Hasil untuk "Geophysics. Cosmic physics"

Sareer Ahmad Mir, Sabeeqa Samad

Abstract Soil erosion is a serious threat to land and water resources, affecting groundwater availability and agricultural productivity on a global scale. Accurate data on soil erosion rates is important for organising effective land conservation strategies. This study investigates the spatiotemporal patterns of soil erosion in the Sindh catchment of Kashmir Valley, India, over a decade (2013–2023) using Revised Universal Soil Loss Equation (RUSLE). The results reveal significant spatial variability in soil erosion rates, with elevated erosion observed in areas with sparse vegetation, steep slopes, and intensive agricultural practices. Between 2013 and 2023, the mean annual soil loss rose from moderate (17.04 t/ha/yr) to moderately high (33.12 t/ha/yr), corresponding to the standard RUSLE erosion severity classification (very slight: 0–5; slight: 5–10; moderate: 10–20; moderately high: 20–40; high: 40–80; severe: 80–120; very severe: >120 t/ha/yr). Different Land Cover/Land Use (LULC) classes exhibited varying rates of soil erosion. In 2013 and 2023, it rose from 13.18 to 53.63 t/ha/yr in agricultural land, from 20.82 to 45.94 t/ha/yr in riverine cover, from 21.96 to 37.72 in barren land, from 10.19 to 27.29 t/ha/yr in forest cover, and from 13.02 to 41.49 t/ha/year in build-up area. However, in glaciated terrain, the average soil loss decreased from 25.47 to 11.93 t/ha/yr in 2023 and from 14.66 to 13.81 t/ha/yr in the waterbody class of land use. These changes highlight the significant role of LULC dynamics, particularly the expansion of build-up areas and agricultural land, in influencing soil erosion patterns. The study highlights the critical implementation of integrated soil conservation measures, reduce soil erosion, and ensure sustainable land management in Sindh catchment.

Luis Q. Gentner, Junyang Gou, Mohammad J. Tourian et al.

Abstract Terrestrial water storage (TWS) plays an important role in describing the Earth system, as water availability is decisive for ecosystems and human development. Since 2002, the Gravity Recovery and Climate Experiment (GRACE) and its Follow‐On (GRACE‐FO) mission have measured TWS anomalies with unprecedented accuracy, enabling a leap in hydrological research. However, the use of the GRACE/‐FO data in climate research is restricted by the lack of measurements prior to 2002 and the 1‐yr gap between the missions. Here we present DeepRec, a deep learning approach for reconstructing GRACE‐like monthly TWS anomalies starting from 1941, covering the global land area except Greenland and Antarctica. DeepRec uses climate reanalysis variables and land use data sets as inputs to capture both natural and anthropogenic variations. Its deep learning architecture combines convolutional layers with a long short‐term memory layer to consider the spatiotemporal variations of the inputs. DeepRec quantifies the aleatoric (data) and epistemic (model) uncertainty in the TWSA estimates through a deep ensemble approach. The reconstruction achieved an area‐weighted mean basin‐scale root mean squared error (RMSE) of 17 mm against GRACE/‐FO (2002–2023) and showed improved accuracy compared to previous reconstructions when evaluated against solutions from satellite laser ranging and DORIS (weighted mean basin‐scale correlation of 0.68 for 1995–2001). Evaluations against the ERA5 water balance showed low and consistent closure errors across time periods, with weighted mean basin‐scale RMSEs of 12 mm for both 1980–2001 and 2002–2019. DeepRec achieved the lowest sea level budget closure error (RMSE of 7 mm) among all evaluated reconstructions for 1984–2001, outperforming others by 3–7 mm.

Xin Lin, Junli Chen, Jing Liu et al.

