Plasma Drift Velocity Research Articles

The variation of ionosonde-derived hmF2 and its comparisons with International Reference Ionosphere (IRI) and Empirical Orthogonal Function (EOF) over Pakistan longitude sector during solar cycle 22

Variations of maximum height of F2 ionospheric layer are analysed over ionospheric stations of Pakistan located at Islamabad (geog. coord. 33.75°N, 72.87°E), Multan (30.18°N, 71.48°E) and Karachi (24.95°N, 67.14°E) during the years, 1987 (LSA), 1990 (HSA) and 1993 (MSA) representing low, high and moderate solar activity years, respectively. Results showed that hmF2 in summer is higher than in winter during LSA and MSA at all stations. However, diurnal pattern is not consistently followed during winters of LSA and MSA. The lowest hmF2 values are observed around sunrise and sunset; whereas, higher values are observed around noon and midnight which may be due to upward and downward plasma drift velocity as diurnal behaviour of hmF2 is similar to diurnal behaviour of E×B drift. No specific latitudinal trend is observed in hmF2 during the period of this study over Pakistan which may be due to the combined effect of E×B drift and energy transferred to ionosphere by atmospheric planetary waves. Solar quiet current seems responsible for the variation of hmF2 over Multan and Islamabad. For Karachi equatorial electrojet seems controlling the daytime hmF2 during LSA. The hmF2 is found to have linear correlation with solar activity and this correlation is stronger with solar index F10.7 as compared to the sunspot numbers. The correlation coefficients for both solar indices are above 80%; whereas, geomagnetic indices Ap and Kp are weakly correlated having correlation coefficients less than 30%. Ionosonde-derived hmF2 are compared with regional model based on expansion of Empirical Orthogonal Function (EOF) with linear and spline interpolation of coefficients of time, seasons, magnetic dip & sunspot numbers and, global model, International Reference Ionosphere (IRI), with International Union of Radio Science (URSI) and Consultative Committee for International Radio (CCIR) options of IRI-2012 and AMTB-2013, SHU-2015 and BSE-1979 sub-models in combination with URSI and CCIR of IRI-2016 versions. The daytime hmF2 values over Pakistan modelled by AMTB of IRI-2016 (with URSI and CCIR) are found to be the most converging of all IRI options during all solar periods. AMTB-2013 also predicted nighttime values with least errors in most cases except during LSA. In addition, IRI showed better equinoctial and annual correlations with ionosonde-derived hmF2 as compared to EOF model. EOF based model showed higher nighttime Mean Absolute Errors (MAE) as compared to IRI. The lowest daytime and nighttime errors in hmF2 are observed over Multan during LSA shown by IRI-2016-AMTB-2013 (using URSI and CCIR) with MAE being 7.8 km and IRI-2016-SHU-2015 (using URSI and CCIR) with MAE being 4.7 km.

The gridded retarding ion drift sensor for the petitSat cubeSat mission.

The Gridded Retarding Ion Drift Sensor (GRIDS) is a small sensor that will fly on the 6 U petitSat CubeSat. It is designed to measure the three-dimensional plasma drift velocity vector in the Earth's ionosphere. The GRIDS also supplies information about the ion temperature, ion density, and the ratio of light to heavy ions present in the ionospheric plasma. It utilizes well-proven techniques that have been successfully validated by similar instruments on larger satellite missions while meeting CubeSat-compatible requirements for low mass, size, and power consumption. GRIDS performs the functions of a Retarding Potential Analyzer (RPA) and an Ion Drift Meter (IDM) by combining the features of both types of instruments in a single package. The sensor alternates RPA and IDM measurements to produce the full set of measurement parameters listed above. On the petitSat mission, GRIDS will help identify and characterize a phenomenon known as plasma blobs (or enhancements).

