Function Of Magnetic Latitude Research Articles

On the Contribution of Latitude‐Dependent ULF Waves to the Radial Transport of Off‐Equatorial Relativistic Electrons in the Radiation Belts

AbstractUltra‐low frequency (ULF) waves radially diffuse hundreds‐keV to few‐MeV electrons in the magnetosphere, as the range of drift frequencies of such electrons overlaps with the wave frequencies, leading to resonant interactions. Theoretically this process is described by analytic expressions of the resonant interactions between electrons and ULF wave modes in a background magnetic field. However, most expressions of the radial diffusion rates are derived for equatorially mirroring electrons and are based on estimates of the power of ULF waves that are obtained either from spacecraft close to the equatorial plane or from the ground but mapped to the equatorial plane. Based on recent statistical in situ observations, it was found that the wave power of magnetic fluctuations is significantly enhanced away from the magnetic equator. In this study, the distribution of the wave amplitudes as a function of magnetic latitude is compared against models simulating the natural modes of oscillation of magnetospheric field lines, with which they are found to be consistent. Energetic electrons are subsequently traced in 3D model fields that include a latitudinal dependence that is similar to measurements and to the natural modes of oscillation. Particle tracing simulations show a significant dependence of the radial transport of relativistic electrons on pitch angle, with off‐equatorial electrons experiencing considerably higher radial transport, as they interact with ULF wave fluctuations of higher amplitude than equatorial electrons. These findings point to the need for incorporating pitch‐angle‐dependent radial diffusion coefficients in global radiation belt models.

GPS phase scintillation at high latitudes during geomagnetic storms of 7–17 March 2012 – Part 2: Interhemispheric comparison

Abstract. During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7–17 March 2012 caused geomagnetic storms that strongly affected high-latitude ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time (MLT), the scintillation was observed in the ionospheric cusp, the tongue of ionization fragmented into patches, sun-aligned arcs in the polar cap, and nightside auroral oval and subauroral latitudes. Complementing a companion paper (Prikryl et al., 2015a) that focuses on the high-latitude ionospheric response to variable solar wind in the North American sector, interhemispheric comparison reveals commonalities as well as differences and asymmetries between the northern and southern high latitudes, as a consequence of the coupling between the solar wind and magnetosphere. The interhemispheric asymmetries are caused by the dawn–dusk component of the interplanetary magnetic field controlling the MLT of the cusp entry of the storm-enhanced density plasma into the polar cap and the orientation relative to the noon–midnight meridian of the tongue of ionization.

GPS phase scintillation at high latitudes during geomagnetic storms of 7–17 March 2012 – Part 1: The North American sector

Abstract. The interval of geomagnetic storms of 7–17 March 2012 was selected at the Climate and Weather of the Sun-Earth System (CAWSES) II Workshop for group study of space weather effects during the ascending phase of solar cycle 24 (Tsurutani et al., 2014). The high-latitude ionospheric response to a series of storms is studied using arrays of GPS receivers, HF radars, ionosondes, riometers, magnetometers, and auroral imagers focusing on GPS phase scintillation. Four geomagnetic storms showed varied responses to solar wind conditions characterized by the interplanetary magnetic field (IMF) and solar wind dynamic pressure. As a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere–ionosphere system. Large southward IMF and high solar wind dynamic pressure resulted in the strongest scintillation in the nightside auroral oval. Scintillation occurrence was correlated with ground magnetic field perturbations and riometer absorption enhancements, and collocated with mapped auroral emission. During periods of southward IMF, scintillation was also collocated with ionospheric convection in the expanded dawn and dusk cells, with the antisunward convection in the polar cap and with a tongue of ionization fractured into patches. In contrast, large northward IMF combined with a strong solar wind dynamic pressure pulse was followed by scintillation caused by transpolar arcs in the polar cap.

