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EUropean Heliospheric FORecasting Information Asset (EUHFORIA) is a physics‐based data‐driven solar wind and coronal mass ejections (CMEs) propagation model designed for space weather forecasting and event analysis investigations. Although EUHFORIA can predict the solar wind plasma and magnetic field properties at Earth, it is not equipped to quantify the geo‐effectiveness of the solar transients in terms of geomagnetic indices like the disturbance storm time (Dst) index and the auroral indices, that quantify the impact of the magnetized plasma encounters on Earth's magnetosphere. Therefore, we couple EUHFORIA with the Open Geospace General Circulation Model (OpenGGCM), a magnetohydrodynamic model of the response of Earth's magnetosphere, ionosphere, and thermosphere to transient solar wind characteristics. In this coupling, OpenGGCM is driven by the solar wind and interplanetary magnetic field obtained from EUHFORIA simulations to produce the magnetospheric and ionospheric response to the CMEs. This coupling is validated with two observed geo‐effective CME events driven with the spheromak flux‐rope CME model. We compare these simulation results with the indices obtained from OpenGGCM simulations driven by the measured solar wind data from spacecraft. We further employ the dynamic time warping (DTW) technique to assess the model performance in predicting Dst. The main highlight of this study is to use EUHFORIA simulated time series to predict the Dst and auroral indices 1–2 days in advance, as compared to using the observed solar wind data at L1, which only provides predictions 1–2 hr before the actual impact. Plain Language Summary: Coronal mass ejections (CMEs) are gigantic eruptions of magnetized and charged matter (plasma) from the Sun that can propagate all the way to Earth and interact with Earth's magnetic shield, the magnetosphere. They can cause major disruptions in space‐ and ground‐based technologies, and in turn, affect our socio‐economic lives on Earth. Hence, we predict the arrival time of the CMEs and quantify the impact of such geomagnetic storms. Even with the 24 × 7 monitoring of the Sun from Earth's perspective, it is not possible to accurately predict the arrival times of Earth‐directed CMEs, and most importantly, assess the severity of the associated storms. Therefore, we perform 3D physics‐based modeling with the EUHFORIA model to track the CMEs from the Sun to Earth. EUropean Heliospheric FORecasting Information Asset (EUHFORIA) provides the plasma and magnetic field conditions near Earth. However, with just EUHFORIA output we cannot quantify the geomagnetic impact of the CMEs. Therefore, EUHFORIA output is used as input to OpenGGCM, a 3D physics‐based model that simulates the response of magnetosphere, ionosphere, and thermosphere to CME impact. With the joint EUHFORIA and OpenGGCM simulations, geomagnetic indices can be predicted 1–2 days in advance, thus making this a promising methodology for CME‐induced space weather forecasting. Key Points: The coupling of EUropean Heliospheric FORecasting Information Asset (EUHFORIA) with Open Geospace General Circulation Model (OpenGGCM), self‐consistently provides physics‐based predictions of the geo‐effectiveness of coronal mass ejections impactsGeomagnetic indices can be predicted 1–2 days in advance with EUHFORIA, as opposed to the much shorter predictions with real‐time L1 dataWe employ an advanced metric, Dynamic Time Warping, to account for time shifts, and to assess the model performance in predicting Dst [ABSTRACT FROM AUTHOR]

Carrier‐selective contact is a fundamental issue for solar cells. For silicon heterojunction (SHJ) solar cells, it is important to improve hole transport because of the low doping efficiency of boron in amorphous silicon and the barrier stemming from valence band offset. Here, we develop a carbon dioxide (CO2) plasma treatment (PT) process to form dipoles and defect states. We find a dipole moment caused by longitudinal distribution of H and O atoms. It improves hole transport and blocks electron transport and thus suppresses carrier recombination. In the meantime, the CO2 PT process also results in defect states, which reduce passivation performance but improve hole hopping in the intrinsic amorphous layer. As a balance, an appropriate CO2 PT process at the i/p interface increases fill factor and power conversion efficiency of SHJ solar cells. We emphasize, based on sufficient evidences, this work finds a distinct role of the CO2 plasma in SHJ solar cells opposed to reported mechanisms. [ABSTRACT FROM AUTHOR]

The United Nations 2030 plan establishes the incorporation of the Sustainable Development Goals (SDGs) as a multidisciplinary focus for training new specialized human resources. In engineering, the SDGs have been integrated into the curriculum as optional subjects. In this report, we present an investigation into implementing the SDGs in a Biomimicry and Sustainability course offered during the spring and fall semesters of 2022, with 194 students divided into six groups. Using challenge-based learning, students proposed utilizing wind or solar resources to generate electricity in a selected region. They were asked to conduct extensive research and precise engineering calculations to ensure the viability of their alternative energy sources. Additionally, each group had to select three or more SDGs that best aligned with their proposal, justifying their choices. The evaluation of the reports was based on rubrics and checklists that assessed the integrity of their argumentation and the adequacy of the report components. Most students chose SDGs 7, 11, and 13. In an anonymous survey, students expressed that incorporating the SDGs into the assignment significantly enhanced the importance of their learning experience. We recommend that other educators follow suit and incorporate the SDGs into their students’ projects or proposals, irrespective of whether their institution has a sustainability plan, aiming to transform sustainability into a competency rather than a fixed concept. [ABSTRACT FROM AUTHOR]

Electromagnetic Ion Cyclotron (EMIC) waves mediate energy transfer from the solar wind to the magnetosphere, relativistic electron precipitation, or thermalization of the ring current population, to name a few. How these processes take place depends on the wave properties, such as the wavevector and polarization. However, inferring the wavevector from in‐situ measurements is problematic since one needs to disentangle spatial and time variations. Using 8 years of Magnetospheric Multiscale (MMS) mission observations in the dayside magnetosphere, we present an algorithm to detect proton‐band EMIC waves in the Earth's dayside magnetosphere, and find that they are present roughly 15% of the time. Their normalized frequency presents a dawn‐dusk asymmetry, with waves in the dawn flank magnetosphere having larger frequency than in the dusk, subsolar, and dawn near subsolar region. It is shown that the observations are unstable to the ion cyclotron instability. We obtain the wave polarization and wavevector by comparing Single Value Decomposition and Ampere methods. We observe that for most waves the perpendicular wavenumber (k⊥) is larger than the inverse of the proton gyroradius (ρi), that is, k⊥ρi > 1, while the parallel wavenumber is smaller than the inverse of the ion gyroradius, that is, k‖ρi < 1. Left‐hand polarized waves are associated with small wave normal angles (θBk < 30°), while linearly polarized waves are associated with large wave normal angles (θBk > 30°). This work constitutes, to our knowledge, the first attempt to statistically infer the full wavevector of proton‐band EMIC waves observed in the outer magnetosphere. Key Points: We conduct a statistical analysis of proton‐band Electromagnetic Ion Cyclotron (EMIC) waves in dayside magnetosphere using 8 years of Magnetospheric Multiscale data and measure full wavevectorsThe normalized frequency of EMIC waves presents a dawn‐dusk asymmetryThe perpendicular wavevector is, for most of the waves, larger than the inverse of proton gyroradius and ion inertial lengths [ABSTRACT FROM AUTHOR]

Transient events like hot flow anomalies and foreshock bubbles are common in the Earth's foreshock. These foreshock transients may play an important role in the solar wind‐magnetosphere interaction. They typically occur when backstreaming ions accumulate at the intersection of interplanetary magnetic field (IMF) discontinuities with the bow shock. Discontinuity orientations play a key role in determining when and where transients form in the foreshock and strike the magnetopause. They also play a role in determining the amplitude, and significance, of individual transients. We investigate properties of the IMF discontinuity normals across two solar cycles. We compare Advanced Composition Explorer (ACE) IMF discontinuity observations for 2001, 2002, 2012, and 2014 (solar maximum) and 2008, 2009, 2019, and 2020 (solar minimum). We employ both the Minimum variance analysis (MVA) and Cross‐product methods to determine phase front normals. Most discontinuity normals point earthward and dawnward at longitudes ranging from 180° to 250°. A greater range of normal can be seen during solar minimum than during solar maximum. Normals lie further from the Sun‐Earth line when solar wind densities are low and velocities are high. This provides a natural explanation for the observed tendency of transients to occur for low solar wind densities and high velocities in terms of longer discontinuity interaction times with the bow shock. Key Points: ACE discontinuity normals for solar maximum and minimum periods during two solar cycles were used, employing MVA and Cross‐Product methodsMost of the discontinuity normals are directed earthward and dawnward and the majority fall in the equatorial planeThe discontinuity normal is highly dependent on solar wind speed and density [ABSTRACT FROM AUTHOR]

Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular oxygen ions (O+ and O2+ ${\mathrm{O}}_{2}^{+}$) at Mars. We use MAVEN data to evaluate ion escape from 1 February 2016 through 25 May 2022. We find that Martian O+ and O2+ ${\mathrm{O}}_{2}^{+}$ both have increased escape flux with increased solar wind kinetic energy flux and this relationship is generally logarithmic. Increased solar wind electromagnetic energy flux also corresponds to increased O+ and O2+ ${\mathrm{O}}_{2}^{+}$ escape flux, however, increased solar wind electromagnetic energy flux seems to first dampen ion escape until a threshold level is reached, at which point ion escape increases with increasing electromagnetic energy flux. Increased solar irradiance (both total and ionizing) does not obviously increase escape of O+ and O2+ ${\mathrm{O}}_{2}^{+}$. Our results suggest that the solar wind electromagnetic energy flux should be considered along with the kinetic energy flux as an important driver of ion escape, and that other parameters should be considered when evaluating solar irradiance's impact on O+ and O2+ ${\mathrm{O}}_{2}^{+}$ escape. Plain Language Summary: Mars was once like Earth with a dense atmosphere enabling liquid water to exist on its surface. However, in the billions of years since then, Mars has lost much of its atmosphere to space. We study how energy inputs from the Sun and from the solar wind can drive escape of the ionized constituents of water from Mars' atmosphere. Ion escape is one of several processes of atmospheric loss, and it is a particularly effective process for removing species heavier than hydrogen and helium from terrestrial atmospheres. We find that previously unconsidered energy fluxes may play an important role in driving ion escape. Key Points: Increased solar wind electromagnetic energy flux increases escape of O+ and O2+ ${\mathrm{O}}_{2}^{+}$O+ and O2+ ${\mathrm{O}}_{2}^{+}$ have increased escape rates with increased solar wind kinetic energyUnclear dependence on increased solar irradiance for O+ and O2+ ${\mathrm{O}}_{2}^{+}$ escape [ABSTRACT FROM AUTHOR]

This study delves into a Pick‐Up Ion (PUI) event captured by the Mars Ion and Neutral Particle Analyzer aboard Tianwen‐1, revealing a faster acceleration than expected within the Martian magnetosheath. This event suggests the presence of a convection electric field considerably stronger than that typically observed in the solar wind. Through Magnetohydrodynamic simulation, we identified two regions of intensified convection electric fields within the inner magnetosheath, prominently manifested at mid to high solar zenith angles (SZA = 40°–70°) in the X‐Z plane of the Mars Solar Electric field coordinates. Tianwen‐1 observed that the peak of the electric field strength, up to five times of that in the solar wind, is located at the upper edge or within the Magnetic Pileup Boundary. Further study by test particle simulations showed acceleration by the electric field effectively doubles the energy gain of PUIs, in comparison to scenarios absent of this extra acceleration. It is revealed that the presence of such electric field regions within the Martian magnetosheath is a prevailing feature, shaped by the solar wind's interaction with Mars and modulated by the planet's rotating crustal magnetic fields. Plain Language Summary: The interaction between planets and their upstream solar wind holds great significance for the long‐time climate evolution of planets. Mars lacks a global dipole magnetic field, which makes it easier for these planetary ions to escape through acceleration by the solar wind convection electric field. The observations of Tianwen‐1 and Mars Atmosphere and Volatile Evolution satellites provide a great opportunity to study the acceleration of planetary ions by this electric field. Through a case study involving observation and simulation, we confirm that there are two regions in the Martian magnetosheath, where the convection electric field is stronger than in the solar wind. This electric field may rapidly energize the ions and possibly result in intensified ion escape. Key Points: In the Martian magnetosheath, joint effects of the plasma flow around Mars and the interplanetary magnetic field pileup result in enhanced convection electric fieldThe strong E field envelops a large part of the Magnetic Pileup Boundary (MPB), with the maximum at the med‐high solar zenith angles, at the upper edge or within the MPBThe crustal magnetic fields modulate the distribution of the strong E field, leading to hemispheric asymmetry [ABSTRACT FROM AUTHOR]

Hot flow anomalies (HFAs) are typical and important foreshock transients characterized by large flow deflection and plasma heating. HFAs can deform the Earth's bow shock by dynamic pressure perturbation resulting in disturbance in the magnetosphere and ionosphere. Traditionally, HFAs are believed to be associated with discontinuities. But recently, HFA‐like structures were simulated by a magnetohydrodynamics (MHD) model without the discontinuity prerequisite. In this study, three HFA‐like structures are shown to present the MHD formation mechanism. Multi‐points observation by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission tracks the formation of an HFA from a density depletion upstream. HFAs with high‐ or low‐ density cores are observed by the Magnetospheric Multiscale mission in the flank region. The comparisons of the observation and their simulation show general agreement, particularly in the presence of a core with strong heating and velocity deflection, and two compression regions (shocks) with clear maxima in the ram pressure with a strongly inclined normal boundary at the leading edge and moderately inclined at the trailing edge. Agreement is better when the MHD simulations used a transient change to quasi‐parallel solar wind magnetic field during the events. Key Points: Hot flow anomalies (HFAs) can form from the reformation of the fast shock geometry by a low‐density flux tubeHFAs with either high‐ or low‐density cores are reproduced by a magnetohydrodynamics (MHD) modelThe observations and the corresponding MHD model have good consistencies [ABSTRACT FROM AUTHOR]

Ion escape has played a key role in atmospheric loss on ancient Mars due to intense solar activity. Under the existence of a strong global intrinsic magnetic field, as expected on ancient Mars, differential flows between different ion species can be important for ion escape. To assess effects of differential flows, we here developed a new global multifluid magnetohydrodynamics model with a cubed sphere grid named Multifluid Atmospheric Escape Simulations Toward Real elucidatiOn (MAESTRO). A test simulation under present‐day Mars conditions showed solar wind‐Mars interactions, for example, plasma boundaries, ionospheric profiles, and tailward outflows, consistent with observations and simulation studies. We then conducted multifluid and multispecies simulations with six different dipole field strengths under ancient Mars conditions. The multifluid cases show asymmetric outflow distributions with respect to the solar wind convection electric field, as pointed out by previous studies on present‐day Mars. Compared with multispecies cases, the multifluid representation increases the escape rates of O2+ and CO2+ by more than two orders of magnitude in the strong dipole field cases where the cusp outflow is dominant. The O+ escape rate is slightly lower in the multifluid cases with no or weak dipole field due to suppression of ion pickup in the −E hemisphere, while it is reduced by one order of magnitude in the strongest dipole field case. The existence of a dipole field can reduce the total escape rate by a factor of six. The impact on atmospheric evolution is diminished but still significant. Plain Language Summary: Mars lost a significant part of the atmosphere during its early period and experienced a drastic climate change. The escape of charged atmospheric particles to space, called ion escape, is a significant removal process of the atmosphere because the activity of the young Sun was much stronger and stripped out the upper atmosphere of early Mars more powerfully. However, it is thought that Mars once had an intrinsic magnetic field like Earth, which can affect the escape of charged particles via electromagnetic forces. To reproduce the realistic processes and morphology of ion escape under the presence of a planetary intrinsic magnetic field, we developed a new simulation model that treats each ion species as a separate fluid. The simulation results of the new model show much stronger molecular ion outflow from the ionosphere at relatively low altitudes compared to our previous studies. The outflow enhancement is more remarkable when a stronger intrinsic magnetic field is assumed. On the other hand, atomic ion escape from high altitudes is not affected largely. The new model indicates that the effects of a planetary intrinsic magnetic field on ion escape are reduced, though still of significance. Key Points: A new global multifluid magnetohydrodynamics (MHD) model of solar wind‐Mars interactions with a cubed sphere grid system named Multifluid Atmospheric Escape Simulations Toward Real elucidatiOn is developedThe multispecies MHD cases underestimate outflows of ionospheric ions in strong dipole field cases where cusp outflow is importantThe effects of the multifluid representation on the O+ escape rate are small in no and weak dipole field cases where ion pickup is dominant [ABSTRACT FROM AUTHOR]

The ion foreshock is highly dynamic, disturbing the bow shock and the magnetosphere‐ionosphere system. To forecast foreshock‐driven space weather effects, it is necessary to model foreshock ions as a function of upstream shock parameters. Case studies in the accompanying paper show that magnetosheath ions sometimes exhibit strong field‐aligned asymmetry toward the upstream direction, which may be responsible for enhancing magnetosheath leakage and therefore foreshock ion density. To understand the conditions leading to such asymmetry and the potential for enhanced leakage, we perform case studies and a statistical study of magnetosheath and foreshock region data surrounding ∼500 Time History of Events and Macroscale Interactions during Substorms mission bow shock crossings. We quantify the asymmetry using the heat flux along the field‐aligned direction. We show that the strong field‐aligned heat flux persists across the entire magnetosheath from the magnetopause to the bow shock. Ion distribution functions reveal that the strong heat flux is caused by a secondary thermal population. We find that stronger asymmetry events exhibit heat flux preferentially toward the upstream direction near the bow shock and occur under larger IMF strength and larger solar wind dynamic pressure and/or energy flux. Additionally, we show that near the bow shock, magnetosheath leakage is a significant contributor to foreshock ions, and through enhancing the leakage the magnetosheath ion asymmetry can modulate the foreshock ion velocity and density. Our results imply that likely due to field line draping and compression against the magnetopause that leads to a directional mirror force, modeling the foreshock ions necessitates a more global accounting of downstream conditions. Key Points: Ion field‐aligned asymmetry persists across the magnetosheath, caused by a secondary thermal population of magnetosheath ionsLarger IMF strength and solar wind dynamic pressure and/or energy flux favor stronger field‐aligned asymmetryNear the bow shock, the foreshock ion velocity and density are modulated by the magnetosheath ion field‐aligned asymmetry [ABSTRACT FROM AUTHOR]