Plasma current regulated by balance between driving and restricting forces

In many plasma applications, the plasma current, which is determined by the plasma density and drift velocity, is an important parameter when investigating the induced phenomenon and its effects. However, it is unclear which physical parameters are responsible for regulating the current. Plasma is generated by a balance between the driving and restricting forces. The driving force originates from the electric and magnetic fields, and the restricting force originates from collisions between different species (electrons, ions, and neutral particles). When the electric field fluctuates over time, the pressure of the driving force is generated. The pressure of the driving force depends on the square of the electric field and the reciprocal of the repetition frequency. The pressure of the restricting force depends on the gas flow velocity and the collision frequency. When electrons and/or ions flow with the flowing neutral gas, a plasma current is generated from flowing charged particles. The magnitude of the plasma current is linearly proportional to the pressure caused by the driving force, and the variation in the plasma current depends on the pressure caused by the restricting force. In addition, the plasma current varies with the applied period of the voltage. Consequently, the plasma charge, which is the time integral of the plasma current, shows a linear relationship with the driving force and is thus regulated by the force balance between the driving and restricting forces. Therefore, the plasma current value and its generation time are regulated by the strength, applied period, and repetition frequency of the applied voltage and the neutral gas flow velocity.

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.

Solar Flare Effects on 150‐km Echoes Observed Over Jicamarca: WACCM‐X Simulations

AbstractJicamarca Radio Observatory observations and Whole Atmosphere Community Climate Model with thermosphere‐ionosphere eXtension (WACCM‐X) simulations are used to investigate the effects of the 7 September 2005 X‐17 solar flare on 150‐km echoes, electron densities, and vertical plasma drifts. The solar flare produces a remarkably similar response in the observed 150‐km echoes and simulated electron densities. The results provide additional evidence of the relationship between the background electron density and the layering structure that is seen in 150‐km echoes. The simulations also capture a similar rapid decrease in vertical plasma drift velocity that is seen in the observations. The simulated change in vertical plasma drift is, however, weaker than the observed decrease at the longitude of Jicamarca, though it is stronger east of Jicamarca. The effect of the solar flare on the vertical plasma drifts is primarily attributed to changes in conductivity due to the enhanced ionization during the solar flare.

Optimization of the Collective Thomson scattering diagnostic for future operation

Collective Thomson scattering (CTS) is a microwave diagnostic allowing measurements of a number of plasma parameters such as the bulk ion temperature, the plasma composition, drift velocities and fast ion velocity distribution function. A CTS system has been successfully installed and commissioned on the Wendelstein 7-X (W7-X) stellarator. The measured spectra are analyzed by the means of the CTS forward model eCTS and the Minerva scientific framework enabling the use of Bayesian inference of relevant plasma parameters. Here we discuss the options for further optimization of the CTS diagnostic and focus on two topics of importance for the inference of bulk ion temperature values from CTS spectra: influence of impurities on the CTS spectra and the width of the notch filters that are employed to protect the receiver from high-power radiation. In addition to that we discuss the possibility of effective charge measurements by CTS. We explore the existence of an optimal notch filter width.

Ionospheric storm of September 2017 observed at ionospheric station Pruhonice, the Czech Republic

The ionospheric effects induced by the September 2017 storm have been exceptional compared to other events in the solar cycle 24. This paper gathers results of the ionospheric observations at the European middle latitude station Pruhonice. It consists of evaluation of ionospheric vertical and oblique sounding, Digisonde drift measurement, and data obtained from the Continuous Doppler Sounding System. We observed strong ionospheric response with an unusual stratification of ionospheric layers, Large Scale Traveling ionospheric disturbances, changes in electron density, and increase and oscillations in plasma drift velocity.

