An eight-year global look at correlations between total electron content, earthquakes and solar wind

Modeling and forecasting vibrio vulnificus concentration of long-range dependence on marine environmental conditions.

Ecovoltaic solar energy development effects to microclimate, temperature, and soil moisture in panel array interspaces in a warm desert.

Synergistic cyclic optimization strategy for the data screening and forecasting of solar power, Wind power, and electricity load

Assessing the impact of renewable energy firms on ESG-related uncertainty: Evidence from Germany's low-carbon transition.

Abstract On 2023 March 13, Parker Solar Probe was located about 0.23 au from the Sun when it was crossed by a very fast interplanetary shock. The intensities of ∼0.08–10 MeV energetic protons were markedly enhanced at the shock crossing. At energies from ∼0.1 to 1 MeV, the intensity at the shock was 3–4 orders of magnitude larger than it was ∼4 hr prior. In this study, we investigate the possible source of particles that led to this enhancement. Pre-existing high-energy particles that were present during the few-hour period prior to the shock could possibly serve as a source, assuming they are accelerated to even higher energies by the shock. We apply a “seeds test”—which determines the expected enhancement at the shock—to test this. We find that none of the pre-existing particle populations identified can account for the observed enhancement at the shock. The solar wind itself provides a very abundant source. To test whether shock-heated thermal solar wind could account for the source, we perform a series of self-consistent hybrid plasma simulations of this event and make direct comparisons with the observed particle spectra and magnetic field. We conclude that shock-heated solar wind protons are the source of energetic particles in this event. The direct comparisons of our simulations and observations also suggest that the shock was moving about 1350 km s −1 and had an Alfvén Mach number of about 4, both of which are considerably lower than previously estimated.

Abstract Quasi-separatrix layers (QSLs) at the Sun are created in regions where channels of open magnetic flux have footpoints near regions of large-scale closed magnetic flux. These regions show rapid changes in curvature and field strength. Numerical simulations of a relaxed coronal magnetic field and solar wind using the Magnetohydrodynamic Algorithm outside a Sphere model coupled to the Energetic Particle Radiation Environment Module model indicate common sources of energetic particles over broad longitudinal distributions in the background solar wind. These regions accelerate energetic particles from QSLs and current sheets. Here, we develop an analytical framework to describe the acceleration of energetic particles due to the magnetic field changes within and near separatrix layers. The reduced field strength near the separatrix layer drives magnetic field magnitude changes that accelerate energetic particles in the presence of plasma flow along the structure. Separatrix layers are prone to magnetic reconnection, creating fluctuations in the field that propagate out from the Sun, and release material previously contained within closed magnetic field structures, which are often rich in heavy ions and 3 He ions. Thus, we present a model of energetic particles accelerated from separatrix layers in the corona. Our results provide a plausible source for seed populations near the Sun.

Abstract We perform a comprehensive superposed epoch analysis of more than 200 corotating interaction regions (CIRs) using WIND spacecraft observations at 1 au. The stream interfaces are identified by minimum variance analysis, and turbulence properties are evaluated using wavelet transforms over a wide range of temporal scales. The analysis of normalized cross helicity ( σ c ) and normalized residual energy ( σ r ) reveals distinct turbulence behaviors across frequencies. The spectral indices of both magnetic and velocity fluctuations smoothly transition from steeper in the slow wind to shallower in the fast wind, while a localized steepening of the velocity spectra near the interface indicates enhanced dissipation due to compression. Across broad frequency bands, σ c shows a clear dip at the stream interface—signifying increased inward Alfvén wave energy—whereas σ r displays a peak–valley–peak structure mainly driven by large-scale velocity shear. In lower-frequency ranges, velocity shear artificially enhances velocity fluctuation energy, producing strong peaks in σ r , while higher-frequency ranges show a smooth increase of σ r from slow wind to fast wind. Nearly half of the analyzed CIRs are accompanied by a heliospheric current sheet (HCS), with many HCSs closely aligned with the stream interface, suggesting an intrinsic link between the two structures. Our findings offer valuable clues for reconciling discrepancies among earlier observational and simulation studies, and provide new insight into how compression and velocity shear modulate solar wind turbulence near CIRs.