High-latitude GPS phase scintillation and cycle slips during high-speed solar wind streams and interplanetary coronal mass ejections: a superposed epoch analysis

Results of a superposed epoch (SPE) analysis of occurrence of phase scintillation and cycle slips at high latitudes keyed by arrival times of high-speed solar wind streams (HSS) and interplanetary coronal mass ejections (ICME) for years 2008 to 2012 are presented. Phase scintillation index σ Φ is obtained in real time from L1 signal recorded at the rate of 50 Hz by specialized global positioning system (GPS) ionospheric scintillation and total electron content (TEC) monitors (GISTMs) deployed as a part of the Canadian High Arctic Ionospheric Network (CHAIN). The phase scintillation, mapped as a function of magnetic latitude and magnetic local time, occurs predominantly on the dayside in the cusp and in the nightside auroral oval. The scintillation occurrence peaks on days of HSS or ICME impacts at the Earth's magnetosphere and tapers off a few days later, which is similar to day-to-day variability of geomagnetic activity and riometer absorption at high latitudes. ICMEs that are identified as magnetic clouds are significantly more geoeffective than HSSs and ICMEs with no or weak magnetic cloud characteristics. On their arrival day, magnetic clouds result in higher occurrence, and thus probability, of scintillation in the nightside auroral zone. The SPE analysis results are used to obtain cumulative probability distribution functions for the phase scintillation occurrence that can be employed in probabilistic forecast of phase scintillation at high latitudes.

GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm

Abstract. The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S4 and σΦ are stored in real time from an array of high-rate scintillation receivers of the Canadian High Arctic Ionospheric Network (CHAIN). Ionospheric phase scintillation was observed at high latitudes during a moderate geomagnetic storm (Dst = −61 nT) that was caused by a moderate solar wind plasma stream compounded with the impact of two coronal mass ejections. The most intense phase scintillation (σΦ ~ 1 rad) occurred in the cusp and the polar cap where it was co-located with a strong ionospheric convection, an extended tongue of ionisation and dense polar cap patches that were observed with ionosondes and HF radars. At sub-auroral latitudes, a sub-auroral polarisation stream that was observed by mid-latitude radars was associated with weak scintillation (defined arbitrarily as σΦ < 0.5 rad). In the auroral zone, moderate scintillation coincided with auroral breakups observed by an all-sky imager, a riometer and a magnetometer in Yellowknife. To overcome the limited geographic coverage by GISTMs other GNSS data sampled at 1 Hz can be used to obtain scintillation proxy indices. In this study, a phase scintillation proxy index (delta phase rate, DPR) is obtained from 1-Hz data from CHAIN and other GPS receivers. The 50-Hz and 1-Hz phase scintillation indices are correlated. The percentage occurrences of σΦ > 0.1 rad and DPR > 2 mm s−1, both mapped as a function of magnetic latitude and magnetic local time, are very similar.

Ion drift meter calibration and photoemission correction for the C/NOFS satellite

The Ion Drift Meter (IDM) onboard the Communication/Navigation Outage Forecasting System (C/NOFS) measures ion arrival angles transverse to the satellite path and requires precise attitude determination for proper conversion to ambient ion drift. Low ionospheric densities during the 2008/9 solar minimum restricted quality measurements to altitudes near perigee, limiting the daily local time coverage of the satellite. As the primary ionospheric boundary condition available to calibrate the IDM requires that the integral of meridional (vertical) ion drifts be zero over all local times and longitudes, the limited daily local time coverage necessitated a new calibration procedure. A procedure is presented that utilizes the median meridional drift over all local times determined over a 67 day perigee precession period to calibrate the instrument. Offsets are isolated for both measurement directions by exploiting the different symmetry relationships that the spacecraft orientation has with respect to the meridional direction as a function of magnetic latitude. The low ionospheric densities along with the equatorial orbit of C/NOFS also allowed photoemission currents within the instrument to be detected. A numerical model of photoemission within the drift meter is presented in detail and used to generate a first order software correction to remove a large portion of this error from measurements. Both the photoemission correction and the drift meter calibration procedure are supported by a comparison to vertical ion drifts measured by the Jicamarca Radar Observatory.