The ring current, an equatorial near‐Earth current, fluctuates in response to solar wind plasma interactions with Earth's magnetosphere. Despite extensive research on storm‐time ring current energization, direct evidence of the energy transport into the inner‐magnetosphere that powers this current remains scarce. Recent observations revealing that very‐near‐Earth reconnection (VNERX, occurring at geocentric distance <14 RE) can occur during storms suggest that such reconnection could play an important role in ring current development. Here we address how common VNERX is. We use inner‐magnetosphere and plasma sheet observations from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites spanning 13 years. During this period, THEMIS observed 512 storms and 7 VNERX events. All VNERX events occurred during storm main‐phase at or near the pre‐midnight sector (None were observed during storm recovery‐phase.). The events occurred within 1 RE of the modeled neutral sheet, suggesting that VNERX events are elusive because they lie near the neutral sheet. Since THEMIS spent 5,253 hr within 1 RE of the modeled neutral sheet during storm main‐phase, the inferred observational VNERX occurrence rate is 1.3 per 1,000 hr of storm main‐phase. This rate is lower than published ion‐diffusion‐region occurrence rates seen in the near‐Earth plasma sheet during non‐storm times (likely substorms). These results suggest that while VNERX events might be significant for the storm‐time ring current's initial buildup (during storm main‐phase), other transport mechanisms, like enhanced global convection, may be responsible for maintaining the strength of the ring current during storm recovery‐phase. Key Points: Very‐Near‐Earth reconnection (VNERX) events have an observed occurrence rate of 1.3 events per 1,000 hr of storm main phaseVNERX may be important for the initial buildup of the main‐phase ring currentVNERX is predominately observed in the pre‐midnight sector [ABSTRACT FROM AUTHOR]

Certain forms of solar wind transients contain significant enhancements of dynamic pressure and may effectively drive magnetosphere dynamics, including substorms and storms. An integral element of such driving is the generation of a wide range of electromagnetic waves within the inner magnetosphere, either by compressionally heated plasma or by substorm plasma sheet injections. Consequently, solar wind transient impacts are traditionally associated with energetic electron scattering and losses into the atmosphere by electromagnetic waves. In this study, we show the first direct measurements of two such transient‐driven precipitation events as measured by the low‐altitude Electron Losses and Fields Investigation CubeSats. The first event demonstrates storm‐time generated electromagnetic ion cyclotron waves efficiently precipitating sub‐relativistic and relativistic electrons from >300 keV to 2 MeV at the duskside. The second event demonstrates whistler‐mode waves leading to scattering of electrons from 50 to 700 keV on the dawnside. These observations confirm the importance of solar wind transients in driving energetic electron losses and subsequent dynamics in the ionosphere. Key Points: A corotating interaction region (CIR) and interplanetary coronal mass ejection (ICME), both including interplanetary shocks, are observed resulting in relativistic electron precipitation from low‐altitude orbitDuskside precipitation after CIR impact is driven by intense electromagnetic ion cyclotron waves, showing distinct energy‐L dispersion from magnetic field distortionDawnside precipitation after ICME impact is driven by intense whistler‐mode waves resonating with electrons at high latitudes [ABSTRACT FROM AUTHOR]

The ionospheric convection electric field is often assumed to be a potential field. This assumption is not always valid, especially when the ionosphere changes on short time scales T≲5 $T\lesssim 5$ min. We present a technique for estimating the induction electric field using ground magnetometer measurements. The technique is demonstrated on real and simulated data for sudden increases in solar wind dynamic pressure of ∼ ${\sim} $1 and 10 nPa, respectively. For the real data, the ionospheric induction electric field is 0.15 ± $\pm $ 0.015 mV/m, and the corresponding compressional flow is 2.5 ± $\pm $ 0.3 m/s. For the simulated data, the induction electric field and compressional flow reach 3 mV/m and 50 m/s, respectively. The induction electric field can locally constitute tens of percent of the total electric field. Inclusion of the induction electric field increased the total Joule heating by 2.4%. Locally the Joule heating changed by tens of percent. This corresponds to energy dissipation that is not accounted for in existing models. Plain Language Summary: In the study of ionospheric dynamics, it is often assumed that the ionospheric electric field is a potential field. This means the contribution from induction is neglected. The induction electric field is described by Faraday's law and relates to temporal changes in the magnetic field. This assumption only holds when the ionospheric dynamics change slowly. In this study, we present a technique for calculating the ionospheric induction electric field using measurements of the magnetic field on the ground. We demonstrate the technique on real and simulated data of a dynamic event, that is, a sudden commencement. We find that the induction electric field, on a global scale, is small compared to the potential electric field. Inclusion of the induction electric field increased the total energy dissipation, that is, Joule heating, by only a couple of percent but resulted in local variations of tens of percent. Furthermore, we quantified and visualized the compression flow which is the compression and expansion of the magnetic field related to the temporal evolution of a dynamic ionospheric event. Key Points: A method for estimating the induction electric field using ground magnetometer measurements is presentedLocally, the estimated induction electric field can constitute tens of percent of the total electric fieldThe spatial pattern of ionospheric Joule heating is shown to be highly affected by the induction electric field, even during weak induction [ABSTRACT FROM AUTHOR]

The secondary processes driven by the velocity shear driven Kelvin‐Helmholtz Instability (KHI) in the magnetized plasmas have been shown to be important in producing plasma transport and heating from the shocked solar wind into the Earth's magnetosphere (MSP). The plasma transport into the MSP due to KHI has been shown to be strongest during northward interplanetary magnetic field (IMF) via KHI driven low‐ and mid‐latitude reconnection process. In a recent article, Li et al. (2023), https://doi.org/10.1029/2023gl105539 show Magnetosphere Multi‐Scale (MMS) spacecraft observations of multiple, Alfvénic reconnection jets during southward IMF at the dawn‐side MSP flank. The quasi‐periodic oscillations in plasma parameters and compressed, ion‐scale current sheets were strongly indicative of the MMS crossing regions of MSP‐like and magnetosheath‐like plasma within Kelvin‐Helmholtz waves. In this brief commentary, the importance of this new discovery for magnetospheric and solar wind dynamics is discussed. Plain Language Summary: Earth's magnetic field serves as a protective barrier, forming a magnetic bubble known as the magnetosphere in the solar wind. Acting like a shield, the magnetopause is a crucial surface that delineates the separation between the solar wind and the plasma enveloped within Earth's magnetosphere. However, this shield is not impervious; a phenomenon called magnetic reconnection can compromise it, permitting direct access for solar wind plasma. This process is particularly effective when the interplanetary magnetic field (IMF) carried by the solar wind opposes Earth's magnetic field direction, a configuration known as "southward" IMF. Under these conditions, the Earth's magnetic field opens at the dayside, facilitating the accumulation of mass, momentum, and energy into the night‐side magnetotail. In a recent discovery, NASA's four Magnetosphere Multiscale spacecraft revealed that magnetic reconnection can also occur during southward IMF at the tail flanks of our magnetic bubble. This reconnection, strongly driven by colossal waves with wavelengths of 56,000 km (Kelvin‐Helmholtz waves) creates portals in our magnetic shield, enabling both the escape and entry of particles. In this brief commentary, the importance of this finding is discussed, both for magnetospheric and solar wind dynamics. Key Points: Kelvin‐Helmholtz Instability (KHI) can generate compressed current sheets, effectively driving magnetic reconnection at flanks during southward interplanetary magnetic fieldKHI driven reconnection can aid energetic particle escape from the magnetosphereKHI driven reconnection may also play role for energetic particle dynamics within solar wind structures [ABSTRACT FROM AUTHOR]