On developing a new ionospheric plasma index for Brazilian equatorial F region irregularities

Abstract. F region vertical drifts (Vz) are the result of the interaction between ionospheric plasma with the zonal electric field and the Earth's magnetic field. Abrupt variations in Vz are strongly associated with the occurrence of plasma irregularities (spread F) during the nighttime periods. These irregularities are manifestations of space weather in the ionosphere's environment without necessarily requiring a solar burst. In this context, the Brazilian Space Weather Study and Monitoring Program (Embrace) of the National Institute for Space Research (INPE) has been developing different indexes to analyze these ionospheric irregularities in the Brazilian sector. Therefore, the main purpose of this work is to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity, named AV. It is based on the maximum value of Vz (Vzp), which in turn is calculated through its relationship with the virtual height parameter, h′F, measured by the Digisonde Portable Sounder (DPS-4D) installed in São Luís (2∘ S, 44∘ W; dip: −2.3∘). This index quantifies the time relationship between the Vz peak and the irregularity observed in the ionograms. Thus, in this study, we analyzed 7 years of data, between 2009 and 2015, divided by season in order to construct a standardized scale. The results show there is a delay of at least 15 min between the Vzp observation and the irregularity occurrence. Finally, we believe that this proposed index allows for evaluating the impacts of ionospheric phenomena in the space weather environment.

Method for Determining Neutral Wind Velocity Vectors Using Measurements of Internal Gravity Wave Group and Phase Velocities

This study presents a new method for determining a neutral wind velocity vector. The basis of the method is measurement of the group velocities of internal gravity waves. Using the case of the Boussinesq dispersion relation, we demonstrated the ability to measure a neutral wind velocity vector using the group velocity and wave vector data. An algorithm for obtaining the group velocity vector from the wave vector spectrum is proposed. The new method was tested by comparing the obtained winter wind pattern with wind data from other sources. Testing the new method showed that it is in quantitative agreement with the Fabry–Pérot interferometer wind measurements for zonal and vertical wind velocities. The differences in meridional wind velocities are also discussed here. Of particular interest were the results related to the measurement of vertical wind velocities. We demonstrated that two independent methods gave the presence of vertical wind velocities with amplitude of ~20 m/s. Estimation of vertical wind contribution to plasma drift velocity indicated the importance of vertical wind measurements and the need to take them into account in physical and empirical models of the ionosphere and thermosphere.

Total electron content and scintillations over Maseno, Kenya, during high solar activity year

Proper characterization of total electron content (TEC) and scintillation is very important to global positioning system (GPS) users in communication, navigation, ionospheric or atmospheric studies. Quiet time variation of TEC is useful in the estimation and removal of ionospheric delay for global navigation satellite systems single-frequency positioning. During geomagnetic storms, the variations of ionosphere deviate from their quiet day pattern and can cause significant effects on short-term prediction of various ionospheric parameters. The dynamics of the ionosphere change from region to region; therefore, in order to evaluate and improve the performance of global models of the ionosphere, numerous studies of variations using measured ionospheric parameters from stations globally are useful. This paper presents for the first time variations in the TEC and scintillation at Maseno University (geomagnetic coordinates, 9.64°S, 108.59°E), Kenya, investigated using a NovAtelGSV400B GPS receiver for the high solar activity year 2014. The GPS-measured TEC values were compared with the modeled TEC values by the latest International Reference Ionosphere model (IRI-2016), with a view to evaluate the performance of this version of the model. The largest TEC values were observed from 1300 to 1500 h local time throughout the year with the largest diurnal values occurring in March equinox and smallest during June solstice. The largest TEC values are attributed to extreme ultraviolet radiation coupled with upward $$\vec{E} \times \vec{B}$$ plasma drift velocity. Nighttime enhancements in TEC attributed to the ‘fountain’ effect occurred during some months. Scintillation correlated with depletions in TEC occurred in the period between 1600 h local time to 1900 h local time (post-sunset) sector during some months, with the strongest value of − 0.91 being experienced in March equinox. Scintillation was absent during geomagnetic storms studied mainly as a result of the time of onset of the recovery phases of the storms. In addition, the geomagnetic storms were manifested in GPS-measured TEC as negative ionospheric storms. The IRI-2016 model gave a good prediction of measured values except for its overestimation of measured TEC in the months of May and June. Further, a new insight shown by the results is the ability of the IRI-2016 model to predict post-sunset TEC enhancements during some months contrary to previous versions reported by other researchers in East Africa. However, model is not quickly sensitive to transitions from one season to another. This result contributes to the improvement of the current IRI model by recommending the introduction of an input into the model that is sensitive to transitions in seasons in future versions of the model.

