Indices Of Geomagnetic Activity Research Articles

Forecasting ionospheric TEC using least squares support vector machine and moth-flame optimization methods in China

The total electron content (TEC) of the ionosphere is an important parameter to describe the ionosphere, and it is a great significance to monitor and predict it accurately. In this paper, a hybrid ionospheric TEC prediction model based on the least squares support vector machine (LSSVM) and the Moth-Flame Optimization (MFO) algorithm is proposed. The parameters of the LSSVM model are optimized by the MFO algorithm. We use observation data of 15 GNSS stations from the Crustal Movement Observation Network of China (CMONOC) to extract ionospheric TEC from 2012 to 2019. The ionospheric TEC is forecasted using solar and geomagnetic activity indices in both the low solar activity year (2019) and the high solar activity year (2015). The results show that the prediction performance of the MFO_LSSVM model is significantly better than that of the IRI model, SVM model, and LSSVM model. Compared with the other three models, there are more stable prediction results in the low and high solar activity years. At the same time, the predicted value of the MFO_LSSVM model has a good correlation with the measured value, and it also has good prediction potential in areas with active geomagnetic activity. The comparison with the Long Short-Term Memory (LSTM) model shows that the MFO_LSSVM model has better performance than the single LSTM model. In conclusion, the MFO_LSSVM model can accurately predict ionospheric TEC in China, and has better accuracy than traditional long-term and short-term models.

Tidal Composition Analysis of Global Sq Current System

AbstractIn this study, we examine the spatiotemporal variability of the global equivalent ionospheric current system estimated from geomagnetic Solar‐quiet (Sq) variations at 124 mid‐ to low‐latitude ground‐based magnetometer stations during 1–31 May 2020. In this period, geomagnetic activity was particularly low, that is, the hourly geomagnetic activity index Hp60 did not exceed 4o. The spherical harmonic analysis is performed on the Sq variations to estimate the equivalent current function at each universal time hour. Hourly maps of the global Sq current system are used to evaluate, for the first time, the tidal composition of mid‐latitude Sq currents and its temporal evolution. Although tides are known to be an important driver of Sq currents, the tidal composition analysis was difficult in previous studies that focused on Sq currents at particular longitude sectors. Our results show that the migrating tidal components (DW1, SW2, and TW3) are predominant in both hemispheres. This is as expected from the strong day‐night contrast in ionospheric conductivities. The day‐to‐day variations of the migrating tidal components are, however, not strongly correlated between the two hemispheres, suggesting that these variations arise not only from the global effect of solar radiation on ionospheric conductivities but also from the local effect of neutral winds. Variations associated with non‐migrating tides are also found. Especially, eastward‐propagating diurnal and semidiurnal tides with zonal wavenumber 1 (DE1 and SE1) are the largest non‐migrating components. Their production mechanisms remain to be understood.

Reconstruction of Carrington Rotation Means of Open Solar Flux over the Past 154 Years

We generate reconstructions of signed open solar flux (OSF) for the past 154 years using observations of geomagnetic activity. Previous reconstructions have been limited to annual resolution, but this is here increased by a factor of more than 13 by using averages over Carrington rotation (CR) intervals. We use two indices of geomagnetic activity, the homogeneous aa index, aaH, and the IDV(1d) index; a combination of the two is fitted to OSF estimates from near-Earth interplanetary satellite data. For 1995 – 2022, these are corrected for excess flux (i.e. orthogardenhose flux and switchbacks) using strahl electrons. For 1970 – 2022, we also use the absolute values of the radial component of the near-Earth interplanetary magnetic field 〈|〈Br〉τ|〉CR\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}${\\langle }|{\\langle }B_{r}{\\rangle }_{\ au }|{\\rangle }_{CR}$\\end{document}, where the excess flux is allowed for by adopting the optimum averaging interval τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}${\ au }$\\end{document} of 20 h. However, in the interval 1970 – 1995, data gaps in the interplanetary data are a serious problem. The errors that these missing data cause in CR averages of OSF are evaluated by synthetically masking data for CRs that have a full complement, using the same number and time series of data gaps as for the CR in question. Given the potential for missing data to generate large errors, we use the near-continuous 1995 – 2022 data to derive the best-fit combination of the geomagnetic data and employ the 1970 – 1995 data for testing in which we can readily allow for the errors caused by data gaps. Errors caused by inaccuracies in the geomagnetic data are shown to be considerably smaller than the uncertainties due to the polynomial fitting. It is shown that the new reconstructions are consistent with the previous annual estimates and that there is considerable variability in the OSF values from one CR to the next; in particular, in high-activity solar cycles, there can be individual CRs in which the OSF exceeds that for adjacent CRs by a factor as large as two.

