Southward Interplanetary Magnetic Field Research Articles

Annual and Seasonal Occurrence Pattern of Auroral Kilometric Radiation Associated with the Interplanetary Magnetic Field* *Released on March 1st, 2024.

Auroral kilometric radiation (AKR) is a widely existing strong radio emission from the Earth’s magnetosphere and is generated by suprathermal (1–10 keV) electrons in the polar cavity. Previous works have demonstrated that AKR can contribute to the coupling of the magnetosphere–ionosphere–atmosphere, but its relation to the interplanetary magnetic field (IMF) has not been studied so far. Here, we examine the data of Van Allen Probes and identify a total of 5000 AKR events from 2012 October to 2019 July. Most AKR events (4282) correspond to the dominant parallel component B∥(=(Bx)2+(By)2) of IMF. There are the most (1391) events in 2018 (the solar minimum year) and the least (258) events in 2014 (the solar maximum year), corresponding to more (less) occurrences for the longer duration (> 30 minutes) of southward IMF (B z < 0) in 2018 (2014). In the Earth’s Northern Hemisphere, there are the most (865) events in the autumn (August–October), corresponding to dominant B x < 0. In the Earth’s Southern Hemisphere, there are the most (830) events in the autumn (February–April), corresponding to dominant B x > 0. The probable reason for the above results is that the longer duration of B z < 0 can yield the longer magnetic reconnection, and the dominant B x < 0 (B x > 0) is favorable for the single-lobe magnetic reconnection in the northern (southern) hemisphere, allowing more suprathermal electrons into the polar source cavity and generating more AKRs. These current results suggest that IMF is very important for the occurrence of AKR and can be widely applied to similar auroral radio emissions in other magnetized planets of the solar system.

On the Importance of the Kelvin‐Helmholtz Instability on Magnetospheric and Solar Wind Dynamics During High Magnetic Shear

AbstractThe 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.

Tracking the Subsolar Bow Shock and Magnetopause: Applying the Magnetosheath Velocity Gradient Method

AbstractBoth the bow shock and magnetopause move in response to varying solar wind and magnetospheric conditions. Tracking their locations can provide important clues to the state of the solar wind‐magnetosphere interaction, but is difficult with single spacecraft observations. This paper employs multipoint THEMIS observations of velocity gradients in the subsolar magnetosheath to remotely sense boundary locations on a continual basis for various solar wind conditions. We present three cases: (a) continuous northward IMF and no magnetopause motion; (b) southward IMF and no magnetopause motion with evidence of nightside activity; and (c) southward IMF and pressure increase with inward motion. When observing spacecraft are located near the Sun‐Earth line, inferred boundary locations agree well with the predictions of the BATS‐R‐US global magnetohydrodynamic model, confirming the utility of both the new method and the models. Results show that boundaries often lie nearly at rest with amplitudes less than 0.5 RE. They provide evidence indicating that nightside reconnection and a strong sunward convection in the outer magnetosphere can counteract the magnetopause erosion expected when a southward interplanetary magnetic field (IMF) initiates reconnection on the dayside magnetopause.

How Solar Wind Controls the Recovery Phase Morphology of Intense Magnetic Storms

AbstractGeomagnetic storms are critical space weather phenomena resulting from the interaction between the solar wind and the Earth's magnetosphere. However, most studies focus on the main phase of magnetic storms, leaving the morphology of the recovery phase an open question. In this study, we analyze 82 intense magnetic storms with the minimum Dst index ≤ −100 nT between 1995 and 2018, finding that these storms can be classified into two distinct types: one‐stage recovery storms that exhibit a single rapid exponential recovery and two‐stage recovery storms that are characterized by a rapid exponential recovery in the early recovery phase and a slow linear recovery in the later recovery phase. We find that the two‐stage recovery storms are dominant, accounting for approximately 60% of the events. Interestingly, the proportion of two‐stage recovery storms peaks during solar minimum. The two‐stage recovery storms tend to be accompanied by more Alfvén waves with long‐duration and intense southward interplanetary magnetic fields. In addition, we find that the decay rate of the Dst index in the later recovery phase is correlated with the average BZ of the interplanetary magnetic field when the solar wind has a high degree of Alfvénicity. Overall, our results shed new light on the recovery phase morphology of intense magnetic storms and highlight the role of Alfvén waves in this process.