Results of Observations of Ionospheric Plasma Drift in the Polarization Jet Region

Doppler measurement data from the Yakutsk subauroral ionospheric station have been used to reveal for the first time new and previously unknown dynamic phenomena during the development of the polarization jet. This study of horizontal and vertical velocities of ionospheric drifts reveals that the peaks of vertical and horizontal velocity components do not always coincide during the observation of a polarization jet. The horizontal plasma drift velocities are ~300–600 m/s on average (there are events with velocities of 900–1000 m/s). The vertical drift velocities are 30–50 m/s on average (there are events with velocities of 100–150 m/s). Analysis of ground-based ionospheric data has revealed that all events with the development of the polarization jet over Yakutsk were uniformly divided into four cases. In the first case, the vertical velocities in the polarization jet band reached a maximum simultaneously with horizontal velocities. In the other two cases, the times of the vertical velocity peaks are shifted to both sides of the reference time by ±1 h. In the latter case, the vertical velocities have similar peaks on both sides of horizontal velocity peaks.

Toward an Integrated View of Ionospheric Plasma Instabilities: 3. Explicit Growth Rate and Oscillation Frequency for Arbitrary Altitude

AbstractGeneral analytic expressions are derived for the growth rate γ and oscillation frequency in the ion frame of unstable plasma waves generated by ionospheric plasma instabilities including the Farley‐Buneman instability (FBI) and the gradient‐drift instability (GDI). The explicit expressions are developed for arbitrary altitude and scales in the local approximation. Limits of applicability are carefully considered focusing on the dependence on the electron density gradients G=∇n/n and wavelengths λ. It is shown that the key parameter that controls the applicability is the growth rate γ normalized to the ion collision frequency νi, with the developed expressions being valid for slow growths γ/νi<0.1. It is also shown that the commonly used assumption about the equivalency of the wave phase velocity Vph and the plasma drift velocity Vd fails in the F region at gradients as weak as G=10−5m−1. The developed analytic expressions for arbitrary altitude/scale offer a straightforward way of reconciling various altitude‐ and scale‐specific cases (e.g., FBI/GDI modes in the E region), with the often‐neglected ion inertia shown to play a critical role in the reconciliation. The new ion inertia effect is found to be represented by the quantity in the growth rate expression. The effect is found to reduce the standard FBI factor and amplify the GDI factor, and, due to the inverse relationship with the ion inertia, the effect becomes progressively stronger at larger altitudes and/or wavelengths.

Physical processes in the ionosphere during the solar eclipse on March 20, 2015 over Kharkiv, Ukraine (49.6° N, 36.3° E)

We present the results of observations of variations in the mid-latitude ionospheric parameters and physical processes in the geospace during March 20, 2015 partial solar eclipse over Kharkiv (49.60° N, 36.30° E) where the eclipse magnitude was about 0.54. The Kharkiv incoherent scatter (IS) radar and digital ionosonde were used for ionospheric observations and estimations of the parameters of the thermal and dynamical processes. At the time of the maximum obscuration of the Sun's area, an increase in the ionospheric F2 peak height by about 40 km was observed. At the same time, the electron density at altitudes of 190 and 210 km decreased by approximately 18.5 and 16.5%, respectively. During the eclipse, a decrease in the electron temperature and apparent changes in the vertical plasma drift velocity were observed. The observations and analysis have shown that the solar eclipse led to significant restructuring of the thermal and dynamic state of the ionospheric plasma over Kharkiv.