Abstract Velocity distribution functions (VDFs) are an essential observable for studying kinetic and wave–particle processes in solar wind plasmas. To experimentally distinguish modes of heating, acceleration, and turbulence in the solar wind, precise representations of particle phase-space VDFs are needed. In the first paper of this series, we developed the Slepian basis reconstruction (SBR) method to approximate fully agyrotropic continuous distributions from discrete measurements of electrostatic analyzers (ESAs). The method enables accurate determination of plasma moments, preserves kinetic features, and prescribes smooth gradients in phase space. In this paper, we extend the SBR method by imposing gyrotropic symmetry (g-SBR). Incorporating this symmetry enables high-fidelity reconstruction of VDFs that are partially measured, as from an ESA with a limited field of view (FOV). We introduce three frameworks for g-SBR, the gyrotropic SBR: (A) 1D angular Slepian functions on a polar cap, (B) 2D Slepian functions in a Cartesian plane, and (C) a hybrid method. We employ model distributions representing multiple anisotropic ion populations in the solar wind to benchmark these methods, and we show that the g-SBR method produces a reconstruction that preserves kinetic structures and plasma moments, even with a strongly limited FOV. For our choice of model distribution, g-SBR can recover ≥​​​​​​90% of the density when only 20% is measured. We provide the package gdf for open-source use and contribution by the heliophysics community. This work establishes direct pathways to bridge particle observations with kinetic theory and simulations, facilitating the investigation of gyrotropic plasma heating phenomena across the heliosphere.

Multidisciplinary efforts to catalogue the existence of elements and their material forms remain ongoing, particularly for carbon, which is abundant in several forms, such as graphene, carbon nanotubes (CNTs), and diamond. This study presents the first identification of graphitic carbon in lunar samples taken by Chang'E-6 (CE-6) mission from the far side of the Moon, which was observed through multiple spectroscopy and microscopy techniques at identical locations. Although CNTs have been predominantly assumed to require artificial preparation, the study findings demonstrate that these materials exist in nature. Specifically, single-walled CNTs were identified in the CE-6 lunar samples, which were formed through micrometeorite impacts and an Fe-driven catalysis process under early volcanic activities and solar wind irradiation on the lunar surface. These findings, together with previously reported natural few-layered graphene on the Moon's near side, may inspire a paradigm shift in carbon science and offer new pathways for designing Human-fabricated novel and emerging materials.

We study Jupiter’s DAM radio storms to identify the features that may correlate with solar wind and coronal mass ejections (CME). We investigate the dynamics of DAM storms and burst features, and explain them by considering MHD processes associated with Io and the presence of gas in Jupiter’s lower magnetosphere. DAM radio storms occur when plasma injected by Io or by solar wind propagating along Jupiter's magnetic field lines into the auroral zone of Jupiter’s lower magnetosphere together with low-frequency Alfvén wave. Those MHD oscillations in low magnetosphere can trigger ionization processes and create streamers, activating maser instabilities in the electron plasma. This can occur under the influence of dense solar wind and CME that penetrate to Jupiter's magnetosphere, creating high-latitude currents with non-Io radio storms, and enhancing Io-dependent sources of DAM radio emissions. We found that dynamics of development of Io-dependent and non-Io DAM radio storms have similar features and evolutionary peculiarities. That time periodicities (5 min and 20 min durations) may connected with MHD instabilities activated by Io, that modulate the current sheets system in all auroral zone. The power of Io-dependent storms is modulated by the solar wind pressure on the magnetosphere of Jupiter. On the other hand, in non-Io radio sources associated with solar plasma injections, due to the content of high-energy ions which scatter on the gas fluids, a number of specific radio bursts are formed, for example, having zebra structures on high-resolution dynamic spectra.

