Plasma Parcels Research Articles

Solar Wind Structures from the Gaussianity of Magnetic Magnitude

The heliosphere is permeated with highly structured solar wind originating from the Sun. One of the primary science objectives of Parker Solar Probe (PSP) is to determine the structures and dynamics of the plasma and magnetic fields at the sources of the solar wind. However, establishing the connection between in situ measurements and structures and dynamics in the solar atmosphere is challenging: most of the magnetic footpoint mapping techniques have significant uncertainties in the source localization of a plasma parcel observed in situ, and the PSP plasma measurements suffer from a limited field of view. Therefore, it lacks a universal tool to self-contextualize the in situ measurements. Here we develop a novel time series visualization method named Gaussianity Scalogram. Utilizing this method, by analyzing the magnetic magnitude data from both PSP and Ulysses, we successfully identify in situ structures that are possible remnants of solar atmospheric and magnetic structures spanning more than 7 orders of magnitude, from years to seconds, including polar and midlatitude coronal holes, as well as structures compatible with supergranulation, “jetlets” and “picoflares.” Furthermore, computer simulations of Alfvénic turbulence successfully reproduce the Gaussianization of magnetic magnitude, supporting the observed distribution. Building upon these discoveries, the Gaussianity Scalogram can help future studies to reveal the fractal-like fine structures in the solar wind time series from both PSP and a decades-old data archive.

Identification of a single plasma parcel during a radial alignment of the Parker Solar Probe and Solar Orbiter

Configurations in which two spacecraft, such as the Parker Solar Probe (PSP) and Solar Orbiter, are radially aligned provide opportunities for studying the evolution of a single solar wind parcel during so-called plasma line-ups. The most critical part of these studies arguably is the identification of what can be considered the same plasma crossing both spacecraft. We present here a method that allowed us to determine what we think to be the same plasma parcel that passed through PSP (∼0.075 au) and Solar Orbiter (∼0.9 au) after their radial alignment on April 29, 2021. We started by modeling the plasma propagation in order to obtain a first estimation of the plasma line-up intervals. The identification of the same density structure (with a crossing duration ∼1.5 h) that passed through the two spacecraft allowed us to specify and confirm this estimate. Our main finding is that the density structure was very stable and remained well recognizable from PSP to Solar Orbiter despite its journey of ∼137 hours in the inner heliosphere. We found, moreover, that the slow solar wind plasma parcel was significantly accelerated (from ∼200 to ∼300 km s−1) during its propagation.

Radial evolution of the accuracy of ballistic solar wind backmapping

Context.Solar wind backmapping is a technique employed to connect in situ measurements of heliospheric plasma structures to their origin near the Sun. The most widely used method is ballistic mapping, which neglects the effects of solar wind acceleration and corotation and instead models the solar wind as a constant radial outflow whose speed is determined by measurements in the heliosphere. This results in plasma parcel streamlines that form an Archimedean spiral (the Parker spiral) when viewed in the solar corotating frame. This simplified approach assumes that the effects of solar wind acceleration and corotation compensate for each other in the deviation of the source longitude. Most backmapping techniques so far considered magnetic connectivity from a heliocentric distance of 1 au to the Sun.Aims.We quantify the angular deviation between different backmapping methods that depends on the location of the radial probe and on the variation in the solar wind speed with radial distance. We assess these differences depending on source longitude and solar wind propagation time.Methods.We estimated backmapping source longitudes and travel times using (1) the ballistic approximation (constant speed), (2) a physically justified method using the empirically constrained acceleration profile Iso-poly, derived from Parker solar wind equations and also a model of solar wind tangential flows that accounts for corotational effects. We compared the differences across mapped heliocentric distances and for different asymptotic solar wind speeds.Results.The ballistic method results in a Carrington longitude of the source with a maximum deviation of 4″ below 3 au compared to the physics-based mapping method taken as reference. However, the travel time especially for the slow solar wind could be underestimated by 1.5 days at 1 au compared to non-constant speed profile. This time latency may lead to an association of incorrect solar source regions with given in situ measurements. Neglecting corotational effects and accounting for acceleration alone causes a large systematic shift in the backmapped source longitude.Conclusions.Incorporating both acceleration and corotational effects leads to a more physics-based representation of the plasma trajectories through the heliosphere compared to the ballistic assumption. This approach accurately assesses the travel time and provides a more realistic estimate of the longitudinal separation between a plasma parcel measured in situ and its source region. Nonetheless, it requires knowledge of the radial density and Alfvén speed profiles to compute the tangential flow. Therefore, we propose a compromise for computing the source longitude that employs the commonly used ballistic approach and the travel times computed from the derived radial acceleration speed profile. Moreover, we conclude that this approach remains valid at all radial distances we studied and is not limited to data obtained at 1 au.