Investigations of the degree of asymmetry across the dayside magnetopause under southward interplanetary magnetic field using GEOTAIL observations

The magnetic reconnection environment around the dayside geomagnetopause under long-lasting southward interplanetary magnetic field (IMF) conditions is investigated using the in-situ observation by GEOTAIL satellite from 1994 to 2019. We focus on the degrees of asymmetry in the plasma density, ion temperature and the magnetic field strength between both sides of the magnetopause, that is, the ratio of the value in the magnetosphere to that in the magnetosheath in order to compute the much more realistic current sheet systems in numerical simulations. To exclude all of the interplanetary disturbance events such as Corotating Interaction Regions (CIRs) and Coronal Mass Ejections (CMEs), we investigate magnetopause crossings under long-lasting southward IMF conditions. GEOTAIL satellite sometimes repeatedly across the magnetopause during each pass due to the oscillating of the magnetopause. The degrees of asymmetry vary even during a single pass. This variation depends on the locus of the observation point, particularly the GSM Y-position, not on the time. The degrees of asymmetry in the plasma density, ion temperature and the magnetic field strength have significant variation in the data. The data points of the degree of asymmetry in the plasma density significantly spread in the duskside, while that in the magnetic field strength further widely spread in the dawnside. The degree of asymmetry in the plasma density and that in the magnetic field strength have fixed negative correlation on a log–log scale.Graphical

Multi-process driven unusually large equatorial perturbation electric fields during the April 2023 geomagnetic storm

The low latitude ionosphere and thermosphere are strongly disturbed during and shortly after geomagnetic storms. We use novel Jicamarca radar measurements, ACE satellite solar wind, and SuperMAG geomagnetic field observations to study the electrodynamic response of the equatorial ionosphere to the 23, 24 April 2023 geomagnetic storm. We also compare our data with results from previous experimental and modeling studies of equatorial storm-time electrodynamics. We show, for the first time, unusually large equatorial vertical and zonal plasma drift (zonal and meridional electric field) perturbations driven simultaneously by multi storm-time electric field mechanisms during both the storm main and recovery phases. These include daytime undershielding and overshielding prompt penetration electric fields driven by solar wind electric fields and dynamic pressure changes, substorms, as well as disturbance dynamo electric fields, which are not well reproduced by current empirical models. Our nighttime measurements, over an extended period of large and slowly decreasing southward IMF Bz, show very large, substorm-driven, vertical and zonal drift fluctuations superposed on large undershield driven upward and westward drifts up to about 01 LT, and the occurrence of equatorial spread F irregularities with very strong spatial and temporal structuring. These nighttime observations cannot be explained by present models of equatorial storm-time electrodynamics.

Characterization of Magnetic Flux Contents for Two Flux Transfer Events From Both In Situ and Ionospheric Observations

AbstractFlux transfer events (FTEs) are a type of magnetospheric phenomena that exhibit distinctive observational signatures from the in situ spacecraft measurements. They are generally believed to possess a magnetic field configuration of a magnetic flux rope and formed through magnetic reconnection at the dayside magnetopause, sometimes accompanied with enhanced plasma convection in the ionosphere. We examine two FTE intervals under the condition of southward interplanetary magnetic field (IMF) with a dawn‐dusk component. We apply the Grad‐Shafranov (GS) reconstruction method to the in situ measurements by the Magnetospheric Multiscale (MMS) spacecraft to derive the magnetic flux contents associated with the FTE flux ropes. In particular, given a cylindrical magnetic flux rope configuration derived from the GS reconstruction, the magnetic flux content can be characterized by both the toroidal (axial) and poloidal fluxes. We then estimate the amount of magnetic flux (i.e., the reconnection flux) encompassed by the area “opened” in the ionosphere, based on the ground‐based Super Dual Auroral Radar Network (SuperDARN) observations. We find that for event 1, the FTE flux rope is oriented in the approximate dawn‐dusk direction, and the amount of its total poloidal magnetic flux falls within the range of the corresponding reconnection flux. For event 2, the FTE flux rope is oriented in the north‐south direction. Both the FTE flux and the reconnection flux have greater uncertainty. We provide a detailed description about a formation scenario of sequential magnetic reconnection between adjacent field lines based on the FTE flux rope configurations from our results.

