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We investigate the long-term persistence of the time series of energetic neutral atom (ENA) fluxes recorded by the Interstellar Boundary Explorer (IBEX). ENAs provide global information about the outer heliosphere and its interactions with the very local interstellar medium. To avoid the IBEX Ribbon, here, we focus our analysis solely on the polar regions N60°–N90° and S60°–S90°. Each year, IBEX takes two measurements of every pixel in the sky. We make use of the whole set of 14 yr of IBEX data and adhere to the correct time order for the construction of the flux time series. We examine in detail both the trend and the fluctuations of these time series. Using modern methods of time series analysis and persistence characterization, we show that the time series (i) trend is influenced by the solar cycle, (ii) persistence can be established independently of the presence of this trend, and (iii) statistical properties of the fluctuations differs between north and south, pointing to the existence of anisotropy and thus a north–south asymmetry. [ABSTRACT FROM AUTHOR]

We examine the role of refractory organics as a major C carrier in the outer protosolar nebula and its implications for the compositions of large Kuiper Belt objects (KBOs) and CI chondrites. By utilizing Rosetta measurements of refractory organics in comet 67P/Churyumov–Gerasimenko, we show that they would make up a large fraction of the protosolar C inventory in the KBO-forming region based on the current widely adopted solar abundances. However, this would free up too much O to form water ice, producing solid material that is not sufficiently rock-rich to explain the uncompressed density of the Pluto–Charon system and other large KBOs; the former has been argued as the most representative value we have for the bulk composition of large KBOs. This inconsistency further highlights the solar abundances problem—an ongoing challenge in reconciling spectroscopically determined heavy-element abundances with helioseismology constraints. By employing a new data set from solar CNO neutrinos and solar wind measurements of C, N, and O, we show that the uncompressed density of the Pluto–Charon system can be reproduced over a wide range of scenarios. We show that a lack of sulfates in Ryugu and Bennu samples implies a lower amount of water ice initially accreted into CI chondrite parent bodies than previously thought. These data are found to be consistent with the solar C/O ratio implied by the new data set. Our predictions can be tested by future neutrino, helioseismology, and cosmochemical measurements. [ABSTRACT FROM AUTHOR]

Since November 2021, the Tianwen-1 mission has activated its scientific instrument, the Mars Ion and Neutral Particle Analyzer (MINPA), to detect particles within Martian space. To evaluate the reliability of the plasma parameters from the MINPA measurements, in this study, we analyze and reduce the background signal (or noise) appearing in the MINPA data and then calculate the plasma moments based on the noise-reduced data. Remarkably, our findings reveal a strong correlation between the velocity measurements from MINPA and those from the Solar Wind Ion Analyzer (SWIA) onboard the MAVEN spacecraft, underscoring MINPA's accuracy. Similarly, temperature measurements correlate with SWIA data, albeit with a tendency towards underestimation and greater variability. A significant limitation, however, is MINPA's 2 π field of view (FOV), which restricts its ability to observe ions omnidirectionally, leading to a substantial underestimation of number density and thermal pressure compared to SWIA measurements. Addressing this challenge necessitates a sophisticated approach that fully accommodates the FOV constraints to derive accurate values for these parameters. Moreover, our comprehensive investigation into the noise origins traced it back to electronic noise within MINPA's circuitry. This study confirms MINPA's operational efficacy and potential to yield dependable plasma parameters with further procedures and contributes valuable insights for the design of future scientific instruments. [ABSTRACT FROM AUTHOR]

The orientation of Interplanetary Magnetic Field (IMF B) components plays a major role in magnetospheric Energetic Particles Precipitation (EPP). This is because the IMF B components in the Geocentric Solar Magnetospheric (GSM) coordinate system control magnetic reconnection at the subsolar magnetopause. This study intends to unravel the dependence of the preceding conditions of the orientations of IMF B components that drove geomagnetic storms on the EPPs produced in the Van Allen radiation belt. We classified the geomagnetic storms based on their drivers and IMF B z orientations prior to the storms' onset. Energetic particle fluxes, IMF B, and solar wind data were used. The study showed that electrons are more reactive to solar wind speed than protons. Additionally, storms with southward IMF B z orientation caused more EPP enhancement than with northward orientation. Our results also showed that protons are more influenced by magnetospheric compression than electrons at the northward orientation of IMF B z. In fact, at this point, the proton's motion violates adiabatic invariants. As particles interact with electric fields, a significant population of EPPs is produced by pitch angle diffusion. Generally, IMF B x and IMF B y are often anticorrelated. The preceding conditions of orientations of the IMF B x indicated weaker dependence on auroral indices, and invariably on energetic particles precipitation than the IMF B y. [ABSTRACT FROM AUTHOR]

The Ionosphere, a crucial region of Earth's atmosphere extending from approximately 50 to 1000 km above the Earth's surface, plays a pivotal role in global communication, navigation, and satellite-based technologies. Among its various parameters, Total Electron Content (TEC) stands out as a key metric, representing the integrated electron density along a specific path through the ionosphere. This research focuses on analyzing TEC variations during Indonesian earthquakes between 2004 and 2024 using a Recurrent Neural Network (RNN) model. The study investigates the ionospheric response to seismic activity, particularly in Indonesia, a region prone to earthquakes due to its location within the Pacific Ring of Fire and complex tectonic setting involving multiple lithospheric plates. The RNN model, designed to predict TEC variations during earthquakes, utilizes data on solar and geomagnetic activity, including the Kp index, solar wind, and geomagnetic storm activity, obtained from the OMNIWEB data centre, along with TEC data from the IONOLAB data servers for the BAKO station in Cibinong, Indonesia. The earthquakes considered for observation include significant events such as the 2004 Indian Ocean earthquake and tsunami, the 2012 Wharton Basin earthquake, and subsequent seismic events up to 2024. Statistical metrics such as Mean Bias Deviation (MBD), Relative Error (REL_E), Absolute Error (ABS_E), and Root Mean Square Error (RMSE) are used to evaluate the predictive capability of the RNN model and compare it with the International Reference Ionosphere (IRI) 2020 model, a widely accepted empirical model for describing ionospheric parameters. The comparison reveals the performance of the RNN model in capturing TEC variations during seismic events, providing valuable insights for earthquake monitoring and early warning systems. [ABSTRACT FROM AUTHOR]

Kinetic Alfvén waves (KAWs) are simulated with a 3D particle-in-cell (PIC) code by using the eigenvector relations of density, velocity, electric, and magnetic field fluctuations derived from a two-fluid KAW model. Similar simulations are also performed with a whistler waves setup. The 2D two-fluid eigenvector relations are converted into 3D by using rotation of the reference frame. The initial condition for the simulations is a superposition of several waves at scales slightly larger than the ion skin depth. The nonlinear interactions produce a transfer of energy to smaller scales. The magnetic field perturbation ratios, velocity perturbation, and density perturbation ratios are calculated from the simulation at higher wavenumbers and compared with the analytically expected ratios for KAWs and whistler waves. We find that in both types of simulations, initialized either with an ensemble of KAWs or with whistlers, the observed polarization relations at later times match better with the KAW relations compared to whistlers. This indicates a preference for excitation of KAW fluctuations at smaller scales. The power spectrum in the perpendicular direction is calculated, and it shows similar indices as measured in the solar wind power spectrum in the transition (sub-ion) region. The power law extends to smaller scales when a higher ion-to-electron mass ratio is taken. The 2D magnetic power spectrum in magnetic field parallel and perpendicular directions shows typical anisotropy where the power spreads more in the perpendicular direction than in the parallel direction. This study shows that KAWs can explain features of the sub-ion range plasma turbulence in the solar wind. [ABSTRACT FROM AUTHOR]

A unique event known as the disappearing solar wind (DSW), characterized by an extremely low-density solar wind stream, occurred at Mars on 2022 December 26–27. As this stream flowed past Mars, several properties of the Mars–solar wind interaction changed in response to the density drop. We utilize in situ plasma measurements from the Mars Atmosphere and Volatile EvolutioN spacecraft to examine heavy ion escape during this event. We find that escaping ions with energies above and below 30 eV responded differently to the reduction in solar wind density. High-energy ions experienced a decrease in flux, whereas low-energy ions experienced an increase, regardless of whether they were escaping through the plume or tailward channel. Furthermore, we observe a net reduction in the flux of plume escaping ions during the DSW period, primarily due to a considerable reduction in the high-energy component, which typically dominates plume escape. In contrast, the overall flux of tailward escaping ions increased during this period. These variations in heavy ion escape are mainly attributed to substantial reductions in solar wind dynamic pressure and momentum density. This paper provides new insights into the dynamics of heavy ion escape under an exceptional state of the Mars–solar wind interaction. [ABSTRACT FROM AUTHOR]