Electron–Ion Heating Partition in Imbalanced Solar-wind Turbulence

A likely candidate mechanism to heat the solar corona and solar wind is low-frequency “Alfvénic” turbulence sourced by magnetic fluctuations near the solar surface. Depending on its properties, such turbulence can heat different species via different mechanisms, and the comparison of theoretical predictions to observed temperatures, wind speeds, anisotropies, and their variation with heliocentric radius provides a sensitive test of this physics. Here we explore the importance of normalized cross helicity, or imbalance, for controlling solar-wind heating, since it is a key parameter of magnetized turbulence and varies systematically with wind speed and radius. Based on a hybrid-kinetic simulation in which the forcing’s imbalance decreases with time—a crude model for a plasma parcel entrained in the outflowing wind—we demonstrate how significant changes to the turbulence and heating result from the “helicity barrier” effect. Its dissolution at low imbalance causes its characteristic features—strong perpendicular ion heating with a steep “transition-range” drop in electromagnetic fluctuation spectra—to disappear, driving a larger fraction of the energy into electrons and parallel ion heat, and halting the emission of ion-scale waves. These predictions seem to agree with a diverse array of solar-wind observations, offering to explain a variety of complex correlations and features within a single theoretical framework.

Linear Mode Decomposition in Magnetohydrodynamics Revisited

Small-amplitude fluctuations in the magnetized solar wind are measured typically by a single spacecraft. In the magnetohydrodynamics (MHD) description, fluctuations are typically expressed in terms of the fundamental modes admitted by the system. An important question is how to resolve an observed set of fluctuations, typically plasma moments such as the density, velocity, pressure, and magnetic field fluctuations, into their constituent fundamental MHD modal components. Despite its importance in understanding the basic elements of waves and turbulence in the solar wind, this problem has not yet been fully resolved. Here, we introduce a new method that identifies between wave modes and advected structures such as magnetic islands or entropy modes and computes the phase information associated with the eligible MHD modes. The mode-decomposition method developed here identifies the admissible modes in an MHD plasma from a set of plasma and magnetic field fluctuations measured by a single spacecraft at a specific frequency and an inferred wavenumber k m . We present data from three typical intervals measured by the Wind and Solar Orbiter spacecraft at ∼1 au and show how the new method identifies both propagating (wave) and nonpropagating (structures) modes, including entropy and magnetic island modes. This allows us to identify and characterize the separate MHD modes in an observed plasma parcel and to derive wavenumber spectra of entropic density, fast and slow magnetosonic, Alfvénic, and magnetic island fluctuations for the first time. These results help identify the fundamental building blocks of turbulence in the magnetized solar wind.