Simulation of the SMILE Soft X-ray Imager response to a southward interplanetary magnetic field turning

Simulation of the SMILE Soft X-ray Imager response to a southward interplanetary magnetic field turning

Hybrid-Vlasov simulation of soft X-ray emissions at the Earth’s dayside magnetospheric boundaries

Solar wind charge exchange produces emissions in the soft X-ray energy range which can enable the study of near-Earth space regions such as the magnetopause, the magnetosheath and the polar cusps by remote sensing techniques. The Solar wind–Magnetosphere–Ionosphere Link Explorer (SMILE) and Lunar Environment heliospheric X-ray Imager (LEXI) missions aim to obtain soft X-ray images of near-Earth space thanks to their Soft X-ray Imager (SXI) instruments. While earlier modeling works have already simulated soft X-ray images as might be obtained by SMILE SXI during its mission, the numerical models used so far are all based on the magnetohydrodynamics description of the space plasma.To investigate the possible signatures of ion-kinetic-scale processes in soft X-ray images,we use for the first time a global hybrid-Vlasov simulation of the geospace from the Vlasiator model. The simulation is driven by fast and tenuous solar wind conditions and purely southward interplanetary magnetic field. We first produce global X-ray images of the dayside near-Earth space by placing a virtual imaging satellite at two different locations,providing meridional and equatorial views. We then analyze regional features present in the images and show that they correspond to signatures in soft X-ray emissions of mirror mode wave structures in the magnetosheath and flux transfer events (FTEs) at the magnetopause. Our results suggest that, although the time scales associated with the motion of those transient phenomena will likely be significantly smaller than the integration time of the SMILE and LEXI imagers, mirror-mode structures and FTEs can cumulatively produce detectable signatures in the soft X-ray images. For instance, a local increase by 30% in the proton density at the dayside magnetopause resulting from the transit of multiple FTEs leads to a 12% enhancement in the line-of-sight- and timeintegrated soft X-ray emissivity originating from this region. Likewise, a proton density increase by 14% in the magnetosheath associated with mirror-mode structures can result in an enhancement in the soft X-ray signal by 4%. These are likely conservative estimates, given that the solar wind conditions used in the Vlasiator run can be expected to generate weaker soft X-ray emissions than the more common denser solar wind. These results will contribute to the preparatory work for the SMILE and LEXI missions by providing the community with quantitative estimates of the effects of small-scale, transient phenomena occurring on the dayside.

Statistical Analysis of Electric Currents Within the Magnetosheath Using Dayside Magnetospheric Multiscale Mission Observations

AbstractEarth's magnetosheath is the region of shocked plasma that mediates coupling between the solar wind and magnetosphere. Magnetohydrodynamic (MHD) simulations predict electric current closure across the magnetosheath from the bow shock to the magnetopause. These currents provide a J × B force that diverts plasma flow along the flanks of the magnetosphere. Observations by the NASA Magnetospheric Multiscale (MMS) mission show that within the magnetosheath there are large amplitude, localized currents during periods of intense turbulence. We perform a statistical analysis of magnetic field data from the first 6 years (2015–2021) of the MMS mission during intervals when the satellites are on the dayside and generate statistical maps of electric current derived using the curlometer technique. We find that during the low magnetosonic Mach number regime (MMS &lt; 5), the predicted current closure pattern becomes apparent for northward and southward IMF orientations, but not dawnward or duskward. For MMS &gt; 5, results suggest that for all IMF orientations this large‐scale current closure pattern is not apparent, even after separating out quasi‐perpendicular (θbn ≥ 45°) and quasi‐parallel (θbn &lt; 45°) bow shock conditions. Instead, the magnetosheath is dominated by small‐scale filamented current sheets that may be attributed to magnetosheath turbulence.

