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This paper describes a catalog of simultaneous observations of the Earth's magnetosheath by ESA's Cluster and NASA's MMS missions. The catalog is built from a visual inspection of summary plots provided by the two missions complemented by an analysis of high‐resolution magnetic field data. The catalog includes 117 events when Cluster 4 and MMS 4 crossed simultaneously the magnetosheath between January–April, 2017–2021. The dynamical and turbulent features of the magnetosheath are strongly influenced by θBn, the angle between the interplanetary magnetic field (IMF) and the shock normal direction. To facilitate such investigations, we also determine the bow shock geometry for each event based on two different approaches: (a) a minimum variance analysis of in‐situ magnetic field measurements, and (b) a geometrical approach which considers a bow shock model parameterized by OMNI data. A description of spacecraft trajectory during each event is also provided. Additional data describe the relative distances between Cluster 4 and MMS 4, a classification of each event as either quasi‐parallel or quasi‐perpendicular, and the distribution of events per magnetospheric flank. The time intervals for the Cluster ‐ MMS conjunctions are included in the catalog, as well as all associated figures and tables discussed in this paper are made available through an independent online data repository, and can be freely downloaded and used by any interested researcher. Key Points: We use in‐situ measurements from Cluster 4 and MMS 4 to build a catalog/database of simultaneous observations of the Earth's magnetosheathEmpirical models and minimum variance analysis of the magnetic field allow for an estimation of the bow‐shock orientation for each eventWe also provide details on the relative spacecraft position and an analysis of the bow‐shock geometry [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]

The United Nations International Multiple Micronutrient Antenatal Preparation (UNIMMAP) of a multiple micronutrient supplement (MMS) for pregnant women is a proven evidence‐based nutrition intervention and is listed on the World Health Organization (WHO) Model List of Essential Medicines. The 2024 revision of the Expert Consensus on an Open‐Access UNIMMAP MMS Product Specification provides both purchasers and manufacturers with unified guidance on the production of UNIMMAP MMS. More specifically, it outlines the minimum requirements for the manufacture of UNIMMAP MMS and provides guidance on quality and regulatory standards based on whether the product is manufactured as a medicinal product or a dietary supplement. The product specification includes ingredients, excipients/food additives, and processing aids used in manufacturing UNIMMAP MMS; stability testing for different climatic zones; packaging and labeling considerations; pharmacopeial standards, manufacturing practices, certificates of analysis, change control, and quality agreement; finished product test specifications, including tablet characterization and purity/strength assay; analytical test methods; and storage and transportation requirements. [ABSTRACT FROM AUTHOR]

Mali national policy recommends that women take iron and folic acid supplements (IFA) from the time of the first antenatal care (ANC) visit, throughout pregnancy and during the first 3 months after delivery. In 2020, the World Health Organization (WHO) updated their ANC guidelines to recommend the United Nations International Multiple Micronutrient Antenatal Preparation (UNIMMAP) formulation of multiple micronutrient supplements (MMS) in the context of rigorous research, including implementation research. In Bamako, Mali, a codesign process was used to tailor antenatal care MMS packaging and counselling materials aimed at optimizing delivery and uptake of and adherence to MMS. This paper presents the codesign process along with the results of a post‐intervention qualitative assessment to evaluate the behaviour change intervention. At the conclusion of the intervention, we conducted semistructured qualitative interviews with 24 women who had received the intervention and six pharmacy managers from the six health centres participating in the study. We conducted two focus groups with midwives who had delivered the intervention and two group discussions with family members of women who had received the intervention. Respondent perspectives reveal an easy experience transitioning from previously used IFA. Women and providers concur that the intervention counselling materials and visual aids were instrumental in influencing the perceived benefit and uptake of MMS. Family members play an influential role in pregnant women's decision‐making regarding MMS uptake. MMS and the associated implementation strategies developed through the codesign process were found to be a highly acceptable intervention. [ABSTRACT FROM AUTHOR]

The MMS satellites traversed a ∼6 di‐wide and ∼500 km/s southward reconnection exhaust at the dayside magnetopause on 6 December 2015 and ∼29 di from the associated X‐line region. A narrow ∼0.26–0.34 di layer of enhanced ±3.5 nW/m3 oscillating energy conversion perpendicular to the magnetic field resides in this exhaust. It contained two regions of diverging in‐plane electric fields in general agreement with two clockwise electron flow vortices and a proposed increase of the electron vorticity ∇ × Ve. The layer developed sunward of a unipolar Hall magnetic field for a duskward BM/BL ∼ 0.9 guide field. Each electron flow vortex supported a local ∆BM ∼ 10 nT strengthening of this Hall field. The presence of this electron‐scale layer in a southward exhaust for a duskward guide field is consistent with a two‐dimensional simulation of a similar structure that evolved from an X‐line into a northward exhaust for a similar strength dawnward guide field. Plain Language Summary: Magnetic reconnection is a critical process that drives large‐scale plasma convection in the Earth's magnetosphere. In this letter, we report new direct MMS observations for the presence of two electron flow vortices within a sub‐ion scale energy conversion channel that resides in a dayside magnetopause reconnection exhaust. Each of the two electron‐scale flow vortices is shown to contribute a significant fraction toward the large‐scale Hall magnetic field. Key Points: Electron‐scale 0.3 di layer of oscillating energy conversion and electron vorticity detected in 6 di wide reconnection jet 30 di from EDRTwo regions of in‐plane diverging electric field in energy conversion layer consistent with two measured clockwise electron flow vorticesOut‐of‐plane magnetic field increased ∼10 nT from each passing electron vortex immediately sunward of 50 nT unipolar Hall magnetic field [ABSTRACT FROM AUTHOR]

Theoretical analysis has revealed a specific resonance that shares the same condition as Landau resonance, but instead involves wave electromagnetic fields rather than traditionally electrostatic fields. While this resonance, referred to as electromagnetic Landau resonance due to its properties, is considered significant for magnetospheric dynamics, rare reports or evaluations based on observations have been made thus far. Here, we present an event detected by the Magnetospheric Multiscale mission near the dayside magnetopause. During this event, ∼748‐eV protons are observed to be in resonance with a wave. Detailed data analysis demonstrates the resonant velocity closely matches the wave's parallel phase speed, which, combined with the significant work done by wave perpendicular electric field, confirms this interaction as electromagnetic Landau resonance. Further investigation indicates these protons are being secularly accelerated within this resonance. Consequently, our observations provide the first empirical evidence supporting the previously suggested theoretical importance of the electromagnetic Landau resonance. Plain Language Summary: The electromagnetic Landau resonance shares the same resonance condition as the normal Landau resonance, but differs in that it involves the electromagnetic components of wave fields instead of the electrostatic components found in the case of the latter. Although it has been examined in theories and confirmed to occur in space plasmas experimentally, this resonance, especially the accompanying evolution of particle velocity distributions, has yet to be evaluated quantitatively through spacecraft observations. In this paper, we report the first observation of this resonance obtained by the Magnetospheric Multiscale mission near the dayside magnetosphere. In the reported case, protons of ∼400–1,000 eV are found to be in resonance with a wave. A more detailed examination of the observed fields and protons shows the corresponding resonant velocity is nearly identical to the wave's parallel phase speed. This observation, combined with the significant work done by wave perpendicular electric field, conclusively confirms the observed interaction as the electromagnetic Landau resonance. Further investigation indicates the protons are secularly accelerated by the wave via this resonance. Hence, our observations provide empirical evidence supporting the previously suggested theoretical significance of the electromagnetic Landau resonance. Key Points: MMS observations of electromagnetic Landau resonance near the dayside magnetopause are presentedThis resonance follows the same condition as the Landau resonance, but modulates particles via the electromagnetic components of wave fieldsAnalysis of the observed fields and protons provide conclusive evidence for this resonance accelerating protons [ABSTRACT FROM AUTHOR]

This letter uses simultaneous observations from Magnetosphere Multiscale (MMS) and Time History of Events and Macroscale Interactions during Substorms (THEMIS) to address the dynamics of the magnetopause and magnetosheath boundary layers during the main phase of a storm during which the interplanetary magnetic field (IMF) reverses from south to north. Near the dawn terminator, MMS observes two boundary layers comprising open and closed field lines and containing energetic electrons and ring current oxygen. Some closed field line regions exhibit sunward convection, presenting an avenue to replenish dayside magnetic flux lost during the storm. Meanwhile, THEMIS observes two boundary layers in the pre‐noon sector which strongly resemble those observed at the flank by MMS. Observations from the three THEMIS spacecraft indicate the boundary layers are still evolving several hours after the IMF has turned northward. These observations advance our knowledge of the dynamic magnetopause and magnetosheath boundary layers under the combined effects of an ongoing storm and changing IMF. Plain Language Summary: Earth's magnetic field, the magnetosphere, acts as a shield protecting the near Earth environment from the solar wind. During active times, this shield can be damaged and reduced in size, but during quieter times, the shield can expand and repair itself. This letter uses observations from multiple spacecraft to better understand how the edges of our magnetosphere change during the transition from active to more quiet times. We observe the development of boundary layers at the dayside and flanks of the magnetosphere. Convection in and around these layers can contribute to the growth of the magnetosphere after it has been eroded during active times. These observations also place limits on the size of the boundary layers and how quickly they may develop. Key Points: Direct evidence of sunward transport of closed magnetic flux is observed by Magnetosphere Multiscale (MMS) at the dawn flank terminatorMMS and Time History of Events and Macroscale Interactions during Substorms (THEMIS) observe nearly identical boundary layers at the dawn flank and pre‐noon sectorsBoundary layers and sunward convecting flux tubes are populated with energetic electrons and ring current oxygen ions [ABSTRACT FROM AUTHOR]