Improvements to the Empirical Solar Wind Forecast (ESWF) model

The empirical solar wind forecast (ESWF) model in its current version 2.0 runs as a space-safety service in the frame of ESA’s Heliospheric Weather Expert Service Centre. The ESWF model forecasts the solar-wind speed at Earth with a lead time of 4 days. The algorithm uses an empirical relation found between the area of solar coronal-holes (CHs), as observed in EUV within a 15^{circ} meridional slice, and the in-situ measured solar-wind speed at 1 AU. This relation however, forecasts Gaussian type speed profiles, as the CH rotates in and out of the meridional slice, causing some discrepancy in the timing between forecasted and observed solar-wind speed. With adaptations to the ESWF 2.0 algorithm we improve the precision and accuracy of the ESWF speed profiles. For that we implement compression and rarefaction effects occurring between solar-wind streams of different velocities in interplanetary space. By considering the propagation times for plasma parcels between the Sun and Earth and their interactions, we achieve the asymmetrical shape of the speed profile that is characteristic of high-speed streams (HSS). By further implementing CH segmentation, co-latitude information and dynamic thresholding, we find that the newly developed ESWF 3.2 performs significantly better than ESWF 2.0. For a sample of 294 different HSSs, we derive a relative increase in hits of the timing and peak velocity by 13.9%. The Pearson correlation coefficient increases by 14.3% from 0.35 to 0.40.

Observation and Modeling of the Solar Wind Turbulence Evolution in the Sub-Mercury Inner Heliosphere

This letter exploits the radial alignment between the Parker Solar Probe and BepiColombo in late 2022 February, when both spacecraft were within Mercury’s orbit. This allows the study of the turbulent evolution, namely, the change in spectral and intermittency properties, of the same plasma parcel during its expansion from 0.11 to 0.33 au, a still unexplored region. The observational analysis of the solar wind turbulent features at the two different evolution stages is complemented by a theoretical description based on the turbulence transport model equations for nearly incompressible magnetohydrodynamics. The results provide strong evidence that the solar wind turbulence already undergoes significant evolution at distances less than 0.3 au from the Sun, which can be satisfactorily explained as due to evolving slab fluctuations. This work represents a step forward in understanding the processes that control the transition from weak to strong turbulence in the solar wind and in properly modeling the heliosphere.

Modeling of Joint Parker Solar Probe–Metis/Solar Orbiter Observations

We present the first theoretical modeling of joint Parker Solar Probe (PSP)–Metis/Solar Orbiter (SolO) quadrature observations. The combined observations describe the evolution of a slow solar wind plasma parcel from the extended solar corona (3.5–6.3 R ⊙) to the very inner heliosphere (23.2 R ⊙). The Metis/SolO instrument remotely measures the solar wind speed finding a range from 96 to 201 km s−1, and PSP measures the solar wind plasma in situ, observing a radial speed of 219.34 km s−1. We find theoretically and observationally that the solar wind speed accelerates rapidly within 3.3–4 R ⊙ and then increases more gradually with distance. Similarly, we find that the theoretical solar wind density is consistent with the remotely and in-situ observed solar wind density. The normalized cross helicity and normalized residual energy observed by PSP are 0.96 and −0.07, respectively, indicating that the slow solar wind is very Alfvénic. The theoretical NI/slab results are very similar to PSP measurements, which is a consequence of the highly magnetic field-aligned radial flow ensuring that PSP can measure slab fluctuations and not 2D ones. Finally, we calculate the theoretical 2D and slab turbulence pressure, finding that the theoretical slab pressure is very similar to that observed by PSP.

How the area of solar coronal holes affects the properties of high-speed solar wind streams near Earth: An analytical model