The dayside particle precipitation during the passage of a solar wind rotational discontinuity (RD) event on 10 April 2015 is examined and reviewed. The RD leads to complex structures at the magnetopause, boundary layer, mantle, and cusp even though the geomagnetic activity level remains low. Particle precipitation data from DMSP F17 reveal the formation of an unusual boundary layer where the low energy (cold) ions exhibit energy-latitude dispersion that is usually associated with mantle while the high energy (hot) ions look like typical magnetospheric ions. DMSP F17 and F19 observe a double cusp that is a signature of magnetic reconnection occurring at both high- and low-latitudes due to the dominant IMF By. A global MHD simulation of the event supports the existence of the simultaneous reconnections at high- and low-latitude magnetopause that are consistent with the anti-parallel and component merging models, respectively. Finally, Cluster C2, located at high-latitude and high-altitude in the southern hemisphere, observes velocity fluctuations and reversals with peak-to-peak amplitudes >800 km s-1 as it crosses the magnetopause. Guided by the MHD simulation, the Cluster observation can be interpreted as the spacecraft crossing reconnection outflows while moving from one side of the X-line to the other. [ABSTRACT FROM AUTHOR]

We evaluate the temporal complementarity in daily averages between wind and solar power potential in Chile using Spearman's correlation coefficient. We used hourly wind speed and solar radiation data for 176 geographic points from 2004 to 2016. The results allow us to identify four zones: Zone A1 on the coast and in the valleys in the north of Chile between latitudes 18° S and 36° S, with moderate positive correlation; Zone A2 in the north Andes between latitudes 25° S and 33° S, with weak negative correlation; Zone B in the center-south part of the country between latitudes 36° S and 51° S with moderate negative correlation; and Zone C in the south, between latitudes 51° S and 55° S with null or weak positive correlation. On the one hand, the interannual analysis shows that Zone A1 keeps uniform correlation values with negative asymmetry, i.e., higher correlation values. On the other hand, there is positive asymmetry in most of the years in Zone A2, i.e., lower (or negative) values of correlation. Zone B shows an interannual oscillation of the median correlation, while Zone C shows a larger dispersion in the interannual results. Significance analysis shows that 163 out of the 176 points are statistically significant, while Zones A1, A2, and B have significant correlations, with Zone C being marginally significant. The results obtained are relevant information for further studies on the location of hybrid generation facilities. We expect our methodology to be instrumental in Chile's energetic transition to a 100% renewable generation matrix. [ABSTRACT FROM AUTHOR]

The variation in key parameters of the solar–terrestrial space during two consecutive auroral disturbances (the magnetic storm index, Dst index = −422 nT) that occurred during the 18–23 November 2003 period was analyzed in this paper, as well as the spatiotemporal characteristics of NO 5.3 μm radiation with an altitude around the location of 55°N 160°W. The altitude was divided into four regions (50–100 km, 100–150 km, 150–200 km, and 200–250 km), and it was found that the greatest amplification occurs at the altitude of 200–250 km. However, the radiance reached a maximum of 3.38 × 10−3 W/m2/sr at the altitude of 123 km during the aurora event, which was approximately 10 times higher than the usual value during "quiet periods". Based on these findings, the spatiotemporal variations in NO 5.3 μm radiance within the range of latitude 51°S–83°N and longitude of 60°W–160°W were analyzed at 120 km, revealing an asymmetry between the northern and southern hemispheres during the recovery period. Additionally, the recovery was also influenced by the superposition of a second auroral event. The data used in this study were obtained from the OMNI database and the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) infrared radiometer onboard the TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) satellite. Finally, the correlation of NO 5.3 μm radiance at 120 km with temperature, solar wind speed, auroral electrojet index (AE index), and Dst index were analyzed. It was found that only the Dst index had a good correlation with the radiance value. Furthermore, the correlation between the Dst index and radiance at different altitudes was also analyzed, and the highest correlation was found at 170 km. [ABSTRACT FROM AUTHOR]

Magnetic flux ropes are ubiquitous in various space environments, including the solar corona, interplanetary solar wind, and planetary magnetospheres. When these flux ropes intertwine, magnetic reconnection may occur at the interface, forming disentangled new ropes. Some of these newly formed ropes contain reversed helicity along their axes, diverging from the traditional flux rope model. We introduce new observations and interpretations of these newly formed flux ropes from existing Hall Magnetohydrodynamics model results. We first examine the time‐varying local magnetic field direction at the impact interface to assess the likelihood of reconnection. Then we investigate the electric current system to describe the evolution of these structures, which potentially accelerate particles and heat the plasma. This study offers novel insights into the dynamics of space plasmas and suggests a potential solar wind heating source, calling for further synthetic observations. Plain Language Summary: This research examines a special type of systematically twisted magnetic fields, known as flux ropes, in the sun's atmosphere, the solar wind, and near planets. Built on earlier model results, this examination brings a new understanding of how these special flux ropes emerge from collisions between flux ropes. These results use a commonly used simulation tool for large‐scale plasmas to study the new ropes formed after two flux ropes are pushed toward each other long enough. In some cases, each of the new ropes may have opposite twists between their two ends. We then examine how the magnetic field changes across the interface during the evolution. Changes in electric currents found in these situations further explain the formation and evolution of the new rope pairs. This examination helps to better understand the behavior of space plasma's heating of the solar wind and its control of space weather. Key Points: We examine the interaction of magnetic flux ropes that consist of opposite helicity along their axes using numerical simulationsWe present the evolution of their current system, from which we anticipate a significant amount of energy releaseThese structures could be present on the solar surface, in the solar wind, and in magnetospheres [ABSTRACT FROM AUTHOR]

• A synchrony exists between input and dissipated energy during storms' main phases. • The overall energy budgets exhibited maximum values during storms' main phases. • The highest output energy was observed between 0400 and 0800 UT. The solar wind-magnetosphere energy transfer is one major way of quantifying the impacts of space weather on the Earth's environment. Studies on solar wind-magnetosphere energy transfer in terms of sub-daily time scales are quite sparse. Consequently, in order to investigate storm-time characteristics of the solar wind-magnetosphere energy transfer at a 4-hourly time scale over solar cycle 23, a total of 85 major geomagnetic storms (Dst ≤ −100 nT) were categorized into bins, using the points of minimum Dst values as reference points. Additionally, the monthly statistics of the storms occurrences over the solar cycle was carried out. The statistics followed a semi-annual periodicity, with a lesser peak in the months of May and August, and a major peak in October and November. Furthermore, the energy dissipated was estimated by the summation of aurora precipitation, Joule heating, and the ring current injection. Overall, from the data analyzed, we observed storm-time intensification of energy transfer. The magnetosphere received the highest energy during the time interval 0400–0800 UT (0900–1300 LT in the American sector, and most impactful there), while the lowest energy transfer was recorded between 0000 and 0400 UT (0200–0600 LT in the African/European sector, and least impactful there). We observed a synchrony between the energy dissipated and energy input for the storms' main phases. Generally, storms driven by a composite of two Interplanetary Coronal Mass Ejections (ICMEs) transients transferred highest energy into the magnetosphere, while those driven by Co-rotating Interaction Regions (CIRs) transferred lowest energy. [ABSTRACT FROM AUTHOR]

We investigate variations in the position of the magnetopause in response to the interplanetary magnetic field (IMF), and different phases of magnetospheric substorms. The average location of magnetopause is examined using magnetic field observations from multiple satellites (THEMIS, RBSP, and MMS), and the Shue model utilizing OMNI solar wind data for a period of five years from 2016–2020. We estimate average position of the magnetopause using Shue model through superposed epoch analysis of standoff distance and tail flaring angle at different substorm timings (onset, peak and end) and from in-situ measurements through 2D equatorial maps of average Δ BZ under IMF | Bz |> 0 conditions. Our findings reveal the occurrence of substorms during both northward and southward IMF orientations and highlight an earthward movement of the magnetopause during substorm onset and peak, followed by a relaxation during the substorm end time, for both northward and southward IMF orientations. Notably, the magnetopause undergoes significant compression and reaches its closest point to the Earth during instances of strong southward IMF (BZ < -5), particularly during the substorm peak. The empirical model provides accurate estimation of the magnetopause location during periods of both strong northward and southward IMF | Bz |>5, as the model curve traverses a distinct location (Δ BZ = 0) representing the magnetopause shown in the 2D average map of Δ BZ. [ABSTRACT FROM AUTHOR]

The boundary between the interplanetary magnetic field and the terrestrial magnetic field is the magnetopause. This magnetopause is influenced by dynamic changes in the solar wind, that is different solar wind conditions lead to a change in the shape and location of the magnetopause. The interaction between the solar wind and the magnetosphere can be studied from in-situ spacecraft observations. Many studies focus on the equatorial plane, as this is where recent spacecraft constellations such as THEMIS or MMS operate. However, to fully capture the interaction, it is important to study the high latitude regions as well. The Cluster spacecraft allow us to collect a dataset of high-latitude magnetopause crossings and study magnetopause motion in this region, as well as deviations from established magnetopause models. We use multi-spacecraft analysis tools to investigate the direction of magnetopause motion in the high latitudes and compare the occurrence of crossings at different locations with the result in the equatorial plane. We find that the high-latitude magnetopause motion is generally consistent with previously reported values and seems to be more often associated with a closed magnetopause boundary. We show that on average the magnetopause moves faster inwards than outwards. Furthermore, the occurrence of magnetopause positions beyond those predicted by the Shue et al. (1998) model at high latitudes is found to be caused by the similar solar wind parameters as in the equatorial plane. Finally, we highlight the importance of the dipole tilt angle at high latitudes. Our results may be useful for the interpretation of plasma measurements from the upcoming SMILE mission (Branduardi-Raymont et al., 2018), as this spacecraft will also fly frequently through the high-latitude magnetopause. [ABSTRACT FROM AUTHOR]