Analysis of ionospheric anomalies before the Fukushima Mw 7.3 earthquake of March 16, 2022

Abstract In order to study the coupling relationship between earthquakes and ionospheric disturbances, TEC data during the Mw 7.3 earthquake that occurred near Fukushima, Japan on March 16, 2022, were processed using global ionospheric data provided by the Center for Orbit Determination in Europe (CODE). In this paper, the sliding quartile interval method is used to eliminate solar activity in a 27-day window, including sunspot number (SSN), F10.7 cm radio flux (F10.7), total solar irradiation (TSI), solar wind velocity (Vsw) and geomagnetic activity. The impact of disturbance storm time index (DST) and global geomagnetic activity index (KP) on TEC anomaly disturbance can obtain more accurate TEC anomaly information. The results indicate that when the solar and geomagnetic activity cycles are inconsistent with the TEC anomalies on fifth day before the earthquake, the TEC anomalies above the epicenter are significantly greater than those observed in other regions, and the corresponding magnetic conjugate region is accompanied by anomalies, which is the characteristic of TEC anomalies caused by earthquakes. This means that the detected TEC anomalies can be used as a potential ionospheric precursors, indicating that the Fukushima earthquake is imminent.

A Floor in the Sun's Photospheric Magnetic Field: Implications for an Independent Small-scale Dynamo

Clette recently showed that F 10.7 systematically approaches a quiet Sun daily value of 67 solar flux units (sfu) at solar minima as the number of spotless days on the Sun increases. Previously, a floor of ∼2.8 nT had been proposed for the solar wind (SW) magnetic field strength (B). F 10.7, which closely tracks the Sun's unsigned photospheric magnetic flux, and SW B exhibit different relationships to their floors at 11 yr solar minima during the last ∼50 yr. While F 10.7 approaches 67 sfu at each minimum, the corresponding SW B is offset above ∼2.8 nT by an amount approximately proportional to the solar polar field strength—which varied by a factor of ∼2.5 during this interval. This difference is substantiated by ∼130 yr of reconstructed F 10.7 (via the range of the diurnal variation of the East-component (rY) of the geomagnetic field) and SW B (based on the interdiurnal variability geomagnetic activity index). For the last ∼60 yr, the contribution of the slow SW to SW B has exhibited a floor-like behavior at ∼2 nT, in contrast to the contributions of coronal mass ejections and high-speed streams that vary with the solar cycle. These observations, as well as recent SW studies based on Parker Solar Probe and Solar Dynamics Observatory data, suggest that (1) the Sun has a small-scale turbulent dynamo that is independent of the 11 yr sunspot cycle; and (2) the small-scale magnetic fields generated by this nonvarying turbulent dynamo maintain a constant open flux carried to the heliosphere by the Sun's floor-like slow SW.

Forecasting Ionospheric foF2 Using Bidirectional LSTM and Attention Mechanism

AbstractThe critical frequency of ionospheric F2 layer (foF2) is an important ionospheric characteristic parameter. In this paper, a deep learning model based on Bidirectional long short‐term memory (BiLSTM) and attention mechanism is implemented for predicting the foF2 parameter. The inputs of models are the foF2 of globally available ionospheric ionosonde stations, geographic longitude and latitude, world time (UT), geomagnetic activity index, and solar activity index from 2015 to 2017. The superiority of the model is analyzed from different latitudes, seasons, and geomagnetic conditions. The results show that the prediction performance of the Bidirectional long short‐term memory model based on attention mechanism (BiLSTM‐Attention) is better than other models. The performance of the prediction model is optimal at high latitudes. The root mean square error (RMSE) and correlation coefficient (R) of the BiLSTM‐Attention model are 0.539 MHZ and 0.908 MHz at high latitudes, respectively. In terms of RMSE, it is 25.243%, 18.209%, and 11.203% lower than those of the international reference ionosphere (IRI), LSTM, and BiLSTM models, respectively. The prediction results of the four seasons show that the models are more applicable in winter. Compared with the IRI model, the RMSE of the BiLSTM‐Attention model in spring, summer, autumn, and winter is reduced by 24.344%, 21.181%, 25.058%, and 30.948%, respectively. The prediction effect of the BiLSTM‐Attention model is improved in the magnetic quiet period, the magnetic moderate period and the magnetic storm period. Also, the improvement effect is more obvious in the magnetostatic day, and the RMSE is reduced by 27.462% compared with the IRI model.