The purpose of the work is to build an updated model of the illumination of artificial satellites in circular Earth orbits and to study the duration and nature of solar illumination in orbits with different inclinations and altitudes throughout the year. The mathematical model uses the equation of the circular cone of the shadow, built taking into account the movement of the Sun relative to the Earth. The center of the cross section of the base of the cone coincides with the center of the Earth. The motion of the satellite is simulated by Kepler’s orbit. The computer model makes it possible to determine with a given accuracy the duration of the satellite’s stay in the Earth’s shadow. Simulation of the duration of illumination of satellites at two altitudes has been performed: 5,000 km and 35,786 km (geosynchronous orbit altitude) throughout the year. Curves of the duration of the satellites’ stay in the shadow are given. The shape of the curves varies from a nearly straight line for inclined orbits 25°, then they become periodic, and then divide into two parts, resembling the shape of a parabola. Among all the possible inclinations of the orbits of satellites, extreme ones have been detected. These are orbits with an angle of inclination 23°26', which defines a straight orbit. On them, an artificial satellite falls into the Earth’s shadow throughout the year at each orbit. The second group of extreme orbits are orbits with inclinations, in which the satellite falls into the shadow only near the time of the equinoxes. Shortest duration of stay of satellites in the shadow moving in orbits with an angle of inclination 113°26'. Falling into the shadow lasts from 15.02 to 23.04 and from 19.08 to 27.10 for an altitude of 5,000 km, and from 12.03 to 28.03 and from 14.09 to 01.10 for an altitude of 35,786 km. The results of the simulations will allow us to clarify the effect of sunlight and solar wind pressure on the motion of satellites over time. This will allow the use of additional satellite accelerations resulting from radiative impact to change the orbits of space debris and clean up near-Earth space.

Abstract Traditionally, fast solar wind is considered to originate in solar source regions that are continuously open to the heliosphere. In contrast, slow solar wind is considered to originate in source regions that are only intermittently open to the heliosphere. In fast wind, the gradient of the solar wind helium abundance ( A He ) with increasing solar wind speed ( v sw ) is approximately 0 and A He is fixed at ∼50% of the photospheric value. In slow wind, this gradient is large, A He is highly variable, and it does not exceed this ∼50% value. Although the normalized cross helicity in fast wind is typically observed to approach 1, this is not universally true, and B. L. Alterman & R. D’Amicis show that ∇ v sw A He in fast wind unexpectedly increases with decreasing ∣ σ c ∣. We show that these large ∇ v sw A He are due to the presence of compressive fluctuations in fast wind. Accounting for the solar wind’s compressibility (∣ δn H / n H ∣), there exist two subsets of enhanced A He in excess of typical fast wind values. The subset corresponding to large solar wind compressibility is likely from neither continuously nor intermittently open sources. The portion of the solar wind speed distribution over which these fluctuations are most significant corresponds to the range of Alfvén-wave-poor solar wind from continuously open source regions, which is likely analogous to the Alfvénic slow wind. The other subset corresponds to typical Alfvénic fast solar wind. Mapping the results of this work to B. L. Alterman & R. D’Amicis and vice versa shows that, in any given ∣ δn H / n H ∣ quantile, ∣ σ c ∣ ≲ 0.65 is an upper bound on non-Alfvénic cross helicity. Similarly, ∣ δn H / n H ∣ ≲ 0.15 in any given ∣ σ c ∣ quantile is an upper bound on incompressible solar wind fluctuations. We conclude that ∣ δn H / n H ∣ is essential for characterizing the solar wind helium abundance and possibly regulating it.

Context. Determining which mechanisms regulate proton and alpha particle temperature anisotropies in the solar wind is an outstanding problem in collisionless plasma systems. For decades, the occurrence distributions of the various charged particle species measured in the near-Earth solar wind have been known to be characterized by peculiar rhombic shapes in ( β ∥ , T ⊥ / T ∥ ) phase space, where β ∥ is the ratio of parallel (with respect to the ambient magnetic field) plasma thermal pressure and the ambient magnetic field energy density and T ⊥, ∥ are temperatures in the perpendicular or parallel directions. Despite this fact, a convincing explanation for the physical mechanisms producing the low- β edges had not been forthcoming until recently. Aims. Recent works have provided plausible explanations for the origin of these distributions by invoking the combined effects of collisions and instability excitation; however, the initial applications were limited to proton and electron plasmas. In the present paper, the same coupled mechanism is extended to include alpha particles (He ++ ), which dynamically couple to the protons. Methods. We performed an ensemble simulation based upon the collisional relaxation equation that couples the protons and alpha particle dynamics in the low-beta regime. We also carried out another ensemble simulation based on the instability-induced quasi-linear relaxation equation for the high-beta regime. Results. We find that the combined effects provide a satisfactory first-order explanation of the observed temperature distribution, resolving one of the long-standing problems in contemporary heliospheric physics. Conclusions. The findings of the present study demonstrate that the collisional relaxation is adequate to describe the existence of an outer boundary associated with the proton and alpha particle occurrence distribution in the low-beta regime. For the high-beta regime, it is known that the instability-induced relaxation is important, and the present ensemble simulation confirms this notion.