Since the 1970s it has been empirically known that the area of solar coronal holes affects the properties of high-speed solar wind streams (HSSs) at Earth. We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show how the area of coronal holes and the size of their boundary regions affect the HSS velocity, temperature, and density near Earth. We assume that velocity, temperature, and density profiles form across the HSS cross section close to the Sun and that these spatial profiles translate into corresponding temporal profiles in a given radial direction due to the solar rotation. These temporal distributions drive the stream interface to the preceding slow solar wind plasma and disperse with distance from the Sun. The HSS properties at 1 AU are then given by all HSS plasma parcels launched from the Sun that did not run into the stream interface at Earth distance. We show that the velocity plateau region of HSSs as seen at 1 AU, if apparent, originates from the center region of the HSS close to the Sun, whereas the velocity tail at 1 AU originates from the trailing boundary region. Small HSSs can be described to entirely consist of boundary region plasma, which intrinsically results in smaller peak velocities. The peak velocity of HSSs at Earth further depends on the longitudinal width of the HSS close to the Sun. The shorter the longitudinal width of an HSS close to the Sun, the more of its “fastest” HSS plasma parcels from the HSS core and trailing boundary region have impinged upon the stream interface with the preceding slow solar wind, and the smaller is the peak velocity of the HSS at Earth. As the longitudinal width is statistically correlated to the area of coronal holes, this also explains the well-known empirical relationship between coronal hole areas and HSS peak velocities. Further, the temperature and density of HSS plasma parcels at Earth depend on their radial expansion from the Sun to Earth. The radial expansion is determined by the velocity gradient across the HSS boundary region close to the Sun and gives the velocity-temperature and density-temperature relationships at Earth their specific shape. When considering a large number of HSSs, the assumed correlation between the HSS velocities and temperatures close to the Sun degrades only slightly up to 1 AU, but the correlation between the velocities and densities is strongly disrupted up to 1 AU due to the radial expansion. Finally, we show how the number of particles of the piled-up slow solar wind in the stream interaction region depends on the velocities and densities of the HSS and preceding slow solar wind plasma.

Charge State Calculation for Global Solar Wind Modeling

Abstract The charge state composition of the solar wind carries information about the electron temperature, density, and velocity of plasma in the solar corona that cannot always be measured with remote sensing techniques, due to limitations in instrumental sensitivity and field of view as well as line-of-sight integration issues. However, in situ measurements of the wind charge state distribution only provide the end result of the solar wind evolution from the source region to the freeze-in point. By using 3D global modeling it is possible to follow solar wind plasma parcels of different origin along the path of their journey and study the evolution of their charge states as well as the driving physical processes. For this purpose, we implemented nonequilibrium ionization calculations within the Space Weather Modeling Framework’s solar corona and inner heliosphere modules, to the Alfvén Wave Solar Model (AWSoM). The charge state calculations are carried out parallel to the AWSoM calculations, including all the elements and ions whose ionization-recombination rates are included in the CHIANTI database, namely, from H to Zn. In this work, we describe the implementation of the charge state calculation, and compare simulation results to in situ measurements from the Advanced Composition Explorer and Ulysses spacecraft, and study charge state evolution of plasma parcels along different wind trajectories and wind types.

The “Singular” Behavior of the Solar Wind Scaling Features during Parker Solar Probe–BepiColombo Radial Alignment

Abstract At the end of 2020 September, the Parker Solar Probe (PSP) and BepiColombo were radially aligned: PSP was orbiting near 0.17 au and BepiColombo near 0.6 au. This geometry is of particular interest for investigating the evolution of solar wind properties at different heliocentric distances by observing the same solar wind plasma parcels. In this work, we use the magnetic field observations from both spacecraft to characterize both the topology of the magnetic field at different heliocentric distances (scalings, high-order statistics, and multifractal features) and its evolution when moving from near-Sun to far-Sun locations. We observe a breakdown of the statistical self-similar nature of the solar wind plasma with an increase in the efficiency of the nonlinear energy cascade mechanism when moving away from the Sun. We find a complex organization of large field gradients to dissipate the excess of kinetic energy across the inertial range near the Sun, whereas the topological organization of small fluctuations is still primarily responsible for the energy transfer rate at 0.6 au. These results provide, for the first time, evidence of the different roles of dissipation mechanisms near and far away from the Sun.