Using the high‐time‐resolution data from the Magnetospheric Multiscale mission, precursor waves upstream of foreshock transient (FT) shocks are statistically investigated using the four‐spacecraft timing method. The wave frequencies and wave vectors determined in the plasma rest frame (PRF) are shown to follow the cold plasma dispersion relation for whistler waves. Combining with the feature of the right‐hand polarization in the PRF, the precursors are identified as whistler‐mode waves around the lower hybrid frequency. The occurrence of whistler precursors is independent of the Alfvén Mach number and the FT shock normal angle. More importantly, all the whistler precursors have group velocities pointing upstream in the shock frame, suggesting the dispersive radiation to be a possible generation mechanism. The study improves the understanding of not only the whistler precursors but also the overall FT shock dynamics. Plain Language Summary: The characteristics of the precursor waves upstream of foreshock transient (FT) shocks are determined in the plasma rest frame using the multi‐point measurements from the Magnetospheric Multiscale mission with appropriate separation scales. The statistical results demonstrate for the first time that the precursors upstream of FT shocks are lower hybrid frequency whistler‐mode waves. The presence or absence of large amplitude whistler precursors does not depend on the FT shock normal angle and the Alfvén Mach number. These results have important implications on the nature of the whistler precursors and the dynamics of the FT shocks. Key Points: Precursor waves upstream of foreshock transient shocks are found to follow the whistler wave dispersion relation in the plasma rest frameThe occurrence of whistler precursors is independent of the Alfvén Mach numbers and normal angles of the foreshock transient shocksThe observed wave characteristics are consistent with that the precursors are generated through the dispersive radiation mechanism [ABSTRACT FROM AUTHOR]

The Earth's magnetopause is an ion‐scale boundary that separates the magnetosphere from the shocked solar wind. At such boundary, energy‐conversion processes frequently occur. Previous studies suggested that such energy conversions are related to the magnetic reconnection process. Here, we report a new mechanism that the coaction between the twisted magnetic structure and lower‐hybrid waves can also drive energy conversion (J⋅ E, J is current density and E is electric field) at the magnetopause boundary layer, by using high‐resolution measurements of the four Magnetospheric Multiscale spacecraft. We find that such energy conversion is efficient (with magnitude up to 20 nW/m3) and is attributed to an intense current filament (j ≈ 3,800 nA/m2) and a fluctuating electric field driven by lower‐hybrid waves. With the help of the First‐Order Taylor Expansion method, we find that the intense current filament is driven by a twisted magnetic structure at electron scale. Our study improves the understanding of energy‐conversion processes at the Earth's magnetopause. Plain Language Summary: Solar wind‐magnetosphere coupling is a key process during the solar‐terrestrial energy chain and the space weather forecast. A significant amount of the solar wind energy is converted at the Earth's magnetopause, and thus, uncovering the mechanism of energy‐conversion processes is of key importance in understanding such a coupling process between solar wind and magnetosphere. Here, we report a new mechanism that the coaction between the twisted magnetic structure and fluctuating electric field can also drive energy conversion. It's found that the energy conversion is efficient and is attributed to an intense current filament driven by the twisted magnetic structure and a fluctuating electric field provided by lower‐hybrid waves. Key Points: An intense current filament (up to 3,800 nA/m2) accompanied by energy conversion (up to 20 nW/m3) are observed at the magnetopause boundary layerThe intense current filament is driven by an electron‐scale twisted magnetic structureThe energy conversion at the current filament is driven by the coaction between the twisted magnetic structure and the lower‐hybrid waves [ABSTRACT FROM AUTHOR]

Antenatal multiple micronutrient supplementation (MMS) is an intervention that can help reach three of the six global nutrition targets, either directly or indirectly: a reduction in low birth weight, stunting, and anaemia in women of reproductive age. To support global guideline development and national decision‐making on investments into maternal nutrition, Nutrition International developed a modelling tool called the MMS cost–benefit tool to help users understand whether antenatal MMS is better value for money than iron and folic acid supplementation (IFAS) during pregnancy. The MMS cost–benefit tool can generate estimates on the potential health impact, budget impact, economic value, cost‐effectiveness and benefit–cost ratio of investing in MMS compared to IFAS in LMICs. In the 33 countries with data included in the tool, the MMS cost–benefit tool shows that transitioning is expected to generate substantial health benefits in terms of morbidity and mortality averted and can be very cost‐effective in multiple scenarios for these countries. The cost per DALY averted averages at US$ 23.61 and benefit–cost ratio ranges from US$ 41–US$ 1304: $1.0, which suggest MMS is good value for money compared with IFAS. With its user‐friendly design, open access availability, and online data‐driven analytics, the MMS cost–benefit tool can be a powerful resource for governments and nutrition partners seeking timely and evidence‐based analyses to inform policy‐decision and investments towards the scale‐up of MMS for pregnant women globally. Key points: With recent evidence and updated World Health Organization's guidance encouraging low‐ and middle‐income countries (LMICs) to consider multiple micronutrient supplementation (MMS) for pregnant women, national governments are looking for additional analysis on the cost and cost–benefit of this nutrition intervention.Nutrition International's MMS cost–benefit tool is an evidence‐based, open‐access, and dynamic tool designed for governments and their partners to inform policy decisions and investments into MMS as part of maternal nutrition programming.The MMS cost–benefit tool uses a rigorous methodology to estimate the potential health impact, budget impact, economic value, cost‐effectiveness, and benefit‐cost ratio of investing in MMS compared to IFAS for 33 LMICS and has the capability to conduct custom analysis.The MMS cost–benefit tool's analysis demonstrates that investing in MMS compared to IFAS for antenatal care programming is consistently cost‐effective in LMICs and the long‐term economic value of health benefits generated by MMS far outweighs the costs. [ABSTRACT FROM AUTHOR]

Electron heating at collisionless shocks in space is a combination of adiabatic heating due to large‐scale electric and magnetic fields and non‐adiabatic scattering by high‐frequency fluctuations. The scales at which heating happens hints to what physical processes are taking place. In this letter, we study electron heating scales with data from the Magnetospheric Multiscale (MMS) spacecraft at Earth's quasi‐perpendicular bow shock. We utilize the tight tetrahedron formation and high‐resolution plasma measurements of MMS to directly measure the electron temperature gradient. From this, we reconstruct the electron temperature profile inside the shock ramp and find that the electron temperature increase takes place on ion or sub‐ion scales. Further, we use Liouville mapping to investigate the electron distributions through the ramp to estimate the deHoffmann‐Teller potential and electric field. We find that electron heating is highly non‐adiabatic at the high‐Mach number shocks studied here. Plain Language Summary: Shock waves appear whenever a supersonic medium, such as a plasma, encounters an obstacle. The plasma, which consists of charged ions and free electrons, is heated by the shock wave through interactions with the electromagnetic fields. In this work, we investigate how electrons are heated at plasma shocks. A key parameter to electron heating is the thickness of the layer where the heating takes place. Here, we use observations from the four Magnetospheric Multiscale spacecraft that regularly cross the standing bow shock that forms when the supersonic plasma, known as the solar wind, encounters Earth's magnetic field. We find that the thickness of the shock is larger than previously reported and is on the scales where ion physics dominate. We also find that the electron heating deviates significantly from simple adiabatic heating. Key Points: Using multipoint data from Magnetospheric Multiscale, we find that electron heating takes place on ion scales in the quasi‐perpendicular shock rampWe show that the time series of the temperature does not represent the spatial profile due to varying shock ramp speedElectron distributions in the ramp and downstream of the shock show that electrons are heated non‐adiabatically [ABSTRACT FROM AUTHOR]

To understand the entry of the cool low‐latitude mantle ions into the tail plasma sheet near the flanks under persistent interplanetary magnetic field By, we evaluate the role of the cross‐field diffusive transport by kinetic Alfvén waves (KAWs) by investigating two events observed by multiscale (MMS) spacecraft. Around the separatrix between the open and closed field‐line regions, a two‐component mixing of hot plasma sheet ions of a few keV with cool mantle ions of a few hundred eV was observed, indicating transport across the separatrix. The waves observed between 0.01 and 10 Hz around the separatrix had characteristics consistent with those of KAWs. The consistency allowed us to estimate the wave vectors as a function of frequency by fitting KAW dispersion to the observations. Using the observed wave powers, plasma moments, and the estimated wave vectors, we computed the cross‐field diffusion rates associated with KAWs. The diffusion rates were found to be comparable to or larger than the Bohm diffusion rates during the intervals when the two‐component mixing was observed, indicating that the KAW diffusive transport can play a role in the entry of low‐latitude mantle ions into the plasma sheet. Key Points: We investigate cross‐field diffusive transport for the mixing of cold low‐latitude mantle ions and hot plasma sheet ions observed by MMSThe waves around the separatrix between the low‐latitude mantle and plasma sheet show the characteristics of kinetic Alfvén waves (KAWs)Estimated diffusive transport rates through KAWs are sufficiently large to cause the observed ion mixing [ABSTRACT FROM AUTHOR]