Abstract Turbulence is a ubiquitous process that transfers energy across many spatial and temporal scales, thereby influencing particle transport and heating. Recent progress has improved our understanding of the anisotropy of turbulence with respect to the mean magnetic field; however, its exact form and implications for magnetic topology and energy transfer remain unclear. In this study, we investigate the nature of magnetic anisotropy in compressible magnetohydrodynamic turbulence within low- β solar wind using measurements from the Cluster spacecraft. By decomposing small-amplitude fluctuations into Alfvén and compressible modes, we reveal that magnetic anisotropy is largely mode dependent: Alfvénic fluctuations are broadly distributed in propagation angle, whereas compressible fluctuations are concentrated near the quasi-parallel (slab) direction, a feature closely linked to collisionless damping of compressible modes. For β → 0, compressible modes become dominant within the slab component at smaller scales. These findings advance our understanding of magnetic anisotropy in solar wind turbulence and offer a new perspective on the three-dimensional turbulence cascade, with broad implications for particle transport, acceleration, and magnetic reconnection.

Abstract During solar cycle minimum, polar coronal holes show a prominent radio brightening cap. The analysis of polar microwave enhanced radiation in polar coronal holes is helpful for understanding the magnetic field characteristics and the origin of the solar wind. Using the Koshix synthesis method on Nobeyama Radioheliograph data, we identified microwave bright points (BPs) superposed on the microwave brightening cap of the northern polar coronal hole. These microwave BPs manifested intermittently at fixed locations, with their radiation intensities displaying multiperiodic oscillations (20 s, 50 s, and 2.5 minutes). Multiwavelength analysis revealed that nearly all BPs were adjacent to or coincide with 171 Å open structures, indicating a strong correlation between microwave BPs and solar wind, propagating along the open field lines. At lower layers, BPs were associated with bright ribbons in the chromosphere and local enhanced magnetic structures in photosphere. The 20 s lifetime of microwave BP enhancement corresponds to their shortest oscillation period, which, in the temporal characteristics of Alfvén waves, implies a localized heating or a small-scale magnetic reconnection process modulated by Alfvén waves at the root of open magnetic field lines. The microwave 2.5 minute and 171 Å 5 minute oscillations likely stem from chromospheric and photospheric oscillation leakage/propagation, respectively. And longer-period (12 minute) oscillations in 171 Å open structures may link to large-scale coronal hole evolution. The multiperiod oscillatory processes in the polar coronal hole imply complex plasma dynamics inside, which contributes to our understanding of the origin and propagation of solar wind along the open structures in the coronal hole.

Abstract The ionization state of plasmas leaving the Sun freezes in low in the solar corona and carries information about the inner corona through the heliosphere. In situ charge state measurements provide excellent diagnostic tools for studying the early evolution and energetics of the solar wind and coronal mass ejections (CMEs). Three-dimensional global magnetohydrodynamics models allow us to link the measured in situ charge states to the heating/cooling mechanisms in the low corona to understand its evolution. In this final paper of the series, we use the 2008 April 9 CME (the “Cartwheel CME”) simulated with the Alfvén Wave Solar atmosphere Model to understand the evolution of the charge states. The highest-ionization material in the flux rope is caused by the high temperatures early in the eruption, which freezes in quickly due to the large adiabatic expansion rates. The prominence preserves low ionization state material to 1 au because of the high radiative cooling rates, but only occupies about 10% of the cross-sectional area of the CME, making it less likely to be observed in situ. We discuss in situ charge state distribution properties that can be used for understanding CME plasmas and their heating processes. We show that between the Extreme ultraviolet Imaging Spectrometer slit location (1.1 R ⊙ ) and the freeze-in height, there is a significant amount of unobserved charge state evolution that would be lost without the use of models.