Three‐Dimensional Global Hybrid Simulations of Mercury's Disappearing Dayside Magnetosphere

AbstractAn important discovery of MESSENGER is the occurrence of dayside disappearing magnetosphere (DDM) events that occur when the solar wind dynamic pressure is extremely high and the interplanetary magnetic field (IMF) is both intense and southward. In this study, we investigate the DDM events at Mercury under extreme solar wind conditions using a three‐dimensional (3‐D) global hybrid simulation model. Our results show that when the solar wind dynamic pressure is 107 nPa and the magnitude of the purely southward IMF is 50 nT, most of the dayside magnetosphere disappears within 10 s after the interaction between the solar wind and the planetary magnetic field starts. During the DDM event, the ion flux is significantly enhanced at most of the planetary dayside surface and reaches its maximum value of about 1010 cm−2 s−1 at the low‐latitude surface, which is much larger than that under normal solar wind conditions. During the DDM events, the dayside bow shock mostly disappears for about 9 s and then reappears. Moreover, the time evolution of magnetopause standoff distance under different solar wind conditions is also studied. When the solar wind dynamic pressure exceeds 25 nPa and the IMF is purely southward, a part of the dayside magnetosphere disappears. Under the same IMF, the higher the solar wind dynamic pressure, the faster the magnetopause standoff distance reaches the planetary surface. When the solar wind conditions are normal (with a dynamic pressure of 8 nPa) or the IMF is purely northward, the dayside magnetosphere does not disappear. The results provide a clear physical image of DDM events from a 3‐D perspective.

A Numerical Investigation on the Formation of the Stalling of the Cross‐Polar Jet in Midnight Thermospheric Winds

AbstractThermospheric winds usually flow from noon to the midnight inside the polar cap and spill further equatorward around midnight, due to the combined effects of solar radiation‐driven pressure gradient and ion drag. Recent observations from the Scanning Doppler Imager at Poker Flat indicated a distinct feature that the cross‐polar jet stalls over short horizontal distances around the magnetic midnight. However, the mechanisms responsible for the occurrence of stalling have not been well understood. In this study, we investigated the physical mechanisms of the stalling of the cross‐polar jet based on the Thermosphere Ionosphere Electrodynamics General Circulation Model simulations. The model reproduced the general stalling features at midnight over a short horizontal distance. The occurrence of stalling is mainly associated with Joule heating, which enhances the neutral temperature and then turns winds poleward by the pressure gradient force, and ion‐neutral coupling, which drags neutral winds westward in the pre magnetic local time midnight sector and contributes to the poleward turning of the meridional winds by the poleward Coriolis force. Meanwhile, the stalling region has a large latitudinal range and depends on the interplanetary magnetic field (IMF). Under southward IMF Bz, thermospheric winds are likely to stall at lower latitudes associated with strong ionospheric convection. The stalling of the cross‐polar jet in the midnight thermospheric winds has UT/longitude dependence, which could be associated with the orientation of the alignment of geomagnetic and geographic poles with respect to ionospheric convection.

Statistical analysis of equatorial electrojet responses to the transient changes of solar wind conditions

Introduction: Prior case studies have indicated that changes in solar wind conditions have a significant impact on equatorial ionospheric electrodynamics. However, there have been limited statistical studies on this topic, impairing our understanding of the coupling between solar wind, magnetosphere, and equatorial ionosphere electrodynamics.Methods: In this study, we conducted a superposed epoch analysis of long-term data from the South America equatorial electrojet (EEJ) spanning from 2001 to 2021 examining the responses of the equatorial ionospheric electric field to step-like changes in solar wind velocity, density, dynamic pressure, and interplanetary magnetic field (IMF) Bz.Result: Our study shows that step-like changes in solar wind velocity, density, and dynamic pressure can trigger changes in EEJ within ∼20–40 min. EEJ exhibits the highest sensitivity to variations in solar wind velocity while being relatively less sensitive to changes in dynamic pressure. Furthermore, the response of EEJ shows greater responsiveness to northward IMF Bz compared to southward IMF Bz.Discussion: Our work provides statistical evidence of how changes in solar wind can lead to changes in low-latitude ionospheric EEJ. We inferred that the changes in solar wind conditions cause magnetospheric deformation and changes in magnetic reconnection rates, leading to the fluctuations of the ionospheric electric field and the resultant EEJ variations.

