Level Of Geomagnetic Activity Research Articles

A new model for plasmapause locations derived from IMAGE RPI and Van Allen probe data

The outer boundary of the plasmasphere, the plasmapause, is characterized by a sharp electron density gradient that changes under varying space weather conditions. We developed a new model, called Neustrelitz/ESOC PlasmaPause Model (NEPPM), for providing plasmapause location in terms of -shell utilizing electron density measurements from the Van Allen probes from 2012 to 2018 and the IMAGE satellite data from 2001 to 2005. Both datasets were preprocessed, and algorithms were developed for automatic detection of plasmapause location. The suggested model provides a simple ellipse-based approach determined by the semi-major axis, the eccentricity, and the orientation angle of the semi-major axis. The modelled varies as a function of the index and magnetic local time . The NEPPM results are compared with the Global Core Plasma Model (GCPM). The plasmapause bulge in the evening hours follows the level of geomagnetic activity. The NEPPM will complete the NPSM (Neustrelitz PlasmaSphere Model), which was derived from dual-frequency GPS measurements on-board the CHAMP satellite mission.

Reconstruction Analysis of Global Ionospheric Outflow Patterns

AbstractIonospheric outflow supplies nearly all of the heavy ions observed within the magnetosphere, as well as a significant fraction of the proton density. While much is known about upflow and outflow energization processes, the full global pattern of outflow and its evolution is only known statistically or through numerical modeling. Because of the dominant role of heavy ions in several key physical processes, this unknown nature of the full outflow pattern leads to significant uncertainty in understanding geospace dynamics, especially surrounding storm intervals. That is, global models risk not accurately reproducing the main features of intense space storms because the amount of ionospheric outflow is poorly specified and thus magnetospheric composition and mass loading could be ill‐defined. This study defines a potential mission to observe ionospheric outflow from several platforms, allowing for a reasonable and sufficient reconstruction of the full outflow pattern on an orbital cadence. An observing system simulation experiment is conducted, revealing that four well‐placed satellites are sufficient for reasonably accurate outflow reconstructions. The science scope of this mission could include the following: reveal the global structure of ionospheric outflow; relate outflow patterns to geomagnetic activity level; and determine the spatial and temporal nature of outflow composition. The science objectives could be focused to be achieved with minimal instrumentation (only a low‐energy ion spectrometer to obtain outflow reconstructions) or with a larger scientific scope by including contextual instrumentation.

Complex dayside particle precipitation observed during the passage of a solar wind rotational discontinuity

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

Joint Observations of Energy Transport and Dissipation during Plasma Flow Vortex in the Terrestrial Magnetotail

Plasma flow vorticity is ubiquitous in space and plays a key role in material mixing and energy transfer. The five THEMIS satellites orbiting in different regions of the terrestrial magnetotail provide an unprecedented opportunity to study the temporal–spatial evolution characteristics of a plasma flow vortex on large spatial scales. We present an analysis of the flow vorticity that occurred between 05:50 and 06:30 UT on 2009 March 23 during a quiet time of the terrestrial magnetotail. The uneven distributions of the density and temperature of the vortex observed by the three near-Earth satellites (THA, THD, and THE) indicate that the plasma in the solar wind gradually mixed into the near-Earth magnetotail through a series of nonequilibrium processes. Both the flow vortices and dipolarization observed by the three near-Earth satellites were about 10 minutes earlier than those observed by the two satellites (THB and THC) in the mid-magnetotail. Further analysis of the relationship between vorticity, field-aligned current, and energy transport reveals that the flow vortex interacted with the surrounding plasma during its tailward propagation. The field-aligned current related to the vorticity could only generate a pseudo-breakup of the aurora in the ionosphere. Thus, we speculate that this flow vortex mainly transports mass and energy from the solar wind to the near-magnetotail, propagates tailward to the mid-magnetotail, and heats the encountered plasma by dissipating its bulk flow and dominant thermal energy. These results shed light on the mass mixing, energy transport, and dissipation of the plasma flow vortex during quiet levels of geomagnetic activity on large spatial scales.