Inward-propagating Plasma Parcels in the Solar Corona: Models with Aerodynamic Drag, Ablation, and Snowplow Accretion

Abstract Although the solar wind flows primarily outward from the Sun to interplanetary space, there are times when small-scale plasma inflows are observed. Inward-propagating density fluctuations in polar coronal holes were detected by the COR2 coronagraph on board the STEREO-A spacecraft at heliocentric distances of 7–12 solar radii, and these fluctuations appear to undergo substantial deceleration as they move closer to the Sun. Models of linear magnetohydrodynamic waves have not been able to explain these deceleration patterns, so they have been interpreted more recently as jets from coronal sites of magnetic reconnection. In this paper, we develop a range of dynamical models of discrete plasma parcels with the goal of better understanding the observed deceleration trend. We found that parcels with a constant mass do not behave like the observed flows, and neither do parcels undergoing ablative mass loss. However, parcels that accrete mass in a snowplow-like fashion can become decelerated as observed. We also extrapolated OMNI in situ data down to the so-called Alfvén surface and found that the initial launch point for the observed parcels may often be above this critical radius. In other words, in order for the parcels to flow back down to the Sun, their initial speeds are probably somewhat nonlinear (i.e., supra-Alfvénic), and thus the parcels may be associated with structures such as shocks, jets, or shear instabilities.

Evolution of Solar Wind Turbulence from 0.1 to 1 au during the First Parker Solar Probe–Solar Orbiter Radial Alignment

Abstract The first radial alignment between Parker Solar Probe and Solar Orbiter spacecraft is used to investigate the evolution of solar wind turbulence in the inner heliosphere. Assuming ballistic propagation, two 1.5 hr intervals are tentatively identified as providing measurements of the same plasma parcels traveling from 0.1 to 1 au. Using magnetic field measurements from both spacecraft, the properties of turbulence in the two intervals are assessed. Magnetic spectral density, flatness, and high-order moment scaling laws are calculated. The Hilbert–Huang transform is additionally used to mitigate short sample and poor stationarity effects. Results show that the plasma evolves from a highly Alfvénic, less-developed turbulence state near the Sun, to fully developed and intermittent turbulence at 1 au. These observations provide strong evidence for the radial evolution of solar wind turbulence.

The Interplanetary and Magnetospheric causes of Geomagnetically Induced Currents (GICs) > 10 A in the Mäntsälä Finland Pipeline: 1999 through 2019

The interplanetary and magnetospheric phenomena time-coincident with intense geomagnetically induced current (GIC) > 10 A and > 30 A events during 21 years (1999 through 2019) at the Mäntsälä, Finland (57.9° magnetic latitude) gas pipeline have been studied. Although forward shocks and substorms are predominant causes of intense GICs, some newly discovered geoeffective interplanetary features are: solar wind plasma parcel (PP) impingements, possible interplanetary magnetic field (IMF) northward (Bn) and southward (Bs) turnings, and reverse shocks. The PPs are possibly the loop and filament portions of coronal mass ejections (CMEs). From a study of > 30 A GIC events, it is found that supersubstorm (SSS: SML < −2500 nT) and intense substorm (−2500 nT < SML < −2000 nT) auroral electrojet intensifications are the most frequent (76%) cause of all of these GIC events. These events occur most often (76%) in superstorm (SYM-H ≤ −250 nT) main phases, but they can occur in other storm phases and lesser intensity storms as well. After substorms, PPs were the most frequent causes of Mäntsälä GIC > 30 A events. Forward shocks were the third most frequent cause of the > 30 A events. Shock-related GICs were observed to occur at all local times. The two “Halloween” superstorms of 29–30 and 30–31 October 2003 produced by far the greatest number of GICs in the interval of study (9 > 30 A GICs and 168 > 10 A GICs). In the first Halloween superstorm, a shock-triggered SSS (SML < −3548 nT) caused 33, 57, 51 and 52 A GICs. The 57 A GIC was the most intense event of the superstorm and of this study. It is possible that this SSS is a new form of substorm. Equally intense magnetic storms were also studied but their related GICs were far less numerous and less intense.