Rotated object detection plays a vital role in remote sensing interpretation, with broad applications in urban planning, port monitoring, and disaster response. However, the significant scale variations, complex orientations, and cluttered backgrounds in remote sensing images pose considerable challenges to accurate detection. To address these issues, this article proposes an efficient rotated object detection framework that integrates state space models with vision transformers to achieve an optimal balance between accuracy and computational efficiency. The proposed framework employs a MobileMamba backbone enhanced with a multireceptive field feature interaction module for effective local–global feature representation. An EfficientViT-FPN neck enables efficient multiscale feature fusion, while a refined Rotated RetinaNet head incorporates five-parameter rotated box regression with angle-aware constraints to improve the orientation estimation. Comprehensive experiments on the DOTA-v1.0 and SRSDD-v1.0 datasets demonstrate that our approach achieves superior detection accuracy with significantly reduced computational overhead, making it particularly suitable for practical remote sensing applications.

Cihan Yalçın, Hurşit Canli, Mustafa Kumral et al.

The present study reviews the subsurface distribution and geometry of clay-rich strata within the Oligo–Miocene Çukurçeşme Formation in the Şile area (Istanbul) using an integrated methodology combining Vertical Electrical Sounding (VES) and Ground Penetrating Radar (GPR). A total of 30 VES measurements were obtained and analyzed by 1D inversion, and the resultant models were assembled into 2D pseudosections to designate laterally continuous conductive layers. Low-resistivity zones seen across the profiles were interpreted as clay-dominant, aquiferous strata based on their distinctive electrical response and field observations. GPR data acquired with a 38–50 MHz antenna yielded high-resolution insights into the near-surface strata. Radargrams displayed continuous, moderately inclined reflectors indicative of the upper margins of clayey strata; however, signal attenuation restricted imaging at deeper levels. The integration of VES-derived resistivity structure with GPR reflections improved the interpretation of the clay layer's geometry and revealed thickness variations throughout the study area. The aggregated findings demonstrate that clay-rich strata often occur at depths of approximately 5 to 40 meters, with localized thickening influenced by structural and depositional factors. The concordance between VES and GPR interpretations enhances the credibility of the subsurface model generated in this work. This study demonstrates the efficacy of combining VES and GPR techniques to characterize diverse near-surface formations in regions where clay predominates, thereby influencing electrical and electromagnetic responses. The results establish a geophysical framework for subsurface characterization in analogous geological contexts and facilitate future research to enhance the stratigraphic and structural understanding of the Çukurçeşme Formation.

Noelia Otero, Atahan Özer, Jackie Ma

Abstract Accurate forecasts on subseasonal (S2S) timescales are essential for the preparation and mitigation of the impacts of high‐impact events, such as flash droughts. To improve the accuracy of soil moisture forecasts—a critical factor in identifying flash droughts—we present a hybrid modeling framework that combines dynamical forecasts from the European Centre for Medium‐Range Weather Forecasts with deep learning (DL) models. This approach not only corrects biases in numerical weather prediction models but also improves spatial resolution, increasing the accuracy of S2S forecasts. By using deterministic inputs, such as the ensemble mean and spread, we further assess the uncertainty of forecasts through dropout neural networks via Monte Carlo sampling. Our results demonstrate that the DL models outperform baseline methods, offering skillful S2S forecasts of soil moisture. This advanced hybrid framework provides more accurate soil moisture predictions, ultimately supporting improved strategies for managing and mitigating the impacts of flash droughts.

Azadeh Kazemi, Giuseppe T. Cirella, Amir Hedayatiaghmashhadi et al.

This research investigates the complex interplay between urban heat island (UHI) and urban pollution island in the context of rapid urbanization. Using remote-sensed land surface temperature (LST), the UHI is categorized into five intensity levels. Air pollution monitoring in Arak city, including green spaces, roads, and industrial areas, combines in situ and remote sensing observations for a comprehensive 2019–2020 seasonal analysis. Findings reveal distinct surface UHI patterns, peaking in spring near highly industrialized areas with low greenery and high nitrogen compounds. A significant correlation between LST and pollutant levels is observed in summer in areas with both roads and industrial facilities. Industrial zones consistently exhibit higher LST intensity than green spaces throughout the year. Fall and winter analyses show unique pollution patterns, with sulfur dioxide concentrations peaking near roads in fall due to traffic congestion, and higher nitric oxide and nitrogen dioxide levels in areas with limited green spaces. These observations underscore the intricate relationship between surface UHI and pollutant concentrations, highlighting the multifaceted nature of urban environmental dynamics across diverse seasons and land-use categories.

