Geomagnetizm i aèronomiâ

ISSN (print): 0016-7940

Media registration certificate: No. 0110280 dated 02/08/1993

Founder: Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation named after. N.V. Pushkov RAS, Russian Academy of Sciences

Editor-in-Chief: Kuznetsov Vladimir Dmitrievich - Dr. Phys.-Math. sciences

Number of issues per year: 6

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Vol 63, No 5 (2023)

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Preflare X-Ray Pulsations with Sources Outside the Main Flare Active Region
Zimovets I.V., Sharykin I.N., Kaltman T.I., Stupishin A.G., Nizamov B.A.

Earlier, we showed that according to the nature of the location of sources of preflare X-ray pulsations
relative to the main solar flare, events are divided into at least two types: in type I events, the sources of
pulsations and the main flare are in the same active region (AR) and in type II events they are in different
regions. This paper presents an analysis of a type II event in which, according to data from the Ramaty High-
Energy Solar Spectroscopic Imager (RHESSI) space observatory, X-ray sources of preflare quasi-periodic
pulsations (with a period P = 1.5 ± 0.1 min), which began at ~1802 UT, were located in AR 11884 in the Western
Hemisphere, and the sources of the main flare M1.0 SOL2013-11-05T18:08 were located in AR 11890 in
the Eastern Hemisphere. The pulsations were also observed with the Gamma-Ray Burst Monitor (GBM)
aboard the Fermi space observatory and the X-Ray Sensor (XRS) aboard the Geostationary Operational
Environmental Satellite (GOES), excluding the possibility of their artificial origin. According to the data of
the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) in the extreme
ultraviolet range, it was found that the sources of pulsations were located at the base of coronal jets that flowed
out at velocities of ~100–1500 km/s. The distance between AR 11884 and AR 11890 was ~1.4 RS. It would
take ~17–250 min for the jet plasma to reach AR 11890, which is much longer than the time interval between
the onset of pulsations (jets) and the flare (~6 min). No loops connecting AR 11884 and AR 11890 were
observed in the corona. Moreover, no connection of these regions by magnetic field lines extrapolated from
the photosphere to the corona in the potential approximation was found. These arguments indicate that the
jets (and associated pulsations) could not be the trigger for the flare. Thus, a vivid example of an event is presented
in which there was no physical connection between preflare X-ray pulsations (and jets) and the flare
that followed them. This event demonstrates the importance of spatially resolved observations in the study of
pulsations on the Sun and stars.

Geomagnetizm i aèronomiâ. 2023;63(5):547-560
pages 547-560 views
The Flare Emission of the May 4, 2022 Event and Its Millimeter Component
Smirnova V.V., Tsap Y.T., Ryzhov V.S., Motorina G.G., Morgachev A.S., Bárta M.

Based on observations at the RT-7.5 radio telescope of the Bauman Moscow State Technical University
at a wavelength of 3.2 mm (93 GHz), along with other ground-based and space instruments (Siberian
radioheliograph, Solar Dynamics Observatory (SDO), Metsähovi radio observatory), the origin of millimeter
radiation from a solar flare was investigated for the SOL2022-05-04T08:45 X-ray class M 5.7 flare. An
analysis of the time profiles of radiation in the X-ray and centimeter ranges showed that the millimeter emission
source is not associated with hot (5 × 105–107 K) coronal plasma. This is also evidenced by the estimate
of the sub-THz flux of radiating hot plasma according to the AIA/SDO data, which turned out to be much
less than the observed values. Indications were obtained of the development of thermal instability in flare
ultraviolet loops. The relationship between the millimeter emission of the flare and the heat source in the
solar chromosphere has been substantiated.

Geomagnetizm i aèronomiâ. 2023;63(5):561-569
pages 561-569 views
The Influence of Corotating Regions of Interaction of the Solar Wind on Long-Term Variations in the Intensity of Galactic Cosmic Rays
Kalinin M.S., Krainev M.B., Luo S., Potgieter M.S.

An analysis of the data of spacecraft that scanned large areas of the heliosphere, as well as the results
of magnetohydrodynamic calculations, indicates that the corotating interaction regions of solar wind (SW),
which are almost always present in the low- and mid-latitude heliosphere, sometimes strongly change the
large-scale characteristics of the heliosphere that are important for long-term variations in the intensity of
galactic cosmic rays (GCRs). In particular, for Carrington rotation no. 2066 (January–February 2008), these
regions enhance magnetic fields in the inner (r < 3–5 AU) heliosphere and weaken them in the middle and
far heliosphere, as well as significantly changing the polarity distribution of heliospheric magnetic fields. The
assumption is made that in this situation the influence of the corotating interaction regions should lead to an
increase in the GCR intensity in many regions of the heliosphere. This paper discusses the process of changing
the polarity distribution of heliospheric magnetic fields due to the interaction of SW streams for Carrington
rotation no. 2066 of different speeds, the simple model of the heliospheric magnetic field without an
interaction between the SW streams of different speeds, as well as the results of numerical two-dimensional
finite-difference calculations of longitude-averaged GCR intensity with the use of this model in comparison
with a three-dimensional Monte Carlo calculation based on three-dimensional magnetohydrodynamic simulation
of the heliosphere.