Numerical modelling of the IMF influence on the large-scale structure of the ionosphere, including the poles displacement

The interplanetary magnetic field (IMF), frozen into the solar wind plasma, determines the level of geomagnetic activity and significantly affects the large-scale structure of the high-latitude ionosphere. Variations in the IMF components lead to non-stationarity of the magnetospheric convection electric field, causing changes in the spatio-temporal distribution of charged particles in the ionosphere. The situation is complicated by the fact that the geographic and geomagnetic poles do not coincide, which leads to universal time control (UT control) of the parameters of the high-latitude ionosphere. The effect of the poles displacement is most manifest in winter. Therefore, in this work, within the framework of a nonstationary mathematical model of the F-region of the ionosphere in Euler variables, taking into account the displacement between the geographic and geomagnetic poles, we study the influence of the interplanetary magnetic field components on the large-scale structure of the high-latitude ionosphere in winter. For this, the Weimer model of high-latitude electric potentials, which depends on the IMF, was used. As a result, of numerical modelling, it is shown that the IMF components affect the shape, size and spatio-temporal location of the main structural features of the high-latitude ionosphere depending on universal time. The obtained effect of ionisation tongue separation requires experimental confirmation. The obtained results demonstrate that the developed non-stationary three-dimensional model of the ionosphere in Euler variables can be applied to the study of ionospheric disturbances, including ionospheric disturbances associated with changes in the IMF components.

Long-Term Study of the Synchronization Effect between Geomagnetic Field Variations and Minute-Scale Heart-Rate Oscillations in Healthy People

This study aimed to investigate the effect of human heart-rate synchronization with variations in the geomagnetic field (GMF) (“biogeophysical synchronization effect”). We analyzed 403 electrocardiogram (ECG) recordings of 100 or 120 min that were obtained in 2012–2023 from two middle-aged female volunteers in good health. The minute-value series of the GMF vector from the INTERMAGNET network was used. Each ECG recording was individually examined using cross-correlation and wavelet analysis. The findings from two separate experimental sets (306 recordings from Volunteer A and 97 from Volunteer B) displayed notable similarity in all aspects analyzed: (1) For both participants, the biogeophysical synchronization effect is observed in 40–53% of the recordings as a statistically significant (p < 0.0045) correlation between minute heart-rate (HR) time-series values and at least one of the horizontal components of the GMF, with a time shift between values of [−5, +5] min. (2) Wavelet analysis indicates that the spectra of the HR series and at least one GMF component exhibit similarity in 58–61% of cases. (3) The synchronization is most evident within the period range between 8–13 min. The probability of the synchronization effect manifestation was independent of the geomagnetic activity (GMA) level, which was recorded during the observations.

Comparison of Ring Current Proton Losses Between Contributions From Scattering by Field Line Curvature and EMIC Waves

AbstractAlthough both the field line curvature (FLC) and electromagnetic ion cyclotron (EMIC) waves are recognized to contribute importantly to the loss of energetic protons in the Earth's ring current, their quantitative differences in scattering ring current protons are still not fully understood. In this study, using a realistic, nondipolar magnetic field model, we perform a detailed analysis of the scattering effects of ring current protons and the resultant proton lifetimes due to FLC and EMIC waves at different L‐shells under different levels of geomagnetic activity. We find that compared with EMIC wave‐driven scattering, FLC scattering has a stronger dependence on L‐shell and geomagnetic activity. Pitch angle scattering efficiency due to FLC enhances significantly as proton energy increases. In contrast, scattering by H+ band EMIC waves tends to be weaker with increasing proton energy, while the scattering rates by He+ band EMIC waves increase first and then decrease. The results of proton lifetime against pitch angle scattering show that EMIC wave‐driven scattering dominates the loss of ring current protons at lower L‐shells (L < 6), especially during geomagnetically quiet conditions. During geomagnetically active conditions at L ≥ 6, EMIC wave‐driven scattering dominates at lower proton energies, while FLC scattering dominates at higher proton energies. This study improves the current understanding of the relative contributions of scattering by FLC and EMIC waves to the Earth's ring current proton dynamics.