Open Magnetic Fields in the Martian Magnetosphere Revealing Dipole-like Intrinsic Magnetic Fields at Mars

Mars’s magnetosphere is hybrid, having contributions from both an induced magnetosphere like Venus and the localized crustal magnetic fields. However, the planetary fields also include large-scale, more global components. In this study, we investigate their role in Mars’s magnetospheric topological responses to the interplanetary magnetic field (IMF) clock angle using observations from the Mars Atmospheric Volatile and EvolutioN mission. We show that the large-scale planetary field has a “dipole-like” influence on the Mars global magnetosphere by examining the open field topology. We find that the “dipole-like” planetary field, as at Earth, results in a more open magnetosphere during southward IMF. The clock angle effects on the twisted magnetotail current sheet are similarly consistent with this analogy. It reinforces the idea that Mars’s magnetosphere and solar wind interaction are more Earth-like than previously thought.

Identification of Penetration and Disturbance Dynamo Electric Fields and Their Effects on the Generation of Equatorial Plasma Bubbles

AbstractA very challenging task in ionospheric studies is to determine the separate contributions of penetration and disturbance dynamo processes in the generation of equatorial plasma drift during magnetic storms. In this study, we analyze the ion drift measured by the Communications/Navigation Outage Forecasting System satellite during the magnetic storm on 15–16 July 2012. A unique feature of this storm is the exceptionally long period of continuous southward interplanetary magnetic field (IMF) for 32 hr. The storm‐induced net change of the meridional/vertical ion drift, the difference drift between the storm time and the quiet time, is derived during the storm main phase and the first 20 hr of the recovery phase with southward IMF. The difference drift during the recovery phase cannot be explained by the disturbance dynamo effect alone. A new method is used to separate the drifts caused by the penetration and disturbance dynamo processes. The penetration drift is represented by an empirical pattern of penetration electric field and depends on the IMF magnitude, and the disturbance dynamo drift is obtained by subtracting the penetration drift from the measured difference drift. The derived disturbance dynamo drift is in good agreement with previous statistical pattern. This is the first effort to identify the separate contributions of the penetration and disturbance dynamo processes to the total drift from observed data. The results have important implications in identifying storm‐time penetration and disturbance dynamo electric fields and their effects on the generation and evolution of plasma bubbles.

Data‐Based Modeling of the Magnetosheath Magnetic Field

AbstractA quantitative model of the magnetosheath (MS) magnetic structure is developed, using a multi‐year set of Geotail, Themis, Cluster, and MMS magnetometer and plasma instrument data. The MS database is created using an identification algorithm, based on observed magnetic field magnitudes and proton densities, normalized by their concurrent interplanetary values, followed by additional filtering with the help of standard bow shock (BS) and magnetopause (MP) models. The model architecture is based on the toroidal/poloidal formalism and a coordinate system that naturally accounts for the tailward flaring of both boundaries. The magnetic field expansions include 960 free coefficients, derived by fitting the model to a grand data set, split into independent training and validation subsets with 1,291,380 and 411,933 1‐min records, respectively. The model faithfully reproduces basic types of the interplanetary magnetic field (IMF) wrapping around the MP. Regular IMF sectors result in strongly dawn‐dusk asymmetric draping, with much larger magnitudes at the quasi‐perpendicular dusk side of BS, and weaker at the quasi‐parallel dawn side, where the MS field lines are bent and dragged tailward. Except in the case of the flow‐aligned IMF orientation, the subsolar field steadily grows toward the MP, and the effect is clearly IMF Bz‐dependent: the field and its gradient are larger (smaller) for northward (southward) IMF Bz, implying a pile‐up of the magnetic flux in the first case and stronger reconnection in the second. Model distributions of the MS field magnitude reveal local depressions, associated with polar cusps near the high‐latitude limits of data coverage.

Unusual Magnetospheric Dynamics During Intense Substorm Initiated by Strong Magnetospheric Compression

