma during large-scale structure (LSS) formation in comparison with other existing constraints.