Coronal mass ejections (CMEs) from pseudostreamers represent a significant fraction of large-scale eruptions from the Sun. In some cases, these CMEs take a narrow jet-like form reminiscent of coronal jets; in others, they have a much broader fan-shaped morphology like CMEs from helmet streamers. We present results from a magnetohydrodynamic simulation of a broad pseudostreamer CME. The early evolution of the eruption is initiated through a combination of breakout interchange reconnection at the overlying null point and ideal instability of the flux rope that forms within the pseudostreamer. This stage is characterized by a rolling motion and deflection of the flux rope toward the breakout current layer. The stretching out of the strapping field forms a flare current sheet below the flux rope; reconnection onset there forms low-lying flare arcade loops and the two-ribbon flare footprint. Once the CME flux rope breaches the rising breakout current layer, interchange reconnection with the external open field disconnects one leg from the Sun. This induces a whip-like rotation of the flux rope, generating the unstructured fan shape characteristic of pseudostreamer CMEs. Interchange reconnection behind the CME releases torsional Alfvén waves and bursty dense outflows into the solar wind. Our results demonstrate that pseudostreamer CMEs follow the same overall magnetic evolution as coronal jets, although they present different morphologies of their ejecta. We conclude that pseudostreamer CMEs should be considered a class of eruptions that are distinct from helmet-streamer CMEs, in agreement with previous observational studies. [ABSTRACT FROM AUTHOR]

The foreshock region filled with turbulences is a natural lab for studying interactions between plasma and waves. The underlying processes are vital for dissipating the energy carried by the solar wind into the Martian environment. In this study, we analyze an ultralow-frequency wave observed on 2015 August 14 by Mars Atmosphere and Volatile Evolution upstream of the Martian bow shock. The wave properties match with those of 30 s waves; the dispersion calculation shows that the upstream plasma was capable of generating the observed waves. The analysis of the ion behaviors implies the wave generated without a field-aligned beam, while the growth rate of waves seems to be modulated by the interplanetary magnetic field conditions. These results indicate the unique role of the Martian foreshock in the interaction between the solar wind and the planet. [ABSTRACT FROM AUTHOR]

Partially ionized plasmas universally exist in various astrophysical environments, such as the solar atmosphere and the E region of the ionosphere. In these contexts, the existence and propagation of waves in plasmas could be significantly influenced by effects of weakly ionized plasma (e.g., ion–neutral collisions). In this work, we investigate electrostatic ion cyclotron (EIC) waves in partially ionized plasmas based on the multifluid model with adiabatic electrons. Two distinct branches of EIC waves coexist in partially ionized plasmas: one branch is the conventional EIC waves; the other branch propagates around the "effective ion cyclotron frequency" which originates from self-consistent ion–neutral collisions. Furthermore, theoretical predictions in the new branch of EIC waves are qualitatively consistent with laboratory observations. In addition, a comparison between our theory and the previous work is also performed. This work can aid in understanding the acceleration and transverse heating of ions in partially ionized astrophysical plasmas where the ion–neutral collisions are frequent. [ABSTRACT FROM AUTHOR]

Using a classification scheme for solar-wind type based on the heliocentric distance of the observation, we look at near-perihelion observations from Parker Solar Probe Encounters 4 to 14 to study the sources of the slow Alfvénic solar wind (SASW). Through Potential Field Source Surface (PFSS) modeling and ballistic mapping, we connect streams to their solar source and find that a primary population of SASW comes from low magnetic field strength regions (low- B 0), likely small coronal holes (CHs) and their overexpanded boundaries, while a second population of high field strength (high- B 0) seems to emerge from non-CH structures potentially through interchange reconnection with nearby open field lines. This low- B 0 SASW shows larger expansion than the fast solar wind (FSW) but similar mass flux, potentially indicating additional heating below the critical point, and emergence from a cooler structure, which could lead to slower wind emerging from CH-like structures. We show that this low- B 0 SASW shows stronger preferential acceleration of alpha particles (similar to the FSW) than the high- B 0 SASW, and that this is a velocity-dependent phenomenon as found in previous studies. To have additional confidence in our mapping results, we quantify the error on both the PFSS model and ballistic mapping and discuss how additional multipoint observations of plasma parameters and composition would allow us to better constrain our models and connect the solar wind to its source. [ABSTRACT FROM AUTHOR]

Magnetic holes (MHs) are transient magnetic structures responsible for energy conversion in space plasma. Using single-spacecraft measurements from Mars Atmosphere and Volatile EvolutioN (MAVEN), the existence of MHs on Mars has been confirmed. However, due to the limitations of single-spacecraft observations, significant uncertainty also arises on the identification of the spatial scale and 3D geometry of MHs. In this study, we report a series of MHs successively detected by Tianwen-1 near the high-latitude magnetopause and by the MAVEN spacecraft near the subsolar magnetopause. The large separation between Tianwen-1 and MAVEN (∼4 R M) suggests these MHs are macroscale structures extending along the axial direction. Additionally, we observe whistler waves generated by electron perpendicular anisotropy in one of the macroscale MHs. This study is the first joint observation of Martian MHs, shedding light on the research of transient magnetic structures on Mars. [ABSTRACT FROM AUTHOR]

Space weather prediction is a central focus of solar-terrestrial studies, with forecasts of geomagnetic storms deemed critical due to their significant practical implications. We have gathered facts that highlight the effects of geomagnetic storms on electric power systems and satellites. Recent studies indicate that geomagnetic storms of moderate intensity are statistically associated with larger spike amplitudes of telluric currents potentially leading to power outages compared to those caused by major storms. This underscores the importance of building reliable forecasts for all geomagnetic storms, especially given that solar cycles 20–24 saw less than 1% of storms classified as severe or extreme. A major challenge in current prediction models, even those utilizing advanced machine learning techniques, is the decline in accuracy for forecast lead times beyond 3 h, limiting the ability to mitigate infrastructure damage effectively. In this work, we provide a concise overview of geomagnetic storm statistics, describe key forecasting methods, recent advancements, and discuss the challenges in achieving accurate and timely storm predictions. [ABSTRACT FROM AUTHOR]

The Apollo 16 regolith breccia sample suite provides a record of lunar regolith formation from the basin‐forming epoch (~3.9 Ga) through to a time of declining impactor flux (~2 Ga). These rocks have been characterized into three groups: the "ancient," "young," and "soil‐like" regolith breccias on the basis of their petrographic characteristics, and, in the case of the "ancient" and "young" regolith breccias, noble gas inventory. This study investigates the as‐yet unexamined noble gas records of the "soil‐like" regolith breccias to understand more recent regolith evolution processes that occurred at the Apollo 16 landing site. The range of gas concentrations measured for each noble gas in these samples is comparable to those previously reported for the local Apollo 16 soils. The "soil‐like" regolith breccias were found to be more gas rich than the gas poor "young" and "ancient" regolith breccias, consistent with them having formed from comparatively mature soil(s). Our results further confirm the scientific value of lunar regolith breccias and bulk regolith samples as probes of the impact history and the space environment of the lunar surface across a wide range of time. [ABSTRACT FROM AUTHOR]

This paper offers a fresh perspective on solar chromosphere heating and plasma outflows, focusing on the contribution of waves generated by solar granulation. Utilizing a 2.5D numerical experiment for the partially ionized lower solar atmosphere, we investigate the dissipation of these waves and their impact on plasma outflows and chromospheric heating via ion-neutral collisions. Employing the JOint ANalytical and Numerical Approach code, we adopt two-fluid model equations, examining partially ionized hydrogen plasma dynamics, including protons+electrons and neutrals, treated as two separate fluids that are coupled through ion-neutral collisions. Our investigation focuses on a quiet solar chromosphere region characterized by gravitational stratification and magnetic confinement by an initially set single magnetic arcade. The primary source of the waves is the solar convection beneath the photosphere. Our results demonstrate that ion-neutral collisions result in the dissipation of such waves, releasing thermal energy that heats the chromosphere plasma. Notably, this is accompanied by upward-directed plasma flows. Finally, we conclude that wave dissipation due to ion-neutral collisions in the two-fluid plasma model induces chromosphere heating and plasma outflows. [ABSTRACT FROM AUTHOR]