High‐Energy Electron Flux Enhancement Pattern in the Outer Radiation Belt in Response to the Interplanetary Coronal Mass Ejections

AbstractThe high‐energy electron flux enhancement pattern in the outer radiation belt is observed under the influence of the Interplanetary Coronal Mass Ejections (ICMEs). Ten events were selected during the Van Allen Probes era, with the high‐energy electron flux enhancement starting close to L* = 4. A schematic diagram of the main physical processes responsible for this kind of high‐energy electron flux enhancement is presented, considering the energy deposited in the inner magnetosphere under the influence of ICMEs. Superposed Epoch Analysis is applied to the interplanetary medium parameters, the magnetopause standoff distance, the storm‐time geomagnetic activity indices, the Ultra‐Low Frequency (ULF) waves, and the whistler‐mode chorus waves. A compressed magnetopause, Bz component preferentially southward and storm indices considerably high are observed at the beginning of the electron flux enhancements. The modeled parameters of the chorus waves at the dayside/nightside sectors show the high acceleration efficiency at the beginning of the electron flux enhancement pattern II. These results suggest that the local acceleration driven by chorus waves is essential to these electron flux enhancements at low L*. In contrast, although the ULF waves are detected at the beginning of the studied electron flux enhancements, their contribution is insignificant.

Hysteresis effect between geomagnetic activity indices (Ap, Dst) and interplanetary medium parameters in solar activity cycles 21–24

We have studied the relationship of geomagnetic activity indices (Ap, Dst) on time intervals, equal to solar cycles (∼11 years), with solar activity indicators and heliospheric parameters. It is shown that the plots of the Ap and Dst indices versus solar activity indicators, as well as versus heliospheric parameters, i.e. solar wind and IMF parameters in the ascending and descending phases of solar activity cycles 21–24 do not coincide, which is indicative of the hysteresis phenomenon. The Ap and Dst indices form hysteresis loops with all parameters we analyze during cycles 21–24. The shape and area of the hysteresis loops, as well as the direction of rotation, clockwise or counterclockwise, depend significantly on indicators of solar activity, heliospheric parameters and change from cycle to cycle. We have found a tendency for the extension and area of the hysteresis loops to decrease from cycle 21 to cycle 24. Analysis of the variability in the shape and size of the hysteresis loops formed by the Ap and Dst indices with solar indicators and heliospheric parameters gives reason to believe that the obtained loops reflect the long-term evolution of the solar wind energy flux, which determines global geomagnetic activity and the magnetospheric ring current intensity in the ascending and descending phases of solar activity cycles 21‒24.

Эффект гистерезиса между индексами геомагнитной активности (Ap, Dst) и параметрами межпланетной среды в 21-24 циклах солнечной активности

We have studied the relationship of geomagnetic activity indices (Ap, Dst) on time intervals, equal to solar cycles (∼11 years), with solar activity indicators and heliospheric parameters. It is shown that the plots of the Ap and Dst indices versus solar activity indicators, as well as versus heliospheric parameters, i.e. solar wind and IMF parameters in the ascending and descending phases of solar activity cycles 21–24 do not coincide, which is indicative of the hysteresis phenomenon. The Ap and Dst indices form hysteresis loops with all parameters we analyze during cycles 21–24. The shape and area of the hysteresis loops, as well as the direction of rotation, clockwise or counterclockwise, depend significantly on indicators of solar activity, heliospheric parameters and change from cycle to cycle. We have found a tendency for the extension and area of the hysteresis loops to decrease from cycle 21 to cycle 24. Analysis of the variability in the shape and size of the hysteresis loops formed by the Ap and Dst indices with solar indicators and heliospheric parameters gives reason to believe that the obtained loops reflect the long-term evolution of the solar wind energy flux, which determines global geomagnetic activity and the magnetospheric ring current intensity in the ascending and descending phases of solar activity cycles 21‒24.