During a storm‐time interval around winter solstice, observations by the Magnetospheric Multi‐Scale (MMS) Mission show multiple distinct magnetopause boundary layers (BLs) in the vicinity of the southern cusp. The microphysics of the solar wind‐magnetosphere interaction during storm times are not well understood, because the observations are relatively lacking. This event enables the opportunity to probe the storm‐time magnetopause, and observations support that MMS was near a reconnection site equatorward of the southern cusp, suggesting active reconnection in close proximity to closed magnetic flux regions in the BL. The Grid Agnostic magnetohydrodynamics (MHD) for Extended Research Applications global MHD simulation shows evidence for transient secondary reconnection sites near the southern cusp, demonstrating mechanisms to form closed field line regions of the BL. Plain Language Summary: The physical processes by which the solar wind plasma penetrates Earth's magnetic shield are hotly debated. Furthermore, it is even less understood how the solar wind‐magnetosphere interaction plays out during geomagnetic storms, since observations are harder to obtain. Large geomagnetic storms sparked by strong solar activity occur only a few times yearly, and planning spacecraft observations during these times is extremely difficult. Fortunately, the Magnetospheric Multi‐Scale spacecraft constellation obtained storm‐time observations which provide the opportunity to reveal properties of the disturbed outer magnetosphere, in particular, at the interface of solar wind and geomagnetic fields. The event in this study shows magnetic reconnection occurring in an unusual location, which helps to understand the possible origin of the different observed boundary layers and how plasma is transported across them. Key Points: Around the minimum storm‐time SYM‐H, Magnetospheric Multi‐Scale encountered different magnetopause boundary layers (BLs) with multiple entries into the magnetosphereBz remains negative during one magnetopause crossing, indicating an encounter with the magnetosphere in the vicinity of the southern cuspObservations and global simulations support that secondary reconnection near the southern cusp produces closed BL magnetic flux [ABSTRACT FROM AUTHOR]

We use the Magnetospheric Multiscale mission to observe a bi‐directional electron acceleration event in the electron foreshock upstream of Earth's quasi‐perpendicular collisionless bow shock. The acceleration region is associated with a decrease in wave activity, inconsistent with common electron acceleration mechanisms such as Diffusive Shock Acceleration and Stochastic Shock Drift Acceleration. We propose a two‐step acceleration process where an electron field‐aligned beam acts as a seed population further accelerated by a shrinking magnetic bottle process, with the shock acting as the magnetic mirror(s). Plain Language Summary: Collisionless shock waves are believed to be an important source of accelerating particles up to cosmic ray energies throughout our universe. In this letter, we use spacecraft data from the Magnetospheric Multiscale mission to study an energetic electron event observed at Earth's bow shock. The event displays inconsistencies with common electron acceleration mechanisms previously studied at collisionless shocks. We propose a two‐step acceleration mechanism, combining two known mechanisms for charged particle acceleration, and provide observational evidence supporting our theory. We conclude that plasma wave‐particle interactions at the shock play a crucial role in the energization of these electrons. Key Points: Using Magnetospheric Multiscale data we observe bi‐directional energetic electrons at Earth's collisionless bow shockThe observations are inconsistent with common electron acceleration mechanisms at shocksWe propose a two‐step acceleration process where a field‐aligned electron beam is further accelerated by a shrinking magnetic bottle [ABSTRACT FROM AUTHOR]

The Magnetospheric Multiscale (MMS) mission has probed Earth's magnetosphere, magnetosheath, and near‐Earth solar wind for over 8 years. We utilize an unsupervised learning algorithm, Gaussian mixture model clustering, along with feature generation and simple post‐cleaning methods to automatically classify 8 years of MMS dayside observations into four plasma regions (magnetosphere, magnetosheath, solar wind, and ion foreshock) at 1‐min resolution. With these plasma regions distinguished, we have also identified boundary surfaces (e.g., magnetopause, bow shock). We validate our results on manually generated and rule based region labels described in the literature. We report overlap rates in our cluster determined magnetopauses and bow shocks against Scientist‐in‐the Loop (SITL) identified transitions and published databases. Our features are general and our model is extensible, potentially making it applicable to observational data from multiple other missions. Key Points: We use an extensible unsupervised Gaussian mixture model (GMM) algorithm to automatically classify 8 years of dayside magnetospheric multiscale (MMS) plasma dataOur model distinguishes between solar wind, ion foreshock, magnetosheath, and magnetosphere with 97.8% accuracy compared to manual labelsWe provide classified labels and transitions at 1‐min resolution and stable region specific lists for all 8 years of dayside MMS data [ABSTRACT FROM AUTHOR]

Near‐Earth plasma surges sunward during enhanced magnetospheric convection (driven by dayside magnetic reconnection) to form a pathway feature called a plasmaspheric plume. This study uses Magnetospheric Multiscale (MMS) observations to investigate the heating of warm ions (H+ and He+) inside plumes. We identify 287 plume events using targeted in‐situ‐observational criteria and plasmapause test particle simulations. One plume‐crossing event by MMS shows that the scalar temperatures of warm He+ increase from ∼10 to ∼40 eV during simultaneous observations of helium‐band electromagnetic ion cyclotron (EMIC) waves, while H+ temperature is almost constant. Next, we analyze all individual observations to investigate warm‐ion heating and its possible association with EMIC waves. The statistical results show that EMIC waves associated with the plume have left‐hand polarizations and small normal angles and the temperatures of warm He+ are always higher than those of warm H+. Also, the minimum resonant energies for H+ are mostly above 100 eV, whereas 17% of warm He+ observations show that they can interact with the H+‐band EMIC waves via cyclotron resonance. These observations suggest that while EMIC waves play a role, there is an unknown mechanism for warm‐ion heating inside the plume that requires more investigation. Key Points: Warm He+ heating inside the plasmaspheric plume results from the interaction with electromagnetic ion cyclotron (EMIC) wavesCoincident with plumes and EMIC waves, warm He+ is more heated than warm H+Statistical results indicate that resonant interactions with EMIC waves are insufficient to account for all the observed warm ion heating [ABSTRACT FROM AUTHOR]

Dayside diffuse auroras (DDAs) originate from the precipitation of energetic electrons in the central plasma sheet, induced by wave‐particle interactions. This study examines a specific case characterized by the detection of whistler mode chorus and electron cyclotron harmonic (ECH) waves using the Magnetospheric Multiscale (MMS) satellites, along with the conjugate observation of DDA at the Yellow River (YR) station. ECH waves are observed shortly after the satellite enters the magnetosphere from the magnetosheath and persist throughout the magnetosphere region. Chorus waves are also observed within the magnetosphere, and probably generated near the B minima, followed by the propagation along magnetic field lines. Analysis of MMS particle data reveals an increase in low‐energy electrons and scattering of high‐energy electrons during periods of enhanced whistler mode chorus waves. These precipitated electrons manifest as DDA phenomena. The observed evidence demonstrates the simultaneous occurrence of ECH, chorus waves, electron pitch angle scattering, and DDA. Moreover, the concurrent presence of these waves in the outer magnetosphere during the dayside raises important considerations regarding the relative roles of different plasma waves, particle energization, precipitation dynamics, and the overall development of DDA phenomena. Key Points: Magnetospheric Multiscale (MMS) observations reveal the presence of both electron cyclotron harmonic and chorus waves in proximity to the magnetopause and within the magnetosphereIntensification of whistler mode chorus waves is accompanied by scattering of energetic electrons and an increase of low‐energies electronsThe Yellow River Station observed dayside diffuse aurora near the footprint of MMS [ABSTRACT FROM AUTHOR]

We investigate the magnetic forces (the magnetic pressure gradient force, the curvature force, and their sum the j × B‐force) associated with earthward bursty bulk flows (BBFs) using Magnetospheric Multiscale (MMS) data from five tail seasons (2017–2021). For the first time, the magnetic forces are inferred downtail of XGSM = −20 RE and in the GSM XY and YZ planes. The results suggest that BBFs tend to be accelerated earthward by the magnetic pressure gradient force tailward of ∼19 RE and decelerated closer to that distance in the 2017–2018 data. The force magnitudes increase with distance. This is in accordance with earlier Cluster results. In the 2019–2021 data, the pressure gradient force magnitudes are generally smaller and no clear distance for the acceleration reversal can be determined. The curvature forces for both 2017–2018 and 2019–2021 BBFs indicate earthward acceleration independent of distance, consistent with the Cluster measurements. The sum, the j × B‐force, suggests for the 2017–2018 BBFs earthward acceleration tailward of XGSM ∼15 RE and deceleration within that distance, also consistent with Cluster. In contrast, the 2019–2021 BBFs show general earthward acceleration by j × B independent of distance. In the GSM XY plane, the average (j × B)xy vectors are earthward, and in the premidnight and postmidnight dawnward for the 2017–2018 BBFs. For 2019–2021, the average (j × B)xy vectors have components toward the tail center. In the GSM YZ plane, the average (j × B)yz vectors are toward the neutral sheet. Key Points: Magnetic force densities associated with BBFs are evaluated first time downtail of XGSM = −20 RE and studied in the GSM XY and YZ planesj × B and the magnetic pressure gradient force densities have statistically different characteristics for the BBFs in 2017–2018 and 2019–2021The (j × B)yz‐vectors are generally directed toward the neutral sheet in the BBFs [ABSTRACT FROM AUTHOR]

