Ground Level Enhancement Events Research Articles

Probabilistic risk assessment of solar particle events considering the cost of countermeasures to reduce the aviation radiation dose

Cosmic-ray exposure to flight crews and passengers, which is called aviation radiation exposure, is an important topic in radiological protection, particularly for solar energetic particles (SEP). We therefore assessed the risks associated with the countermeasure costs to reduce SEP doses and dose rates for eight flight routes during five ground level enhancements (GLE). A four-dimensional dose-rate database developed by the Warning System for Aviation Exposure to Solar Energetic Particles, WASAVIES, was employed in the SEP dose evaluation. As for the cost estimation, we considered two countermeasures; one is the cancellation of the flight, and the other is the reduction of flight altitudes. Then, we estimated the annual occurrence frequency of significant GLE events that would bring the maximum flight route dose and dose rate over 1.0 mSv and 80 μSv/h, respectively, based on past records of GLE as well as historically large events observed by the cosmogenic nuclide concentrations in tree rings and ice cores. Our calculations suggest that GLE events of a magnitude sufficient to exceed the above dose and dose rate thresholds, requiring a change in flight conditions, occur once every 47 and 17 years, respectively, and their conservatively-estimated annual risks associated with the countermeasure costs are up to around 1.5 thousand USD in the cases of daily-operated long-distance flights.

The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-Ray Emission from the Sun

Abstract We report that the number of >500 MeV protons (Ng ) inferred from sustained gamma-ray emission (SGRE) from the Sun is significantly correlated with that of protons propagating into space (N SEP) as solar energetic particles (SEPs). Under the shock paradigm for SGRE, shocks driven by coronal mass ejections (CMEs) accelerate high-energy protons sending them toward the Sun to produce SGRE by interacting with the atmospheric particles. Particles also escape into the space away from the Sun to be detected as SEP events. Therefore, the significant N SEP–N g correlation (correlation coefficient 0.77) is consistent with the common shock origin for the two proton populations. Furthermore, the underlying CMEs have properties akin to those involved in ground level enhancement events indicating the presence of high-energy (up to ∼GeV) particles required for SGRE. We show that the observed gamma-ray flux is an underestimate in limb events (central meridian distance >60°) because SGRE sources are partially occulted when the emission is spatially extended. With the assumption that the SEP spectrum at the shock nose is hard and that the 100 MeV particles are accelerated throughout the shock surface (half width in the range 60°–120°) we find that the latitudinal widths of SEP distributions are energy dependent with the smallest width at the highest energies. Not using the energy-dependent width results in an underestimate of N SEP in SGRE events occurring at relatively higher latitudes. Taking these two effects into account removes the apparent lack of N SEP–N g correlation reported in previous studies.

Extreme space weather events caused by super active regions during solar cycles 21-24

Extreme space weather events including ≥X5.0 flares, ground level enhancement (GLE) events and super geomagnetic storms (Dst ≤ –250 nT) caused by super active regions (SARs) during solar cycles 21–24 were studied. The total number of ≥X5.0 solar flares was 62, among which 41 were X5.0-X9.9 flares and 21 were ≥X10.0 flares. We found that 83.9% of the ≥X5.0 flares were produced by SARs; 78.05% of the X5.0-X9.9 and 95.24% of the ≥X10.0 solar flares were produced by SARs; 46 GLEs were registered during solar cycles 21–24, and 25 GLEs were caused by SARs, indicating that 54.3% of the GLEs were caused by SARs; 24 super geomagnetic storms were recorded during solar cycles 21–24, and 12 of them were caused by SARs, namely 50% of the super geomagnetic storms were caused by SARs. We ascertained that only 29 SARs produced ≥X5.0 flares, 15 SARs generated GLEs and 10 SARs triggered super geomagnetic storms. Of the 51 SARs, only 33 SARs produced at least one extreme space weather event, while none of the other 18 SARs could trigger an extreme space weather event. There were only four SARs and each of them generated not only a ≥X5.0 flare, but also a GLE event and a super geomagnetic storm. Most of the extreme space weather events caused by the SARs appeared during solar cycles 22 and 23, especially for GLE events and super geomagnetic storms. The longitudinal distributions of source locations for the extreme space weather events caused by SARs were also studied.