Influence of geomagnetic activity on the southern atmosphere and its cross‐seasonal association with SAM

AbstractThis study investigates the interannual cross‐seasonal association between the winter energetic particle precipitation, which is related to the geomagnetic activity (GA), and the southern annular mode (SAM) in the following summer by employing the ERA5 reanalysis dataset. The results reveal a marked negative correlation between these variables on an interannual timescale. Therefore, we analyse the GA signatures in the southern atmosphere and find that the evolution of SAM to the negative phase driven by GA may be caused by the following two mechanisms: First, for high GA levels, the middle and lower stratospheric polar vortex becomes weaker from October to November, with considerable changes in the stratospheric thermal structure and more anomalous planetary wave upwelling, accompanied by weakening of the circumpolar westerly. Over time, the anomalous signal from the upper layer can be transmitted downward and is conducive to inducing and strengthening the negative SAM in the following summer, which may serve as the stratospheric pathway for the geomagnetic impact on the SAM and Southern Hemisphere (SH) climate. Second, another possible way is that the preceding GA also appreciably regulates negative anomalies in the Ferrel circulation in SH, implying poleward anomalies in the direction of the pressure gradient, which promotes the development and enhancement of the negative phase of the SAM. In addition, easterly quasi‐biennial oscillation conditioning plays a positive role in the response of the southern atmosphere to geomagnetic forcing, thereby strengthening the connection between them.

Responses of the wintertime auroral E-region neutral wind to varying levels of geomagnetic activity

Introduction: The auroral E-region is an important interface where forces from the magnetosphere and the lower atmosphere converge and have a significant effect on the vertical structure of the neutral winds. The resulting vertical neutral wind structure has been reported to be associated with altitude-dependent and nonlinear effects from different forces. We conduct a statistical examination of the reactions of wintertime neutral winds to four various degrees of geomagnetic activity, with a focus on the impacts of ion drag.Methods: We derive neutral winds using the PFISR measurements covering 2010–2019 and will give a statistical view of the auroral E-region neutral wind with a focus on the winter nighttime during different disturbed conditions. We investigate the effects of the geomagnetic activity on the neutral winds and the tidal components by dividing the dataset into 4 subsets. Tidal decomposition is conducted by least square fitting of the seasonal median winds to obtain the mean, diurnal amplitude, diurnal phase, semidiurnal amplitude, and semidiurnal phase.Results and discussion: We find that 1) when geomagnetic activity increases, dawn-dusk asymmetry exists in both zonal and meridional winds in the upper E-region with stronger zonal wind in the dusk sector than in the dawn sector and much stronger meridional wind in the dawn sector than in the dusk sector. 2) Tidal decomposition results reveal that geomagnetic activity has more significant effects on the meridional diurnal amplitude than zonal diurnal amplitude while the zonal and meridional semidiurnal amplitudes show similar changes when the geomagnetic activity increases. In addition, the maximum semidiurnal amplitude, particularly in the zonal direction, appears at a higher altitude with larger values as geomagnetic activity increases, indicating an ascending transition altitude for the semidiurnal oscillations. The ascending trend of maximum semidiurnal amplitude appearing at higher altitudes during more disturbed conditions has not been reported before. 3) Zonal wind over 110 km demonstrates increasing ion drag effects in the evening sector and the effects of coupled ion drag and other factors after midnight.

IonosphericTotal Electron Content Changes during the 15 February 2018 and 30 April 2022 Solar Eclipses over South America and Antarctica

This is one of the first papers to study the ionospheric effects of two solar eclipses that occurred in South America and Antarctica under geomagnetic activity in different seasons (summer and autumn) and their impact on the equatorial ionization anomaly (EIA). The changes in total electron content (TEC) during the 15 February 2018 and 30 April 2022 partial solar eclipses will be analyzed. The study is based on more than 390 GPS stations, Swarm-A, and DMSP F18 satellite measurements, such as TEC, electron density, and electron temperature. The ionospheric behaviors over the two-fifth days on both sides of each eclipse were used as a reference for estimating TEC changes. Regional TEC maps were created for the analysis. Background TEC levels were significantly higher during the 2022 eclipse than during the 2018 eclipse because ionospheric levels depend on solar index parameters. On the days of the 2018 and 2022 eclipses, the ionospheric enhancement was noticeable due to levels of geomagnetic activity. Although geomagnetic forcing impacted the ionosphere, both eclipses had evident depletions under the penumbra, wherein differential vertical TEC (DVTEC) reached values <−40%. The duration of the ionospheric effects persisted after 24 UT. Also, while a noticeable TEC depletion (DVTEC ∼−50%) of the southern EIA crest was observed during the 2018 eclipse (hemisphere summer), an evident TEC enhancement (DVTEC > 30%) at the same crest was seen during the eclipse of 2022 (hemisphere autumn). Swarm-A and DMSP F18 satellite measurements and analysis of other solar eclipses in the sector under quiet conditions supported the ionospheric behavior.