Alexander Cede, Alexander Cede, Alexander Cede et al.

A technique to determine the radiometric stability of the Earth Polychromatic Imaging Camera (EPIC) and the National Institute of Standards and Technology Advanced Radiometer (NISTAR), the two Earth-viewing instruments operating aboard the Deep Space Climate Observatory (DSCOVR) satellite, which is orbiting the Sun at the Lagrange-1 point, L1, approximately 1.5 million kilometers away from Earth, has been developed and applied. Apart from the satellite’s own measurements, it only uses output from the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis of the global climate data center (ERA5). This method can be applied to all channels (and not just a subset) and can be repeated periodically to track the instruments’ stability. The method includes the removal of climatological diurnal and seasonal cycles, a multivariate regression fitting with selected ERA5 model output parameters, and referencing the data to the EPIC 551-nm channel, which has been determined to show no drift over the entire mission lifetime together with the NISTAR photodiode channel (200–1,100 nm). The obtained sensitivity changes were very small, ranging from a maximum total degradation of 3% over 10 years in the short UV (<340 nm) to no detectable changes for some channels. For the EPIC UV channels, the derived results were confirmed through a comparison of the EPIC data with radiances from the Ozone Mapping and Profiler Suite (OMPS). We attribute this excellent instrument performance mostly to the L1 orbit, which is not only an ideal location for Earth observation, but is also extremely beneficial (quiet) with respect to instrument performance. At L1, there are only minor temperature variations and much smaller exposure to charged particles from the Sun compared to satellites orbiting the Earth, which are fully or partly inside the Earth’s radiation belts. In this sense, L1 can be considered “observational and instrumental heaven.” The technique described here could only be applied because DSCOVR has two different instruments (EPIC and NISTAR) observing the same Earth flux input. This suggests that it is extremely useful (maybe even essential) to combine imaging instruments (like EPIC) with integrating instruments (like NISTAR) in remote sensing applications.

V. Baryshnikov, V. Babkin, S. Buzin et al.

B. Jiang

Abstract We present a two-state Kalman estimator of gravity acceleration and evaluate its performance by numerical simulations and post-measurement demonstration with real-world atomic gravimetry. We show that the estimator-enhanced gravimetry significantly improves upon both short-term sensitivity and long-term stability. The estimates of gravity acceleration demonstrate a $$\tau ^{1/2}$$ τ 1 / 2 feature well under white phase noise in the short term, and continue to improve as $$\tau ^{-1/2}$$ τ - 1 / 2 or improve faster as $$\tau ^{-1}$$ τ - 1 in the long term. This work validates the estimation of gravity acceleration as a key topic for future atomic gravimetry. Graphical abstract The performance of atomic gravimetry is limited by noises and other systematic or geophysical effects. By building a Kaman estimator rooted in the physics of atom interferometry, we realize significant improvements in both short-term sensitivity and long-term stability. This demonstration of estimator-enhanced gravimetry would be of great interest for static measurements of gravity, such as metrology or geophysics (Color online)

Qi Zheng, Rory Bingham, Oliver Andrews

Abstract The Cape Horn Current (CHC) is one of the components of the Antarctic Circumpolar Current system that enables it to fulfill its crucial role as a conduit between ocean basins. Despite this, to‐date there have been very few measurements of CHC strength and none continuous in time or space. Here, we use a combination of ocean models, one free‐running and one data‐assimilating, and satellite altimetry (1993–2021) to estimate the time‐dependent strength of the CHC at 10 transects along its length. We find the time‐mean CHC transport increases from 0.4 ± 0.5 Sv near 49°S to 5.3 ± 2.2 Sv at Cape Horn, with peak‐to‐peak interannual fluctuations of 0.8–3.4 Sv. Although, theoretically, increased run‐off from a wasting Patagonian Ice‐field would strengthen its flow, the CHC appears quite stable over the last 29 years, with little evidence of a coherent, long‐term increase or decrease in the strength of the current.