The anomalous cosmic rays have been studied for about fifty years. Through theoretical and numerical models, we can learn how and where they are originating. When Voyager 1 and 2 spacecraft observed the solar wind termination shock, the main efforts were focused on try to explain the source spectrum and the acceleration mechanism. Nevertheless, there is another feature of the spectrum that need a better understanding, and it is related with the peak intensity in the energy spectrum, that occurred at different energies in consecutive solar minima. Qualitatively, it can be explained in terms of drifts and its relation with the acceleration process. In the past some works have been partially successful to explain the observations. In this paper we do another effort to explain the shift in the peak intensity of anomalous cosmic ray energy spectrum. We use a numerical model which includes diffusive shock acceleration, and the effects of the heliosheath. The present work analyzes the role played by different factors in the energy shift of the peak intensity between two successive minima, in particular the location of the region of observations with respect to the shock, the heliospheric distance, the effects of turbulence on the reduction of weak scattering drifts, as well as a possible latitudinal dependence in the ion injection on the shock. [ABSTRACT FROM AUTHOR]

TianQin (TQ) mission, the sole proposed gravitational wave detection project in geocentric orbit at an altitude of approximately 1 0 5 km, traverses diverse geomagnetic regions. This paper employs a hybrid model to simulate the ambient magnetic field along the TQ orbit, investigating magnetically-induced acceleration noise under varying satellite-sun angles (SSA) and solar activity levels. The highest noise level, approximately 1 0 − 16 ms − 2 Hz − 1 / 2 , occurs during transregional periods between the magnetosheath (MSH) and magnetotail (MTL). Noise within the MSH region is an order of magnitude lower than the former, with the MTL region exhibiting the lowest levels, although geomagnetic storms can equalize noise in both regions. Statistical analysis indicates that noise in the MTL region correlates with SSA and solar wind dynamic pressure, displaying a spectral characteristic of f − 1. 03 ± 0. 075 , while the MSH region shows a Kolmogorov turbulence spectrum near the flank and f − 0. 5 at the subsolar region. [Display omitted] • Efficient and accurate hybrid model for simulating ambient magnetic fields in far-Earth orbit. • Identified peak noise levels during transregional periods between the magnetosheath and magnetotail. • Demonstrated significant influence of solar activity and satellite-sun angles on magnetically-induced noise. • Provided essential insights on noise management for future geocentric gravitational wave detectors. [ABSTRACT FROM AUTHOR]

The terrestrial bow shock is the boundary where supersonic solar wind slows down abruptly near the magnetopause. The shock front geometry could be modulated by surface waves to form rippled structures, which impact the acceleration process of the solar wind particles. However, the rippled structures are hard to be identified unambiguously due to the similar signatures in single‐spacecraft observations between rippled shocks and reforming shocks. Here, we utilize the four‐spacecraft observations from the MMS mission to investigate an event of quasi‐perpendicular bow shock crossing. The periodic oscillations of shock normal directions and normal velocities support the scenario of surface wave propagation in the tangential direction. We also reconstruct the shock profile along the normal direction, and its monotonic shape further excludes the occurrence of shock reformation. These ripples are found to modulate the reflected ions and whistler wave packets, which adds to the complexity of the bow shock plasma environments. Plain Language Summary: Collisionless shocks are ubiquitous structures in the space and astrophysical plasma environments where significant energy conversion occurs between electromagnetic energy, kinetic energy, and thermal energy. These structures often exhibit nonstationary signatures, from which important information on the associated plasma dynamics can be extracted. In this paper, we report the spacecraft observations of a bow shock crossing with periodic enhancements of the magnetic field strength. Such signatures have been previously attributed either to the rippled shock structures or to the shock reformation process. These two potential processes are examined via simultaneous observations at four different locations, which shows the periodic oscillations of the local shock normal directions indicative of rippled rather than reforming shocks. We also show that the rippled shocks could spatially modulate the reflected ions and whistler wave packets, so they can also be detected periodically by the spacecraft. This phenomenon has been reported on other planets across a wide range of Mach numbers, indicating that the shock ripples, universal in the plasma universe, play a critical role in impacting particle dynamics and shock evolution processes. Key Points: Periodic magnetic strength enhancements are observed during the bow shock crossing of the MMS spacecraftMulti‐spacecraft analysis supports the scenario of shock ripples rather than the shock reformation processThe surface waves alter the shock geometry, modulating the reflected ions and whistler wave packets [ABSTRACT FROM AUTHOR]

CI chondrites have been a proxy for the solar system since the mid‐20th century. The photospheric and CI chondrite abundances (P and CI, respectively) show a strong correlation. CI as a proxy is also justified by the (i) smoothness of their abundances plotted as a function of odd mass number and (ii) agreement within the error of P as determined spectroscopically. But our statistical assessment of spectroscopic studies and solar wind from the Genesis mission indicates that the small, ~10%–30%, differences (residuals) between CI and P depend on the 50% condensation temperature (Tc50). So, if CI is to be used as a proxy for P, Cosmochemists may want to add a correction to individual elements. Our work is consistent with two published hypotheses: that (i) residuals are linear with Tc50 and (ii) that elements having Tc50 > 1343 K are depleted relative to those with 495 K < Tc50 < 1343 K in CI. We discuss other interpretations which are also feasible. Understanding these small differences of the CI and P for different elements and their variation with Tc50 can help constrain future models of solar system formation and the history of CI chondrites. [ABSTRACT FROM AUTHOR]

Plumes are considered to play an important role in the origin of the solar wind. However, an understanding of their thermodynamic evolution is not complete. Here, we perform a detailed study of a plume inside a coronal hole throughout its lifetime, using the observations from the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager. We find that the plume's formation is preceded by frequent occurrences of small-scale jets and jetlets at its base, leading to the gradual development of plume haze. The plume rapidly developed within the first 6 hr into its well-known morphology. Light curves from all extreme ultraviolet channels exhibit a similar profile, suggesting its multithermal nature and intensity modulation over its lifespan. Moreover, the photospheric magnetic field dynamics at the plume's base are highly correlated with its light curve in 171 Å. We calculate outflow velocities, observed prominently in the 171 Å passband and mildly in the 193 and 211 Å passbands, with median speeds lower in higher temperature bands but occasionally comparable to the respective sound speeds. When data are averaged over larger spatial scales, the plume appears isothermal along its length, with constant temperature throughout its lifetime. However, an analysis of the differential emission measure at full resolution reveals the presence of higher-temperature plasma, indicating internal temperature structures within the plume. These results provide new insights into the formation, dynamics, and thermal properties of coronal plumes, placing tighter constraints on models to understand their thermodynamic evolution and potential role in the solar wind. [ABSTRACT FROM AUTHOR]

Interplanetary coronal mass ejections (ICMEs), characterized by their magnetic flux ropes, could potentially trigger geomagnetic disturbances. They have been attracting extensive investigations for decades. Despite numerous ICME models proposed in the past, few account for the curvature of the flux rope axis. In this study, we use conjunction observations from ACE, STEREO A and B, Juno and Solar Orbiter to analyze the evolution of the rope orientation of ICME flux ropes. Our findings indicate that the orientation of these ropes changes independently of the scale of the ropes or the distance they travel between spacecrafts. Furthermore, we estimate and compare the major radii of these flux ropes, uncovering a diverse range of distributions that do not seem to depend on the flux rope's width. These results provide fresh insights and constraints for global ICME models, thereby contributing to the advancement of space weather research. [ABSTRACT FROM AUTHOR]