Distance to the Energetic Neutral Hydrogen Source from the Heliotail

Abstract The interaction of the solar wind (SW) with the partially ionized interstellar medium forms the heliosphere. As the supersonic SW flows away from the Sun and incorporates pickup ions (PUIs), they are slowed, compressed, and heated at a termination shock, creating an energetic ion population in the inner heliosheath. The neutralization of PUIs in the heliosheath creates energetic neutral atoms (ENAs) at ∼keV energies that travel ballistically and can be observed at 1 au by the Interstellar Boundary Explorer (IBEX). IBEX uses single-pixel cameras to map ENAs from the heliosphere. In this study, we analyze IBEX observations of >1 keV ENAs from the heliotail during 2009–2017. The ENA spectral index maximizes near the ecliptic plane and decreases at higher latitudes, reflecting the latitudinal structure of the SW. We show that the angular spread of this structure can be used to derive the distance at which the observed ENAs originate, i.e., their cooling length. Using Ulysses observations of the SW we determine that the distance from the Sun to the source of ∼1–6 keV ENAs in the heliotail is ≥289 ± 35 au in 2009–2013 and ≥489 ± 56 au in 2014–2017, using the distance to the termination shock in the downwind direction as 160 au based on the analysis of McComas et al. The increase in ENA source distance over time suggests that IBEX is observing a fast/hotter plasma parcel propagating down the heliotail before being replaced by slow/cooler plasma as the solar cycle evolves.

Analysis of Plasma Irregularities on a Range of Scintillation‐Scales Using the Resolute Bay Incoherent Scatter Radars

AbstractScintillation in the polar cap ionosphere is observed with a Coherent Electromagnetic Radio Tomography (CERTO) receiver while the Resolute Bay Incoherent Scatter Radars (RISR) provide background plasma conditions in a 3D volume. We interpret fluctuations in the very high frequency (VHF) and ultrahigh frequency (UHF) signal associated with mid‐scale ionospheric structuring using 3D density gradients and plasma drift velocity vectors and calculate the maximum gradient drift instability growth rate. Plasma structuring is evident for any plasma density gradient, but sub‐kilometer structures are less likely on the leading edge of polar patches, possibly due to a much faster diffusion rate for small‐scale structures. Structures are much more uniformly distributed around density enhancements that do not have clear leading and trailing edges. Although the gradient drift instability is an important factor in polar cap structuring, linear growth rates are most successful at predicting structuring around isolated density enhancements in consistent plasma flows. For more general density gradients, the time history of a plasma parcel and local diffusion rates must also be considered.

Heliospheric magnetic field structures: Predictions & Implications

The observational implication of braided solar magnetic fields opens a new venue for an interpretation of various solar and interplanetary phenomena. Direct imaging of the coronal fields at frequencies corresponding to atomic transition of hot (∼1MK) plasma pinpoints to their braiding structure, while solar wind measurements of magnetized plasma parcels with distinct orientation, large field deviation and intermittent fading of energetic flare ions suggest that coronal braided field may have been carried by the solar wind to 1AU. The interconnection between the mathematical braids and knots is applied to the topologically non-trivial magnetized structures and their dynamics, from solar corona to the interplanetary medium. The analysis of braided magnetic configurations results in conjectures regarding (i) their stability under large oscillations of magnetic loops, (ii) the structure and stability of the coronal field through successive emergence/decay of heated magnetic braids, and (ii) their evolution into the solar wind. It is anticipated that the resulting conjectures will add to the understanding of the physical processes in the magnetosphere (Van Allen, Cluster satellites) and particularly will attain confirmation with the launch of the Parker Solar Probe.