GLE # 67 Event on 2 November 2003: An Analysis of the Spectral and Anisotropy Characteristics Using Verified Yield Function and Detrended Neutron Monitor Data

During Solar Cycle 23 16 ground-level enhancement events were registered by the global neutron monitor network. In this work we focus on the period with increased solar activity during late October – early November 2003 producing a sequence of three events, specifically on ground-level enhancement GLE 67 on 2 November 2003. On the basis of an analysis of neutron monitor and space-borne data we derived the spectra and pitch-angle distribution of high-energy solar particles with their dynamical evolution throughout the event. According to our analysis, the best fit of the spectral and angular properties of solar particles was obtained by a modified power-law rigidity spectrum and a double Gaussian, respectively. The derived angular distribution is consistent with the observations where an early count rate increase at Oulu neutron monitor with asymptotic viewing direction in the anti-Sun direction was registered. The quality of the fit and model constraints were assessed by a forward modeling. The event integrated particle fluence was derived using two different methods. The derived results are briefly discussed.

Magnetic Cloud and Sheath in the Ground-level Enhancement Event of 2000 July 14. II. Effects on the Forbush Decrease

Abstract Forbush decreases (Fds) in galactic cosmic ray intensity are related to interplanetary coronal mass ejections (ICMEs). The parallel diffusion of particles is reduced because the magnetic turbulence level in the sheath region bounded by the ICME’s leading edge and shock is high. In the sheath and magnetic cloud (MC) energetic particles would feel an enhanced magnetic focusing effect caused by the strong inhomogeneity of the background magnetic field. Therefore, particles would be partially blocked in the sheath–MC structure. Here, we study two-step Fds by considering the magnetic turbulence and background magnetic field in the sheath–MC structure with diffusion coefficients calculated using theoretical models, to reproduce the Fd associated with the ground-level enhancement event on 2000 July 14 by solving the focused transport equation. The sheath and MC are set to spherical caps that are portions of spherical shells with enhanced background magnetic field. The magnetic turbulence levels in the sheath and MC are set to higher and lower than those in ambient solar wind, respectively. In general, the simulation result conforms to the main characteristics of the Fd observation, such as the pre-increase precursor, amplitude, total recovery time, and two-step decrease of the flux at the arrival of the sheath and MC. It is suggested that the sheath plays an important role in the amplitude of the Fd while the MC contributes to the formation of the second-step decrease and prolonged recovery time. It is also inferred that both magnetic turbulence and background magnetic field in the sheath–MC structure are important for reproducing the observed two-step Fd.

Research on the peak energy spectrum of the solar cosmic ray ground level enhancement event (GLE72)

The ground level enhancement (GLE) event energy spectrum provides important information about the acceleration and propagation of cosmic ray. In this paper, we analyze the proton flux peak energy spectrum of recent GLE event (2017.09 GLE72) by using GOES15 satellite and neutron monitor experiment data. The method of adjacent averaging smoothing and weighted average are applied to study GOES15 satellite data, and obtain the flux peak and flux peak time. By fitting, the energy spectrum index of proton flux peak is 1.88 in the satellite observation energy range. Again, the energy spectrum index of the neutron monitor observation energy range, 4.86, is obtained by using the new neutron monitor yield function. It can be seen that the peak energy spectrum index given by satellites in the lower energy range (5–433 MeV) is much smaller than that given by the neutron monitor in the higher energy range (0.44–19 GeV). This means that, the energy spectrum in the lower energy range is harder than that in the higher energy range. Hence, the results of the energy spectrum could be explained qualitatively by the re-acceleration mechanism of high energy solar particles. In the low corona region, first, the particles released by the solar flare are accelerated, and the energy spectrum index of the high-energy range is twice that of the low-energy range. Then part of the solar high energy particles from the low corona enter into the CME, where they will be re-acceleration by the shock wave. The GLE72 event high energy range energy spectrum index given by the neutron monitor experiment is 4.86, so the energy spectrum index in low energy range should be 4.86/2 = 2.43. However, the low energy range energy spectrum index is 1.88 (lower than 2.43 in low energy range). The reason may be that the energy spectrum index is further reduced due to the re-acceleration effect in the shock wave generated by the CME. The observation of GLE event is one of the main research subjects of the Large High Altitude Air Shower Observatory (LHAASO). Also, the GLE72 proton peak energy spectrum results provide important information to observe solar high energy particles in the LHAASO experiment.