F. Fiuza, G. Swadling, A. Grassi et al.

A. Chudaykin, M. Ivanov

We present a Markov-Chain Monte-Carlo (MCMC) forecast for the precision of neutrino mass and cosmological parameter measurements with a Euclid-like galaxy clustering survey. We use a complete perturbation theory model for the galaxy one-loop power spectrum and tree-level bispectrum, which includes bias, redshift space distortions, IR resummation for baryon acoustic oscillations and UV counterterms. The latter encapsulate various effects of short-scale dynamics which cannot be modeled within perturbation theory. Our MCMC procedure consistently computes the non-linear power spectra and bispectra as we scan over different cosmologies. The second ingredient of our approach is the theoretical error covariance which captures uncertainties due to higher-order non-linear corrections omitted in our model. Having specified characteristics of a Euclid-like spectroscopic survey, we generate and fit mock galaxy power spectrum and bispectrum likelihoods. Our results suggest that even under very agnostic assumptions about non-linearities and short-scale physics a future Euclid-like survey will be able to measure the sum of neutrino masses with a standard deviation of 28 meV . When combined with the Planck cosmic microwave background likelihood, this uncertainty decreases to 13 meV . Over-optimistically reducing the theoretical error on the bispectrum down to the two-loop level marginally tightens this bound to 11 meV . Moreover, we show that the future large-scale structure (LSS) spectroscopic data will greatly improve constraints on the other cosmological parameters, e.g. reaching a percent (per mille) error on the Hubble constant with LSS alone (LSS + Planck).

L. Maillard, J. Boucharel, M. F. Stuecker et al.

Abstract Feedbacks from tropical instability waves (TIWs) on the seasonal cycle of the eastern Pacific Ocean are studied using two eddy‐rich ocean simulations, with and without TIWs. By warming the equatorial waters by up to 0.4°C through nonlinear advection in boreal summer and fall, TIWs reduce the amplitude of the seasonal cycle in upper ocean temperatures. In addition, TIWs stabilize the upper part of the Equatorial Undercurrent (EUC) through enhanced barotropic energy conversion, leading to a year‐round weakening by −0.15 m s−1 and preventing an unrealistic re‐intensification in boreal fall usually found in non‐eddy resolving models. A coarser simulation at 1‐degree horizontal resolution fails to reproduce the TIW‐induced nonlinear warming of equatorial waters, but succeeds in inhibiting the EUC re‐intensification. This suggests a threshold effect in TIW strength, associated with the model's ability to simulate eddies, which may be responsible for long‐standing biases displayed by global climate models in this region.

Michael J. Mazur, Stanimir Metchev, Stanimir Metchev et al.

We present the technical design, construction and testing of the Colibri telescope array at Elginfield Observatory near London, Ontario, Canada. Three 50-cm telescopes are arranged in a triangular array and are separated by 110–160 m. During operation, they will monitor field stars at the intersections of the ecliptic and galactic plane for serendipitous stellar occultations (SSOs) by trans-Neptunian objects (TNOs). At a frame rate of 40 frames per second (fps), Fresnel diffraction in the occultation light curve can be resolved and, with coincident detections, be used to estimate basic properties of the occulting object. Using off-the-shelf components, the Colibri system streams imagery to disk at a rate of 1.5 GB/s for next-day processing by a custom occultation detection pipeline.The imaging system has been tested and is found to perform well, given the moderate site conditions. Limiting magnitudes at 40 fps are found to be about 12.1 (temporal SNR = 5, visible light Gaia G band) with time-series standard deviations ranging from about 0.035 mag to >0.2 mag. SNR is observed to decrease linearly with magnitude for stars fainter than about G = 9.5 mag. Brighter than this limit, SNR is constant, suggesting that atmospheric scintillation is the dominant noise source. Astrometric solutions show errors typically less than ±0.3 pixels (0.8 arc seconds) without a need for high-order corrections.