Standard magnetic reconnection couples with both electron‐ and ion dynamics. Recently, a new type of magnetic reconnection, electron‐only reconnection without the coupling of ion dynamics, has been observed in space. Using a two‐dimensional particle‐in‐cell simulation, we show that in the externally‐driven magnetotail, electron‐only reconnection is a transition from quiet current sheet to standard reconnection. We find that (a) energy conversion j ⋅ E′ is around zero in quiet current sheet but nonzero in electron‐only reconnection, and (b) ion temperature does not change across electron‐only reconnection but peaks at the center of standard reconnection. These two differences can be used as criteria to distinguish magnetotail electron‐only reconnection from quiet current sheet and standard reconnection, respectively. Based on the two criteria, we justify that the MMS 17 June 2017 event is a magnetotail electron‐only reconnection event. Plain Language Summary: The Earth has a long stretched magnetic tail, that is, magnetotail, formed by the interaction between the geomagnetic field and the plasma (ions and electrons) wind originated from the Sun. At the center of the magnetotail, there is a current sheet flanked by two different topologies of magnetic field lines. Magnetic reconnection, a fundamental plasma process during which magnetic field line topologies change, can occur in this magnetotail current sheet. Based on computer simulations in the past 20 years, a standard reconnection model with both ion and electron dynamics has been established, which can well describe magnetic reconnection observed in the magnetotail. Recently, a new type of reconnection with solely electron dynamics has been observed to occur in the magnetotail. Here using computer simulations, we show that electron‐only reconnection in the magnetotail is a transition from magnetotail current sheet to standard reconnection. Based on the simulation results, we give two criteria for identification of electron‐only reconnection in spacecraft observations in the magnetotail, using which we justify that the MMS 17 June 2017 event is a magnetotail electron‐only reconnection event. Key Points: Energy conversion j ⋅ E′ is around zero in quiet current sheet but nonzero in electron‐only reconnectionIon temperature does not change in electron‐only reconnection but peaks in standard reconnectionWe justify that the MMS 17 June 2017 event is a magnetotail electron‐only reconnection event [ABSTRACT FROM AUTHOR]

This research examines the plasma processes under penetration of the plasma clouds (plasmoids) across the magnetopause which is modeled as a tangential discontinuity (TD). Cases with the parallel magnetic field in both sides out of the TD are under investigation. Plasma parameters and magnetic field were chosen from the MMS mission and other spacecraft observations. The results are important for understanding the following basic space plasma physics problems: (a) plasma cloud deformation and strong phase mixing with magnetospheric plasma; (b) the transfer of mass, momentum and energy of magnetosheath and magnetic cloud plasma into magnetospheric plasmas; (c) necessary conditions for plasma cloud penetration via the magnetopause; (d) wave generation by plasma clouds inside the magnetopause. Key Points: Plasma clouds (fragments) experience a significant slowdown when moving through magnetosheath plasmasWave‐particle interactions provide a strong phase mixing between plasma cloudsand magnetosheath, and magnetospheric plasmas3‐D hybrid modeling and spacecraft observations provethe mass, momentum and energy transport from the magnetosheath tomagnetosphere [ABSTRACT FROM AUTHOR]

Thin current sheets (TCSs) have been postulated to be a necessary precondition for reconnection onset. Magnetic reconnection X‐lines in the magnetotail have been observed to be more common duskward of midnight. We take advantage of the MMS tetrahedral formation during the 2017–2020 MMS tail seasons to calculate the thickness of the cross‐tail neutral sheet relative to ion gyroradius. While a similar technique was applied to Cluster data, current sheet thickness over a broader range of radial distances has not been robustly explored before this study. We compare our analysis to recent theories regarding mechanisms of tail current sheet thinning and to recent simulations. We find MMS spent more than twice as long in ion‐scale TCSs in the pre‐midnight sector than post‐midnight, despite nearly even plasma sheet dwell time. The dawn‐dusk asymmetry in the distribution of Ion Diffusion Regions, as previously reported in relation to regions of TCSs, is also analyzed. Plain Language Summary: Magnetic reconnection is an important mechanism for energy transfer in the magnetosphere. In order for reconnection to begin, however, the reconnecting current sheet must first become very thin. Reconnection and related phenomena have been observed in the geomagnetic tail closer to dusk than dawn on the nightside, although the reasons for this have not been clearly understood. Recent simulations of the geomagnetic tail suggest that the central current sheet in the tail should be thinner pre‐midnight than post‐midnight, possibly explaining why reconnection happens more often on the pre‐midnight than the post‐midnight sector. We use 19 months of MMS data in the tail, comprising the tail seasons of 4 years from 2017 to 2020, to estimate the thickness of the tail neutral sheet relative to relevant ion scales from dawn flank to dusk flank and both closer to and further away from the Earth than has been done in the past. We then compare the thickness we measure with the simulation predictions and with the location of previously identified reconnection locations in the same time period. Key Points: Distribution of ion‐scale tail current sheets (CS) seen by MMS during 2017–2020 using magnetic curvature as proxy for CS thicknessLocation of tail CS with thickness at or below ion gyro‐scale compared to location of reconnection‐related Ion Diffusion RegionsObservations compared to recent particle‐in‐cell simulations [ABSTRACT FROM AUTHOR]

Global simulations predict that the low‐latitude mantle may be an important pathway for the solar wind entry into the tail magnetosphere close to the current sheet when interplanetary magnetic field (IMF) By dominates over IMF Bz. To evaluate this entry mechanism in the near‐Earth tail (X ∼ −10–−20 RE), we investigate the predictions from 3D global hybrid simulations as well as in situ observations by magnetospheric multiscale (MMS) spacecraft. The simulations predict that the low‐latitude mantle plasma can appear in the near‐Earth tail lobe extending inward approximately 5 RE from the flank magnetopause. The low‐latitude mantle plasma appears in the dawnside northern lobe and duskside southern lobe during positive IMF By, while the opposite asymmetry is seen during negative IMF By. After a change in the IMF By direction arriving at the bow shock nose, it takes another ∼15–30 min for the asymmetry to completely reverse to the opposite sense in the near‐Earth tail. We present six MMS events in the tail lobe showing that the existence and absence of the low‐latitude mantle plasma is consistent with the predicted asymmetries. Statistical analysis of 5 years of MMS observations shows that the dependencies of the magnitudes of the lobe densities and tailward field‐aligned flow speeds on the IMF By directions are consistent with the predicted contributions from the low‐latitude mantle plasma in the expected lobe regions. Key Points: Global hybrid simulations predict that the low‐latitude mantle plasma can form in the near‐Earth lobe controlled by interplanetary magnetic field (IMF) ByLow‐latitude mantle is in dawnside northern lobe and duskside southern lobe for positive IMF By. The asymmetry reverses for negative IMF ByStatistical analysis of magnetospheric multiscale data supports the simulation predicted dependence of near‐Earth low‐latitude mantle on the IMF By direction [ABSTRACT FROM AUTHOR]

Thin current sheets (TCS) formed in Earth's magnetotail and hosting magnetic field line reconnection are important element of magnetospheric dynamics. In this paper, a statistical survey of 163 TCS crossing events in Earth's magnetotail using observations by MMS during 2017–2020 is performed. We find that magnetotail TCSs typically have a very strong current density primarily carried by electrons, with a thickness of a few ion inertial lengths. Our statistical results reveal different characteristics between TCSs located on the duskside and dawnside. Specifically, we find that TCSs on the duskside have a smaller thickness, higher current density, and stronger Hall electric field than on the dawnside. Our results also show that there is a correlation between the TCS thickness and the Hall electric field magnitude, with a stronger Hall electric field present in thinner TCSs. Our statistics results confirm previously reported key TCS dawn‐dusk asymmetries, with the main advance of directly measurable plasma currents. TCS characteristics of the presented data set will be useful for initialization of realistic numerical simulations and theoretical investigations of TCS instabilities resulted in various dynamical models of the magnetotail. Key Points: We collect a data set of 163 thin current sheet crossing events in Earth's magnetotail using MMS data during 2017–2020The thin current sheet has a smaller thickness, a higher current density and a stronger Hall electric field on the duskside than the dawnsideThe Hall electric field in the magnetotail thin current sheet is stronger when the current sheet is thinner [ABSTRACT FROM AUTHOR]