Magnetic Cloud and Sheath in the Ground-level Enhancement Event of 2000 July 14. I. Effects on the Solar Energetic Particles

Abstract Ground-level enhancements generally accompany fast interplanetary coronal mass ejections (ICMEs), and ICME-driven shocks are sources of solar energetic particles (SEPs). Observations of the GLE event of 2000 July 14 show that a very fast and strong magnetic cloud (MC) is behind the ICME shock and the proton intensity-time profiles observed at 1 au had a rapid two-step decrease near the sheath and MC. Therefore, we study the effect of sheath and MC on SEPs accelerated by an ICME shock by numerically solving the focused transport equation. The shock is regarded as a moving source of SEPs with an assumed particle distribution function. The sheath and MC are set to thick spherical caps with enhanced magnetic field, and the turbulence levels in the sheath and MC are set to be higher and lower than those of the ambient solar wind, respectively. The simulation results of proton intensity-time profiles agree well with the observations in energies ranging from ∼1 to ∼100 MeV, and the two-step decrease is reproduced when the sheath and MC arrived at the Earth. The simulation results show that the sheath-MC structure reduced the proton intensities for about 2 days after the shock passed through the Earth. It is found that the sheath contributed most of the decrease while the MC facilitated the formation of the second step decrease. The simulation also infers that the coordination of magnetic field and turbulence in sheath-MC structure can produce a stronger reduction of SEP intensities.

Investigation of the Cosmic Rays Associated with Ground Level Enhancement Events during Solar Cycle 24

In the Sun, particles mostly protons (positively charged) with energies up to several hundred (MeV) are escaped during periods of intense flare activity. These particles are solar cosmic radiation, which are very small particles move at nearly the speed of light through space. The flare and coronal mass ejection (CME) may also cause a sharp rise in the cosmic ray intensity (CRI) at the Earth atmosphere. There are indications that the most energetic events occurred in the minimum phase of solar activity. When cosmic rays enter the Earth’s atmosphere they collide with atoms and molecules, as the Sun’s magnetic field became weak the cosmic rays are flooding into the solar system from deep space, causing health risks to space travelers. Sudden increases in the cosmic ray intensity called Ground level enhancements (GLEs) are measured or recorded on Earth’s sea level by neutron monitor (NM). The main objective of this research is to find the relation between cosmic ray and the GLE events and other solar activity parameters during the period years (2008-2019) for solar cycle (24). In this work satellite data of GLE based on ground level station Oulu NM (ONM) are taken is situated in north Finland at the height of 15m above sea level in the geographic coordinates (65.05°N; 25.47°E). The observational spectrum of two GLEs occurred during solar cycle 24 are investigated, one in 17 May 2012 which known as GLE71 and the other in 10 September 2017 as GLE72, in which the solar energetic particle was the larger in this solar cycle. Data of these two events indicate that the presence of different between them are due to populations of different energy spectrum, period of time occurrence, and increasing rate of (CRI).