Geomagnetizm i aèronomiâ. 2023;63(5):570-580
pages 570-580 views
Forbush Decreases Associated with Coronal Holes, Coronal Ejections from Active Regions, and Filament Ejections: Comparison in Solar Cycles 23 and 24
Melkumyan A.A., Belov A.V., Abunina M.A., Shlyk N.S., Abunin A.A., Oleneva V.A., Yanke V.G.

In this paper, we study the similarities and differences of Forbush decreases in solar cycles 23 and
24. Groups of events associated with various types of solar sources were analyzed: coronal mass ejections from
active regions accompanied by solar flares (CME1 group), filament ejections outside active regions (CME2
group), and high-velocity streams from coronal holes (CH group). The distributions and relations of various
parameters were studied: the amplitude of Forbush decreases, the maximum values of the hourly decrease in
the cosmic ray density, the equatorial cosmic ray anisotropy, the solar wind velocity, and the magnetic field
strength, as well as the values of the solar wind velocity and the magnetic field strength 1 hour before the onset
of the Forbush decrease during the event. The results showed that the number of events, parameter values,
and their relations depend on the phase and cycle of solar activity. In the 24th cycle, the number of events in
the CME1 group decreased, did not change in CME2, and increased in CH. The values of the parameters
and the difference between them in various groups of events are higher in cycle 23, which is characterized by
greater asymmetry and long “tails” of distributions. The magnitude of the Forbush decreases in the CME1
group in cycle 23 depends more strongly on the solar wind velocity while, in cycle 24, on the magnetic field
strength, as in the CME2 group in both solar cycles. Multiple linear regression describes the dependences of
the parameters of Forbush reductions in the CME1 and CME2 groups in the 23rd cycle and in the CME1
group in the 24th cycle well.

Geomagnetizm i aèronomiâ. 2023;63(5):581-598
pages 581-598 views
An Empirical Model for Estimating the Velocities and Delays of Interplanetary Coronal Mass Ejections
Shlyk N.S., Belov A.V., Abunina M.A., Abunin A.A.

We studied the behavior of the interplanetary coronal mass ejection velocity as a function of the
source heliolongitude (associated solar flare), initial ejection velocity, and background solar wind velocity.
The modeling is based on data on 364 ejections of solar matter accompanied by flares observed in the
SOHO/LASCO coronograph, whose interplanetary analogues were subsequently recorded near the Earth in
the period from 1995 to 2021. A model is described that makes it possible to estimate the transit and maximum
velocities of the corresponding interplanetary disturbance, as well as the time of its arrival to the Earth. The
average absolute error in estimating the propagation time of interplanetary coronal mass ejections for the considered
364 events is 11.5 h, and the average relative error is 16.5%.

Geomagnetizm i aèronomiâ. 2023;63(5):599-608
pages 599-608 views
A Nonlinear Dependence on the Geomagnetic Activity of the Ratio of the Maximum Stream Flux of Charged Particles in a Geostationary Orbit to the Minimum Stream Flux
Smolin S.V.

A new mathematical model was proposed using an ordinary differential equation that analytically
(when the index of geomagnetic activity Kp = const or Kp ≈ const) or numerically (if Kp(t) ≠ const) describes
perpendicular (for a pitch angle of 90°) differential or integral fluxes of relativistic electrons in a geostationary
(geosynchronous) orbit, as well as in any circular orbit in the Earth’s magnetosphere. The model assumes that
the fluxes depend on the local time LT in orbit, the Kp, MacIlvwaine parameter and L, and the perpendicular
differential flux or integral flux of relativistic electrons taken at 0000:00 LT. We use observations of relativistic
(>2 MeV) electron fluxes averaged over the local time hour along the orbit of the GOES spacecraft from 1995
to 2009. The model is compared with these data. Almost perfect agreement was obtained for observations
with the model, where the prediction efficiency of predicting the accuracy of the model at PE = 0.9989. Using
similar data from the GOES 10 allows one to obtain PE = 0.9924. The proposed formulas make it possible to
find, for example, the average value of the perpendicular integral flux of relativistic electrons per day and to
predict the maximum perpendicular integral flux of relativistic electrons in the geostationary orbit approximately
1 day ahead. The nonlinear effect is theoretically predicted in the form of a nonlinear dependence of
the ratio of the maximum perpendicular integral flux to the minimum flux of charged particles in the geostationary
orbit from the Kp-index of geomagnetic activity. Thus far, comparison of the model has been made
with the averaged integral relativistic electron flows fluxes produced for the 0 ≤ Kp < 6 range with a predicted
maximum flow flux ratio of 24.4139 times at Kp = 8 and with the prediction efficiency of predicting the accuracy
of the nonlinear effect PE = 0.8678.