The strongly coupled hydrodynamic, magnetic, and radiation properties of the plasma in the solar chromosphere make it a region of the Sun's atmosphere that is poorly understood. We use data obtained with the high-resolution Visible Broadband Imager (VBI) equipped with an H β filter and the Visible Spectro-Polarimeter (ViSP) on the Daniel K. Inouye Solar Telescope to investigate the fine-scale structure of the plage chromosphere. To aid in the interpretation of the VBI imaging data, we also analyze spectra from the CHROMospheric Imaging Spectrometer on the Swedish Solar Telescope. The analysis of spectral properties, such as enhanced line widths and line depths, explains the high contrast of the fibrils relative to the background atmosphere demonstrating that H β is an excellent diagnostic for the enigmatic fine-scale structure of the chromosphere. A correlation between the parameters of the H β line indicates that opacity broadening created by overdense fibrils could be the main reason for the spectral line broadening frequently observed in chromospheric fine-scale structures. Spectropolarimetric inversions of the ViSP data in the Ca ii 8542 Å and Fe i 6301/6302 Å lines are used to construct semiempirical models of the plage atmosphere. Inversion outputs indicate the existence of dense fibrils in the Ca ii 8542 Å line. The analyses of the ViSP data show that the morphological characteristics, such as orientation, inclination, and length of fibrils, are defined by the topology of the magnetic field in the photosphere. Chromospheric maps reveal a prominent magnetic canopy in the area where fibrils are directed toward the observer. [ABSTRACT FROM AUTHOR]

We describe a novel method for modeling the global, steady solar wind using photospheric magnetic fields as a driving boundary condition. Prior wind models in this class include both rapid heuristic methods that use potential field extrapolation and variants thereof, trading rigor for computation speed, and detailed 3D magnetohydrodynamic (MHD) models that attempt to simulate the entire solar corona with a degree of physical rigor, but require large amounts of computation. The Field Line Universal relaXer, an open-source numerical code that implements the "fluxon" semi-Lagrangian approach to MHD modeling, provides an intermediate approach between these two general classes. In particular, the fluxon approach to MHD describes the magnetic field through discrete analogs of magnetic field lines, relaxing these structures to a stationary state of force balance. In this work we introduce a 1D solar wind solution along each field line, providing an ensemble of solutions that are interpolated back onto a uniform grid at an outer boundary surface. This provides advantages in physical rigor over heuristic semianalytic techniques, and in computational efficiency over full 3D MHD techniques. Here we describe the underlying methodology and the FLUXPipe modeling pipeline process. [ABSTRACT FROM AUTHOR]

In a previous study, Huang et al. used the Alfvén Wave Solar atmosphere Model, one of the widely used solar wind models in the community, driven by ADAPT-GONG magnetograms to simulate the solar wind in the last solar cycle and found that the optimal Poynting flux parameter can be estimated from either the open field area or the average unsigned radial component of the magnetic field in the open field regions. It was also found that the average energy deposition rate (Poynting flux) in the open field regions is approximately constant. In the current study, we expand the previous work by using GONG magnetograms to simulate the solar wind for the same Carrington rotations and determine if the results are similar to the ones obtained with ADAPT-GONG magnetograms. Our results indicate that similar correlations can be obtained from the GONG maps. Moreover, we report that ADAPT-GONG magnetograms can consistently provide better comparisons with 1 au solar wind observations than GONG magnetograms, based on the best simulations selected by the minimum of the average curve distance for the solar wind speed and density. [ABSTRACT FROM AUTHOR]

To shed light on potential differences in the magnetosphere-solar wind coupling processes between both cycles, this study examines the link between solar wind characteristics and the Dst index during Solar Cycles (SCs) 24 and 25. In this study, we look into the correlation between geomagnetic storms and several solar wind parameters (solar wind speed, solar wind plasma temperature, solar wind proton density, and flow pressure), sunspot number, Ey, cosmic ray intensity (CRI) and geomagnetic index Dst for SC 24 (start Dec 2008 to end Dec 2019) and SC 25 (start Dec 2019 to 10th August 2023). With the use of the superposed epoch method (Chree analysis), comparative research has been conducted. Solar wind plasma temperature is a geoeffective parameter for SC 24, according to the findings of the current investigation. Compared to other solar wind parameters, the temperature (0.7) of the solar wind has a stronger link with geomagnetic storms. For SCs 24 and 25, the correlation between Dst and CRI is 0.2 and 0.9, respectively. SC 24 and 25 for Dst and Ey have correlations of -0.5 and -0.9, respectively. These variables are highly correlated. There is a modest link between sunspot number and Dst. Which solar wind parameter increases or causes these severe geomagnetic storms was the primary motivation for this investigation. Such understandings are essential for enhancing our capacity to forecast and mitigate the effects of geomagnetic storms on technological systems and societal infrastructure, as well as our comprehension of the dynamics of space weather. [ABSTRACT FROM AUTHOR]

The applicability of the ERA5 reanalysis for estimating wind and solar energy generation over the contiguous United States is evaluated using wind speed and irradiance variables from multiple observational data sets. After converting ERA5 and observed meteorological variables into wind power and solar power, comparisons demonstrate that significant errors in the ERA5 reanalysis exist that limit its direct applicability for a wind and solar energy analysis. Overall, ERA5-derived solar power is biased high, while ERA5-derived wind power is biased low. During winter, the ERA5-derived solar power is biased high by 23% on average, while on an annual basis, the ERA5-derived wind power is biased low by 20%. ERA5-derived solar power errors are found to have consistent characteristics across the contiguous United States. Errors for the shortest duration and most extreme solar negative anomaly events are relatively small in the ERA5 when completely overcast conditions occur in both the ERA5 and observations. However, longer-duration anomaly events on weekly to monthly timescales, which include partially cloudy days or a mix of cloudy and sunny days, have significant ERA5 errors. At 10 days duration, the ERA5-derived average solar power produced during the largest negative anomaly events is 62% greater than observed. The ERA5 wind speed and derived wind power negative biases are largely consistent across the central and northwestern U.S., and offshore, while the northeastern U.S. has an overall small net bias. For the ERA5-derived most extreme negative anomaly wind power events, at some sites at 10 days duration, the ERA5-derived wind power produced can be less than half of that observed. Corrections to ERA5 are derived using a quantile–quantile method for solar power and linear regression of wind speed for wind power. These methods are shown to avoid potential over-inflation of the reanalysis variability resulting from differences between point measurements and the temporally and spatially smoother reanalysis values. The corrections greatly reduce the ERA5 errors, including those for extreme events associated with wind and solar energy droughts, which will be most challenging for electric grid operation. [ABSTRACT FROM AUTHOR]

An anomaly in the behavior of galactic cosmic rays in September 2014–February 2015 was studied, which manifested itself as significant modulation of their flux with a period close to the Sun's rotation. The state of the solar magnetic field and changes in the parameters of the solar wind and interplanetary magnetic field during the specified period are analyzed. The reasons for the longitudinal asymmetry in the distribution of galactic cosmic rays in the inner heliosphere are discussed. It has been established that the studied period is divided into two parts with different physical conditions on the Sun. Conclusions are drawn on the decisive joint influence of sporadic and recurrent events: repeatedly renewed "magnetic traps" created by successive coronal mass ejections from the same longitudinal zone, and anomalously expanded polar coronal holes with an enhanced magnetic field. [ABSTRACT FROM AUTHOR]