Wenqing Tang, Simon H. Yueh, Alexander G. Fore et al.

Remote sensing of sea surface salinity (SSS) near land is difficult due to land contamination. In this article, we assess SSS retrieved from the soil moisture active passive (SMAP) mission in coastal region. SMAP SSS products from the Jet Propulsion Laboratory (JPL), and from the remote sensing systems (RSS) are collocated with in situ data collected by saildrones during the North American West Coast Survey. Satellite and saildrone salinity measurements reveal consistent large-scale features: the fresh water (low SSS) assocciated with the Columbia River discharge, and the relatively salty water (high SSS) near Baja California associated with regional upwelling. The standard deviation of the difference for collocations with SMAP Level 3 (eight days average) between 40 and 100 km from land is 0.51 (0.56) psu for JPL V5 (RSS V4 70 km). This is encouraging for the potential application of SMAP SSS in monitoring coastal zone freshwater particularly where there exists large freshwater variance. We analyze the different land correction approaches independently developed at JPL and RSS using SMAP level 2 matchups. We found that JPL's land correction method is more promising in pushing SMAP SSS retrieval towards land. For future improvement, we suggest implementing dynamic land correction versus the current climatology-based static land correction to reduce uncertainty in estimating land contribution. In level 2 to level 3 processing, a more rigorous quality control may help to eliminate outliers and deliver reliable level 3 products without over-smoothing, which is important in resolving coastal processes such as fronts or upwelling.

A. Candela, A. Cocco, N. D’Ambrosio et al.

In the context of the PTOLEMY project, the need for a site with a rather low cosmogenic induced background led us to measure the differential muon flux inside the bunker of Monte Soratte, located about 50~km north of Rome (Italy). The measurement was performed with the Cosmic Ray Cube (CRC), a portable tracking device. The simple operation of the Cosmic Ray Cube was crucial to finalise the measurements, as they were carried out during the COVID-19 lockdown and in a site devoid of scientific equipment. The muon flux measured at the Soratte hypogeum is above two orders of magnitude lower than the flux observed on the surface, suggesting the possible use of the Mt. Soratte bunker for hosting astroparticle physics experiments requiring a low environmental background.

A. Panov, I. Astapov, G. Beskin et al.

Abstract A wide-angle Cerenkov array TAIGA-HiSCORE (FOV $$\sim$$ 0.6 sr), was originally created as a part of TAIGA installation for high-energy gamma-ray astronomy and cosmic ray physics. Array now consist on nearly 100 optical stations on the area of 1 km $${}^{2}$$ . Due to high accuracy and stability ( $$\sim$$ 1 ns) of time synchronization of the optical stations the accuracy of EAS arrival direction reconstruction is reached 0.1 $${}^{\circ}$$ . It was proven that the array can also be used to search for nanosecond events of the optical range. The report discusses the method of searching for optical transients using the HiSCORE array and demonstrates its performance on a real example of detecting signals from an artificial Earth satellite. The search for this short flares in the HiSCORE data of the winter season 2018–2019 is carried out. One candidate for double repeater has been detected, but the estimated probability of random simulation of such a transient by background EAS events is not less than 10 $$\%$$ , which does not allow us to say that the detected candidate corresponds to a real astrophysical transient. An upper bound on the frequency of optical spikes with flux density of more than $$10^{-4}\textrm{ erg/s/cm}^{2}$$ and a duration of more than 5 ns is established as $$\sim 2\times 10^{-3}$$  events/sr/h.