Исследование влияния геомагнитной активности на функционирование систем железнодорожной автоматики в Арктической зоне России

The authors study the possible influence of geomagnetic activity of railway automatics in the Russian Arctic. For the analysis they use the indices of global and regional geomagnetic activity along with the archive of failures on the Northern section of the Oktyabrskaya railway in 2001—2006. The geomagnetic activity is found to be higher for days with failures than for days without the ones. This effect manifests itself in different types of geomagnetic disturbances, including magnetic storms, characterized by the storm index Dst, auroral activations, quantified in AE and EI indices, as well as in local index WY indicating spectral power of geomagnetic variations in milliHerz frequency range. The maximum differences for days with and without failures are obtained for index values averaged over 2—4 days. At the same time, the researchers have found no significant differences between failures for which a cause not related to geomagnetic disturbance is a priori indicated, and those for which such a cause is not identified.

Parametrization of Energetic Ion and Electron Fluxes in the Near‐Earth Magnetotail

AbstractThe near‐Earth plasma sheet region is the main source of energetic (tens to hundreds keV) ion and electron populations transported by convection and injections into the inner magnetosphere. Energetic ions from the plasma sheet contribute to the ring current, whereas energetic electrons contribute to the radiation belt seed population for further acceleration to relativistic energies. Near‐Earth plasma sheet energetic fluxes have been traditionally used to set boundary conditions for radiation belt and ring current models. This study provides an empirical parametrization for ∼75 keV flux intensity as a function of the geomagnetic activity index auroral electrojet and the equatorial magnetic field Bz. Such parametrization includes the dynamic magnetic field configuration in the near‐Earth plasma sheet and may be merged with empirical magnetic field models. We also provide models extending this parametrization to the [20, 300] keV of electron energy range and [75, 300] keV of ion energy range. The parametrization is developed based on THEMIS and Geostationary Operational Environmental Satellite measurements, and verified by comparison with MMS measurements in the near‐Earth plasma sheet. This parametrization incorporates meso‐scale transient flux variations associated with Bz perturbations into ring current and radiation belt simulations.

Understanding Quiet and Storm Time EMIC Waves—Van Allen Probes Results

AbstractGeomagnetic indices have been used as a proxy for studying electromagnetic ion cyclotron (EMIC) wave occurrences under different geomagnetic conditions. However, the drivers of EMIC waves are different during non‐storm, storm time and during individual storm phases. Using ∼7 years of data from the twin Van Allen Probes, we demonstrate that the occurrence probability of EMIC waves are not well captured by a specific geomagnetic activity index alone, but is rather well manifested by considering individual storm phases. We show EMIC wave occurrence statistics during different storm phases (pre‐onset, main and recovery) for geomagnetic activity indices Sym‐H, AE, and Kp and solar wind dynamic pressure Pdyn, illustrating that the occurrence rates vary significantly during different storm phases even for a given geomagnetic index. We also utilize this large database to show EMIC wave occurrence distribution, and how various wave and plasma parameters behave under different geomagnetic conditions. EMIC waves occur 2.9 times more often during geomagnetic storms than during non‐storm times. The majority (72%) of storm time EMIC waves occur during the recovery phase due to long recovering time, while the highest occurrence rates are in the pre‐onset phase, followed by main and recovery phases. EMIC waves in the main phase have occurrence peaks in the dusk to pre‐midnight sectors while recovery phase events spread to more Magnetic Local Time (MLT) sectors with peaks in the morning sector. Wave amplitudes are found to be evenly distributed across different MLT sectors during all geomagnetic conditions.