Geomagnetizm i aèronomiâ. 2023;63(5):609-618
pages 609-618 views
Statistical Analysis of the Critical Frequency foF2 Dependence on Various Solar Activity Indices
Danilov A.D., Berbeneva N.A.

A description of the ionospheric F2-layer critical frequency foF2 dependence on solar activity by
various indices (proxies) has been analyzed. The results of the vertical ionospheric sounding at the Juliusruh
station during 2 winter months (January and February), 2 equinox months (March and October), and a summer
month (June) are considered. Five solar proxies: Ly-α, MgII, Rz, F30, and F10.7 have been analyzed.
The changes in foF2 are compared to the corresponding changes in 1957–1980. The determination coefficient
R2 according to the Fisher F-test is used as a measure of the quality of the description of the foF2 dependence
on SA by each of the proxies. It has been found that a well-pronounced diurnal variation in the R2 value
is observed in winter months: this is higher at the near-noon hours than at night. In other words, all indices
describe the foF2 behavior better in the daytime than at night. A well-pronounced diurnal variation in R2 is
also observed for four proxies in the equinoctial months, whereas that variation is pronounced much less for
Rz: a strong scatter of the R2 values is seen. A diurnal variation in the R2 is absent completely in June: jumps
from one hour to another are observed. This analysis allows us to conclude that the most reliable SA proxies
for description of the foF2 dependence on SA at all LT hours are MgII, F30, and Ly-α.

Geomagnetizm i aèronomiâ. 2023;63(5):619-629
pages 619-629 views
Properties of the Variability of the Maximum Density of the F2-Layer over Almaty at Different Levels of Solar and Geomagnetic Activity
Deminov M.G., Deminova G.F., Depuev V.K., Depueva A.K.

The properties of the variability of the maximum density of the F2-layer Nm at different levels of
solar and geomagnetic activity have been analyzed based on hourly data of the Almaty station (43.2° N, 104° E)
for 1958–1988. The standard deviation σ(x) of the fluctuations of Nm relative to the quiet level
(x = (Nm/Nm0 – 1) × 100, %) and the average shift of these fluctuations xave are used to characterize this
variability. In this path, an empirical model of the F2-layer maximum density Nm0 for low geomagnetic activity
has been created. It has been found that the variability of Nm depends weakly on the level of solar activity.
The dependence of the variability of Nm on geomagnetic activity is one of the main ones, along with the
dependences of this variability on time of day and season. In general, the variance σ2(x) is smaller for quiet
conditions than for periods of high geomagnetic activity. However, during periods of high geomagnetic activity,
a further increase in geomagnetic activity does not lead to an increase in the variance σ2(x). The saturation
in the increase in the variance σ2(x) against the background of a continuing increase in geomagnetic activity
and the absence of this saturation for the average shift xave seems to be a stable property of the variability of
the mid-latitude ionosphere during periods of geomagnetic storms. This conclusion is based on an additional
analysis of ionospheric variability according to data from the Irkutsk and Yamagawa stations, which are
located about 10 degrees north and south of Almaty station, respectively.

Geomagnetizm i aèronomiâ. 2023;63(5):630-637
pages 630-637 views
Development of a Method for Recovery of the Energy Spectra of Precipitating Electrons from the Data of Measurements in the Atmosphere
Makhmutov V.S., Maurchev E.A., Bazilevskaya G.A., Mironova I.A.

Regular measurements of fluxes of charged particles in the Earth’s atmosphere conducted by the
Lebedev Physical Institute (LPI) made it possible to register since 1963 more than 500 cases of precipitation
of energetic electrons in the northern polar latitudes. The obtained experimental data represent the world’s
only database on the precipitation of electrons registered directly in the Earth’s atmosphere. Primary precipitating
electrons are absorbed in the upper layers of the atmosphere. However, the fluxes of secondary photons
generated by them can penetrate deep into the atmosphere, sometimes to heights of ~20 km, which are
accessible for balloon measurements by the Lebedev Physical Institute. This paper presents a new technique
for reconstructing the energy spectrum of precipitating electrons developed on the basis of the Monte Carlo
simulation of the processes of electron propagation in the atmosphere. The applicability of the technique to
the accumulated experimental data is shown, and new results are presented for individual events recorded in
the atmosphere.