Plasmasphere Control of ULF Wave Distribution at Different Geomagnetic Conditions

AbstractMagnetic storms and substorms cause global disturbances in the Earth's magnetosphere. Plasma clouds injected from the magnetotail during storm or substorm drift around the Earth and generate ultra‐low frequency (ULF) waves via various mechanisms. At the same time, the inner part of the magnetosphere called plasmasphere is filled with cold particles and its characteristics are sensitive to the geomagnetic activity level. Previous theoretical and some observational studies suggested plasmasphere and its boundary, plasmapause, are special regions for ULF waves to interact with charged particles. We present a statistical analysis of ULF waves during different geomagnetic conditions. We utilized Arase satellite magnetic field and electron density measurements from March 2017 to December 2020 to investigate spatial distribution of ULF waves and its dependence on the plasmapause location. A 1–2 RE gap between the plasmapause and a region of high transverse waves occurrence rate was found. This gap keeps during quiet geomagnetic conditions when plasmasphere expands, and we concluded that the plasmapause controls the ULF wave distribution in the magnetosphere. ULF wave occurrence rate significantly decreases at quiet time, but dayside and dawnside maxima still occur for poloidal and compressional, and toroidal waves, respectively. Thus, we can distinguish internally and externally excited waves. Average wave frequency distribution revealed field‐line resonance character of toroidal waves as frequency increases toward the Earth. Poloidal and compressional waves distributions clearly distinguish low frequency externally excited waves and high frequency storm‐time pulsations.

Программное обеспечение для автоматизированного распознавания и оцифровки архивных данных оптических наблюдений полярных сияний

One of the main tools for recording auroras is the optical observation of the sky in automatic mode using all-sky cameras. The results of observations are recorded in special mnemonic tables, ascaplots. Ascaplots provide daily information on the presence or absence of cloud cover and auroras in various parts of the sky and are traditionally used to study the daily distribution of auroras in a given spatial region, as well as to calculate the probability of their observation in other regions in accordance with the level of geomagnetic activity. At the same time, the processing of ascaplots is currently carried out manually, which is associated with significant time costs and a high proportion of errors due to the human factor. To increase the efficiency of ascaplot processing, we propose an approach that automates the recognition and digitization of data from optical observations of auroras. A formalization of the ascaplot structure is proposed, which is used to process the ascaplot image, extract the corresponding observation results, and form the resulting data set. The approach involves the use of machine vision algorithms and the use of a specialized mask - a debug image for digitization, which is a color image in which the general position of the ascaplot cells is specified. The proposed approach and the corresponding algorithms are implemented in the form of software that provides recognition and digitization of archival data from optical observations of auroras. The solution is a single-user desktop software that allows the user to convert ascaplot images into tables in batch mode, available for further processing and analysis. The results of the computational experiments have shown that the use of the proposed software will make it possible to avoid errors in the digitization of ascaplots, on the one hand, and significantly increase the speed of the corresponding computational operations, on the other. Taken together, this will improve the efficiency of processing ascaplots and conducting research in the relevant area.

The Global Variation of Low Ionosphere Under Action of Energetic Electron Precipitation