AbstractWe investigate an unusual sequence and peculiar features of magnetotail changes during a storm‐range substorm initiated by the interplanetary shock. Auroral observations and measurements at several favorably distributed magnetospheric spacecraft allowed the construction of an adaptive time‐dependent magnetospheric model to quantitatively characterize the configurational changes and mapping variations. Several passages of low‐altitude spacecraft in polar orbits near midnight help reveal the magnetic configuration of the nightside tail‐dipole transition region. In this event, an intense auroral and convection activity (accompanied by an up to 1,500 nT increase in the SuperMag AL‐index index) emerged in the highly compressed magnetosphere after the passage of interplanetary shock followed by strongly southward interplanetary magnetic field (IMF). This directly driven phase of the activity continued for an hour and resulted in the formation of a hybrid magnetic configuration with dipolarized midtail and stretched field lines in the transition region. Observations of energetic particle isotropy boundary latitudes near midnight are consistent with the modeled magnetic configuration. In concert with a downward turn of the solar wind (SW) flow, and weakening of the IMF driver and convection, an unusual stretching signature of the inner magnetosphere magnetic field was observed as close as at r ∼ 5 to 7 Re; which resulted mostly from an increasing downward tilt of the thin azimuthal current. Classic substorm breakup signatures commenced at fairly low, ∼60° magnetic latitude, deep in the closed field line region, in association with the current sheet upward motion. It was followed by strong stepwise poleward auroral expansion. We discuss how these signatures deviate from standard substorm scenarios and may be potentially imparted by the aforementioned changes in SW flow direction and pressure.

Anomalous Response of Mercury’s Magnetosphere to Solar Wind Compression: Comparison to Earth

Magnetic field intensity increases when solar wind compresses a planet’s magnetosphere. The compression can be measured using the ratio of compressed magnetic fields to purely dipolar magnetic fields just inside the magnetopause. For Earth, the ratio is proportional to the subsolar standoff distance of the magnetopause. Data from in-orbit observations by the MESSENGER spacecraft indicate an opposite ratio for Mercury; the compression ratio is inversely proportional to the subsolar standoff distance. The additional magnetic fields induced by currents at the top of Mercury’s core enhance the total magnetic field strength. We also evaluated differences in the subsolar standoff of Mercury’s magnetopause according to the north–south polarity of the interplanetary magnetic field (IMF). Previous studies have not identified meaningful differences in subsolar standoff distance between those in northward versus southward IMF polarities for Mercury; however, we found that the difference is statistically significant at a large IMF B Z (15–20 nT). The magnetic reconnection that occurs behind the cusp for a large northward IMF transfers the magnetic flux to the dayside and increases the subsolar standoff distance. The eroded magnetic flux for a large southward IMF is compensated by the induced magnetic fields.

Kelvin‐Helmholtz Waves and Magnetic Reconnection at the Earth's Magnetopause Under Southward Interplanetary Magnetic Field

AbstractWe present Magnetospheric Multiscale (MMS) observations of a K‐H wave event under southward IMF conditions, accompanied by ongoing magnetic reconnection. The nonlinear K‐H waves are characterized by quasi‐periodic fluctuations, the presence of low‐density and high‐speed ions, and variations in the boundary normal vectors at both the leading and trailing edges. Our observations reveal clear evidence of on‐going magnetic reconnection through the identification of Alfvénic ion jets and the escape of energetic magnetospheric electrons. Among the 36 magnetopause current‐sheet crossings in this event, 19 exhibit unambiguous signatures of reconnection at both the leading (7) and trailing (12) edges. Notably, the estimated current‐sheet thicknesses at both edges are comparable to the ion‐inertial scale, confirming the compression effect resulting from the large‐scale evolution of the K‐H waves. The reconnection jets potentially contribute to the suppression of K‐H growth through boundary‐layer broadening and the development of complex flow and magnetic field patterns.

Electron‐Scale Reconnecting Current Sheet Formed Within the Lower‐Hybrid Wave‐Active Region of Kelvin‐Helmholtz Waves

AbstractWe present Magnetospheric Multiscale observations of an electron‐scale reconnecting current sheet in the mixing region along the trailing edge of a Kelvin‐Helmholtz vortex during southward interplanetary magnetic field conditions. Within this region, we observe intense electrostatic wave activity, consistent with lower‐hybrid waves. These waves lead to the transport of high‐density magnetosheath plasma across the boundary layer into the magnetosphere and generate a mixing region with highly compressed magnetic field lines, leading to the formation of a thin current sheet associated with electron‐scale reconnection signatures. Consistencies between these reconnection signatures and a realistic, local, fully‐kinetic simulation modeling this current sheet indicate a temporal evolution of the observed electron‐scale reconnection current sheet. The multi‐scale and inter‐process character of this event can help us understand plasma mixing connected to the Kelvin‐Helmholtz instability and the temporal evolution of electron‐scale reconnection.