Y. Suzuki, T. Fukuda, H. Kawahara et al.

A nuclear emulsion film is a three-dimensional tracking device that is widely used in cosmic-ray and high energy physics experiments. Scanning with a wide angle acceptance is crucial for obtaining track information in emulsion films. This study presents a new method developed for wide angle acceptance and high-speed track recognition of nuclear emulsion films for neutrino-nucleus interaction measurements. The nuclear emulsion technique can be used to measure tracks of charged particles from neutrino interactions with a low momentum threshold. The detection of the particles with a wide angle acceptance is essential for obtaining detailed information on the interactions in the sub- and multi-GeV neutrino energy region. In the new method developed for a neutrino interaction measurement in J-PARC called NINJA, the angle acceptance is covered up to |tan θx(y)| < 5.0 (80% of all solid angles) with 150 m2/year. This method can also be used to improve the angle accuracy and recognition efficiency of the tracks.

A. R. Lozinski, R. Horne, S. Glauert et al.

Proton flux measurements from the Proton Telescope instrument aboard the CRRES satellite are revisited, and used to drive a radial diffusion model of the inner proton belt at 1.1 ≤ L ≤ 1.65. Our model utilizes a physics‐based evaluation of the cosmic ray albedo neutron decay (CRAND) source, and coulomb collisional loss is driven by a drift averaged density model combining results from the International Reference Ionosphere, NRLMSIS‐00 atmosphere and Radio Plasma Imager plasmasphere models, parameterized by solar activity and season. We drive our model using time‐averaged data at L = 1.65 to calculate steady state profiles of equatorial phase space density, and optimize our choice of radial diffusion coefficients based on four defining parameters to minimize the difference between model and data. This is first performed for a quiet period when the belt can be assumed to represent steady state. Additionally, we investigate fitting steady state solutions to time averages taken during active periods where the data exhibits limited deviation from steady state, demonstrated by CRRES measurements following the March 24, 1991 storm. We also discuss a way to make the optimization process more reliable by excluding periods of variability in plasmaspheric density from any time average. Lastly, we compare our resultant diffusion coefficients to those derived via a similar process in previous work, and diffusion coefficients derived for electrons from ground and in situ observations. We find that higher diffusion coefficients are derived compared with previous work, and suggest more work is required to derive proton diffusion coefficients for different geomagnetic activity levels.

Mansi Dhuria, V. Karambelkar, Vikram Rentala et al.

In the standard cosmology, it is believed that there are two relatively weak and distinct band-limited absorption features, with the first absorption minima near 20 MHz (z ∼ 70) and the other minima at higher frequencies between 50-110 MHz (z ∼ 12-27) in the global cosmological 21 cm signal, which are signatures of collisional gas dynamics in the cosmic dark ages and Lyman-α photons from the first stars at cosmic dawn, respectively. A similar prediction of two distinct band-limited, but stronger, absorption features is expected in models with excess gas cooling, which have been invoked to explain the anomalous EDGES signal. In this work, we explore a novel mechanism, where dark matter spin-flip interactions with electrons through a light axial-vector mediator could directly induce a 21 cm absorption signal which is characteristically different from either of these. We find generically, that our model predicts a strong, broadband absorption signal extending from frequencies as low as 1.4 MHz (z ∼ 1000), from early in the cosmic dark ages where no conventional signal is expected, all the way up to higher frequencies where star formation and X-ray heating effects are expected to terminate the absorption signal. We find a rich set of spectral features that could be probed in current and future experiments looking for the global 21 cm signal. In the standard cosmology and in excess gas cooling models it is expected that the gas spin temperature as inferred from the absorption signal is a tracer of the gas kinetic temperature. However, in our model we find in certain regions of parameter space that the spin temperature and kinetic temperature of the gas evolve differently, and the absorption signal only measures the spin temperature evolution. Large swathes of our model parameter space of interest are safe from existing particle physics constraints, however future searches for short range spin-dependent forces between electrons on the millimeter to nanometer scale have the potential to discover the light mediator responsible for our predicted signal.