The approximately 11-year solar cycle has been shown to impact the heavy ion composition of the solar wind, even when accounting for streams of differing speeds; however, the heavy ion composition observed between the same specific phases of a past solar cycle and the current cycle has rarely, if ever, been compared. Here, we compare the heavy ion composition of the solar wind, as measured in situ during the solar cycle 23 and 25 ascending phases. We examine the mean iron and oxygen charge state composition and the O7+/O6+ ratio in multiple ranges of associated bulk wind speeds. Then, we compare the iron and oxygen charge state composition and relative abundance of iron to oxygen in the traditionally defined fast and slow solar wind. Finally, to determine the impact of individual ion contributions on the solar wind iron abundance, we examine individual ratios of iron and oxygen ions. Although the charge state composition remained broadly similar between these two ascending phases, both the O7+/O6+ ratio and iron fractionation in fast-speed streams were higher in the solar cycle 25 ascending phase than they were during the solar cycle 23 ascending phase, suggesting that equatorial coronal hole fields more frequently reconnected with helmet streamers or active regions in the latter of the two ascending phases; however, more work will need to be done to connect these observations back to their coronal origins. The individual ion ratios used in this work provided a spectrum to analyze the aggregate elemental abundances, and this work, as a whole, is an important step in determining how conditions in the corona may vary between solar cycles between the same phases. [ABSTRACT FROM AUTHOR]

Strong Thermal Emission Velocity Enhancement (STEVE), is a captivating optical phenomenon typically observed in the mid‐latitude ionosphere. This paper presents an intriguing observation of a STEVE event at high‐latitudes, approximately 10 degrees poleward of previously documented observations. This event was recorded in Yellowknife, Canada, by a TREx RGB imager and a citizen scientist. Swarm satellites traversed the latitude of the observation, measuring extreme westwards ion drift velocities exceeding 4 km/s. Such velocities are more typically associated with the subauroral region located at mid‐latitudes, rather than at the high‐latitudes reported here. Significantly, this event occurred without a substorm, which differs from previous STEVE observations. While high‐latitude radars detected fast ionospheric equatorward flows, GOES satellite did not record any injections. These observations suggest that the inner magnetosphere is highly inflated. This unique case study raises new questions surrounding subauroral dynamics and the influence of magnetospheric configurations on ionospheric responses. Plain Language Summary: Strong Thermal Emission Velocity Enhancement, also known as STEVE, is a fascinating nighttime optical phenomenon that takes place in the upper part of Earth's atmosphere. It can be easily recognized by its distinctive appearance as a narrow white‐mauve arc that is associated with strong westward flows and is situated just equatorward of the auroral oval. Previous research has shown that STEVE events occur together with intense ionospheric flows and occur after specific disturbances in the near‐Earth space environment known as substorms. They have found that substorms are important for creating the special conditions that lead to STEVE and other subauroral enhancements. In our study, we focus on a unique STEVE event that did not occur after a substorm. Furthermore, this observation took place under remarkably quiet solar wind conditions; nevertheless, strong ionospheric flows were recorded. This unusual case raises new questions about the atmospheric responses and how it is affected by the configuration of the magnetic field in space. By investigating these special circumstances, we hope to learn more about STEVE and its causes, which will help us advance our knowledge in the complex ionosphere‐magnetosphere‐solar wind coupled system. Key Points: Non‐storm and non‐substorm Strong Thermal Emission Velocity Enhancement (STEVE) occurrenceStrong subauroral flows during quiet geomagnetic conditionsThe ionospheric electrodynamics of this STEVE event differ from previous studies [ABSTRACT FROM AUTHOR]

In this study, we map the origin, acceleration, and propagation of the high-speed solar wind streams (HSS) and observe their impact on the low-latitude Earth's ionosphere. Data from radio-sounding experiments conducted by the Indian Mars Orbiter Mission (MOM) from 2015 May 9–19 is analysed to understand the solar wind speed's evolution at various helio-centric distances. The slope of the turbulence spectrum from 25 to 35 Rs was in the range of 0.2–0.4, indicative of the underdeveloped turbulence corresponding to the high-flow streams. It coincided with the appearance of the earth-facing coronal holes as observed in the coronal EUV images. The particle bulk velocity at L1 showed that the speeds began to rise from 400 km s−1 on May 11th–12th, reaching a peak of around 800 km s−1 on May13th–14th, followed by a gradual decrease to the average slow speeds. Geomagnetic disturbances during the same period manifested as a dip in the DST index values. The GNSS (Global Navigation Satellite System) data from the InSWIM (Indian network for Space Weather Impact Monitoring) network show an appreciable increase in the VTEC (vertical total electron content) of the ionosphere on disturbed days in entire low-latitude ionospheric region in the Indian sector. All these observed parameters correlate well with the HSS arrival. This is a unique study that connects the propagation of the HSS and its impact on near-Earth's environment from the different vantage points in interplanetary space and proposes the application of Radio beacons to improve space weather forecasting. [ABSTRACT FROM AUTHOR]

This study aims to improve the understanding of geomagnetic storms by utilizing machine learning models and analyzing several heliophysical variables, such as the interplanetary magnetic field, proton density, solar wind speed, and proton temperature. Rather than relying on traditional correlation-based methods, we employ advanced machine learning techniques to examine the complex relationships between these factors and geomagnetic storms. Our analysis covers a large dataset spanning six solar cycles, including the current 25th cycle, to provide comprehensive insights into the dynamics of these storms. Our study highlights the significance of the interplanetary magnetic field as a key predictor of geomagnetic storms, challenging previous beliefs that primarily focused on sunspot activity. By using high-resolution data, we uncover new patterns and provide a more detailed analysis of the factors influencing geomagnetic storms. We emphasize the importance of considering a range of heliophysical variables, such as proton temperature and flow pressure, which offer new insights into the complex dynamics driving these storm events. The application of machine learning models, particularly Random Forest and Gradient Boosting, demonstrated superior predictive accuracy compared to traditional methods. Our results reveal that the Dst-index MIN, scalar B, and alpha/proton ratio are among the most influential factors, accounting for a significant portion of the prediction model's accuracy. These findings underscore the utility of machine learning in identifying critical drivers of geomagnetic activity and enhancing forecast precision. Additionally, our research underscores the need for comprehensive models that can accurately predict geomagnetic storms by integrating various data sources. This machine learning approach not only improves predictive accuracy but also enhances our understanding of the underlying mechanisms of space weather. The insights gained from this study have important implications for both scientific research and practical applications, such as improving early warning systems for geomagnetic storms and mitigating their potential impacts on Earth. [ABSTRACT FROM AUTHOR]

At an altitude of 1000 - 2000 km in the Venusian upper ionospheric region, the plasma is composed of H + ions, O + ions, and solar wind (SW) protons with electrons distributed according to the kappa distribution. This research delves into the exploration of nonlinear solitary and periodic waves, including the behavior of two-soliton. The Reductive Perturbation Technique (RPT) is used to derive the Korteweg-de Vries (KdV) equation for studying these nonlinear waves. Subsequently, a travelling wave transformation is employed to establish a planar dynamical system for the obtained KdV equation. Phase portrait is drawn and the associated nonlinear waves are examined adjusting the values of the parameters temperature ratio, unperturbed number density ratios, spectral index and travelling wave speed. Two-soliton solution of the KdV equation is investigated using the Hirota's direct approach. The influence of parameters like the spectral index, unperturbed number density ratios, and temperature ratio on the two-soliton is demonstrated, including the change in the phase shift. The findings from this research provide valuable insights into the dynamics of two-soliton solutions and nonlinear waves in the upper ionosphere of Venus. [ABSTRACT FROM AUTHOR]

• We analyze the impact of plasma noise on Taiji using Wind's electron number density data. • Lomb–Scargle method is used to estimate the spectrum of plasma noise in 10−6 to 10−2 Hz. • The spectrum of plasma noise is fitted by power law and its effect on TDI is estimated. • It provides a basis for estimating plasma noises in similar gravitational wave observatories. In space-based laser interferometric gravitational wave antennas, plasma from the solar wind is an important noise floor source for laser interferometric measurements between two distant spacecraft. In this study, we aim to analyze the impact of solar wind on the inter-satellite laser interferometric measurements of the Taiji mission, a space-based laser interferometric gravitational wave antenna proposed by the University of Chinese Academy of Sciences. Based on the 6.5-year electron number density data from the National Aeronautics and Space Administration Wind spacecraft and considering the uneven sampling characteristics of the data, we employed the Lomb–Scargle spectral analysis method to study the impact of solar wind plasma on intersatellite laser interferometric measurements within the frequency range of 1 × 10 - 6 Hz to 0.01 Hz. The study shows that the effect of the plasma on the intersatellite laser interferometric measurement is approximately 1 pm/ Hz at 3.3 mHz, which is one order of magnitude smaller than the requirements on the displacement noise of the interferometric measurement of the Taiji mission, indicating that the noise due to plasma will not affect the aim of the Taiji mission to detect gravitational waves. The research can be applied to Taiji, Laser Interferometer Space Antenna, and future gravitational wave detection missions. [ABSTRACT FROM AUTHOR]