The triple-dip La Niña of 2020–22: updates to the correlation of ENSO with the termination of solar cycles

The Sun provides the energy required to sustain life on Earth and drive our planet’s atmosphere. However, establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge across the spectrum of Earth-system science. Over the past few years a new picture to describe solar variability has developed, based on observing, understanding and tracing the progression, interaction and intrinsic variability of the magnetized activity bands that belong to the Sun’s 22-year magnetic activity cycle. A solar cycle’s fiducial clock does not run from the canonical min or max, instead resetting when all old cycle polarity magnetic flux is cancelled at the equator, an event dubbed the “termination” of that solar cycle, or terminator. In a recent paper, we demonstrated with high statistical significance, a correlation between the occurrence of termination of the last five solar cycles and the transition from El Niño to La Niña in the Pacific Ocean, and predicted that there would be a transition to La Niña in mid 2020. La Niña did indeed begin in mid-2020, and endured into 2023 as a rare “triple dip” event, but some of the solar predictions made did not occur until late 2021. This work examines what went right, what went wrong, the correlations between El Niño, La Niña and geomagnetic activity indices, and what might be expected for the general trends of large-scale global climate in the next decade.

Hysteresis Phenomena in the Relationship between the Cosmic Ray Cutoff Rigidity and Parameters of the Magnetosphere during a Storm on May 15, 2005

Variations in the cutoff rigidities of cosmic rays (ΔR) depending on the parameters of the solarwind, the interplanetary magnetic field (IMF), and geomagnetic activity were studied at different phases ofthe strong magnetic storm on May 15, 2005. We found that the trajectories ΔR, i.e., the successive values thatΔR takes depending on the parameters under study during the main phase of the storm did not coincide withthe trajectories in the recovery phase, which led to the formation of hysteresis loops. The clearest hysteresisloops are formed for the relationship between ΔR and the Bz component of the IMF, the density and pressureof the solar wind, and the Dst index of geomagnetic activity. The area of the hysteresis loops increases withthe latitude of the cosmic ray observation station.

Ionospheric electric potential as an alternative indicator of solar effect on the lower atmosphere

We have explored the possibility of applying the ionospheric electric potential (EP) as a parameter describing the effects of solar activity on the troposphere. We calculated EP, using the semi-empirical model, where the potential spatial distribution is determined by solar wind, interplanetary magnetic field parameters, and the geomagnetic activity index AL. We have carried out a comparative analysis of EP and the commonly used geomagnetic activity indices in a high-latitude region for 1975–2019. It has been shown that EP can be used as an indicator of solar activity since it describes both short-period disturbances and long-term variations. The revealed similar trends in long-term EP variations and near-surface temperature suggest that the changes in climate system parameters are induced by slower changes in the Sun’s large-scale magnetic field. The performed analysis of EP and near-surface temperature correlation maps has revealed that the atmospheric static stability conditions have an effect on spatial distribution of tropospheric response to solar impact.

Электрический потенциал ионосферы — альтернативный индикатор солнечного воздействия на нижнюю атмосферу

We have explored the possibility of applying the ionospheric electric potential (EP) as a parameter describing the effects of solar activity on the troposphere. We calculated EP, using the semi-empirical model, where the potential spatial distribution is determined by solar wind, interplanetary magnetic field parameters, and the geomagnetic activity index AL. We have carried out a comparative analysis of EP and the commonly used geomagnetic activity indices in a high-latitude region for 1975–2019. It has been shown that EP can be used as an indicator of solar activity since it describes both short-period disturbances and long-term variations. The revealed similar trends in long-term EP variations and near-surface temperature suggest that the changes in climate system parameters are induced by slower changes in the Sun’s large-scale magnetic field. The performed analysis of EP and near-surface temperature correlation maps has revealed that the atmospheric static stability conditions have an effect on spatial distribution of tropospheric response to solar impact.

Локальная диагностика наличия полярных сияний на основе интеллектуального анализа геомагнитных данных

Despite the existing variety of approaches to monitoring space weather and geophysical parameters in the auroral oval region, the issue of effective prediction and diagnostics of auroras as a special state of the upper ionosphere at high latitudes remains virtually unresolved.
 In this paper, we explore the possibility of local diagnostics of auroras through mining of geomagnetic data from ground-based sources. We assess the significance of indicative variables and their statistical relationship.
 So, for example, the application of Bayesian inference to the data from the Lovozero geophysical station for 2012–2020 has shown that the dependence of a posteriori probability of observing auroras in the optical range on the state of geomagnetic parameters is logarithmic, and the degree of its significance is inversely proportional to the discrepancy between empirical data and approximating function.
 The accuracy of the approach to diagnostics of aurora presence based on the random forest method is at least 86 % when using several local predictors and ~80 % when using several global geomagnetic activity indices characterizing the geomagnetic field disturbance in the auroral zone.
 In conclusion, we discuss promising ways to improve the quality metrics of diagnostic models and their scope.