Two sounding rockets, designated TRICE‐2, were launched on 8 December 2018 into the northern cusp region. The two rockets were designated the high‐ and low‐flyers, respectively, and launched 2 min apart to investigate cusp structures, specifically their spatial or temporal nature. 2 hr prior to the cusp encounter by the TRICE‐2 rockets, the MMS satellites, located in the magnetopause boundary layer, observed switching ion beams under very similar IMF conditions as later observed by TRICE‐2. The observed ion beam switch in the boundary layer defined the location of the primary dayside X‐line. Both, TRICE‐2 and MMS, also observed the signatures of multiple X‐lines at the magnetopause, overlapping ion‐energy dispersions in the cusp and counterstreaming ion beams in the magnetopause boundary layer, respectively. In addition to the TRICE‐2 cusp observations, ionospheric convection patterns from the SuperDARN radar are used to explain the vastly different cusp ion signatures observed by the TRICE‐2 rockets. While the high‐flyer rocket progressed north through the center of the cusp, the low‐flyer rocket drifted off to the east and crossed into the dusk convection cell, traveling perpendicular to the ionospheric convection direction before reaching the poleward oriented section of the convection cell also observed by the high‐flyer counterpart. Key Points: TRICE‐2 cusp ion dispersions are explained using the different magnetic foot points of the rockets through the ionospheric convection cellsTRICE‐2 cusp crossing occurred 2 hr after an MMS magnetopause crossing during similar IMF conditionsOverlapping cusp ion energy dispersions result from multiple magnetopause reconnection locations in agreement with MMS observations [ABSTRACT FROM AUTHOR]

Magnetic reconnection is a critically important process in defining the dynamics and energy transport within plasma environments. In near‐Earth space we may track where and when reconnection occurs by identifying associated coherent magnetic structures. On a global scale these structures facilitate the flow of mass and magnetic flux into, within, and out of the magnetospheric system, whilst contributing to local plasma heating. In the Earth's magnetotail there are two similar structures we identify in this work: magnetic flux ropes and loops. We present a robust, automated and model independent method by which encounters with such structures may be identified using the Magnetospheric Multiscale (MMS) mission. The magnetic structures are first identified through their magnetic field signatures at a single spacecraft (MMS1), including checks on the local minimum variance coordinate system. Next, the local curvature of the magnetic field is evaluated with all four MMS spacecraft. Finally, the plasma conditions are checked to ensure that the interpretation is fully self‐consistent. We evaluate the data obtained by MMS between 2017 and 2022. In total we find 181 self‐consistent magnetic flux ropes and 263 magnetic loops, which fit an exponentially decaying size distribution with a scale size comparable to the ion gyroradius (∼0.23 RE/1,400 km). If we remove the requirements on the plasma properties of the structure, we locate 648 potential magnetic flux ropes and 1,073 magnetic loops. The magnetic structures are preferentially observed in the pre‐midnight region of the magnetotail, with most identifications occurring beyond 20 RE. All catalogs are provided to the community. Key Points: Automated, model independent method presented to identify ion‐scale magnetotail magnetic flux ropes and loop‐like plasmoidsWe provide comprehensive catalogs of magnetotail structures observed by MMS between 2017 and 2022 (Smith et al., 2023)Structures show a strong dawn‐dusk asymmetry: predominantly observed pre‐midnight, and follow an exponentially decaying size distribution [ABSTRACT FROM AUTHOR]

In astrophysics and space, supercritical shock is generated when an object interacts with an incoming supersonic plasma stream. Its downstream plasmas are highly turbulent, containing abundant vortices on all scales from magnetohydrodynamic to electron gyroscales. Understanding the production of these vortices is at the forefront, especially on the electron scale. Using ultrafast measurements of NASA's Magnetospheric Multiscale spacecraft, we report on the fortunate multi‐spacecraft observation of the formation of an electron vortex directly generated inside the Earth's quasi‐parallel bow shock transition and propagated to the downstream turbulent magnetosheath. The vortex is generated inside the shock transition by anisotropic ∼100–600 eV electrons trapped in an ion‐scale magnetic hole which could show a tornado‐like magnetic morphology. Our results demonstrate that the electron vortex can develop not only as a product of the forward cascade but also from the shock transition into its downstream turbulence, which adds to the short‐scale turbulence and dissipation. Plain Language Summary: Turbulence is a ubiquitous process in fluids where nonlinear interactions take place to generate dynamically evolving vortex structures across a broad range of scales. It plays a leading role in the cascade of mass and energy transport to increasingly small scales until it is dissipated as heat. In ionized plasmas, turbulence is more complex when considering electromagnetic fields, different kinds of charged particles, waves, and dissipation mechanisms. For studying plasma turbulence, a readily available natural laboratory is the near‐Earth environment. The solar wind plasma encounters the Earth's magnetosphere, generating a supercritical bow shock. The plasma downstream of the bow shock is highly turbulent and contains abundant plasma vortices from the macroscale to the electron gyroscale. Therefore, understanding the bow shock's role in vortex generation is crucial and essential to understanding the development of turbulence in collisionless magnetized plasmas. This paper presents a precise origin of electron‐scale vortex for unpredictable and random plasma turbulence. The vortex can directly start inside the collisionless shock as a small‐scale vortex before being transported downstream turbulence, instead of the popular belief that developing from the downstream turbulence and larger‐scale vortices. Key Points: Electron vortex can directly start inside the supercritical shock as a small‐scale vortex before being transported downstream turbulenceEvidence for its generation inside the shock transition is provided by identifying the energetic shock electron population as its sourceThe vortex could show a tornado‐like magnetic morphology, coupling with a magnetic hole and propagating to the downstream magnetosheath [ABSTRACT FROM AUTHOR]

Dipolarization Front (DF) is an Alfvenic boundary, separating the hot and tenuous plasma of magnetic reconnection downstream from the cold and dense ambient plasma sheet. Numerous studies have shown that the electric field at the front is mainly balanced by the Hall term. Charged particles are efficiently accelerated within the front and pile‐up regions. However, the current system and associated particle dynamics in the front–plasma sheet interaction region ahead of the DF remain not well understood. Utilizing data from the Magnetospheric Multiscale (MMS) mission, we statistically investigate this region based on 70 DF events. Bipolar By is observed ahead of the DF, which results from earthward deflected ions and quasi‐parallel/antiparallel electrons in the interaction region. Moreover, thermal electrons and ions above 4 keV are the main carriers of the current system. Our research reveals the Hall nature ahead of the DF. Plain Language Summary: Dipolarization front (DF), a common magnetic structure at the leading edge of fast plasma jets in the Earth's magnetotail, plays an important role in magnetic energy release and may even modify the magnetotail energy budgets. To date, the physical process within the structure has been well studied. However, the effect of the structure on the background plasma sheet remains elusive. Using recent high‐quality data from the Magnetospheric Multiscale (MMS) mission, we statistically investigate this issue. Ahead of the DF, we find a bipolar By structure, which is consistent with the local Hall current system. The main carriers of the current system are also studied. Our research advances the understanding of the interaction between the DF and ambient undisturbed plasma environment. Key Points: A distinct bipolar magnetic structure of By is found in the front–plasma sheet interaction region ahead of the Dipolarization FrontThe Hall current system consists of the earthward ion component and the quasi‐parallel (antiparallel) electron componentIons above 4 keV and electrons around 1 keV are the main carriers of the Hall current system [ABSTRACT FROM AUTHOR]

Models for collisionless magnetic reconnection in near‐Earth space are distinctly characterized as 2D or 3D. In 2D kinetic models, the frozen‐in law for the electron fluid is usually broken by laminar dynamics involving structures set by the electron orbit size, while in 3D models the width of the electron diffusion region is broadened by turbulent effects. We present an analysis of in situ spacecraft observations from the Earth's magnetotail of a fortuitous encounter with an active reconnection region, mapping the observations onto a 2D spatial domain. While the event likely was perturbed by low‐frequency 3D dynamics, the structure of the electron diffusion region remains consistent with results from a 2D kinetic simulation. As such, the event represents a unique validation of 2D kinetic, and laminar reconnection models. Plain Language Summary: Magnetic reconnection is a fundamental process that occurs in the near‐Earth space environment with implications for the safety and longevity of space‐borne electronics in which magnetic field lines rearrange and release energy. To understand whether reconnection is better described as occurring in a 2D‐plane without variation in the third direction versus 3D with variation in all directions, we analyze spacecraft data from the night‐side of Earth's magnetic field. We conclude for the considered event that the innermost region, where the field lines reconnect, remains consistent with results from a 2D simulation. Key Points: The fluctuating measurements are consistent with a 2D reconnecting geometry, permitting a detailed spacecraft trajectory to be determinedThe Magnetospheric Multiscale Mission data is projected onto a 2D spatial domain, revealing the fine‐scale structure of the electron diffusion region (EDR)The EDR includes profiles with strong gradients in fields and flows, consistent with those observed in a matched 2D kinetic simulation [ABSTRACT FROM AUTHOR]