Featured Application: This article developed an improved InfoGAN wind–solar–load extreme scenario generation approach that can inform power system evaluation in extreme scenarios. In recent years, extreme events have frequently occurred, and the extreme uncertainty of the source-demand side of high-ratio renewable energy systems poses a great challenge to the safe operation of power systems. Accurately generating extreme scenarios related to the source-demand side under a high percentage of new power systems is vital for the safe operation of power systems and the assessment of their reliability. However, at this stage, methods for extreme scenario generation that fully consider the correlation between wind power, solar power, and load are lacking. To address these problems, this paper proposes a method for extreme scenario generation based on information-maximizing generative adversarial networks (InfoGANs) for high-proportion renewable power systems. The example analysis shows that the method for extreme scenario generation proposed in this paper can fully explore the correlation between historical wind–solar–load data, greatly improve the accuracy with which extreme scenarios are generated, and provide effective theories and methodologies for the safe operation of a new type of power system. [ABSTRACT FROM AUTHOR]

Sustainable hydrogen, produced from renewable sources such as solar or wind, plays a decisive role in driving industrial decarbonization. Among hydrogen production technologies, steam electrolysis, and solar‐driven thermochemical cycles using reducible solid oxides show promise but face challenges due to high operation temperatures. Microwave‐driven redox chemical looping enables the direct, contactless electrification of the process, reducing the operation temperature and complexity. Previous works showed that microwaves can efficiently drive reduction/water‐splitting cycles using Gd‐doped ceria at low temperatures (<250 °C), but adjustment of material properties is needed. Here, the key properties of materials are explored that affect the redox mechanism by screening a series of doped ceria materials to enhance microwave‐driven hydrogen production. Evaluation of trivalent dopants (La3+, Gd3+, Y3+, Yb3+, Er3+, and Nd3+) reveals that reduction correlates with lattice and electronic properties. The composition Ce0.9La0.1O2‐δ achieves 1.41 mL g−1, the highest hydrogen production among the studied series. Its narrower bandgap allows for reaching higher conductivity upon microwave‐driven reduction at lower temperatures, while a larger ionic lattice size boosts solid‐state oxygen diffusion. Overall, this research remarks on the critical properties of ceria‐based materials that enhance hydrogen production in microwave‐driven water‐splitting cycles, supporting the design of more efficient materials for sustainable chemical production technology. [ABSTRACT FROM AUTHOR]

We perform 3D3V hybrid-Vlasov simulations of turbulence with quasi-isotropic, compressible injection near ion scales to mimic the Earth's magnetosheath plasma, and investigate the novel electron-only reconnection, recently observed by NASA's Magnetospheric Multiscale mission, and its impact on ion heating. Retaining electron inertia in the generalized Ohm's law enables collisionless magnetic reconnection. Spectral analysis shows a shift from kinetic Alfvén waves to inertial kinetic Alfvén and inertial whistler waves near electron scales. To distinguish the roles of inertial scale and gyroradius (d i and ρ i), three ion beta (β i = 0.25, 1, 4) values are studied. Ion-electron decoupling increases with β i, as ions become less mobile when the injection scale is closer to ρ i than d i, highlighting the role of ρ i in achieving an electron magnetohydrodynamic regime at sub-ion scales. This regime promotes electron-only reconnection in turbulence with small-scale injection at β i ≳ 1. We observe significant ion heating even at large β i, with Q i/ ϵ ≈ 69%, 91%, and 96% at β i = 0.25, 1, and 4, respectively. While ion heating is anisotropic at β i ≤ 1 (T i,⊥ > T i,∥), it is marginally anisotropic at β i > 1 (T i,⊥ ≳ T i,∥). Our results show ion turbulent heating in collisionless plasmas is sensitive to the separation between injection scales (λ inj) and ρ i, β i, and finite- k ∥ effects, necessitating further investigation for accurate modeling. These findings have implications for other collisionless astrophysical environments, like high- β plasmas in intracluster medium, where processes such as microinstabilities or shocks may inject energy near ion-kinetic scales. [ABSTRACT FROM AUTHOR]

The magnetic field in the Sun's corona stores energy that can be released to heat plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to several snapshots. In this work, we present observations, using the Upgraded Coronal Multi-channel Polarimeter, that provide 114 magnetograms of the global corona above the solar limb spanning ~8 months. We determined the magnetic field distribution with altitude in the corona and monitored the evolution at different latitudes over multiple solar rotations. The field strength between 1.05 and 1.60 solar radii varies from <1 to ~20 gauss. A signature of active longitudes appears in the coronal magnetic field measurements. Coronal models are generally consistent with our observations, though they have larger discrepancies in high-latitude regions. [ABSTRACT FROM AUTHOR]

A mechanism of formation of plasma-dust system above the surface of Enceladus, the Saturn moon, illuminated by the solar radiation is proposed. It is demonstrated that the photoelectric effect caused by the sunlight and the influence of the solar-wind plasma create conditions for lifting of dust particles above the surface of the moon as a result of electrostatic repulsion. Based on a self-consistent model describing the electrostatic field and plasma components, including photoelectrons emitted from the Enceladus surface and those emitted from the surface of the dust particles, distribution functions of photoelectrons, dust particles, and their electrostatic charges are determined as functions of altitude and the angle between the local normal and the direction to the Sun. Also determined are the altitude profiles of the electrostatic fields for the corresponding angles between the local normal and the direction of the solar radiation. It is demonstrated that the photoelectric effect plays an important role in formation of dusty plasma near the Enceladus surface despite considerable distance from the Sun. It is established that concentration of photoelectrons above the Enceladus surface can exceed concentration of electrons and ions of the solar wind by an order of magnitude, and the size of the levitating particles is larger than the characteristic size of dust particles lifted above the surface of the Moon due to the fact that Enceladus is much smaller than the Moon. On the contrary, the size of particles levitating above Enceladus is much smaller than the size of particles levitating above the surface of celestial objects smaller than the Enceladus, e.g., the Martian satellites Phobos and Deimos. [ABSTRACT FROM AUTHOR]

Based on decades of single-spacecraft measurements near 1 au as well as data from heliospheric and planetary missions, multi-spacecraft simultaneous measurements in the inner heliosphere on separations of 0.05–0.2 au are required to close existing gaps in our knowledge of solar wind structures, transients, and energetic particles, especially coronal mass ejections (CMEs), stream interaction regions (SIRs), high speed solar wind streams (HSS), and energetic storm particle (ESP) events. The Mission to Investigate Interplanetary Structures and Transients (MIIST) is a concept for a small multi-spacecraft mission to explore the near-Earth heliosphere on these critical scales. It is designed to advance two goals: (a) to determine the spatiotemporal variations and the variability of solar wind structures, transients, and energetic particle fluxes in near-Earth interplanetary (IP) space, and (b) to advance our fundamental knowledge necessary to improve space weather forecasting from in situ data. We present the scientific rationale for this proposed mission, the science requirements, payload, implementation, and concept of mission operation that address a key gap in our knowledge of IP structures and transients within the cost, launch, and schedule limitations of the NASA Heliophysics Small Explorers program. [ABSTRACT FROM AUTHOR]

Under the dynamic influence of near-surface plasma, intricate dynamics of lunar dust have been observed during the Surveyors and Apollo missions in the form of Lunar horizontal glow. These dynamics are primarily driven by electrostatic forces generated by the continual bombardment of solar wind and highly energetic UV photons on the lunar surface and dust particles. This paper revisits the phenomenon of dust charging within the lunar photoelectron sheath and subsequent dynamics. The investigation has been carried out using a comprehensive model of the lunar photoelectron sheath characterized by observed solar spectra, latitude-dependent Fermionic photoelectrons, non-Maxwellian solar wind electrons, and cold ions. A test dust particle is introduced into the sheath, and equilibrium charge and static levitation conditions are derived. The result of dynamical evolution suggests the existence of a narrow parametric regime corresponding to the periodic hopping trajectory of the dust particle over the lunar surface. In other cases, the dust particles are found to re-impact the surface after a single ballistic hop. We further identify that the discrete charging of the dust could be crucial in determining the dust dynamics, particularly in the tenuous plasmas. The analysis of the discrete dust charging model reveals significant discrepancies with the continuous dust charging model and suggests a lower likelihood of static dust levitation in the lunar environment. The present study is important for unraveling the fundamental processes governing surface evolution on the Moon and other airless bodies throughout the Solar System. [ABSTRACT FROM AUTHOR]