Effect of subauroral polarization streams on the thermosphere: A statistical study

Using 2 years of coordinated CHAMP and DMSP observations we have investigated for the first time the relationship between subauroral polarization streams (SAPS), ionospheric Hall current (electrojet), upper thermospheric zonal wind, and mass density at subauroral regions in the dusk and premidnight sectors, separately for both hemispheres. For comparison, we have also analyzed the same parameters as a function of magnetic latitude (30 degrees-80 degrees magnetic latitude) during non-SAPS periods. During periods of non-SAPS, the neutral wind exhibits similar features as during SAPS events in the dusk to premidnight sector, streaming westward in the same direction as the plasma drift. Both neutral and plasma velocities peak at the same latitude regardless of SAPS occurrence. For higher geomagnetic activity both velocities are faster and the peaks shift equatorward. During non-SAPS periods, the ratio between plasma and neutral wind velocity is on average 2.75 +/- 0.4 in both hemispheres irrespective of geomagnetic activity. The neutral wind during SAPS events gets enhanced by a factor of 1.5/1.2 for Kp = 4 in the Northern/Southern Hemisphere, respectively, as compared to non-SAPS time. The velocity difference between SAPS and neutral wind is also larger during SAPS period than during non-SAPS period, and the difference tends to increase with increasing geomagnetic activity. The peak latitude of the eastward auroral electrojet appears 1.5 degrees poleward of the plasma drift during SAPS events, confirming the formation of SAPS equatorward of the high-conductivity channel. These SAPS-induced large winds can heat the upper thermosphere. As a result we observe a 10% enhanced mass density at 400 km altitude with respect to periods without SAPS. In addition a density anomaly peak occurs collocated with the SAPS, displaced from the electrojet peak. We regard this as an indication for efficient thermospheric heating by ion neutral friction.

Wave normal angles of magnetospheric chorus emissions observed on the Polar spacecraft

Using data from the High Frequency Waveform Receiver on board the Polar spacecraft, 1,765 and 993 wave normal angles have been analyzed for 13 orbits containing upper band magnetospheric chorus emissions and 15 orbits containing lower band emissions, respectively. The purpose of this study is to characterize the distribution of the polar wave normal angle, θ, for chorus emissions as a function of magnetic latitude, λ. Understanding wave normal angles is an important step in evaluating resonant wave‐particle interactions. For upper band chorus, wave normal angles tend to remain at or rise toward the resonance cone angle for low latitudes and midlatitudes but move away from the resonance cone angle at higher latitudes. For lower band chorus, wave normal angles with values θ < 20° have the highest probability of occurrence in the latitude range of 10°–50°. Just off the equator, 10° ≤ λ < 25°, there exists a secondary occurrence peak in the range of 50° ≤ θ < 70°. The probability of observing these higher wave normal angles decreases with increasing latitude. The time‐averaged Poynting flux, S, is much larger for lower band chorus waves, which have a mean value of 8.5 × 10−8 W/m2, than for upper band chorus waves, which have a mean value of 1.4 × 10−9 W/m2. S is fairly evenly distributed about its median value, 3.1 × 10−10 W/m2, for all wave normal angles for upper band chorus but deceases as θ increases for lower band chorus.

The role of external triggers in flow shear arcs in the dayside aurora

Abstract. In case studies we relate dayside auroral transients to IMF By-distorted plasma convection cells based on high-resolution observations from the ground. We selected three days representing positive and negative IMF By conditions when SuperDARN returned reliable dayside convection patterns in the sector of our optical observations from Ny Ålesund, Svalbard (76° MLAT). We combine two perspectives on the dayside aurora, the local and the global. In the first we derive the fine-structure of dayside precipitation/convection as a function of magnetic latitude (MLAT) and magnetic local time (MLT), which is necessary to understand the local M-I coupling processes (Birkeland current structure). The larger perspective (quasi-global dayside aurora) may be used to shed light on the solar wind-magnetosphere interconnection topology. The auroral morphology consists of brightening events and poleward moving auroral forms (PMAFs) in the pre- and postnoon sectors longitudinally separated by a band of strongly attenuated aurora near noon. We find that the MLT-dependent spatial structure in the dayside aurora (PMAFs/prenoon – "midday gap aurora" – PMAFs/postnoon) which is present during stable IMF conditions is altered by temporal structure during intervals of IMF/solar wind plasma transients. The focus is on the PMAF substructure (so-called "rebrightening forms") which we identify as dynamical plasma flow shear arcs (FSAs) in By-distorted dawn- and dusk-centered convection cells in the close vicinity of the cusp.