This is an exercise to explore the concentration of lithium, lithium-7 isotope and the possible presence of black dirty ice on the lunar surface using spectral data obtained from the Clementine mission. The main interest in tracing the lithium and presence of dark ice on the lunar surface is closely related to future human settlement missions on the moon. We investigate the distribution of lithium and 7 Li isotope on the lunar surface by employing spectral data from the Clementine images. We utilized visible (VIS–NIR) imagery at wavelengths of 450, 750, 900, 950 and 1000 nm, along with near-infrared (NIR–SWIR) at 1100, 1250, 1500, 2000, 2600 and 2780 nm, encompassing 11 bands in total. This dataset offers a comprehensive coverage of about 80% of the lunar surface, with resolutions ranging from 100 to 500 m, spanning latitudes from 80°S to 80°N. In order to extract quantitative abundance of lithium, ground-truth sites were used to calibrate the Clementine images. Samples (specifically, 12045, 15058, 15475, 15555, 62255, 70035, 74220 and 75075) returned from Apollo missions 12, 15, 16 and 17 have been correlated to the Clementine VIS–NIR bands and five spectral ratios. The five spectral ratios calculated synthesize the main spectral features of sample spectra that were grouped by their lithium and 7 Li content using Principal Component Analysis. The ratios spectrally characterize substrates of anorthosite, silica-rich basalts, olivine-rich basalts, high-Ti mare basalts and Orange and Glasses soils. Our findings reveal a strong linear correlation between the spectral parameters and the lithium content in the eight Apollo samples. With the values of the 11 Clementine bands and the 5 spectral ratios, we performed linear regression models to estimate the concentration of lithium and 7 Li. Also, we calculated Digital Terrain Models (Altitude, Slope, Aspect, DirectInsolation and WindExposition) from LOLA-DTM to discover relations between relief and spatial distribution of the extended models of lithium and 7 Li. The analysis was conducted in a mask polygon around the Apollo 15 landing site. This analysis seeks to uncover potential 7 Li enrichment through spallation processes, influenced by varying exposure to solar wind. To explore the possibility of finding ice mixed with regolith (often referred to as 'black ice'), we extended results to the entire Clementine coverage spectral indices, calculated with a library (350–2500 nm) of ice samples contaminated with various concentrations of volcanic particles. [ABSTRACT FROM AUTHOR]

Electric Solar Wind Sails (E-Sails) are a new type of spacecraft propellantless propulsion system that gathers its energy from solar wind protons and is potentially useful for interplanetary missions. Although optimal interplanetary trajectories have been the subject of thorough research, the substantial variability of the solar wind necessitates the adoption of active guidance strategies, an area that has received significantly less scholarly attention. This paper proposes guidance algorithms for E-Sails based on Model Predictive Control (MPC), a modern control methodology based on online re-planning of the trajectory. To this end, first, properties of E-sail time-optimal orbits are studied applying Pontryagin's Minimum Principle, and then time-optimal orbits for missions to Mars and Jupiter are computed via direct transcription methods. Next, solar wind perturbations are modeled, posing a challenging saturation problem due to their high variability. Guidance strategies based on Shrinking Horizon and Receding Horizon Model Predictive Control (RHMPC) are developed, analyzed and compared using Monte Carlo simulations, successfully implementing MPC to E-sail guidance. Lastly, the RHMPC strategy is successfully tested with accurate historical solar wind data from the WSA-Enlil model. • Solar wind fluctuations implies need of guidance in E-sail interplanetary missions. • Optimal planning for E-sails is performed using direct and indirect methods. • Control saturation due to solar wind pressure is reduced by leaving control margins. • Model predictive control guidance methods are compared with Monte Carlo analysis. • Receding horizon strategy in tested with semi-empirical historical solar wind. [ABSTRACT FROM AUTHOR]

Smart dust devices are tiny systems-on-a-chip platforms capable of sensing, storing and transmitting data wirelessly as part of a large network with distributed capabilities. Previous works investigated the long-term orbital evolution of smart dust in space by studying the combined effect of gravitational perturbations, solar radiation pressure (SRP) and atmospheric drag. In the current work, the problem of finding long-term orbital equilibria conditions for smart dust is recast and extended to include Poynting–Robertson and Solar Wind (PRSW) drag. By including the PRSW effects and defining new equilibrium conditions on the orbital orientation, some additional partial equilibrium solutions are found. Moreover, it is shown that even though PRSW is not dominant compared to SRP or J 2 , it still influences the evolution of the relative Sun-orbit orientation. For orbits with higher initial perigee altitudes, where drag and J 2 effects subside, it is shown that PRSW influences long-term orbital behavior, and should be considered in the orbit design scheme of smart dust devices. [ABSTRACT FROM AUTHOR]

In this work, we present numerical simulations of Stream Interaction Regions (SIRs) and Corotating Interaction Regions (CIRs) using the sunrunner3d tool that employs as a coronal model the boundary conditions obtained by corhel/mas with the pluto code that describes the global 3D structure of the solar wind using the magnetohydrodynamics (MHD) approach in the inner heliosphere. Specifically, we selected a set of SIRs and CIRs observed by the Parker Solar Probe (PSP) and STEREO-A (STA) missions during the Carrington rotations (CRs) 2207 to 2210 and CRs from 2020 to 2022. In order to describe the dynamics of the plasma that constitutes the solar wind background conditions for the selected CRs, we solve the ideal MHD equations in an inertial frame of reference, managing the solar rotation by rotating the boundary values in ϕ (longitude) at a rate corresponding to the sidereal rotation rate of the solar equator. We show that our results using sunrunner3d can globally reproduce the plasma parameters, such as radial velocity, number proton density, and radial magnetic field strength of these large-scale structures, observed by PSP and STA at distances near the Sun and around 1 au, respectively. These results allow exploring the global evolution of SIRs/CIRs in the inner heliosphere using sunrunner3d. [ABSTRACT FROM AUTHOR]

The tendency for low-speed solar wind to show greater spatiotemporal variability and different compositional properties from high-speed wind has led to the prevailing idea of a bimodal solar wind, in which fast wind comes from coronal holes and slow wind comes from coronal streamers. We present observational evidence that most of the slow wind originates from small coronal holes or from just inside the boundaries of large holes, with the rest leaking out from coronal streamers and confined to the immediate vicinity of the heliospheric current and plasma sheets. Although this conclusion was suggested earlier by extrapolations of photospheric field maps, additional support comes from (1) observations of slow wind at Earth following the central-meridian passage of small equatorial holes; (2) observations of slow wind with high Alfvénicity at 1 au by Wind, and more recently near the Sun by Parker Solar Probe and Solar Orbiter; and (3) the finding that 80% of the solar wind observed by Helios at 0.3 – 0.4 au during 1974 – 1978 was Alfvénic. We show that compositional properties such as charge-state ratios vary over the solar cycle and may depend on parameters such as the footpoint field strength B 0 , and thus cannot be used alone to distinguish between coronal hole and noncoronal-hole wind. Finally, we note that magnetograms greatly underestimate the amount of small-scale flux emerging inside coronal holes and other unipolar regions. If this rate is taken to be the same as in the quiet Sun, the energy flux density resulting from interchange reconnection with open field lines is on the order of 3 × 10 5 erg cm−2 s−1 ( B 0 /10 G), sufficient to drive the solar wind. The wind speed depends on the rate of flux-tube expansion, with slower expansion leading to more energy deposition at greater heights and faster wind. [ABSTRACT FROM AUTHOR]

This paper is devoted to the analysis of fluctuations in the solar wind plasma and interplanetary magnetic field parameters observed by Solar Orbiter and WIND spacecraft at different scales ranging from ~103 to 107 km. We consider two long data intervals where the distances between the spacecraft are 0.1 and 0.5 AU, respectively, and they are located close to the Sun–Earth line. Transformation of the fluctuation's properties on the way from the Sun to Earth is analyzed for different types of solar wind associated with quasi-stationary and transient solar phenomena. The time series of bulk speed are shown to undergo a slight modification, even for large spacecraft separation, while the time series of the interplanetary magnetic field magnitude and components as well as proton density may be transformed even at a relatively short distance. Though the large-scale solar wind structures propagate the distance up to 0.5 AU without significant change, local structures at smaller scales may be modified. The statistical properties of the fluctuations such as relative standard deviation or probability distribution function and its moments remain nearly unchanged at different distances between the two spacecraft and are likely to depend mostly on the type of the solar wind. [ABSTRACT FROM AUTHOR]

Geosynchronous magnetopause crossings (GMCs) were analyzed during geomagnetic storms on February 26, March 23, and April 23, 2023. GMC-associated magnetosheath intervals were identified using magnetic data acquired from the GOES-16 and GOES-17 spacecraft. A comparative analysis of various magnetopause models was performed on the base of solar wind conditions measured by the THEMIS-E spacecraft and the Wind interplanetary monitor. The analysis of models was based on statistical parameters for determining magnetosheath intervals. It was shown that for all three storms, the model presented in [1] demonstrated the best accuracy. For events of moderate magnetic storms against the background of small negative Bz component of the interplanetary magnetic field (IMF), good results are obtained with the model described in [2]. For extreme events with very high solar wind pressures and/or very strong negative IMF Bz, the model shown in [3] exhibits good accuracy, and satisfactory accuracy is also demonstrated by models presented in [4, 5]. It was shown that the accuracy of the models was affected by the following factors and effects: the choice of interplanetary monitor, the dependence of the model on the solar wind pressure, the Bz saturation effect, the dawn–dusk magnetopause asymmetry, and the effect of prehistory. [ABSTRACT FROM AUTHOR]