Abstract We started measuring geomagnetically induced current (GIC) in substations around Tokyo, Japan in 2017 to study the GIC effects on power systems. We defined a period with GIC continuously exceeding 3 A as a GIC event to analyze the long-term data. This threshold is sufficiently above the noise level of the measurement data to clearly distinguish the events. Approximately 90% of the GIC events selected using this threshold have duration of less than twenty minutes. The GIC events between February 2018 and December 2024 were analyzed for the GIC data at SFS substation because GIC amplitude observed at SFS was the largest among the four substations where GIC measurements have been conducted. Occurrence of the GIC events with large amplitude and long duration increased according to increase of solar activity towards solar maximum of cycle 25. Most of the GIC events occurred during significant variations in the geomagnetic field associated with magnetic storms regardless of their main or recovery phase although the GIC event with the largest amplitude occurred associated with a sudden commencement (SC) at the start of initial phase of the storms, such as the storm on 10 October 2024. The relationship between the peak H-component geomagnetic variation (∆H) of the magnetic storm and the absolute value of a peak GIC (|A peak |) showed a good correlation with a correlation coefficient of 0.92. The GIC event with the longest duration were recorded in the main phase of the storm on 10 May 2024, which had a minimum provisional Dst of − 406 nT. We also found an example of a long-duration GIC event related to a SC caused by a high-density solar wind region, which was not accompanied by a magnetic storm. Graphical Abstract

Context. The coronal heating problem and the generation of the solar wind remain fundamental challenges in solar physics. While approaches based on, e.g., the Alfvén Wave Solar Model (AWSoM) have proven highly successful in reproducing the large-scale structure of the solar corona, they inherently neglect contributions from additional wave modes that arise when the effects of transverse structuring are fully incorporated into the magnetohydrodynamic (MHD) equations. Aims. In this paper, we compare the respective roles of heating driven by kink waves and Alfvén waves in sustaining a region of the solar atmosphere. We employ newly developed physics and radiative cooling modules within MPI-AMRVAC . Methods. We extended the existing MHD physics module in MPI-AMRVAC by incorporating additional Alfvén and kink wave energy contributions to the MHD equations. We examined their roles in heating the solar atmosphere and driving the solar wind. To validate our approach, we compared our numerical results from Python-based simulations with those obtained using the UAWSoM module in MPI-AMRVAC . Furthermore, we assessed the heating efficiency of kink waves relative to that of pure Alfvén waves through two parameter studies: (1) exploring how different Alfvén wave reflection rates impact the simulated atmosphere and (2) varying the relative magnitudes of Alfvén and kink wave energy injections. Finally, we present the results of a larger scale domain fully sustained by kink wave-driven heating. Results. Our results show that kink wave-driven (UAWSoM) models can sustain a stable atmosphere without requiring any artificial background heating terms, unlike traditional Alfvén-only models. We attribute this to the increased heating rate associated with kink waves compared with Alfvén waves, given the same energy injection. Conclusions. Kink waves have the capacity to sustain a model plasma with temperature and density values representative of coronal conditions, without the need to resort to ad hoc heating terms.

Abstract India's target to achieve net-zero carbon emissions by 2070 highlights the urgent need for a detailed and spatially explicit assessment of its renewable energy potential. Long-term, high-resolution evaluations of solar and wind resources remain limited, and the absence of a rigorous comparison among key datasets hampers the development of a comprehensive renewable energy strategy. This study aims to fill this gap, by quantifying the unconstrained solar photovoltaic (SPV) potential and wind power density (WPD) across Indian states using two benchmark reanalysis datasets i.e. the Indian Monsoon Data Assimilation and Analysis (IMDAA) and the European Centre for Medium Range Weather Forecasts Reanalysis 5th generation (ERA5), covering the period 2000–2020. Critical meteorological parameters, specifically solar irradiance and wind velocity, were subjected to rigorous analysis, and the efficacy of the dataset was corroborated through ground-based observations at various locations in India employing statistical tests. Results confirm that ERA5 performed slightly better than IMDAA for wind, while ERA5 significantly outperforms IMDAA in estimating solar irradiance. Rajasthan exhibits the highest SPV potential, and Gujarat leads in WPD. Seasonal patterns reveal peak SPV potential (~34,000 GW) during the pre-monsoon and highest WPD (~164 W/m²) during the monsoon season. Validation findings suggest that ERA5 outperforms IMDAA in replicating observed spatial and magnitude patterns. It is important to note that this research constitutes pioneering systematic assessments of the IMDAA for the purpose of renewable energy mapping within the context of India, underscoring the critical significance of dataset selection in achieving precision in energy modeling and strategic planning.