Geomagnetizm i aèronomiâ. 2023;63(5):638-643
pages 638-643 views
Long-Term Microwave Observations of Middle Atmospheric Ozone in Apatity during Three Winters
Kulikov Y.Y., Andriyanov A.F., Demin V.I., Demkin V.M., Kirillov A.S., Ryskin V.G., Shishaev V.A.

The results of ground-based microwave observations of ozone in the middle atmosphere in Apatity
(67° N, 33° E) during three winters (2017–2018, 2018–2019 and 2019–2020) are presented. Long-term ozone
observations were carried out during the period of minimum solar activity for cycles 24 and 25. A mobile
microwave spectrometer with an operating frequency of 110.8 GHz was used in the measurements, which
allows tracking the behavior of ozone in the middle atmosphere with a 15-minute time resolution. The microwave
ozone data from ground-based measurements are compared with the MLS/Aura onboard data. Ground
and airborne data are compared with the data of contact measurements with ozonesondes at Sodankyla st.
(67° N, 27° E). In addition, MLS/Aura data from mid-atmospheric temperature soundings are used to interpret
perturbations in the ozone layer associated with sudden stratospheric warmings. A significant influence
sudden stratospheric warming on the ozone vertical distribution at altitudes of 22–60 km was found. At the
same time, the scale of mesospheric ozone variability (60 km) over Apatity is comparable or exceeds the
known model calculations for assessing the impact of solar proton events and auroral electron precipitation
on the ozone of the polar regions.

Geomagnetizm i aèronomiâ. 2023;63(5):644-656
pages 644-656 views
Atmospherics Associated with Sprites from Elf/Vlf Observations on the Kamchatka Pen
Malkin E.I., Kapustina O.V., Druzhin G.I.

Information about the main characteristics of sprites and related lightning discharges is given.
Results are presented of the analysis of atmospherics recorded using the IZMIRAN mobile equipment at the
expedition site near the Levaya Avacha River in September, October 2002 and in August, November 2004 on
the Kamchatka Peninsula. The results of the analysis are given andlectromagnetic radiation from lightning
discharges that occurred on the Kamchatka Peninsula in July and August 2017 that were recorded by the
equipment of the Institute of Cosmophysical Research and Radio Wave Propagation, Far Eastern Branch,
Russian Academy of Sciences at the Karymshina expedition site are presented. The percentage of positive
lightning discharges on the western and southern coasts of the Kamchatka Peninsula, which can be associated
with sprites has been estimated.

Geomagnetizm i aèronomiâ. 2023;63(5):657-666
pages 657-666 views
The Depths to Lithospheric Magnetic Sources under the Baltic Shield
Filippova A.I., Filippov S.V.

We present the results of studying the depths to lithospheric magnetic sources under the Baltic
Shield and adjacent territories of the Russian Plate and the Scandinavian Caledonides. The depths have been
calculated from the global model of the lithospheric geomagnetic field EMAG2v3 by the centroid method.
The minimum depths of the lower boundary of the lithospheric magnetically active layer (30–35 km) were
obtained under the frame of the Baltic Shield, that is, the Russian Plate, the northern and southern parts of
the Scandinavian Caledonides, the maximum (>45 km), under the Scandinavian Peninsula, in the west of
the Svecofennian orogen and the Norrbotten craton. The rest of the territory of the Baltic Shield is characterized
by intermediate depths (38–45 km). Based on a comparison of our estimates of the depth of the lower
boundary of lithospheric magnetic sources with the currently available models of the distribution of the Moho
depth under the study area, it can be seen that for most of the Baltic Shield, the magnetically active layer of the
lithosphere is located within the crust, with the exception of two areas under the Svecofennian orogen and the
eastern part of the Kola Peninsula. This fact supports the hypothesis that the upper mantle has magnetic properties
in regions where positive long-wave anomalies of the geomagnetic field are observed at satellite altitudes.
The obtained results show that the western and eastern parts of the Kola Peninsula can differ not only in the
velocity structure of the crust and upper mantle, which has been previously established by various seismological
methods, but also in the magnetic properties of the upper mantle layer located directly under the crust.

Geomagnetizm i aèronomiâ. 2023;63(5):667-679
pages 667-679 views


pages 680 views

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