The existence of shocklets, a kind of solitary structure, has been demonstrated in the Earth's foreshock regions for decades. Their formation and evolution are believed to be controlled by ions. However, the detailed behavior of ions at them has not been well investigated observationally yet. Here, we investigate a shocklet observed by the Magnetospheric Multiscale mission in the Earth's foreshock. Analysis of ion observations reveals that the solar wind (SW) ions are bunched in gyrophase space when interacting with the whistler precursor of the shocklet, suggesting the occurrence of cyclotron resonance between them. A more detailed examination suggests that the cyclotron resonance induces a net energy flow from the whistler precursor to the SW ions. Thus, the observations presented here indicate that the cyclotron resonance between shocklet whistler precursors and the SW ions could provide a mechanism for shocklet dissipation and SW ion energization. Plain Language Summary: Shocklets, a kind of solitary structure, are thought to play a crucial role in the reformation processes of quasi‐parallel shocks. They are also suggested to be able to efficiently decelerate and heat the solar wind ions and electrons. Their formation and evolution are believed to be controlled by ion dynamics. However, the detailed behavior of ions at them has not been well investigated yet. In this paper, we study in detail a shocklet event observed by the Magnetospheric Multiscale mission in the Earth's foreshock. We especially focus on ion observations. Analysis of the data reveals that the solar wind ions are bunched in gyrophase space when interacting with the shocklet whistler precursor, indicating the occurrence of cyclotron resonance between them. Resulting from this interaction, the solar wind ions exchange energy with the whistler precursor. Viewed in the rest frame of the plasma, this energy flow is directed from the whistler precursor to the solar wind ions. Thus, the observations presented here indicate the cyclotron resonance between shocklet whistler precursors and the solar wind ions could provide a mechanism for shocklet dissipation and solar wind ion energization. Key Points: A shocklet observed by Magnetospheric Multiscale is examined in great detail to reveal the behavior of ions at shockletsGyrophase bunching indicative of cyclotron resonance is observed in the velocity distributions of the solar wind ionsCyclotron resonance could provide a mechanism for shocklet dissipation and solar wind ion energization [ABSTRACT FROM AUTHOR]

The space weather effects at the Earth's magnetosphere are mostly driven by the solar wind that carries the interplanetary magnetic field (IMF). In this paper, we use 2 years of data in the solar wind from lunar orbiting ARTEMIS and MMS spacecraft upstream of the Earth's bow shock to study the structure of the IMF. We determine the lag times of IMF structures and their dependence on spacecraft positions by conducting an information theory analysis and comparing it with two traditional analysis methods: cross‐correlation (CC) analysis and minimum variance of magnetic field analysis (MVAB). For the events with long time intervals (i.e., >4 hr) and with small‐spatial separation between the MMS and ARTEMIS along the yGSM‐direction (i.e., <40Re, where Re is the Earth's radius), the lag times based on the CC and the mutual information (MI) analyses statistically agree with each other, with p‐values of 1.675 × 10−7 and 4.833 × 10−9, with the confidence of 95%. Both the results based on MI and CC have a large deviation from the results from MVAB. For some of the events, such a deviation could be improved by taking the fast mode speed into account; however, p‐tests showed that they were not statistically significant to the 95% confidence level. Plain Language Summary: Typically, single‐point measurements from the Earth‐Sun Lagrange Point‐1 are used to forecast space weather. However, it is important to understand that multi‐point measurements are required to further understand and predict geo‐effective solar wind structures. Three analysis methods using multi‐point measurements from the MMS and THEMIS missions of large solar wind structures as they move from regions around the Moon to regions around Earth's bow shock, are presented and compared in this paper. Information theory analysis (specifically Mutual Information) determines dependence between two variables by quantifying the entropy (uncertainty) in the two variables. Minimum variance analysis calculates the direction of least change in a magnetic field and assumes the solar wind is propagating in that direction. Lag time is calculated by taking the dot products of this direction with both the displacement vector between the two spacecraft, to get a distance, and the ion velocity (from ARTEMIS) to get a speed. The distance is divided by the speed to get a lag time. Cross‐Correlation analysis is a traditional method for measuring similarity between two variables. This paper shows that information theory analysis along with cross‐correlation analysis could be used successfully for space weather forecasting. Key Points: The solar wind data by MMS and THEMIS are analyzed by using information theory to understand the propagation of solar wind structuresMutual information, linear cross‐correlation, and minimum variance analyses sometimes give different lag‐timesInformation theory analysis along with the traditional method of cross‐correlation analysis could be used successfully for space weather forecasting [ABSTRACT FROM AUTHOR]

Background: Skin cancer incidences are increasing. Treatment for basal cell carcinomas (BCCs) can be questioned in certain patients. Treatment options are various, but Mohs micrographic surgery (MMS) has the highest cure rate. It is, however, time‐consuming and results in high logistical burden and treatment costs for both patients and society. Objectives: This study critically re‐evaluates MMS for facial BCCs in older adults. The main objective is to examine all clinical, tumour and patient characteristics in relation to safety and survival to detect a subgroup in which MMS was not the best choice. The overall aim is to identify characteristics that support clinical decision‐making in daily practice. Methods: Patients that received MMS between November 1998 and December 2012 were included. Only patients >75 years with a facial BCC were withheld for analysis. This is a retrospective cohort study, since evaluating the outcome of MMS in accordance with life expectancy is the main objective. Patient charts were evaluated towards comorbidities, complications and survival. Results: This cohort comprises 207 patients. Median survival was 7.85 years. The age‐adjusted Charlson comorbidity index (aCCI) was divided into low/medium scores (aCCI < 6) and high scores (aCCI ≥ 6). Median survival was 11.58 years in the low aCCI group and 3.60 years in the high aCCI group (p < 0.001). There was a very strong association between high aCCI and survival (HR, 6.25; 95% CI, 3.83–10.21). Other characteristics were not associated with survival. Conclusions: Clinicians should assess the aCCI in older patients presenting with a facial BCC before deciding if MMS is an eligible treatment option. High aCCI has shown to be an indicator for low median survival, even in MMS patients with usually high functional status. MMS should be waived as treatment in older patients with high aCCI scores in favour of other, less intensive and less expensive treatment options. [ABSTRACT FROM AUTHOR]

Background: Due to the propensity for local recurrence, Mohs micrographic surgery (MMS) has been suggested for the treatment of dermatofibrosarcoma protuberans (DFSP) and it has shown improved clinical outcomes. Recently, some authors suggested that MMS using paraffin‐embedded sections (paraffin MMS) is superior in DFSP treatment compared with the conventional frozen MMS method. However, there have been no studies comparing frozen and paraffin MMS for the treatment of DFSP. Objectives: To compare the outcomes between DFSP patients who underwent frozen MMS and paraffin MMS. Methods: Seventy‐one DFSP patients treated with frozen MMS (n = 30) or paraffin MMS (n = 41) from 2003 to 2017 at a single institution were retrospectively reviewed. Recurrence rate and recurrence‐free survival between frozen and paraffin MMS were assessed. Results: During the mean follow‐up duration of 25.4 months, four patients (frozen MMS, n = 1; and paraffin MMS, n = 3) showed recurrence after MMS. Although the local recurrence rate of the frozen MMS group (3.3%) was lower than that of the paraffin MMS group (7.3%), the difference was not statistically significant. In addition, recurrence‐free survival was not significantly different between the two groups (P = 0.168). Conclusions: Frozen MMS, which has the advantages of shorter surgery time and immediate closure, is as effective as paraffin MMS in the treatment of DFSP. [ABSTRACT FROM AUTHOR]

Microinjection phenomena, characterized by dispersive oscillations of electron fluxes at the Pc5 period and bi‐directional pitch angle anisotropy, are frequently observed by Magnetospheric Multiscale in the dusk to midnight plasma sheet. In this paper, two such events are analyzed and the features of toroidal mode drift resonance measured meanwhile are shown in detail. The prominent observation is that the fluctuations of the electron flux and the electric field have either −90° or +90° phase difference at the resonant energy, and the phase difference rises as the energy increases. We extend the present theory for drift resonance of toroidal mode wave with only the equatorial moving electrons in a dipole field to include bouncing electrons. The predicted phase differences based on the new theory are consistent well with the observations in the microinjection events. It is thus suggested that drift resonance may act as the forming mechanism for the observed microinjections. Plain Language Summary: In the dusk to midnight plasma sheet, the fluxes of counter‐streaming energetic electrons were often observed to fluctuate at the period about 2 ∼ 6 min, with the higher energy fluxes coming to peaks earlier than those at lower energies. These phenomena were considered to be caused by repetitive injections of electrons with smaller time scale than the substorm‐associated injections, so were named "microinjections." In this paper, we analyze two microinjection events and find that they are likely to result from the drift resonance between local electrons and Ultralow‐frequency compressional toroidal waves. To verify this hypothesis, we extend the present theory for toroidal mode drift resonance from only considering electrons with 90° pitch angles to including all bouncing electrons. We find that the predicted phase relationships of electron fluxes and the wave electric field correspond well with observations. The phase difference between the electron fluxes and the electric field equals to −90° or +90° at the resonant energy and increases with energy. Therefore, we propose that the compressional toroidal mode drift resonance may work as the generation mechanism of microinjections in the two events. Key Points: Evidences of drift resonance between compressional Ultralow‐frequency waves and electrons are observed in microinjection eventsCompressional toroidal mode drift resonance theory is extended to off‐equator regionDrift resonance can be a possible mechanism for the generation of microinjection events [ABSTRACT FROM AUTHOR]