Ionization effect in the Earth’s atmosphere during the sequence of October–November 2003 Halloween GLE events

The effect of precipitating high-energy particles on atmospheric physics and chemistry is extensively studied over the last decade. In majority of the existing models, the precipitating particles induced ionization plays an essential role. For such effects, it is necessary to possess enhanced increase in ion production, specifically during the winter period. In this study, we focus on highly penetrating particles — cosmic rays. The galactic cosmic rays are the main source of ionization in the Earth’s stratosphere and troposphere. On the other hand, the atmospheric ionization may be significantly enhanced during strong solar energetic particle events, mainly over the polar caps. A specific interest is paid to the most energetic solar proton events leading to counting rate enhancement of ground-based detectors, namely the so-called ground level enhancements (GLEs). During solar cycle 23, several strong ground level enhancements were observed. A sequence of three GLEs was observed in October–November 2003, the Halloween events. Here, on the basis of 3-D Monte Carlo model, we computed the energetic particles induced atmospheric ionization, explicitly considering the contribution of cosmic rays with galactic and solar origin. The ion production rates were computed as a function of the altitude above sea level using reconstructed solar energetic particles spectra. The 24 h and event averaged ionization effects relative to the average due to galactic cosmic rays were also computed.

Short-Term Lightning Response to Ground Level Enhancements

Cosmic rays (CRs) are considered the primary energetic particle source of atmospheric ionization on Earth. Under the modulation of severe solar eruption events, CR variations are further speculated to impact the Earth’s lightning activities. Previous researches show that CR intensity and lightning incidence are positively correlated on the time scale of several days to decades. However, to our knowledge, the global lightning response to short-term CR variation has not been studied in the literature. Ground level enhancements (GLEs) provide the opportunity to study such a possible link. As a small fraction of solar energetic particle events that could reach the energy level of several GeVs, GLEs can thus generate atmospheric cascades that could be recorded by ground-based neutron monitors. Furthermore, as GLEs generally take place within several ten minutes to an hour, the lightning variations caused by potential meteorological factors could be maximally diminished in such a short time. During the operational period of the World Wide Lightning Location Network (Aug 2004 to now), three typical GLEs with the intensity greater than 15% are analyzed from the International GLE Database, namely #69 (Jan 20, 2005), #70 (Dec 13, 2006), and #71 (May 17, 2012). For each GLE event, the global lightning incidence presents a positive response to GLE, i.e., a significant enhancement within 20 minutes right after the GLE onset. Meanwhile, the relative amplitude of lightning response seems to be in direct proportion to GLE intensity, i.e., the more intensive the GLE is, the more obvious the increase in the lightning incidence is, which is further verified to be statistically significant by Monte Carlo test. By comparing lightning responses in different latitudinal zones, we find that more intensive lightning responses to GLEs seem to be at higher latitudes.

Modeling the 2017 September 10 solar energetic particle event using the iPATH model

On 2017 September 10, a fast coronal mass ejection (CME) erupted from the active region (AR) 12673, leading to a ground level enhancement (GLE) event at Earth. Using the 2D improved Particle Acceleration and Transport in the Heliosphere (iPATH) model, we model the large solar energetic particle (SEP) event of 2017 September 10 observed at Earth, Mars and STEREO-A. Based on observational evidence, we assume that the CME-driven shock experienced a large lateral expansion shortly after the eruption, which is modeled by a double Gaussian velocity profile in this simulation. We apply the in-situ shock arrival times and the observed CME speeds at multiple spacecraft near Earth and Mars as constraints to adjust the input model parameters. The modeled time intensity profiles and fluence for energetic protons are then compared with observations. Reasonable agreements with observations at Mars and STEREO-A are found. The simulated results at Earth differ from observations of GOES-15. However, the simulated results at a heliocentric longitude 20° west to Earth fit reasonably well with the GOES observation. This can be explained if the pre-event solar wind magnetic field at Earth is not described by a nominal Parker field. Our results suggest that a large lateral expansion of the CME-driven shock and a distorted interplanetary magnetic field due to previous events can be important in understanding this GLE event.