A method for determining the drift velocity of plasma depletions in the equatorial ionosphere using far‐ultraviolet spacecraft observations

The Far‐Ultraviolet Imager (IMAGE‐FUV) on board the NASA IMAGE satellite has been used to observe plasma depletions in the nightside equatorial ionosphere. Observations from periods around spacecraft apogee, during which equatorial regions are visible for several hours, have allowed the velocity of these plasma depletions to be determined. A new method for determining the velocity of these depletions using an image analysis technique, Tracking Of Airglow Depletions (TOAD), has been developed. TOAD allows the objective identification and tracking of depletions. The automation of this process has also allowed for the tracking of a greater number of depletions than previously achieved without requiring any human input, which shows that TOAD is suitable for use with large data sets and for future routine monitoring of the ionosphere from space. Furthermore, this automation allows the drift velocities of each bubble to be determined as a function of magnetic latitude, which will give us the capability of retrieving geophysically important parameters such as the electric field, which are believed to vary rapidly with magnetic latitude.

Magnetospheric toroidal Alfvén wave harmonics and the field line distribution of mass density

Measurements of electric and magnetic field taken by instruments on the Combined Release and Radiation Effects Satellite (CRRES) spacecraft on 29 July 1991 reveal seven or eight toroidal Alfvén wave frequency bands. By using observations of the waves near the magnetic equator and the symmetry of the theoretical modes as a function of magnetic latitude, we can identify which theoretical Alfvén wave harmonic corresponds to a particular frequency band. This, along with the L shell frequency dependence, gives convincing evidence that we are in fact observing the toroidal Alfvén mode. Because the harmonics of the toroidal Alfvén wave have a different response to mass density at different points along a magnetic field line, the frequencies of these harmonics can be used to infer the distribution of mass density along the field line. While there is a significant uncertainty in the results due to the uncertainty in the observed frequencies, it is nevertheless true that both the solution based on the peak (mean) frequencies and the majority of solutions using a Monte Carlo simulation of the effects of uncertainty in frequency show the same result, that there is a local maximum in ρ within about 30° of the magnetic equator. A similar result is found for the wave event observed on 28 August 1990, a local maximum in ρ within about 15° of the magnetic equator. These results imply that heavy ions are preferentially concentrated at the magnetic equator.

The dependence of winter aurora on interplanetary parameters

The dependence of the northern winter aurora on interplanetary parameters is examined for images obtained from the Polar spacecraft Ultraviolet Imager (UVI) during the month of January 1997. Linear correlation analysis is used to relate auroral brightness to interplanetary parameters as a function of magnetic latitude (MLAT) and magnetic local time (MLT). Spatial maps of maximum magnitude correlation coefficient and optimal lag times are presented. In addition, the Method of Natural Orthogonal Components (MNOC) is applied to UVI images and an orthogonal set of eigenmodes of auroral behavior is produced. The dominant eigenmodes are determined to be (1) the main auroral oval brightness, (2) polar cap contraction/expansion, (3) dawn/dusk aurora, and (4) midnight sector brightening/quenching. The temporal coefficients for the various eigenmodes are correlated separately with solar wind parameters and interplanetary magnetic field (IMF) components. The dominant influence of the negative Bz component is confirmed, but the timescale of its influence is found to vary widely. The MNOC procedure allows some of the more subtle relationships between the aurora and the interplanetary parameters to be isolated, particularly those associated with the solar wind density and IMF Bx and By.