In this research, the validity of Bernoulli's theorem for the solar wind crossing the Earth's bow shock has been investigated based on space explorations. Using solar wind plasma and interplanetary magnetic field data from the OMNI database, along with magnetosheath plasma and magnetic field data measured by the magnetospheric multiscale satellite in 2016 and 2018, 95 events were selected to study the Bernoulli invariant from the upstream to the downstream of Earth's bow shock (from the unshocked solar wind region to the shocked magnetosheath region). Statistical investigations show that the differences in the characteristic energy of plasmas between the solar wind region and the magnetosheath region are less than 5%, regardless of the upstream solar wind speed and the satellite's location in the magnetosheath. These results quantitatively support the generalization of Bernoulli's equation to the solar wind flowing through the bow shock, including the contribution of magnetic field energy. [ABSTRACT FROM AUTHOR]

Based on a large amount of experimental material, the hourly values of the solar wind speed and proton temperature were compared; the expected proton temperature and temperature index (the ratio of the observed temperature to the expected one) were calculated. Using the Cosmic Ray Variations Database, from 1997 to 2022 low-temperature periods were identified (intervals lasting more 2 h, in which hourly values of the temperature index less than 0.5). The study investigated (a) statistical relationships between the parameters of low-temperature periods and the characteristics of Forbush decreases associated with different types of solar sources; (b) distributions of parameters of low-temperature periods for interplanetary disturbances containing or not containing a magnetic cloud. The results showed that with increasing duration of the low-temperature period, the proportion of events associated with ejections from active regions increases, while the proportion of recurrent events and events associated with ejections outside active regions decreases. The correlation of the parameters of low-temperature periods with the magnitude of Forbush decreases is weak; with the equatorial anisotropy of cosmic rays, moderate; and with the azimuthal anisotropy, significant. The solar wind speed and magnetic field strength correlate moderately with the temperature index, and the correlation of the range of these parameters with the duration of low-temperature periods is significant or strong. [ABSTRACT FROM AUTHOR]

The Bézier curves submitted by Pierre Bézier in the mid-1950s are splendid differential geometric structures. The paper compares a mechanical–theoretical curve (classical-conventional) with a computer-based artificial neural network (modern). While the reader witnesses hourly TEC (TECU) modeling by the class C0 Bézier structure for the first time, (s)he has the opportunity to evaluate the reliable results of segmented-continuous curves with network. The Bézier structure is established by operating the differential geometrical invariants. The yielding and accuracy of the models are evaluated with the R correlation coefficient and the mean squared error. The discussion demonstrates the harmony of the two different approaches by modeling the 365-day TEC map of 2017. Then, in particular, the outputs of the intense geomagnetic storms of 28 May (Dst = − 125 nT) and 8 September (Dst = − 122 nT) are modeled and compared. Bézier curves are read segmental-continuous every 12-h TEC map in all discussions. The network, on the other hand, employs solar wind parameters to model the TEC atlas. The models obey rigorously the causality principle. The results of the discussion display that the R score reaches around 93% and 98.8% for Bézier curves and the neural network, respectively. Again, it is noticed that the mean squared error of the network model decreases to 1.1308 TECU. The curve model emerges to the reader as an alternative to neural networks in projections of space climate conditions. [ABSTRACT FROM AUTHOR]

The aim of this study is to quantitatively describe the anticipated change in the energy mix of the Sultanate of Oman (Oman) as the country moves forward in its national plan for green hydrogen, in order to become a global producer and exporter. This aim is achieved by curating recent data about energy projects in Oman that are either operating or planned (in a construction or pre-construction stage). Then, these data are processed further to extract useful insights about how the energy mix would change if the planned projects are realized and added to the operating ones. This reveals the serious commitment of the country to accomplish its national plan for green hydrogen (GH), where the green hydrogen production ambition for 2030 is about 1.125 million tons per annum (Mtpa), using a renewable energy capacity of approximately 18 GW. This ambition increases to about 3.5 Mtpa with approximately 70 GW of renewables in 2040, and increases further to about 8 Mtpa with approximately 180 GW of renewables in 2050. As a portrait of Oman's energy mix with the assumption of successfully completing all planned energy projects, we found that the country is expected to have a total capacity of 83.1271 GW, with the share of renewables (solar and wind) reaching 83.133% (as compared to 15.0711 GW with an 8.907% renewables share for operating projects). Nearly all (precisely 99.571%) of the 68.0560 GW planned national energy capacity additions are based on solar or wind energy, while the traditional oil–gas energy is gradually phased out. Green hydrogen production dominates this surge in renewables penetration within the Omani energy mix, with 84.659% of the planned 34.3140 GW solar capacity additions linked with green hydrogen production, for operating water electrolyzers. Similarly, 98.804% of the planned 33.4500 GW wind capacity additions are linked with green hydrogen production. [ABSTRACT FROM AUTHOR]

Storm-time ionospheric electrodynamics effects have been the subject of extensive studies. The solar wind/magnetosphere/ionosphere and thermosphere disturbance wind dynamos have long been identified as the main drivers of low latitude storm-time electrodynamics. Extensive detailed studies showed that climatology of low latitude disturbance electric fields and currents is in good agreement with results from global theoretical and numerical models. Over the last decade, however, numerous studies have highlighted that the response of low latitude electrodynamics to enhanced geomagnetic activity is significantly more complex than previously considered. It is now clear that the electrodynamic disturbance processes are affected by a larger number of solar wind and magnetospheric parameters and that they also have more significant spatial dependence. This is especially pronounced during and after large geomagnetic storms when multiple simultaneous disturbance processes are also active. In this work, we briefly review the main past experimental and modeling studies of low latitude disturbance electric fields, highlight new results, discuss outstanding questions, and present suggestions for future studies. [ABSTRACT FROM AUTHOR]

The article titled "Planet wind: Planetary evolution dominated by electromagnetic forces" discusses the "Planet Wind" hypothesis, which suggests that planetary systems are primarily influenced by electromagnetic forces. It categorizes planetary dissipation into three types and emphasizes the importance of analogical reasoning in understanding planetary systems. The article also discusses the overall trend of solar system evolution, the transmission of matter and energy between celestial bodies, and the unity of opposites in this process. The text highlights the concept of "Planet Wind" as the loss of planetary material in the form of particles and emphasizes the need for a comprehensive research system in planetary science. The author suggests that studying planet wind can provide valuable insights into planetary evolution and mentions China's Tianwen-4 mission as an example of ongoing research in this field. The article titled "Solar System— its origin and evolution" provides a comprehensive overview of the origins and development of our solar system. It explores various theories and scientific evidence, making it a valuable resource for those interested in understanding the formation and evolution of our solar system. [Extracted from the article]

In this paper, we model the high-energy tail of observed solar energetic proton energy distributions with a kappa distribution function. We employ a technique for deriving the thermodynamic parameters of solar energetic proton populations measured by the Parker Solar Probe Integrated Science Investigation of the Sun EPI-Hi high-energy telescope, over energies from 10 to 60 MeV. With this technique, we explore, for the first time, the characteristic thermodynamic properties of the solar energetic protons associated with an interplanetary coronal mass ejection (ICME) and its driven shock. We find that: (1) the spectral index or, equivalently, the thermodynamic parameter kappa of solar energetic protons (κ EP) gradually increases, starting from the pre-ICME region (upstream of the CME-driven shock), reaching a maximum in the CME ejecta (κ EP ≈ 3.5), followed by a gradual decrease throughout the trailing portion of the CME; (2) the solar energetic proton temperature and density (T EP and n EP) appear anticorrelated, a behavior consistent with subisothermal polytropic processes; and (3) values of T EP and κ EP appear to be positively correlated, indicating an increasing entropy with time. Therefore, these proton populations are characterized by a complex and evolving thermodynamic behavior, consisting of multiple subisothermal polytropic processes, and a large-scale trend of increasing temperature, kappa, and entropy. This study and its companion study by Livadiotis et al. open up a new set of procedures for investigating the thermodynamic behavior of energetic particles and their shared thermal properties. [ABSTRACT FROM AUTHOR]