Revised GLE database: Fluences of solar energetic particles as measured by the neutron-monitor network since 1956

Aims.Continuous measurements of ground-based neutron monitors (NMs) form the main data source for studying high-energy high-intensity solar energetic particle (SEP) events that are called ground-level enhancements (GLEs). All available data are collected in the International GLE Database (IGLED), which provides formal NM count-rate increases above the constant pre-increase level which is due to galactic cosmic rays (GCR). This data set is used to reconstruct the energy spectra of GLE events. However, the assumption of a constant GCR background level throughout GLE events is often invalid. Here we thoroughly revise the IGLED and provide a data set of detrended NM count-rate increases that accounts for the variable GCR background.Methods.The formal GLE count-rate increases were corrected for the variable GCR background, which may vary significantly during GLE events. The corresponding integral omnidirectional fluences of SEPs were reconstructed for all GLEs with sufficient strength from the detrended data using the effective rigidity method.Results.The database of the detrended NM count rate is revised for GLE events since 1956. Integral omnidirectional fluences were estimated for 58 GLE events and parametrised for 52 sufficiently strong events using the modified Ellison-Ramaty spectral shape.Conclusions.The IGLED was revised to account for the variable GCR background. Integral omnidirectional fluences reconstructed for most of GLE events were added to IGLED. This forms the basis for more precise studies of parameters of SEP events and thus for solar and space physics.

Small Size Ground Level Enhancements During Solar Cycle 24

We continue the systematical empirical search for small size ground level enhancements (GLEs) (also called “hidden” or sub-GLEs) using data from ground-based instruments for Solar Cycle 24. The starting point of this research is the hypothesis that small size GLEs may be indicative of the acceleration of solar energetic particles (SEPs) by shocks driven by coronal mass ejections (CMEs). A crucial parameter for solving the problem seems to be the SEP energy spectrum at the Earth’s orbit measured by spacecraft detectors and ground-based neutron monitors (NMs). We try to recover the SEP spectrum in a wide range of energies – from GOES non-relativistic energy channels to the relativistic range from NM data, as well as from relevant measurements of some ground-based non-standard (mainly muon) cosmic ray detectors. The main factors that determine the SEP intensity and spectrum shape near the Earth are the source power, location, and/or shock strength. Every “suspected” small GLE is analyzed separately. Finally, we compile the list of statistically confirmed small GLEs and give our interpretation within the frame of the above hypothesis. The three considered models of shock wave acceleration are not suitable to physically and unambiguously explain some features of the observed solar cosmic ray (SCR) spectra. The results emphasize the importance of studying the GLEs of low intensity (hidden GLEs) for better understanding the SEP spectrum formation, especially in the range of relativistic energies. The GLE events from behind-the-limb sources are of special interest.

Single-Event Effects in Ground-Level Infrastructure During Extreme Ground-Level Enhancements

We take an initial look at hard single-event effects (SEEs) in power electronics and static random access memories (SRAMs) during space weather-induced extreme ground-level enhancement (GLE) events. We show that there is a significant risk of failure of silicon power metal-oxide- semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs) at ground level during a 10× February '56 GLE. If the devices are not derated, then we find that 21% of power MOSFETs and 14% of IGBTs are, in the worst case, predicted to fail. The probability of failure increases to 68% and 52% during a once-in-a-10000-year GLE for power MOSFETs and IGBTs, respectively. Silicon carbide devices show a lower failure rate by more than an order of magnitude, where only 2.8% are predicted to fail during a once-in-a-10000-year GLE. It is clear that these events could disrupt critical infrastructure if mitigating precautions are not implemented.

Source of Energetic Protons in the 2014 September 1 Sustained Gamma-ray Emission Event

We report on the source of {>},300~mbox{MeV} protons during the SOL2014-09-01 sustained gamma-ray emission (SGRE) event based on multi-wavelength data from a wide array of space- and ground-based instruments. Based on the eruption geometry we provide concrete explanation for the spatially and temporally extended gamma -ray emission from the eruption. We show that the associated flux rope is of low inclination (roughly oriented in the east–west direction), which enables the associated shock to extend to the frontside. We compare the centroid of the SGRE source with the location of the flux rope’s leg to infer that the high-energy protons must be precipitating between the flux rope leg and the shock front. The durations of the SOL2014-09-01 SGRE event and the type II radio burst agree with the linear relationship between these parameters obtained for other SGRE events with duration geq 3~mbox{hrs}. The fluence spectrum of the SEP event is very hard, indicating the presence of high-energy (GeV) particles in this event. This is further confirmed by the presence of an energetic coronal mass ejection with a speed {>},2000~mbox{km},mbox{s}^{-1}, similar to those in ground level enhancement (GLE) events. The type II radio burst had emission components from metric to kilometric wavelengths as in events associated with GLE events. All these factors indicate that the high-energy particles from the shock were in sufficient numbers needed for the production of gamma -rays via neutral pion decay.