Variations in cosmic ray cutoff rigidities during the March 8–11, 2012 magnetic storm (CAWSES II period)

The geomagnetic cutoff rigidity of cosmic rays (CRs) is the main factor regulating the arrival of CR particles at a given point on Earth's surface or inside the magnetosphere. To study the relationship between cutoffs and near-Earth space parameters, we have selected the strongest magnetic storm that occurred on March 8–11, 2012 during the CAWSES-II interval, recommended by SCOSTEP for detailed studies of solar-terrestrial relations. We have found the geomagnetic cutoffs by two methods: 1) by trajectory calculations in the magnetic field of the perturbed magnetosphere according to the Ts01 model and 2) by the spectrographic global survey method according to the data from the world network of neutron monitors. The largest drop in the cutoffs (−1.1 GV) obtained by the latter method was observed during the recovery phase of the storm. Apparently, this is due to the influence of the supersubstorms that occurred at that time. The analysis has shown that the closest connection of variations in the cutoffs can be traced with the geomagnetic activity index Dst, which indicates the determining contribution of the ring current to the transport of CRs. In addition, we have found a significant connection with the electromagnetic field parameters (with the Bz component of the interplanetary magnetic field and the azimuthal component of the electric field Ey). The dynamic solar wind parameters practically do not control variations in CR geomagnetic cutoff rigidities.

Изменения жесткостей обрезания космических лучей во время бури 8–11 марта 2012 г в период CAWSES-II

The geomagnetic cutoff rigidity of cosmic rays (CRs) is the main factor regulating the arrival of CR particles at a given point on Earth's surface or inside the magnetosphere. To study the relationship between cutoffs and near-Earth space parameters, we have selected the strongest magnetic storm that occurred on March 8–11, 2012 during the CAWSES-II interval, recommended by SCOSTEP for detailed studies of solar-terrestrial relations. We have found the geomagnetic cutoffs by two methods: 1) by trajectory calculations in the magnetic field of the perturbed magnetosphere according to the Ts01 model and 2) by the spectrographic global survey method according to the data from the world network of neutron monitors. The largest drop in the cutoffs (−1.1 GV) obtained by the latter method was observed during the recovery phase of the storm. Apparently, this is due to the influence of the supersubstorms that occurred at that time. The analysis has shown that the closest connection of variations in the cutoffs can be traced with the geomagnetic activity index Dst, which indicates the determining contribution of the ring current to the transport of CRs. In addition, we have found a significant connection with the electromagnetic field parameters (with the Bz component of the interplanetary magnetic field and the azimuthal component of the electric field Ey). The dynamic solar wind parameters practically do not control variations in CR geomagnetic cutoff rigidities.

Local diagnostics of aurora presence based on intelligent analysis of geomagnetic data

Despite the existing variety of approaches to monitoring space weather and geophysical parameters in the auroral oval region, the issue of effective prediction and diagnostics of auroras as a special state of the upper ionosphere at high latitudes remains virtually unresolved.
 In this paper, we explore the possibility of local diagnostics of auroras through mining of geomagnetic data from ground-based sources. We assess the significance of indicative variables and their statistical relationship.
 So, for example, the application of Bayesian inference to the data from the Lovozero geophysical station for 2012–2020 has shown that the dependence of a posteriori probability of observing auroras in the optical range on the state of geomagnetic parameters is logarithmic, and the degree of its significance is inversely proportional to the discrepancy between empirical data and approximating function.
 The accuracy of the approach to diagnostics of aurora presence based on the random forest method is at least 86 % when using several local predictors and ~80 % when using several global geomagnetic activity indices characterizing the geomagnetic field disturbance in the auroral zone.
 In conclusion, we discuss promising ways to improve the quality metrics of diagnostic models and their scope.