AbstractThe density in the D region is hard to observe on a large scale, because the density in this region is too low. In addition to solar radiation changes with a sinusoidal period of 24 hr, the energetic electron precipitation (EEP) is the major source for the ionospheric D region. In this study, we utilized observations from NOAA/MetOp satellites to derive the electron density profile from 60 to 150 km under the influence of EEP. It seems that the derived electron profile is roughly consistent with the observed one. Additionally, using above derived method of low ionospheric (D and E regions) electron profile based on the observations of NOAA/MetOp satellites, the actions of EEP on global ionosphere under different level of geomagnetic activity are analyzed. We find that EEP has a significant impact on the electron density in the altitude range from 60 to 90 km in the L ∼ 4.5–8 and MLT ∼ 9–14 regions, particularly during strong geomagnetic activity. A peak in Total Electron Content (TEC) was observed at MLT ∼ 11–12 and L ∼ 5.5–6, exhibiting an enhancement approximately 19.96 times higher than that observed during quiet periods. However, the effects of EEP decrease as altitude increases. The TEC enhancement at altitudes from 90 to 120 km during strong geomagnetic activity is like that at 60–90 km, but only about 2.08 times higher than that during quiet periods. In addition, only a weak increase is detected around midnight at altitudes from 120 to 150 km.

Polar Cap Patches Scaling Properties: Insights from Swarm Data

Among the effects of space weather, the degradation of air traffic communications and satellite-based navigation systems are the most notable. For this reason, it is of uttermost importance to understand the nature and origin of ionospheric irregularities that are at the base of the observed communication outages. Here we focus on polar cap patches (PCPs) that constitute a special class of ionospheric irregularities observed at very high latitudes in the F region. To this purpose we use the so-called PCP flag, a Swarm Level 2 product, that allows for identifying PCPs. We relate the presence of PCPs to the values of the first- and second-order scaling exponents and intermittency estimated from Swarm A electron density fluctuations and to the values of the Rate Of change of electron Density Index (RODI) for two different levels of geomagnetic activity, over a time span of approximately 3.5 years starting on 16 July 2014. Our findings show that values of RODI, first- and second-order scaling exponents and intermittency corresponding to measurements taken inside PCPs differ from those corresponding to measurements taken outside PCPs. Additionally, the values of the first- and second-order scaling exponents and of intermittency indicate that PCPs are in a turbulent state. Investigation of the coincidence of loss of lock (LoL) events with PCPs displayed that approximately 57.4% of LoLs in the Northern hemisphere and 45.7% in the Southern hemisphere occur in coincidence of PCPs when disturbed geomagnetic activity is considered. During quiet geomagnetic conditions these percentages decrease to 51.4% in the Northern hemisphere and to 20.1% in the Southern hemisphere.

Properties of the Variability of the Maximum Density of the F 2-Layer over Almaty at Different Levels of Solar and Geomagnetic Activity

Properties of the Variability of the Maximum Density of the F 2-Layer over Almaty at Different Levels of Solar and Geomagnetic Activity

Assessing the performance of IRI-2016 and IRI-2020 models using COSMIC-2 GNSS radio occultation TEC data under different magnetic activities over Egypt

Abstract Variations in Total Electron Content (TEC) between the COSMIC-2, IRI-2016, and IRI-2020 are considered under different levels of geomagnetic storm activity: minor, moderate, and severe. TEC values are scrutinized at three levels of the Kp index, which serves as a metric for gauging the strength of a magnetic storm (Kp = 3.0, Kp = 6.0, Kp = 8.0) and across four-time intervals throughout 24 h to understand the performance of the models during both day and night-time conditions. Statistical analysis reveals that the standard deviation of TEC variations is lower during minor storms than moderate and severe. The comparison of variations between COSMIC-2 Radio Occultation TEC and both IRI-2016 and IRI-2020 models revealed more substantial discrepancies during day-time intervals; This was likely attributed to the dynamic and complex nature of the ionosphere influenced by solar radiation and other factors. Comparative analysis across the three levels of storm activity demonstrated that IRI2020 provided improved results over IRI2016, particularly during minor geomagnetic storm events. The study demonstrates that IRI2020 is more accurate than IRI-2016 at forecasting ionospheric conditions, especially at night and during moderate geomagnetic storm activity periods. Both models, however, provide valuable insights during challenging space weather conditions, and the results demonstrate their utility in understanding and forecasting the ionosphere’s behavior. The results yield valuable insights into space weather conditions and their effects on technology and communication, highlighting the potential for further improvement in TEC prediction models.