Spatial asymmetry in topside ion density and vertical E × B plasma drift velocity within 75°E–95°E

The ion density measured by the Ionospheric Plasma and Electrodynamics Instrument (IPEI) on board the ROCSAT -1 over the 75°E and 95°E meridian at 600km altitude has been utilized to examine the latitudinal and longitudinal distribution within the Indian sector, in particular, the north-south and east-west asymmetries of the equatorial ionization anomaly (EIA). A longitudinal gradient in ion density at 600 km higher towards 95°E develops during the noontime and afternoon hours when the EIA is at its peak. The density gradient persists till evening hours when pre-reversal enhancements occur. The vertical E × B plasma drift velocity measured simultaneously by ROCSAT -1 for the same space-time configuration has also been studied. In addition to diurnal, seasonal and solar activity variations in E × B drift velocity, the longitudinal gradient is also observed. The EIA at the altitude of 600 km peaks at different latitudes and are mostly asymmetric about the magnetic equator. From midnight till 0800 LT, the ion density across the equator is nearly uniform in the equinoxes. But in the solstices, the density exhibits a north-south gradient. In the June solstice, density is higher in the northern hemisphere and decreases gradually towards south. The gradient in density reverses in December solstice. Normally, the EIA peaks within 1200 LT and 1600 LT while around 2000 LT, pre-reversal enhancement of ionization occurs affecting the EIA evening structure. The strength of the EIA also exhibits seasonal, year-to-year and hemispheric variations. The longitudinal asymmetry of drift velocity along 75°E and 95°E longitude sectors is the contributing factor behind the observed longitudinal asymmetry in ion density. Significant positive correlation between the strength of the EIA and E × B drift is observed in both longitudes.

Diurnal and Longitudinal Variations of the Structure of an Equatorial Anomaly During Equinoxes According to Intercosmos-19 Satellite Data

Longitudinal and local time variations in the structure of the equatorial anomaly under high solar activity in the equinox are considered according to the Intercosmos-19 topside sounding data. It is shown that the anomaly begins to form at 0800 LT, when the southern crest is formed. The development of the equatorial anomaly is associated with well-known variations in the equatorial ionosphere: a change in the direction of the electric field from the west to the east, which causes vertical plasma drift W (directed upward) and the fountain effect. At 1000 LT, both anomaly crests appear, but they become completely symmetrical only by 1400 LT. The average position of the crests increases from I = 20° at 1000 LT to I = 28° at 1400 LT. The position of the crests is quite strong, sometimes up to 15°, varies with longitude. The foF2 value above the equator and the equatorial anomaly intensity (EAI) at 1200–1400 LT vary with the longitude according to changes in the vertical plasma drift velocity W. At this time, four harmonics are observed in the longitudinal variations of W, foF2, and EAI. The equatorial anomaly intensity increases to the maximum 1.5–2 h after the evening burst in the vertical plasma drift velocity. Longitudinal variations of foF2 for 2000–2200 LT are also associated with corresponding variations in the vertical plasma drift velocity. The equatorial anomaly intensity decreases after the maximum at 2000 LT and the crests decrease in size and shift towards the equator, but the anomaly is well developed at midnight. On the contrary, after midnight, foF2 maxima in the region of the anomaly crests are farther from the equator, but this is obviously associated with the action of the neutral wind. At 0200 LT, in contrast to the morning hours, only the northern crest of the anomaly is clearly pronounced. Thus, in the case of high solar activity during the equinoxes, a well-defined equatorial anomaly is observed from 1000 to 2400 LT. It reaches the maximum at 2000 LT.