As a result of the analysis of data from vertical and oblique sounding of the ionosphere in February–March 2023 using the new ionospheric index, it was found that solar coronal mass ejections (CMEs) of the loop type lead to a long-term decrease in the critical frequencies F-layer of the ionosphere, while other types of CMEs may not lead to significant changes in the state ionosphere. The possible role of high-speed streams of solar wind and energetic protons in the occurrence of ionospheric disturbances is noted. Distance–frequency characteristics of the Cyprus–Nizhny Novgorod route during geomagnetic disturbances are given, which indicate both a strong deformation of the F-layer of the ionosphere and the appearance of z-shaped wave disturbances propagating to a region of lower altitudes. [ABSTRACT FROM AUTHOR]

A study of MHD waves in solar wind plasma during two geoeffective space weather events in February–March 2023 is reported. At that time, various geophysical phenomena were observed on Earth: intense magnetic storms, decreases in the intensity of galactic cosmic rays, auroras, and a number of other manifestations of space weather. To study the situation in near-Earth outer space, we used data from direct measurements of the parameters of the interplanetary medium with the DSCOVR and ACE spacecraft. The application of spectral analysis methods to the data of direct measurements of the solar wind parameters onboard the DSCOVR spacecraft made it possible to study the characteristics and dynamics of Alfén, fast, and slow magnetosonic waves in the inertial frequency range (from ∼0.0001 to ∼0.01 Hz) of the observed solar wind turbulence spectrum during these events. [ABSTRACT FROM AUTHOR]

The paper applies the methods of information theory to the study of the interplanetary magnetic field and its variations as a result of solar activity. The statistical regularities of the projections of the vectors of the interplanetary magnetic field and the speed of the flow of solar wind particles do not carry information about the order of realization for the available states of the studied physical system. At the same time, such characteristics can be obtained from phase diagrams or phase portraits created on the basis of experimental samples in subspaces of the phase space, which display both the values of vector quantities and the sequence order in a particular time series. The paper proposes a method for synthesizing vector graphs in the phase subspace of the interplanetary magnetic field (IMF). Results are considered of the reconstruction and analysis of implemented graphs based on the time series of satellite monitoring of the state of the IMF, provided by the database of the NASA Goddard Space Flight Center since the beginning of 2023. The graph is constructed on the basis of experimental samples for projections of magnetic field vectors. Field vectors converge and diverge at the nodes of the graph, the edges of the graph allow one to control the analyzed trajectory of the system in the phase subspace and restore the transition tree for a particular vector field. The concept of a spherical reference surface of a vector graph is introduced, which allows one to bring the compared implementations of graphs to a single linear scale and a single curvature of the reference surface. Examples are considered under the action of various external factors associated with the solar magnetic field and coronal mass ejections. [ABSTRACT FROM AUTHOR]

Traditional solar cells face the challenges of high cost and limited conversion efficiency, which seriously limits their promotion in practical applications. Therefore, this article proposes a novel GaAs thin-film solar cell based on algae's/GaAs heterojunction. It utilizes the finite difference time domain (FDTD) method to simulate the propagation of electromagnetic waves and the process of light absorption in the cell under specific boundary conditions. The simulation experimental results demonstrate that the introduction of indium tin oxide (ITO) and Ag plasma into solar cell structure significantly enhances the light trapping capability of the cell. Under the irradiation of standard light AM1.5, the proposed cell structure maintains an absorption rate of more than 95% in the wavelength range of 300–743 nm, with an average absorption rate of 97.29%. Especially at the wavelength of 547 nm, it has an absorption rate of up to 99.87%. In addition, the short-circuit current is 30.152 mA/cm2, the open-circuit voltage is 1.226 V, and the photoelectric conversion efficiency (PCE) is increased to 33.22%. The research result indicates when light illuminates the surface of the metal particles after incorporating Ag nanoparticles into the ITO grating, the free electrons within the metal are excited, resulting in a resonance effect. This allows for a highly concentrated and localized electromagnetic wave on the metal surface, which improving the solar cell's absorption efficiency of sunlight. The research will promote the development of photovoltaic technology and provide an effective strategy and reference for the manufacture of high-performance thin-film solar cells. [ABSTRACT FROM AUTHOR]

One of the main features that distinguishes dusty plasma from ordinary (not containing charged dust particles) plasma is anomalous dissipation associated with the process of charging dust particles, leading to new physical phenomena, effects and mechanisms. The process of anomalous dissipation is considered in the context of describing the dynamics of dust particles in the dusty plasma of atmosphereless bodies of the Solar System. A description of the oscillations of a dust particle over the surfaces of Mercury, the Moon, and the Martian satellites Phobos and Deimos is presented, the attenuation of which is determined by the charging frequency of the dust particles, which characterizes anomalous dissipation. The possibility of using an approach that takes into account anomalous dissipation to describe plasma-dust processes in the vicinity of comets is discussed. It is shown that anomalous dissipation plays a significant role in determining the possibility of using the model of levitating dust particles in describing dusty plasma over the surfaces of atmosphereless bodies of the Solar System. The results of numerical calculations are presented, confirming the possibility of using this model for a number of atmospherelesso cosmic bodies. [ABSTRACT FROM AUTHOR]

The study investigates ion flux variations for the substorms in the inner magnetosphere. The effect of substorm-induced magnetic field dipolarization on the O+ and H+ ion flux is analysed for 22 events from the year 2018 using the Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer data on board the Van Allen Probes (VAP/RBSP) satellite. The clear dipolarization signatures are observed using the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) suite from the VAP. These observations provide evidence of the ion flux enhancement at 1–50 keV energy after the substorm onset, in particular, the energy range of 20–50 shows dominance. The typical characteristics of magnetic field dipolarization and its time scales are investigated. It is found that the O+ ion flux enhances greater in magnitude than H+ ion flux at energies 20–50 keV after the substorm onset. In addition to it, the correlation of these enhanced oxygen fluxes with the related interplanetary magnetic field (IMF) B z , solar wind velocity (V sw), and the auroral electrojet (AE) index are found good. The new results reports that the ion flux variation ratio shows the MLT dependence for different energy ranges and found that the peak of the O+/ H+ ion flux ratio centred near midnight for the energy range of 8–20 keV, whereas the O+/ H+ ion flux ratio of the energy 20–50 keV is high within the post-midnight. The possible mechanisms for the enhanced ion flux are discussed. [ABSTRACT FROM AUTHOR]

We explore bursts of broadband pulsations (PiBs) and airglow using the ISTP midlatitude observatories during substorm activations in the course of severe magnetospheric storms. We detected bursty pulsations in the Pi1B short-period range not only when the boundary of the auroral and field-aligned currents (FACs) region was near Irkutsk, but also when the boundary was up to 10° northward. Earlier, we associated such events with sharp pulses of the solar wind (SW) ram pressure, P d , and/or to fast substorm-related variations in FACs during superstorms. In this paper, we show observations of such bursty phenomena during substorm sawtooth events (STEs) in the course of two storms both with and without strong P d pulses or their moderate variations. The possibility of periodic substorm activations during STEs by a global magnetotail instability and excitation of the nighttime Alfvén resonator is discussed. We suppose and test a technique for timing the substorm explosive phase onset by the start of the surge in the spectral power of Pi1B pulsations. [ABSTRACT FROM AUTHOR]

Solar energetic particle (SEP) events have been observed by the Parker Solar Probe (PSP) spacecraft since its launch in 2018. These events include sources from solar flares and coronal mass ejections (CMEs). The IS⊙IS instrument suite on board PSP is measuring ions over energies from ∼ 20 keV nucleon−1 to 200 MeV nucleon−1 and electrons from ∼ 20 keV to 6 MeV. Previous studies sought to group CME characteristics based on their plasma conditions and arrived at general descriptions with large statistical errors, leaving open questions on how to properly group CMEs based solely on their plasma conditions. To help resolve these open questions, the plasma properties of CMEs have been examined in relation to SEPs. Here, we reexamine one plasma property, the solar wind proton temperature, and compare it to the proton SEP intensity in a region immediately downstream of a CME-driven shock for seven CMEs observed at radial distances within 1 au. We find a statistically strong correlation between proton SEP intensity and bulk proton temperature, indicating a clear relationship between SEPs and the conditions in the solar wind. Furthermore, we propose that an indirect coupling of SEP intensity to the level of turbulence and the amount of energy dissipation that results is mainly responsible for the observed correlation between SEP intensity and proton temperature. These results are key to understanding the interaction of SEPs with the bulk solar wind in CME-driven shocks and will improve our ability to model the interplay of shock evolution and particle acceleration. [ABSTRACT FROM AUTHOR]

The Mg ii k and h line intensity ratios can be used to probe the characteristics of the plasma in the solar atmosphere. In this study, using the observations recorded by the Interface Region Imaging Spectrometer, we study the variation of the Mg ii k and h intensity ratio for three flares belonging to X-class, M-class, and C-class, throughout their evolution. We also study the k-to - h intensity ratio as a function of magnetic flux density obtained from the line-of-sight magnetograms recorded by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. Our results reveal that, while the intensity ratios are independent of magnetic flux density, they show significant changes during the evolution of the C-class and M-class flares. The intensity ratios start to increase at the start of the flare and peak during the impulsive phase before the flare peak and decrease rapidly thereafter. The values of the ratios fall even below the preflare level during the peak and decline phases of the flare. These results are important in light of heating and cooling of localized plasma and provide further constraint on the understanding of flare physics. [ABSTRACT FROM AUTHOR]