A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

Abstract. The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities)

Validation of the galactic cosmic ray and geomagnetic transmission models

A very high-momentum resolution particle spectrometer called the Alpha Magnetic Spectrometer (AMS) was flown in the payload bay of the Space Shuttle in a 51.65°×380-km orbit during the last solar minimum. This spectrometer has provided the first high statistics data set for galactic cosmic radiation protons, and helium, as well as limited spectral data on carbon and oxygen nuclei in the International Space Station orbit. First measurements of the albedo protons at this inclination were also made. Because of the high-momentum resolution and high statistics, the data can be separated as a function of magnetic latitude. A related investigation, the balloon borne experiment with a superconducting solenoid spectrometer (BESS), has been flown from Lynn Lake, Canada and has also provided excellent high-resolution data on protons and helium. These two data sets have been used here to study the validity of two galactic cosmic ray models and the geomagnetic transmission function developed from the 1990 geomagnetic reference field model. The predictions of both the CREME96 and NASA/JSC models are in good agreement with the AMS data. The shape of the AMS measured albedo proton spectrum, up to 2 GeV, is in excellent agreement with the previous balloon and satellite observations. A new LIS spectrum was developed that is consistent with both previous and new BESS 3 He observations. Because the astronaut radiation exposures onboard ISS will be highest around the time of the solar minimum, these AMS measurements and these models provide important benchmarks for future radiation studies. AMS-02 slated for launch in September 2003, will provide even better momentum resolution and higher statistics data.

Global Measurements of the Radiation Exposure of Civil Air Crews from 1997 to 1999

The exposure of aircrew to the increased cosmic radiation at aviation flight altitudes will soon be treated in the European Union as an occupational risk, with the consequence that the radiation exposure of aircrew must be determined. This work describes about 200 h of in-flight measurements performed during a period of 22 months from 1997 to 1999 on cargo aircraft. Various monitors were used to measure different radiation field components and to investigate the spatial dose equivalent rate distribution and the spatial radiation field composition. The monitors were rem counters for neutrons, and a scintillator and an ionisation chamber for the directly ionising and photon components. One of the main goals was to calibrate the monitors in the cosmic radiation field at flight altitudes against a tissue-equivalent proportional counter (TEPC) used as a reference instrument for the quantity ambient dose equivalent. The sum of the readings of a neutron rem counter with its response extended to high energy neutrons and of an ionisation chamber was found to be a fair approximation of the total dose equivalent as measured by the TEPC. The 'field calibration factor' determined is 1.0 ± 0.1. The global dose equivalent distributions as a function of magnetic latitude and cut-off rigidity were obtained for the range of altitudes encountered in civil aviation and can be described by simple mathematical functions for use in rough dose-equivalent rate estimates. Surrounding the TEPC with an active shielding detector and the application of coincidence techniques allowed dose equivalent fractions of charged and uncharged particles in the cosmic radiation to be separated. The low-LET radiation component was found to consist of 90% charged particles and 10% photons while the high-LET component contains a fraction of 30% from protons (pions) and 70% from neutrons.

The CME Event of February 21, 1994: Response of the Magnetic Field at the Earth's Surface.

On February 21, 1994, a large coronal mass ejection (CME) passed by the Earth. In the solar wind, the CME front was noted by very large changes in the solar wind dynamic pressure, flow direction, and magnetic field, as measured by several spacecraft. At the Earth's surface, many ground stations also recorded the passage of this CME, as a storm sudden commencement onset. We examine here several interesting features of the surface magnetic field response to this sudden commencement onset. In particular, we use the magnetometer records to examine the propagation time of the initial impulse along the Earth's surface. We also study in detail the initial amplitude change at several stations, and note the variation in the response as a function of magnetic latitude. In addition, we crudely estimate the relative contributions of the Chapman-Ferraro and the ionospheric current system to the surface response. Also of interest is the polarization and period of Psc oscillations superposed on the main impulse at several stations, including polarization reversals as a function of magnetic latitude. Corresponding ionospheric currents at stations along the 210° MM chain are also computed, and very large and sudden changes in the ionospheric current flow patterns are reported during the initial minutes of the sudden commencement onset. These and other results are interpreted in terms of previous models, paradigms, and statistical results.