Interannual Variability of the Daytime Equatorial Ionospheric Electric Field

AbstractUnderstanding the variability of the ionosphere is important for the prediction of space weather and climate. Recent studies have shown that forcing from the lower atmosphere plays a significant role for the short‐term (day‐to‐day) variability of the low‐latitude ionosphere. The present study aims to assess the importance of atmospheric forcing for the variability of the daytime equatorial ionospheric electric field on the interannual (year‐to‐year) time scale. Magnetic field measurements from Huancayo (12.05°S, 75.33°W) are used to augment the equatorial vertical plasma drift velocity (VZ) measurements from the Jicamarca Unattended Long‐term Investigations of the Ionosphere and Atmosphere radar during 2001–2016. VZ can be regarded as a measure of the zonal electric field. After removing the seasonal variation of ∼10 m/s, midday values of VZ show an interannual variation of ∼2 m/s with an oscillation period of 2–3 years. No evidence of solar cycle influence is found. The Ground‐to‐topside Atmosphere‐Ionosphere model for Aeronomy, which takes into account realistic atmospheric variability below 30 km, reproduces the pattern of the observed interannual variation without having to include variable forcing from the magnetosphere. The results indicate that lower atmospheric forcing plays a dominant role for the observed interannual variability of VZ at 1200 local time.

SAMI2 model results for the quiet time low latitude ionosphere over India

Efficacy of SAMI2 model for the Indian low latitude region around 75°E longitudes has been tested for different levels of solar flux. With a slight modification of the plasma drift velocity the SAMI2 model has been successful in reproducing quiet time ionospheric low latitude features like Equatorial Ionization Anomaly. We have also showed the formation of electron hole in the topside equatorial ionosphere in the Indian sector. Simulation results show the formation of electron hole in the altitude range 800–2500 km over the magnetic equator. Indian zone results reveal marked differences with regard to the time of occurrence, seasonal appearances and strength of the electron hole vis-a-vis those reported for the American equatorial region.

Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.

Unusual behavior of quiet-time zonal and vertical plasma drift velocities over Jicamarca during the recent extended solar minimum of 2008

Abstract. The influence of the recent deep and prolonged solar minimum on the daytime zonal and vertical plasma drift velocities during quiet time is investigated in this work. Analyzing the data obtained from incoherent scatter radar from Jicamarca (11.95° S, 76.87° W) we observe an anomalous behavior of the zonal plasma drift during June 2008 characterized by lower than usual daytime westward drift and its early afternoon reversal to eastward. As a case study the zonal drift observed on 24 June 2008 is modeled using a realistic low-latitude ionosphere simulated by the Sheffield University Plasmasphere-Ionosphere Model-INPE (SUPIM-INPE). The results show that an anomalously low zonal wind was mainly responsible for the observed anomalous behavior in the zonal drift. A comparative study of the vertical plasma drifts obtained from magnetometer data for some periods of maximum (2000–2002) and minimum solar activity (1998, 2008, 2010) phases reveal a considerable decrease on the E-region conductivity and the dynamo electric field during 2008. However, we believe that the contribution of these characteristics to the unusual behavior of the zonal plasma drift is significantly smaller than that arising from the anomalously low zonal wind. The SUPIM-INPE result of the critical frequency of the F layer (foF2) over Jicamarca suggested a lower radiation flux than that predicted by solar irradiance model (SOLAR2000) for June 2008.

Large-scale irregularities of the winter polar topside ionosphere according to data from Swarm satellites

An analysis of the electron density measurements (Ne) along the flyby trajectories over the high-latitude region of the Northern Hemisphere under winter conditions in 2014 and 2016 has shown that the main large-scale structure observed by Swarm satellites is the tongue of ionization (TOI). At the maximum of the solar cycle (F10.7 = 160), the average value of Ne in the TOI region at an altitude of 500 km was 8 × 104 cm–3. Two years later, at F10.7 = 100, Ne ~ 5 × 104 cm–3 and Ne ~2.5 × 104 cm–3 were observed at altitudes of 470 and 530 km, respectively. During the dominance of the azimuthal component of the interplanetary magnetic field, the TOI has been observed mainly on the dawn or dusk side depending on the sign of B y . Simultaneous observations of the convective plasma drift velocity in the polar cap show the transpolar flow drift to the dawn (By < 0) or dusk side (B y < 0). Observations and numerical simulation of the Ne distribution have confirmed the significant role of the electric field of the magnetospheric convection in the generation of large-scale irregularities in the polar ionosphere.