Equatorial plasma bubbles features over the Brazilian sector according to the solar cycle and geomagnetic activity level

Equatorial plasma bubbles (EPBs) can lead to signal degradation, affecting the measurement accuracy. Studying EPBs and their characteristics has gained increasing importance. The characteristics of EPBs were investigated using the rate of total electron content (TEC) index (ROTI) maps under different solar and magnetic activity conditions during two periods: July 2014–July 2015 (solar maximum activity with F10.7: 145.9 × 10−22 W⋅m−2⋅Hz−1) and July 2019–July 2020 (solar minimum activity with F10.7: 69.7 × 10−22 W⋅m−2⋅Hz−1). We also divided this analysis according to the magnetic activity levels based on Kp and Dst (disturbance storm time) indices, classified as follows: quiet+ (Kp ≤3 and Dst >−30 nT), quiet− (Kp ≤3 and Dst <−30 nT), disturbed weak (−50 nT <Dst ≤−30 nT), moderate (−100 nT <Dst ≤−50 nT), and intense (Dst ≤−100 nT). The ROTI is calculated using the slant TEC with the carrier phase, and its keograms are used to extract the zonal velocity and distance. Our statistical investigation shows the occurrence rate, duration, zonal drift velocity, and inter-bubble zonal distance of EPBs over the Brazilian sector. The latitudinal extension and zonal drift velocity of EPBs are higher during the solar maximum than those in the solar minimum. In addition, EPBs are found with unusually long durations, remaining until the morning (∼12 UT), and 10% of EPB observations occurred on the winter solstice.

Statistical Study on Plasma Velocities in the Bottom‐Side Ionosphere Over Low Latitude Hainan Station: Digisonde Measurement

AbstractData measured by the Digisonde at the low‐latitude station Hainan from 2003 to 2016 are statistically analyzed to specify the diurnal average variations of the bottom‐side F region ionospheric plasma velocity vector V. This is the first comprehensive analysis of Digisonde measurements of low latitude F region plasma velocities in the East Asian sector that use a database covering more than one solar cycle. The velocity components VN (Northward), VE (Eastward), and VZ (Upward) are analyzed for two levels of solar flux and two levels of geomagnetic activity, respectively. The diurnal variations of the average VZ show three positive peaks near the prereversal enhancement (PRE) period, pre‐midnight, and before sunrise, respectively, and a prominent valley in the early morning. The averaged VZ significantly increased with solar flux in the period of PRE during equinoxes, but it was only slightly affected by Kp. The VE component was westward in daytime and eastward in nighttime. The average eastward VE increased significantly with solar flux but decreased with Kp, whereas the average westward VE exhibited only a small variation with solar flux and Kp. The average VN was almost southward independent of solar flux and Kp. The plasma velocities over the Hainan station were mainly caused by the electric field and neutral wind. Our results show that the features of the vertical and meridional velocities over the Hainan station in the morning are associated with the formation of the equatorial ionization anomaly (EIA).

Geoefficiency of Sporadic Phenomena in Solar Cycle 24

The specific features of solar cycle 24 are discussed, including cosmic ray variations, characteristicsof solar flares, proton events, coronal mass ejections, and the level of geomagnetic activity. It is shownthat in terms of the sunspot number and other manifestations of solar activity, cycle 24 turned out to be themost modest one over the last 100 years of observations. A significant decrease in the geoefficiency of varioussolar events is described, which manifested itself in a smaller number and magnitude of Forbusheffects recorded on the Earth, the enhancements of the fluxes of protons and electrons of different energies,and geomagnetic storms.

Tracking Geomagnetic Storms with Dynamical System Approach: Ground-Based Observations

Using a dynamical systems approach, we examine the persistence and predictability of geomagnetic perturbations across a range of different latitudes and levels of geomagnetic activity. We look at the horizontal components of the magnetic field measured on the ground between 13 and 24 March 2015, at approximately 40 observatories in the Northern Hemisphere. We introduced two dynamical indicators: the extremal index θ, which quantifies the persistence of the system in a particular state and the instantaneous dimension d, which measures the active number of degrees of freedom of the system. The analysis revealed that during disturbed periods, the instantaneous dimension of the horizontal strength of the magnetic field, which depends on latitude, increases, indicating that the geomagnetic response is externally driven. Furthermore, during quiet times, the instantaneous dimension values fluctuate around the state-space dimension, indicating a more stochastic and thus less predictable nature system.