A quantitative description of the spatial distribution and dynamics of the energy flux in the continuous aurora

Energy flux in the continuous (or diffuse) aurora is found to be constant instantaneously along contours that are defined analytically as a function of magnetic latitude and UT, coordinates that are approximately circles in magnetic latitude‐magnetic local time centered at a pole offset from the magnetic pole. As a consequence, the latitudinal distribution in these coordinates is the same instantaneously at all magnetic local times (the observed extent of which is 10 hours); changes that take place in the distribution do so simultaneously (within 15 min of UT resolution) throughout this entire extent. These properties are observed in a case study of 8 hours duration by an array of ground and air based ionospheric sounders that span the 10 hours of magnetic local time at auroral latitudes. Energy flux in the continuous aurora is derived from the resulting ionized auroral E layer critical frequency that is measured simultaneously at 15 min intervals by all members of the array. Two latitudinal distributions are identified. The principal one is a Gaussian distribution at lower latitude; a separate distribution that is of lower intensity occurs at higher latitude. The two correspond respectively to the central plasma sheet and boundary plasma sheet regions of particle precipitation. The central plasma sheet distribution is found in all 32 determinations to be well described by a single Gaussian function, 3.2° full width at half maximum. Accordingly, the dynamics of the entire latitude‐local time distribution can be described quantitatively by the time history of two parameters, the Gaussian maximum energy flux (which varies between extremes of 0.25 and 7 ergs/cm²s) and the latitude of the maximum (which varies throughout a range of 5°). The determination of these parameters every 15 min resolves such rapidly varying features as substorm onset; the 8 hour duration encompasses such long term features as substorm lifetime and UT dependent latitude variation. A number of areas of agreement are found between results reported here and those reported by others. In particular, evidence that the continuous aurora is highly uniform exists not only in this case study but also in statistical studies that find iso‐energy flux contours to be offset circles.

A theoretical study of the ionospheric F region equatorial anomaly—II. results in the American and Asian sectors

When observed noontime values of the maximum electron density, NMAX( F2), in the ionospheric F2 region are plotted as a function of magnetic latitude, a curve is produced which has two peaks, one on either side of the dip equator at ±16° dip latitude. This paper theoretically investigates the daily variation of this latitudinal distribution in NMAX( F2) (the so-called Appleton or equatorial anomaly) and specifically attempts to account for the longitudinal differences observed between the American and Asian sectors. In Part II, models of the neutral atmosphere, production, loss and diffusion rates, neutral wind, and electric field are described and the electron densities obtained by solving the continuity equation utilizing these models are presented. In each sector, the extent to which the equatorial anomaly's daily variation is affected by changes in the geomagnetic field configuration, neutral wind, and E × B drift is examined. It is found that development of the anomaly is most sensitive to the electric field model assumed, and that the observed differences at the magnetic equator between the American and Asian sectors could be accounted for by an upward E × B drift which commences an hour or two earlier in the Asian sector.

A theoretical study of the ionospheric F region equatorial anomaly—I. Theory

When observed noontime values of the maximum electron density, NMAX( F2), in the ionospheric F2 region are plotted as a function of magnetic latitude, a curve is produced which has two peaks, one on either side of the dip equator at ± 16° dip latitude. This paper theoretically investigates the daily variation of this latitudinal distribution of NMAX( F2) (the so-called Appleton or equatorial anomaly) and specifically attempts to account for the longitudinal differences observed between the American and Asian sectors. Part I outlines the theory involved in solving the time-dependent plasma continuity equation in which production, loss, and transport of ionization are taken into account, where the effects of neutral wind, ambipolar diffusion and E × B drift are included in the transport term. By describing the geomagnetic field in two equivalent ways, B = − ▽γ and B = ▽α × ▽β , where α, β and γ are known magnetic scalar potentials, the spherical r, θ and φ space coordinates of the continuity equation are transformed to coordinates which define directions parallel and perpendicular to the magnetic field thus putting the equation in a form suitable for numerical integration.

Suprathermal electrons in the polar ionosphere

Suprathermal electrons energy distributions as function of magnetic latitude in polar ionosphere obtained by Explorer 31 satellite observation