Tracking Filament Evolution in the Low Solar Corona Using Remote Sensing and In Situ Observations

Abstract In the present work, we analyze a filament eruption associated with an interplanetary coronal mass ejection that arrived at L1 on 2011 August 5. In multiwavelength Solar Dynamic Observatory/Advanced Imaging Assembly (AIA) images, three plasma parcels within the filament were tracked at high cadence along the solar corona. A novel absorption diagnostic technique was applied to the filament material traveling along the three chosen trajectories to compute the column density and temperature evolution in time. Kinematics of the filamentary material were estimated using STEREO/Extreme Ultraviolet Imager and STEREO/COR1 observations. The Michigan Ionization Code used inputs of these density, temperature, and speed profiles for the computation of ionization profiles of the filament plasma. Based on these measurements, we conclude that the core plasma was in near ionization equilibrium, and the ionization states were still evolving at the altitudes where they were visible in absorption in AIA images. Additionally, we report that the filament plasma was heterogeneous, and the filamentary material was continuously heated as it expanded in the low solar corona.

Coronal mass ejections are not coherent magnetohydrodynamic structures

Coronal mass ejections (CMEs) are episodic eruptions of solar plasma and magnetic flux that travel out through the solar system, driving extreme space weather. Interpretation of CME observations and their interaction with the solar wind typically assumes CMEs are coherent, almost solid-like objects. We show that supersonic radial propagation of CMEs away from the Sun results in geometric expansion of CME plasma parcels at a speed faster than the local wave speed. Thus information cannot propagate across the CME. Comparing our results with observed properties of over 400 CMEs, we show that CMEs cease to be coherent magnetohydrodynamic structures within 0.3 AU of the Sun. This suggests Earth-directed CMEs are less like billiard balls and more like dust clouds, with apparent coherence only due to similar initial conditions and quasi homogeneity of the medium through which they travel. The incoherence of CMEs suggests interpretation of CME observations requires accurate reconstruction of the ambient solar wind with which they interact, and that simple assumptions about the shape of the CMEs are likely to be invalid when significant spatial/temporal gradients in ambient solar wind conditions are present.

Study of field‐aligned current (FAC), interplanetary electric field component (Ey), interplanetary magnetic field component (Bz), and northward (x) and eastward (y) components of geomagnetic field during supersubstorm

AbstractA dominant process by which energy and momentum are transported from the magnetosphere to the ionosphere is known as field‐aligned current (FAC). It is enhanced during magnetic reconnection and explosive energy release at a substorm. In this paper, we studied FAC, interplanetary electric field component (Ey), interplanetary magnetic field component (Bz), and northward (x) and eastward (y) components of geomagnetic field during three events of supersubstorm occurred on 24 November 2001, 21 January 2005, and 24 August 2005. Large‐scale FAC, supposed to be produced during supersubstorm (SSS), has potentiality to cause blackout on Earth. We examined temporal variations of the x and y components of high‐latitude geomagnetic field during SSS, which is attributed to the FACs. We shall report the characteristics of high‐latitude northward and eastward components of geomagnetic field variation during the growth phase of SSS by the implementation of discrete wavelet transform (DWT) and cross‐correlation analysis. Among three examples of SSS events, the highest peak value of FAC was estimated to be ~19 μAm−2. This is shore up with the prediction made by Parks (1991) and Stasiewicz et al. (1998) that the FACs may vary from a few tens to several hundred μAm−2. Although this peak value of FACs for SSS event is much higher than the average FACs associated with regular substorms or magnetic storms, it is expedient and can be expect for SSS events which might be due to very high density solar wind plasma parcels (PPs) triggering the SSS events. In all events, during growth phase, the FAC increases to extremely high level and the geomagnetic northward component decreases to extremely low level. This represents a strong positive correlation between FAC and geomagnetic northward component. The DWT analysis accounts that the highest amplitude of the wavelet coefficients indicates singularities present in FAC during SSS event. But the amplitude of squared wavelet coefficient is found to be different from each other, which might be due to the solar wind PPs of different density triggering the SSS events. The cross‐correlation analysis suggests that the perturbation on geomagnetic northward component at high latitude during SSS strongly correlates with the fluctuation pattern of FAC density. Hence, the FAC is the primary sources for the eastward‐westward magnetic field perturbations at high latitude.