Effect of Some Solar Energetic Events on Cosmic Ray (CR) Ground Level Enhancement (GLE)

Ground Level Enhancements (GLEs) are sudden and short-lived increases in cosmic rays intensities registered by neutron monitors and usually associated with powerful solar explosive events. This work examines the key features of forty-nine (49) Ground level enhancement (GLE) events with a view to understanding the possible link to their solar sources. These constitute the 22nd -71st GLE as recorded by the Oulu Neutron monitor. We have computed the increase rates of the GLE and have compared them with the associated solar activity parameters. It is observed that GLEs are more associated with Solar flares than CMEs during the minimum and ascending phase of the 11 year solar cycle when compared with GLEs that occurred during the maximum phase of the solar cycle. In general, more GLE events were associated with solar flares originating from the Northern hemisphere of the solar disk as compared with the southern hemisphere flares. 80% of GLE with percentage increase rate (PIR) <10% were linked with strong flares. There was no/weak statistical association between intensity of solar energetic events (solar flares, CMEs, etc) and increase rate of GLE. The harder solar energetic fluxes seem to be responsible for GLEs with high PIR and that the softer fluxes may be responsible for those with low PIR. These results have important implications for our present understanding of potential solar drivers of the GLEs.

On the Shock Source of Sustained Gamma-Ray Emission from the Sun

It has recently been shown that the spatially and temporally extended γ-ray emission in solar eruptions are caused by >300 MeV protons precipitating on the Sun from shocks driven by coronal mass ejections (CMEs). The γ-rays result from the decay of neutral pions produced in the proton-proton interaction when the >300 MeV protons collide with those in the chromosphere. The evidence comes from the close correlation between the durations of the sustained gamma-ray emission (SGRE) and the associated interplanetary (IP) type II radio bursts. In this paper, we provide further evidence that support the idea that protons accelerated in IP shocks driven by CMEs propagate toward the Sun, precipitate in the chromosphere to produce the observed SGRE. We present the statistical properties of the SGRE events and the associated CMEs, flares, and type II radio bursts. It is found that the SGRE CMEs are similar to those associated with ground level enhancement events. The CME speed is well correlated with the SGRE fluence. High CME speed is an important requirement for the occurrence of SGRE, while the flare size is not. Based on these results, we present a schematic model illustrating the spatially and temporally extended nature of SGRE related to the CME flux rope-shock structure.

Particle Acceleration at the Pileup Collision of the Twin Shock

Abstract Ground-level enhancement (GLE) events are often associated with large gradual solar events such as fast coronal mass ejections (CMEs), but not all fast CMEs lead to GLE events. Is there a type of coordinated CME that could produce GLEs with larger intensity and higher energies than those in the normal fast isolated CMEs? Here we propose a twin-shock scenario driven by the twin CME coordinately, in which the posterior shock catches up with the preceding shock and has a pileup collision. In the present study, we chose the first GLE event of the solar cycle 24 occurring on 2012 May 17 as an example to investigate the probable association with the twin-shock scenario. We use a dynamic Monte Carlo method to examine the energy spectrum with relevance to the GLE event. In the twin-shock scenario, the seed energetic particles produced by the normal preceding shock can be injected into the posterior shock for reacceleration efficiently. As a result, we obtain the detailed energy spectrum of the solar energetic particles (SEPs) with different behaviors at the related episodes of the twin-shock evolution. Therefore, we predict that the pileup collision of the twin shock would dominate a concave energy spectral slope in the 2012 May 17 SEP event.

Расчет скорости ионизации вещества атмосферы Земли протонами галактических и солнечных космических лучей

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

Calculating the ionization rate induced by GCR and SCR protons in Earth’s atmosphere

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.