We explore the ability of an unmagnetized planet to retain an atmosphere as a function of its radius. We use a particle-in-cell hybrid code to simulate the global plasma interaction of unmagnetized terrestrial planets at 1 au under average solar wind conditions. We vary the radius of the planet |$(R_\mathrm{ p})$| from Mars-sized (⁠|$3390 \ \mathrm{km}$|⁠) to super-Earth-sized (⁠|$9390 \ \mathrm{km}$|⁠). We inject hydrogen and oxygen ion outflows from the ionosphere and quantify how the ion escape, recirculation, solar wind deposition, and net atmospheric mass flux vary as a function of planetary radius. We find that as the radius and the corresponding ionospheric outflow rate are varied, the fraction of outflowing |$\mathrm{ H^+}$| that escapes remains at |$15.5\pm 1.0{{\ \rm per\, cent}}$|⁠ , while the rest recirculates back towards the planet. The fraction of produced |$\mathrm{ O^+}$| that escapes from a Mars-sized planet is |$27\pm 1{{\ \rm per\, cent}}$|⁠ , and decreases to |$7\pm 1{{\ \rm per\, cent}}$| for super-Earth, suggesting that smaller planets are less able to retain heavy ions. We find, however, that larger planets have lower solar wind deposition fractions because their bow shocks are at greater distances from the surface of the planet. The ionospheric outflow rate at which mass deposition is equal to mass escape is found to be proportional to |$R_\mathrm{ p}^2$|⁠. Lastly, we propose that the bulk gyration of the solar wind at the induced magnetosphere can lead to differential escape trajectories of light and heavy ions. [ABSTRACT FROM AUTHOR]

Current work focuses on the potential of atmospheric agents such as gamma rays and plasma on conventional solar cell efficiency. Improving the device performance by depositing a ZnO or SrTiO 3 layer on the front surface of both monocrystalline and polycrystalline Si cells has been achieved. The electrical parameters detected by measuring the I-V characteristic are discussed. The results were analyzed using modified thermal emission theory to estimate the barrier height (Bo), ideality factor (n), series resistance (Rs) and shunt resistances (Rsh). Gamma irradiation at 1 kGy increased the open circuit voltage (V OC), the short circuit current (I sc), the voltage maximum point (V mp) and the current maximum point (I mp) , hence the maximum output power (P m) and efficiency (η) of both cell types. Concerning the dense plasma focus (DPF), the effect of H2 gas flow was found to increase the efficiency by 16.5 % and 22.5 %, respectively for mono and poly cells. The potential effect of the thin layer SrTiO3 (SrTiO3/Si) or ZnO (ZnO/Si) was recorded to lead to efficiency improvement of 24 % and 23 %, respectively for mono cells. Also, through SEM images, the morphology of the oxide surface was examined. The effect of light trapping and the reduction of recombination by the front layer in both SrTiO3/Si and ZuO/So cells on the PV performance and the role played by grain boundaries in polycrystalline cells were discussed. [ABSTRACT FROM AUTHOR]

Observations of the overall interactions between solar wind and the Earth's magnetosphere are crucial for space weather monitoring. Upcoming missions like the Solar Wind Magnetosphere Ionosphere Link Explorer (SMILE) and the Lunar Environment heliosphere X‐ray Imager (LEXI) aim to make comprehensive global imaging of Earth's magnetosphere using soft X‐ray imager (SXI) in order to understand its dynamic response to solar wind impact. Short‐duration X‐ray images have a low signal‐to‐noise ratio (SNR), limited by cosmic background and Poisson noise. Longer integration times provide better SNR of magnetospheric structures but fail to capture the short‐term dynamics during the integration. Our study introduces a neural network method which is able to estimate the short‐term dynamics during a long integration, driven by OMNI solar wind data and simulated soft X‐ray images. Specifically, an adaptive X‐ray image estimator and a spatio‐temporal discriminator are used. It leverages X‐ray models like Magnetohydrodynamic (MHD) and Jorgensen & Sun model, driven by OMNI data to provide high‐temporal‐resolution prior information on magnetosphere motion, with SXI observation images acting as a posterior constraint on the magnetosphere's state. Experimental validation demonstrates apparent improvements in Peak signal‐to‐noise ratio (PSNR) and Structural Similarity (SSIM) compared to traditional linear and optical flow interpolation methods. The method's flexibility, considering input‐output consistency, enables easy extension to any interval (>3 min), meeting diverse application needs. In conclusion, our study presents a new approach to soft X‐ray image estimation based on neural networks, providing insights into magnetospheric dynamics as observed in soft X‐rays. Plain Language Summary: New missions like SMILE and LEXI are set to provide detailed measurements using soft X‐ray imaging, offering insights into how the magnetosphere responds to solar wind. However, X‐ray observations with a short exposure time suffer from a low signal‐to‐noise ratio, while longer ones miss out on dynamic changes. This study introduces a neural network‐driven method to estimate magnetospheric dynamics using OMNI solar wind data and the expected SXI simulated observations. By combining models and observational data, this method improves upon traditional linear and optical flow interpolation techniques, offering better accuracy in capturing magnetospheric movements. The flexibility of this approach allows for its adaptation to various time intervals, making it a promising tool for studying magnetospheric dynamics in soft X‐rays. Key Points: A method is proposed for dynamically estimating changes in the Earth's magnetosheath using OMNI solar wind data and expected observationsWe use low‐resolution X‐ray images and high‐resolution solar wind data to estimate high‐time‐resolution X‐ray imagesThe method's flexibility enables easy extension to any interval (>3 min) for image estimation tasks, meeting diverse application needs [ABSTRACT FROM AUTHOR]

The Geomagnetism Group at the National Centers for Environmental Information (NCEI), in collaboration with the Cooperative Institute for Research in Environmental Sciences (CIRES), along with various government and industry partners, specializes in developing and providing access to Earth's internal magnetic field models. These models are crucial for applications such as compass navigation and wellbore positioning, offering reference values for the geomagnetic field (total field, dip or inclination, and declination) at any location across the Earth. This study assesses the Weimer geomagnetic perturbation model, proposed by Weimer in 2013, which is an empirical model of magnetic field variations at high latitudes driven by solar wind measurements, as a candidate for capturing geomagnetic field variations in high‐latitude areas. We compare the geomagnetic field variations predicted by the Weimer model against data from the INTERMAGNET and SuperMAG observatory networks. Our findings indicate that the Weimer model achieves a reduction in the standard deviations of high‐latitude magnetic field variations by approximately 20%–30% once quiet‐time baselines are removed from the data set. Furthermore, we compare the performance of the Weimer model against the Space Weather Modeling Framework's Geospace model during specific geomagnetic storms in 2017 and 2018, and we find that the Weimer model is more effective in predicting magnetic variations at high latitudes than the Geospace model during these storms. Additionally, comparisons to magnetometer data collected from high‐latitude directional‐drilling operations align with the trends observed in comparisons with INTERMAGNET and SuperMAG observatory data, confirming the Weimer model's reliability and effectiveness for such applications. Plain Language Summary: The Geomagnetism Group at the National Centers for Environmental Information (NCEI), in collaboration with the Cooperative Institute for Research in Environmental Sciences (CIRES), along with various government and industry partners, develops geomagnetic models that are used for navigation and oil drilling applications. At high latitudes, geomagnetic variations caused by the interaction between the solar wind and the Earth's magnetic field increases uncertainty in the models. This study assesses the Weimer geomagnetic perturbation model as a candidate to compensate for these geomagnetic variations. We compare the model to scientific ground observatories, and show that the model captures 20%–30% of the variation. We also demonstrate that the model is useful in applied setting by comparing the model to data collected from oil drilling operations. Key Points: The Weimer Geomagnetic Perturbation Model is evaluated for real‐time prediction of geomagnetic disturbances at high latitudesThe Weimer model reduces geomagnetic reference errors at high latitudes by 20%–30% based on comparisons to observatory dataMeasurement‐while‐drilling data show that the Weimer model can save valuable rig time by reducing geomagnetic reference model errors [ABSTRACT FROM AUTHOR]