The quiet-time solar wind electrons feature non-thermal characteristics when viewed from the perspective of their velocity distribution functions. They typically have an appearance of being composed of a denser thermal "core" population plus a tenuous energetic "halo" population. At first, such a feature was empirically fitted with the kappa velocity space distribution function, but ever since the ground-breaking work by Tsallis, the space physics community has embraced the potential implication of the kappa distribution as reflecting the non-extensive nature of the space plasma. From the viewpoint of microscopic plasma theory, the formation of the non-thermal electron velocity distribution function can be interpreted in terms of the plasma being in a state of turbulent quasi-equilibrium. Such a finding brings forth the possible existence of a profound inter-relationship between the non-extensive statistical state and the turbulent quasi-equilibrium state. The present paper further develops the idea of solar wind electrons being in the turbulent equilibrium, but, unlike the previous model, which involves the electrostatic turbulence near the plasma oscillation frequency (i.e., Langmuir turbulence), the present paper considers the impact of transverse electromagnetic turbulence, particularly, the turbulence in the whistler-mode frequency range. It is found that the coupling of spontaneously emitted thermal fluctuations and the background turbulence leads to the formation of a non-thermal electron velocity distribution function of the type observed in the solar wind during quiet times. This demonstrates that the whistler-range turbulence represents an alternative mechanism for producing the kappa-like non-thermal distribution, especially close to the Sun and in the near-Earth space environment. [ABSTRACT FROM AUTHOR]

The electric solar wind sail (E-sail) is a new propellant-free propulsion concept. The under-actuated and highly nonlinear features of E-sail systems pose a great challenge to their attitude controller design. Conventional control schemes may not be capable of dealing with this tough problem. To this end, a reinforcement learning (RL)-based control scheme, which can explore and obtain optimal policies in the absence of training datasets, is proposed for the attitude control of a barbell E-sail system. The barbell E-sail comprises two end satellites linked to an insulated confluence point through long and conductive tethers. The voltages of the two tethers can be individually modulated for attitude control. The system attitude dynamics is described using a nonsingular formulation. The control scheme has a two-stage design. In the first stage, an RL controller based on the Proximal Policy Optimization (PPO) algorithm is used to obtain an RL control strategy, which is emulated and updated by neural networks. In the second stage, the attitude feedback control is accomplished with low computation and energy consumption and fast convergence speed by performing a real-time mapping from the system state to the control output using the updated control strategy. Finally, the simulation results demonstrate that the proposed RL-based control scheme can effectively adjust the E-sail to the design attitude by regulating the tether voltage difference. The comparisons with the NMPC scheme also indicate that the developed control scheme can significantly reduce the computation time with control accuracy maintained. • Nonlinear dynamics and inherent constraints of the E-sail system are accounted for. • The reinforcement learning method is first applied to attitude control of the E-sail system. • Easy implementation, low computational cost and wide-range attitude adjustment are achieved. [ABSTRACT FROM AUTHOR]

Altered characteristics of urban microclimates elongating the daily and seasonal exposure periods to heat stress and enlarging the size of the thermal uncomfortable urban surfaces. This situation is human thermal comfort conditions negatively which in turn affect public health and wellbeing. The aim of this study is to determine the spatial distribution of thermal comfort conditions in the neighbourhood of Yakutiye, the center of Erzurum city over the hottest 2 months of the year (July and August) based on long term (2004–2020) meteorological data to show the impact of urban areas on thermal comfort conditions where structured surfaces are dominant. PET index was used to calculate thermal comfort conditions through RayMan model and ArcGIS 10.5 software for their spatial distribution. It was seen as the result of the study that solar radiation and wind are two effective factors on thermal comfort contrarily to each other depending on the characteristics of the city in the mentioned period. Overheating by solar radiation due to concrete structured urban surface is tolerated by north-easterly cool winds. However, lack of moisture source (i.e. green areas) to moderate heat and cold stress is one of the main causes of thermally uncomfortable periods and areas in the city center. In order to improve such negative conditions, mitigating efforts should be focused on creating city parts that comply with spatial planning and design principles, taking into account all natural and human factors from a geographical perspective. [ABSTRACT FROM AUTHOR]

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The boundaries of the auroral oval and auroral electrojets are an important source of information for understanding the coupling between the solar wind and the near-earth plasma environment. Of these two types of boundaries the auroral electrojet boundaries have received comparatively little attention, and even less attention has been given to the connection between the two. Here we introduce a technique for estimating the electrojet boundaries, and other properties such as total current and peak current, from 1-D latitudinal profiles of the eastward component of equivalent current sheet density. We apply this technique to a preexisting database of such currents along the 105° magnetic meridian, estimated using ground-based magnetometers, producing a total of 11 years of 1-min resolution electrojet boundaries during the period 2000-2020. Using statistics and conjunction events we compare our electrojet boundary data set with an existing electrojet boundary data set, based on Swarm satellite measurements, and auroral oval proxies based on particle precipitation and field-aligned currents. This allows us to validate our data set and investigate the feasibility of an auroral oval proxy based on electrojet boundaries. Through this investigation we find the proton precipitation auroral oval is a closer match with the electrojet boundaries. However, the bimodal nature of the electrojet boundaries as we approach the noon and midnight discontinuities makes an average electrojet oval poorly defined. With this and the direct comparisons differing from the statistics, defining the proton auroral oval from electrojet boundaries across all local and universal times is challenging. [ABSTRACT FROM AUTHOR]

We introduce a new framework called Machine Learning (ML) based Auroral Ionospheric electrodynamics Model (ML-AIM). ML-AIM solves a current continuity equation by utilizing the ML model of Field Aligned Currents of Kunduri et al. (2020, https://doi.org/10.1029/2020JA027908), the FAC-derived auroral conductance model of Robinson et al. (2020, https://doi.org/10.1029/2020JA028008), and the solar irradiance conductance model of Moen and Brekke (1993, https://doi.org/10.1029/92gl02109). The ML-AIM inputs are 60-min time histories of solar wind plasma, interplanetary magnetic fields (IMF), and geomagnetic indices, and its outputs are ionospheric electric potential, electric fields, Pedersen/Hall currents, and Joule Heating. We conduct two ML-AIM simulations for a weak geomagnetic activity interval on 14 May 2013 and a geomagnetic storm on 7-8 September 2017. ML-AIM produces physically accurate ionospheric potential patterns such as the two-cell convection pattern and the enhancement of electric potentials during active times. The cross polar cap potentials (ΦPC) from ML-AIM, the Weimer (2005, https://doi.org/10.1029/2004ja010884) model, and the Super Dual Auroral Radar Network (SuperDARN) data-assimilated potentials, are compared to the ones from 3204 polar crossings of the Defense Meteorological Satellite Program F17 satellite, showing better performance of ML-AIM than others. ML-AIM is unique and innovative because it predicts ionospheric responses to the time-varying solar wind and geomagnetic conditions, while the other traditional empirical models like Weimer (2005, https://doi.org/10.1029/2004ja010884) designed to provide a quasi-static ionospheric condition under quasi-steady solar wind/IMF conditions. Plans are underway to improve ML-AIM performance by including a fully ML network of models of aurora precipitation and ionospheric conductance, targeting its characterization of geomagnetically active times. [ABSTRACT FROM AUTHOR]

Some space weather models, such as the Space Weather Modeling Framework (SWMF) used in this study, use solar wind propagated from the first Lagrange point (L1) to the bow shock nose (BSN) to forecast geomagnetic storms. The SWMF is a highly coupled framework of space weather models that include multiple facets of the Geospace environment, such as the magnetosphere and ionosphere. The propagated solar wind measurements are used as a boundary condition for SWMF. The solar wind propagation method is a timeshift based on the calculated phase front normal (PFN) which leads to some uncertainties. For example, the propagated solar wind could have evolved during this timeshift. We use a data set of 123 geomagnetic storms between 2010 and 2019 run by the SWMF Geospace configuration to analyze the impact solar wind propagation and solar wind driving has on the geomagnetic indices. We look at the probability distributions of errors in SYM-H, cross polar cap potential (CPCP), and auroral electrojet indices AL and AU. Through studying the median errors (MdE), standard deviations and standardized regression coefficients, we find that the errors depend on the propagation parameters. Among the results, we show that the accuracy of the simulated SYM-H depends on the spacecraft distance from the Sun-Earth line. We also quantify the dependence of the standard deviation in SYM-H errors on the PFN and solar wind pressure. These statistics provide an insight into how the propagation method affects the final product of the simulation, which are the geomagnetic indices. [ABSTRACT FROM AUTHOR]