Observations at the reconnection site from the Magnetospheric Multiscale mission are used to examine the occurrence of magnetic reconnection along the magnetopause in relation to both the upstream interplanetary magnetic field (IMF) orientation and local magnetosheath variations. While there is a statistically larger number of reconnection intervals observed downstream of the quasi‐parallel bow shock than is accounted for based on the histogram of overall IMF orientations, it is surmised that increased fluctuations downstream of the quasi‐parallel bow shock cause greater large‐scale motion of the magnetopause surface; but do not preferentially enhance the occurrence of steady magnetic reconnection. An examination of the locations of observed reconnection sites relative to model predictions also suggest that enhanced magnetosheath fluctuations do not result in steady reconnection occurring at random locations at the magnetopause. Key Points: Magnetospheric Multiscale (MMS) encounters the magnetopause reconnection site over a wide range of external conditionsThe occurrence of reconnection region encounters is consistent with that of large‐scale magnetopause motion, and depends on interplanetary magnetic field orientationDistributions of MMS locations with respect to model reconnection line predictions are independent of region downstream of the bow shock [ABSTRACT FROM AUTHOR]

Field‐aligned distributions of H+ with energy less than 100 eV in the magnetosphere originate from the ionosphere through ionospheric outflow. Recently, a statistical interhemispheric asymmetry in this ion outflow was reported. In this study, we investigate a case study of asymmetric field‐aligned distributions (E < 100 eV) resulting from asymmetric outflow observed on 13 August 2019 by the Hot Plasma Composition Analyzer onboard the Magnetospheric Multiscale mission. During the reported event, the average phase space density in the parallel direction (pitch angle < 45°) is about 4.7 times higher than in the anti‐parallel direction (pitch angle > 135°), indicating greater outflow from the southern hemisphere. In this event, electron precipitation fluxes are also asymmetric between hemispheres, with more electrons traveling to the southern hemisphere than to the northern hemisphere. Global MHD simulation results (SWMF/BAT‐S‐RUS available from the CCMC) confirm that several ionospheric parameters (joule heating, convection velocities, and energy fluxes of precipitating electrons) are more enhanced in the southern hemisphere. We suggest that these interhemispheric asymmetries might cause a stronger outflow from the southern hemisphere than from the northern hemisphere, to produce the observed asymmetric field‐aligned distributions for the low‐energy H+. Key Points: Low‐energy (E < 100 eV) H+ field‐aligned distributions are asymmetric in the outer magnetosphereConditions in the southern hemisphere ionosphere are favorable and result in asymmetric outflowThe observed low‐energy H+ pitch‐angle distributions are consistent with asymmetric outflow as the cause [ABSTRACT FROM AUTHOR]

This article presents 18 magnetic reconnection electron diffusion region (EDR) candidates found using a neural network algorithm with the Magnetospheric Multiscale Mission phase 1a data at the Earth's dayside magnetopause. These new candidates are compared to the 32 previously reported dayside EDRs listed in Webster et al. (2018), https://doi.org/10.1029/2018ja025245, which constitute the training database of our algorithm. One of the main parameters used is a scalar quantity called "MeanRL" which is based on the asymmetry of the electron velocity distribution function and better identifies electron agyrotropy in the plane perpendicular to the magnetic field. In the light of the new EDR candidates found, we discuss and analyze the sign of the energy dissipation during the reconnection process and the distinction between the inner and outer EDRs, with 40% of the candidates showing negative or oscillating dissipation. We also present in details one of the new identified EDR candidates. Key Points: We report 18 new electron diffusion region (EDR) candidates close to the Earth magnetopause in the Magnetospheric Multiscale Mission (MMS) phase 1a data using a neural networkThe algorithm makes use of a scalar quantity called "MeanRL" to identify the electron perpendicular agyrotropy typical of EDRs from MMS distribution functionsWe analyze and discuss the geometry of EDR based on energy dissipation signatures [ABSTRACT FROM AUTHOR]

Due to the energy crisis and environmental pollution, the research on energy‐efficient building has increasingly attracted attention. The phase change materials (PCMs) play a vital role in increasing the energy utilization efficiency. In order to protect the PCMs from leakage during phase change process, the melamine sponge (MS) and modified melamine sponge (MMS) are considered as the frameworks. The leakage rate of MS and MMS sample were compared. The thermal and fire behavior was investigated by small room model, infrared thermal imager and cone calorimeter. The results show that the leakage rate of MS is much higher than that of MMS. On the condition of the same percentage of PCMs, MMS sample has better temperature control performance. The MS sample releases heat much faster and more than MMS sample. While MMS plays a role in inhibiting ignition. [ABSTRACT FROM AUTHOR]

Magnetic cavities are sudden depressions of magnetic field strength widely observed in the space plasma environments, which are often accompanied by plasma density and pressure enhancement. To describe these cavities, self‐consistent kinetic models have been proposed as equilibrium solutions to the Vlasov‐Maxwell equations. However, observations from the Magnetospheric Multi‐Scale (MMS) constellation have shown the existence of helical magnetic cavities characterized by the presence of azimuthal magnetic field, which could not be reconstructed by the aforementioned models. Here, we take into account another invariant of motion, the canonical axial momentum, to construct the particle distributions and accordingly modify the equilibrium model. The reconstructed magnetic cavity shows excellent agreement with the MMS1 observations not only in the electromagnetic field and plasma moment profiles but also in electron pitch‐angle distributions. With the same set of parameters, the model also predicts signatures of the neighboring MMS3 spacecraft, matching its observations satisfactorily. Plain Language Summary: Magnetic cavities, also referred to as magnetic holes, are ubiquitous in the space plasma environment characterized by depressed magnetic field strength and enhanced plasma pressure. These structures are usually believed to result from plasma instabilities, although recent observations and simulations have suggested their quasi‐stationary nature. Kinetic models of magnetic cavities have been also proposed, which show excellent agreement with spacecraft observations to indicate the formation of quasi‐equilibrium cavities during the turbulent evolution of space plasmas. These models, however, apply only to magnetic cavities with straight field lines, and therefore cannot describe the helical magnetic cavities recently discovered by NASA's Magnetospheric Multi‐Scale (MMS) constellation. In this paper, we propose a revised model by incorporating the canonical axial momentum as an additional invariant of particle motion into the particle distributions, to resolve the self‐consistent profiles of the electromagnetic field and particle distributions within the magnetic cavity. This revision accommodates the field‐aligned current to support the helical field lines, which shows remarkable agreement with the observations from the MMS constellation. Key Points: Spacecraft observations of magnetic cavities are sometimes accompanied by azimuthal magnetic field indicating the helical structureKinetic, equilibrium model of helical magnetic cavities is developed based on four invariants of particle motionThe model reproduces the MMS observations of helical magnetic cavities in both electromagnetic field and particle distributions [ABSTRACT FROM AUTHOR]

Magnetosheath jets are localized dynamic pressure enhancements in the magnetosheath. We make use of the high time resolution burst mode data of the Magnetospheric Multiscale mission for an analysis of waves in plasmas associated with three magnetosheath jets. We find both electromagnetic and electrostatic waves over the frequency range from 0 to 4 kHz that can be probed by the instruments on board the MMS spacecraft. At high frequencies we find electrostatic solitary waves, electron acoustic waves, and whistler waves. Electron acoustic waves and whistler waves show the typical properties expected from theory assuming approximations of a homogeneous plasma and linearity. In addition, 0.2 Hz waves in the magnetic field, 1 Hz electromagnetic waves, and lower hybrid waves are observed. For these waves the approximation of a homogeneous plasma does not hold anymore and the observed waves show properties from several different basic wave modes. In addition, we investigate how the various types of waves are generated. We show evidence that, the 1 Hz waves are connected to gradients in the density and magnetic field. The whistler waves are generated by a butterfly‐shaped pitch‐angle distribution and the electron acoustic waves by a cold electron population. The lower hybrid waves are probably generated by currents at the boundary of the jets. As for the other waves we can only speculate about the generation mechanism due to limitations of the instruments. Studying waves in jets will help to address the microphysics in jets which can help to understand the evolution of jets better. Plain Language Summary: There is a constant plasma flow from the sun, the solar wind. The Earth's magnetic field deflects the solar wind as it flows toward Earth. As the solar wind plasma approaches Earth it gets decelerated and heated at the bow shock. Earthward of the bow shock, the magnetosheath is located where the flow diverges around Earth. In the magnetosheath plasma flows that are denser and faster than normal can sometimes be observed, so called magnetosheath jets. We investigate waves in plasmas in these magnetosheath jets and how they are generated. Studying these waves will help to understand the interaction of magnetosheath jets with their environment. Key Points: MMS burst mode data is used to investigate waves in, and in the vicinity of, magnetosheath jets0.2 Hz waves, 1 Hz waves, whistler waves, electron acoustic waves, lower hybrid waves, and solitary waves are observedWaves with low frequencies cannot be explained by "basic" wave modes that are derived in homogeneous plasmas [ABSTRACT FROM AUTHOR]

Flux transfer events (FTEs), as flux ropes (FRs), are considered key agents for solar wind energy to enter the terrestrial magnetosphere. Recent observations identify entangled flux tubes that collide and pull against each other. Reconnection occurs to disentangle and produce a new pair of FRs with different connectivity. In this paper, we examine the entanglement interface and how such an entanglement process evolves in time by comparing 17 entanglements observed by the Magnetospheric Multiscale (MMS) mission. The By‐dominated interplanetary magnetic field (IMF) distribution of the 17 events agrees with previous findings. We have identified three evolutionary stages characterized by the magnetic field and pressure enhancement. Our study confirms the FR nature of these events and explains how a disparate pair of ropes is formed from two entangled flux tubes, each initially connected to a different hemisphere of the magnetosphere. Plain Language Summary: The Earth's intrinsic magnetic field deflects the solar wind flow at a boundary called the magnetopause. Near this boundary, twisted flux tubes are found. Such tubes may become entangled if they move toward each other, say, from the Southern and Northern Hemispheres. This study analyzes 17 such events and identifies three evolutionary stages as the entanglement proceeds. The results improve our understanding of not only the complex coupling between solar wind and the Earth's magnetic field but other similar processes in space plasma. Key Points: IMF clock angles associated with 17 flux tube entanglement events present peaks near horizontal directionThe entanglement process evolves in three distinguishable stagesMagnetic tension force contributes to the pressure balance at the entanglement interface [ABSTRACT FROM AUTHOR]