A variety of magnetosphere‐ionosphere current systems and waves have been linked to geomagnetic disturbance (GMD) and geomagnetically induced currents (GIC). However, since many location‐specific factors control GMD and GIC intensity, it is often unclear what mechanisms generate the largest GMD and GIC in different locations. We address this challenge through analysis of multi‐satellite measurements and globally distributed magnetometer and GIC measurements. We find embedded within the magnetic cloud of the 23–24 April 2023 coronal mass ejection (CME) storm there was a global scale density pulse lasting for 10–20 min with compression ratio of ∼10 ${\sim} 10$. It caused substantial dayside displacements of the bow shock and magnetopause, changes of 6RE $6{R}_{E}$ and 1.3−2RE $1.3-2{R}_{E}$, respectively, which in turn caused large amplitude GMD in the magnetosphere and on the ground across a wide local time range. At the time this global GMD was observed, GIC measured in New Zealand, Finland, Canada, and the United States were observed. The GIC were comparable (within factors of 2–2.5) to the largest ever recorded during ≥ ${\ge} $14 year monitoring intervals in New Zealand and Finland and represented ∼ ${\sim} $2‐year maxima in the United States during a period with several Kp≥ ${\ge} $7 geomagnetic storms. Additionally, the GIC measurements in the USA and other mid‐latitude locations exhibited wave‐like fluctuations with 1–2 min period. This work suggests that large density pulses in CME should be considered an important driver of large amplitude, global GMD and among the largest GIC at mid‐latitude locations, and that sampling intervals ≤10s ${\le} 10s$ are required to capture these GMD/GIC. Plain Language Summary: We explore how disturbances in the Earth's magnetic field, known as geomagnetic disturbances (GMD), and the resulting geomagnetically induced currents (GIC) in power systems are influenced by different electrical currents and waves in near‐Earth space. One challenge is the lack of easily accessible data on GIC over long periods, which makes it hard to figure out what factors are most responsible for changes in GIC in different places. Also, there is limited research combining data from satellites with data collected on the ground to figure out exactly how GMD and GIC are generated. To tackle these issues, we looked at data collected by multiple satellites in different parts of near‐Earth space along with data from ground magnetometers and GIC measurements distributed around the world. Our results suggest that density pulses from coronal mass ejections, a particular type of structure in the solar wind, are important in causing significant disturbances in the Earth's magnetic field globally and contribute to some of the largest GIC seen in the mid‐latitude region of United States. We emphasize the importance of taking measurements with high sampling rates (≤10s) $(\le 10s)$ to accurately capture these disturbances and the resulting GIC. Key Points: A density pulse embedded in a coronal mass ejection drives global geomagnetic disturbances (GMD) and geomagnetically induced currents (GIC)Measured GIC's comparable to or exceed reference values in several regions, including 58.1 A in the mid‐latitude region of United StatesLarge‐amplitude density pulses are an important driver of GIC and GMD for mid‐latitude regions with large populations [ABSTRACT FROM AUTHOR]

The Iterative Driver Estimation and Assimilation (IDEA) data assimilation technique was used with the Whole Atmosphere Model (WAM) to improve neutral density specification in the upper thermosphere. Two different neutral density data sources were examined to enhance the capability of simulating the global thermospheric state. The first were accelerometer estimates of neutral density from the Challenging Mini‐Satellite Payload (CHAMP) satellite. The second were neutral density estimates from the Global Ultraviolet Imager (GUVI) limb‐scan airglow observations aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. Due to the intensity of the November 2003 storm, two changes were necessary in WAM. The first was allowing the Kp geomagnetic index to exceed 9 and the second was changing the relationship between Kp and the solar wind parameters used to drive the model. With these changes, results show that IDEA effectively captures the thermospheric neutral density at the CHAMP satellite altitude and follows the time‐dependence through the November 2003 storm period. Furthermore, a cross‐comparison was conducted with the GUVI dayside limb scan measurements. GUVI neutral densities within 270–320 km show the closest agreement with WAM when CHAMP data was assimilated by IDEA. We speculate on the potential for observations from GUVI at 300 km to be used as a data source in the IDEA‐WAM simulations. These simulations demonstrate the utility of the IDEA data assimilation technique with physical models and that using either accelerometer observations or ultraviolet airglow limb measurement during extreme storm periods could be used. Plain Language Summary: Strong variations in the neutral density of the thermosphere heavily impact the position of low Earth orbit objects as they respond to radiative inputs from the Sun in the extreme ultraviolet (UV) wavelength range, energetic particle precipitation in the auroral regions, and global‐scale electrical currents generated during geomagnetic storms. In this study, the Iterative Driver Estimation and Assimilation (IDEA) data assimilation technique was used with the Whole Atmosphere Model (WAM) to improve neutral density specification in the upper thermosphere. The Challenging Mini‐Satellite Payload (CHAMP) satellite and the Global Ultraviolet Imager (GUVI) limb scan UV airglow observations aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite were examined to enhance the capability of simulating the global thermospheric state. Results show that IDEA effectively captures the thermospheric neutral density at the CHAMP satellite altitude throughout the November 2003 storm period. Furthermore, GUVI limb scan measurements on the dayside were cross‐compared with IDEA densities. We speculate on the potential for observations from GUVI during the daytime to be used as a data source in the IDEA‐WAM simulations. This study demonstrates data assimilative physical models are capable of improving neutral density specification for better orbit determination and prediction of low Earth orbiting satellites. Key Points: Iterative Driver Estimation and Assimilation (IDEA) data assimilation system greatly improves the Whole Atmosphere Model (WAM) thermospheric neutral density nowcasting capabilityDifferent locations of observed and modeled high‐latitude density hole structures lead to discrepancy between Challenging Mini‐Satellite Payload and the model outputIDEA output is validated against Global Ultraviolet Imager data, indicating a potential use case for limb‐scan measurements in the WAM neutral density forecast [ABSTRACT FROM AUTHOR]

The present study investigates mid‐ and low‐latitude ground magnetic disturbances observed following the arrival of three interplanetary (IP) shocks during the super‐geomagnetic storms of February 1958 and July 1959. One may expect that after IP shocks, the H (northward) magnetic component increases globally but especially on the dayside. However, in each event, the H component was depressed sharply for 1–2 hr in the dawn‐to‐noon sector, whereas it increased in other local time (LT) sectors. Observed magnetic deflections suggest that there existed field‐aligned currents (FACs) flowing into and out of the auroral zone around the western and eastern edges of the LT sector of the dayside H depression. These features strongly suggests that the observed H depression was a remote effect of a R1‐sense FAC system. It was previously reported that similar ground magnetic disturbances were observed after the SSC of the 2003 Halloween storm, which reveals striking similarities to the well‐known H depression observed at Colaba during the 1859 Carrington storm. It is therefore suggested that the external driving behind IP shocks, especially those associated with major storms, is most optimum for the sharp reduction of the dayside H component through the formation and intensification of the dayside FAC system. Associated magnetic disturbances are considered to be larger in magnitude with increasing magnetic latitude, and oriented azimuthally as well as meridionally. Such magnetic disturbances in dayside midlatitudes may not be discussed very often as a target of space weather, but their potential impacts on ground infrastructures probably require closer attention. Plain Language Summary: Geomagnetic storms of February 1958 and July 1959 were historically intense. After the arrival of interplanetary (IP) shocks during these storms, the horizontal component of midlatitude magnetic field was sharply depressed at prenoon, but at other local times (LTs) it enhanced significantly as generally expected from solar wind compression. This LT distribution of magnetic disturbances can be explained by a dayside wedge‐shaped current circuit, which connects the magnetosphere with the ionosphere. Similar ground magnetic disturbances were reported previously for the October 2003 (Halloween) storm, and the extraordinary H depression observed at Colaba during the 1859 Carrington storm was also observed when Colaba was at prenoon. It is therefore suggested that the driver of this dayside current system, probably southward interplanetary magnetic field, often becomes extraordinarily large behind IP shocks, especially those of major storms, and intensifies this current system to unusual levels. The associated magnetic disturbance is expected to be larger at higher latitudes, and oriented in any direction. These features exhibit a distinct contrast to magnetic disturbances caused by other magnetospheric current systems (e.g., the ring current). Dayside ground magnetic disturbances are rarely discussed as a potential cause of hazardous space weather events, but probably deserve closer attention. Key Points: The H magnetic component was depressed sharply in dayside mid‐ and low latitudes following IP shock arrivals during the 1958 and 1959 stormsThe H depression was confined from dawn to noon, and the direction of magnetic deflection depended on local time as expected for an R1 field‐aligned current (FAC) systemFor extreme solar wind driving, this dayside R1 FAC system can be a potential cause of geomagnetic hazards especially in the subauroral zone [ABSTRACT FROM AUTHOR]

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