Dayside magnetosphere interactions are essential for energy and momentum transport between the solar wind and the magnetosphere. In this study, we investigate a new phenomenon within this regime. Sudden enhancements of ion fluxes followed by repeating dropouts and recoveries were observed by Magnetospheric Multiscale on 5 November 2016, which is the very end of the recovery phase from a moderate geomagnetic storm. These repetitive flux variations display energy‐dispersive characteristics with periods relevant to ion bounce motion, suggesting they are corresponding echoes. Alongside the flux variations, bipolar electric field impulses originating from external sources were detected. We traced the source region of the initial injection and found it is located near the spacecraft's position. To elucidate the underlying physics, a test‐particle simulation is conducted. The results reveal that radial transport resulting from impulse‐induced acceleration can give rise to these echoes. Observations demonstrate dayside magnetosphere interactions are more common than we previously considered, which warrants further research. Plain Language Summary: In spacecraft observations, the quasi‐periodical motion of particles in the geomagnetic field can generate repeating signals known as "echoes". Examining the relationship between the periods of echoes and the particle's energy is necessary for determining their types. The present study reports a novel mechanism responsible for generating echoes that arise from the ion bounce motion along magnetic field lines. Observations from both ground‐based stations and spacecraft, as well as numerical simulations, suggest these echoes can result from the acceleration and radial diffusion of ions responding to external field variations. These findings extend the current understanding of interactions in the dayside outer magnetosphere. Key Points: Ion acceleration and corresponding bounce echoes were observed by MMS in the dayside outer magnetosphereObservations and simulations suggest these echoes are driven by the accompanied electric field impulsesImpulse‐induced ion radial transport with positive phase space density radial gradient leads to the observed pattern [ABSTRACT FROM AUTHOR]

We present multi‐point observations of foreshock bubbles (FBs) for comparison with the predictions of hybrid simulations. The four Magnetospheric Multiscale (MMS) spacecraft observed a series of discontinuities in the region upstream from the bow shock on December 18, 2017. Two solar wind discontinuities were associated with fully developed FBs with core regions exhibiting greatly decelerated and deflected antisunward flows, significant increases in temperature, and depressed plasma densities and magnetic field strengths. A single shock lies upstream (sunward) from each of the two bubbles. The connection to the foreshock before and/or after the discontinuities can play an important role in the foreshock transient formation. We present the predictions of a 2.5‐D global hybrid simulation for the presence of the FBs for two different interplanetary magnetic field (IMF) cone angles (66° and 25°). The topology of the simulated FB is nearly hemispherical for small angles, but becomes linear for large angles. We show that the characteristics of the two simulated FBs for the two different discontinuity normals and IMF cone angles are in good agreement with the observational results. Key Points: The Magnetospheric Multiscale (MMS) spacecraft observe two fully developed foreshock bubbles (FBs) whose properties are compared with the predictions of the hybrid code modelA global hybrid simulation predicts the characteristics of two FBs in the region upstream from the bow shockThe simulation results match MMS observations of the two FBs, but uncertainties associated with solar wind conditions need to be considered [ABSTRACT FROM AUTHOR]

Using four‐point measurements from the Magnetospheric Multiscale (MMS) mission, we identify whistler waves at the boundary of an ion scale magnetic hole, which should be locally excited rather than propagated from other regions. Based on the measured local plasma parameters, which include those for bidirectional electron beams with electron temperature anisotropy, the frequency range with the growth rate derived from kinetic theory is consistent with the observations, while the growth rate in the absence of such beams is negative; hence, the observed whistler waves are locally excited by the bidirectional electron beams with electron temperature anisotropy. The dispersion relation, derived from one‐dimensional particle‐in‐cell simulations that are conducted using the inputs of the bidirectional electron beams with electron temperature anisotropy, agrees well with the one from kinetic theory, which further supports this excitation mechanism. Our results shed light on a new excitation mechanism for whistler waves. Plain Language Summary: Whistler waves are nearly field‐aligned propagating and right‐hand polarized electromagnetic modes with the frequency between lower hybrid frequency and electron cyclotron frequency. Whistler waves are frequently and widely detected in the planetary magnetosphere and the interplanetary space and play an important role in the particle dynamics therein. For example, the electrons could be effectively accelerated by the electromagnetic whistler waves. Thanks to the unprecedented high time resolution and multipoint data from the Magnetospheric Multiscale (MMS) mission, the whistler waves are identified at the boundary of a magnetic hole in the magnetosheath. Based on the measured local plasma parameters including bidirectional electron beams with electron temperature anisotropy, both the linear theory based on kinetic plasma and one‐dimensional particle‐in‐cell (PIC) simulations confirm that the observed whistler waves are locally excited by the presence of bidirectional field‐aligned electron beams with electron temperature anisotropy for the first time. Our results shed new light on new excitation mechanism for whistler waves. Key Points: Whistler waves are identified at the boundary of a magnetic holeLinear theory and simulations confirm that whistler waves are excited by bidirectional electron beams with temperature anisotropyOur results shed new light on new excitation mechanism for whistler waves [ABSTRACT FROM AUTHOR]

Background: In November 2018, Mohs micrographic surgery (MMS) was restricted to fellows registered with the Australasian College of Dermatologists. Three new item numbers for the provision of MMS were also introduced. We examine the national and state usage of MMS item numbers based on Medicare claim statistics and Mohs surgeons' self‐reported data, noting the impact of the pandemic and the usage of individual item numbers. Methods: Medicare item number data were obtained from the Medicare Benefits Schedule website for January 2017–December 2021. Self‐reported data were collected on an annual basis by the Royal College of Pathologists of Australasia (RCPA) as part of the Quality Assurance Program (QAP) from 2019 onwards. Data were analysed with the Holt–Winters smoothing method for forecasting. Results: An increasing number of MMS claims were processed each year, with a total of 89,183 for the study period. Since November 2018, 97.7% of procedures have been conducted on the head, neck, genitalia, hand, digits, leg (below the knee) or foot. The provision of services across the country was maintained during the pandemic years of 2020–2021, with an increase in services in Queensland. There were discrepancies between the states for procedures performed in greater than six sections; these constituted more than 35% of claims in Queensland and Western Australia compared to less than 15% in other states. The pandemic impacted certain states more than others, with Victoria and the Northern Territory having significantly fewer presentations than predicted (p < 0.05). Conclusions: Overall, the use of MMS in Australia is in keeping with peer‐developed guidelines, despite discrepancies between states. Although certain states were more severely affected by the pandemic, MMS is increasingly used in Australia. [ABSTRACT FROM AUTHOR]

We report the quasi‐periodic whistler‐mode waves corresponding to electron temperature anisotropy T⊥/T// < 1 at the center of a macroscale magnetic hole (MH) near the Earth's magnetopause observed by the Magnetospheric Multiscale mission. A significant ultra‐low frequency (ULF) wave of background magnetic field was observed in this MH. The ULF wave dramatically exacerbates the evolution of MH and the formation of the donut‐shaped electron pitch angle distribution (PAD) in the macroscale MH. When the whistler‐mode waves were generated, they are consistent with troughs of the ULF wave and density increases, which is also related to the butterfly type PAD at those moments. The analysis of dispersion relation and cyclotron resonance condition indicate that whistler‐mode waves were mainly generated by the butterfly type PAD of electrons. Our results provides new insights into one possible excitation mechanism of whistler‐mode wave. Plain Language Summary: The whistler‐mode wave is an important electromagnetic wave inside the magnetosphere. It is efficient for both the acceleration and precipitation of energetic electrons associated with typical magnetic field structures or boundaries. Moreover, the interactions between whistler‐mode waves and other waves and corresponding wave generation mechanisms have attracted extensively attentions into data observations and computer simulations. In this study, we report an event of quasi‐periodic whistler‐mode waves and a background ultra‐low frequency (ULF) wave at the center of a magnetic hole (MH), which has a negative electron temperature anisotropy T⊥/T∥ − 1 < 0. The whistler‐mode waves have the fluctuations in accordance with troughs of the ULF wave and were excited by the butterfly type pitch angle distribution. It indicates that the ULF wave can modulate the whistler‐mode waves via bringing about the periodic variation of electron phase space density. The result exhibits the complicated processes of wave excitation and wave‐particle interaction in the MH. Key Points: We found whistler‐mode waves and donut‐shaped pitch angle distributions in a macroscale magnetic hole (MH)The formation of donut‐shaped distribution is the result of the combined influence of MH and ultra‐low frequency waveThe butterfly distribution is considered to be the excitation mechanism of whistler‐mode waves [ABSTRACT FROM AUTHOR]