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Vol 58, No 4 (2018)

Article

The Influence of Parameters of the Interplanetary Medium and Magnetosheath Boundaries on the Correlation Coefficient between the Ion Flux Measured in the Solar Wind and the Magnetosheath

Rakhmanova L.S., Riazantseva M.O., Zastenker G.N., Verigin M.I., Yermolaev Y.I., Lodkina I.G.

Abstract

In this paper, the correlation coefficient between the ion fluxes in the solar wind and the magnetosheath is analyzed with the use of data of two satellites of the THEMIS mission and the THEMIS/Spektr-R satellites obtained in 2008 and 2011−2014, respectively. We have distinguished the conditions in which a high level of correlation between the measurements in the solar wind and the magnetosheath is observed, i.e., the correlation coefficient exceeds 0.7. As key factors, we consider both direct parameters of the solar wind, such as the density, the magnetic field magnitude, the magnetosonic Mach number, and the ratio β of the thermal pressure to the magnetic, and a more general factor—the type of large-scale structure of the solar wind. In addition, the effect of the satellite location in the magnetosheath relative to its boundaries—the bow shock and the magnetopause—on the correlation level is considered. It has been shown that, in roughly one third of cases, the plasma structures of the solar wind undergo a strong modification at the bow shock and in the magnetosheath, which results in a low correlation level corresponding to a correlation coefficient of less than 0.5; a high correlation level is observed in half of cases, i.e., the plasma structures are weakly disturbed. It has been determined that (1) the low correlation level in the magnetosheath behind quasi-perpendicular bow shock is more often observed near the magnetopause than in region just behind the bow shock, (2) the probability of observations of a high correlation level is independent of the profile shape of the quasi-perpendicular bow shock, and (3) the high correlation is more probable for the events corresponding to the solar wind of the Corotating Interaction Region (CIR) type than for those with the other solar wind types observed in the considered period.

Geomagnetism and Aeronomy. 2018;58(4):449-456
pages 449-456 views

Diagnostic Analysis of the Solar Proton Flares of September 2017 by Their Radio Bursts

Chertok I.M.

Abstract

The powerful solar flares that occurred on September 4–10, 2017 are analyzed based on a quantitative diagnostics method for proton flares developed at the Institute of Terrestrial Magnetism, the Ionosphere and Radio-Wave Propagation (IZMIRAN) in the 1970–1980s. We show that the fluxes and energy spectra of the protons reached the Earth with the energies of tens of MeV qualitatively and quantitatively correspond to the intensity and frequency spectra of the microwave radio bursts in the range of 2.7–15.4 GHz. Specifically, the flare of September 4 with a peak radio flux S ~ 2000 sfu at the frequency f ~ 3 GHz (i.e., with the soft radio spectrum) was accompanied by a significant proton flux J (>10 MeV) ~100 pfu and a soft energy spectrum with the index γ ~3.0, while the strong flare on September 10 with S ~ 21000 sfu at f ~ 15 GHz (i.e., with the hard radio spectrum) led to a very intense proton event with J (>10 MeV) ~1000 pfu with a hard spectrum (γ ~ 1.4), including the ground level enhancement (GLE72). This is further evidence that microwave radio data can be successfully used in diagnostics of proton flares independently of a specific source of particle acceleration at the Sun, in particular, with the IZMIRAN method.

Geomagnetism and Aeronomy. 2018;58(4):457-463
pages 457-463 views

Chromospheric and Coronal Radio Sources from Observations of the Partial Solar Eclipse of March 20, 2015, at the Mountain Astronomical Station of the Central Astronomical Observatory

Shramko A.D., Guseva S.A.

Abstract

This paper presents the results of processing the data on the partial solar eclipse that occurred on March 20, 2015, and was observed with the RT-3 (λ = 4.9 cm) and RT-2 (λ = 3.2 cm) radio telescopes of the Kislovodsk Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences (MAS CAO RAS). They were compared with observations in the optical and X-ray ranges. The local radio sources at the limb and on the disc of the Sun were identified: an eruptive and a quiet prominence; filaments; a coronal hole; facular plages; and a sunspot group. The curves of the center-to-limb variations in the radio brightness of the undisturbed regions of the Sun were plotted for λ = 4.9 and λ = 3.2 cm. The solar radio maps were presented. The altitude of the radiating layer in the chromosphere above the sunspot and the facular sources for λ = 4.9 cm λ = 3.2 cm was compared.

Geomagnetism and Aeronomy. 2018;58(4):464-468
pages 464-468 views

Generation of EMIC Waves in the Magnetosphere and Precipitation of Energetic Protons: Comparison of the Data from THEMIS High Earth Orbiting Satellites and POES Low Earth Orbiting Satellites

Popova T.A., Yahnin A.G., Demekhov A.G., Chernyaeva S.A.

Abstract

Regions of the detection of electromagnetic ion-cyclotron (EMIC) waves on the THEMIS satellites near the equatorial plane and the precipitation of energetic protons on POES low Earth orbiting satellites are compared with the magnetospheric magnetic field model. It is confirmed that low Earth orbiting satellites detect the precipitation of energetic protons in the regon associated with observations of EMIC waves in the magnetosphere. This is consistent with the idea that protons are scattered in the loss cone as a result of ioncyclotron interaction. Thus, observations of fluxes of energetic protons in low Earth orbits can be used to monitor ion-cyclotron instability regions in the magnetosphere. Simultaneous observations at high and low Earth orbits contribute to the construction of a spatiotemporal pattern of the interaction region of EMIC waves and energetic protons. In addition, it is shown that proton precipitation associated with EMIC waves can cause errors in determining the latitude of the isotropic boundary (the equatorial boundary of isotropic fluxes of energetic protons), which is an indicator of the configuration of the magnetic field in the magnetosphere.

Geomagnetism and Aeronomy. 2018;58(4):469-482
pages 469-482 views

Characteristics of the Energetic Electron Precipitation and Magnetospheric Conditions in 1994

Bazilevskaya G.A., Kalinin M.S., Krainev M.B., Makhmutov V.S., Svirzhevskaya A.K., Svirzhevsky N.S., Stozhkov Y.I., Gvozdevsky B.B.

Abstract

The problem of the rapid depletion and saturation of the Earth’s outer radiation belt with energetic electrons is one of the central problems in the physics of the magnetosphere. The precipitation into the atmosphere and the escape of electrons from the magnetosphere are competing reasons for the depletion of the radiation belt. Long-term measurements of energetic electron precipitation (EEP) in the atmosphere in the experiment of the Lebedev Physical Institute (LPI) can be used to study the relative role of these phenomena. High fluence values of relativistic electrons in the outer belt is a necessary condition for EEP observation; however, the relation of the EEP rate to the condition of the belt is ambiguous, which is shown by the example of observations in 1994.

Geomagnetism and Aeronomy. 2018;58(4):483-492
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Studies of Trends in the Upper Atmosphere for Improving Diagnosis and Forecasts in the Helio–Geophysical Service of the State Committee on Hydrometeorology

Danilov A.D., Repin A.Y., Minligareev V.T., Khotenko E.N.

Abstract

A brief review of the current state of studies of long-term trends in the middle and upper atmosphere and ionosphere is presented. It is shown that the present trends in the density and temperature of the upper atmosphere and parameters of the ionospheric layers may lead to changes in the aforementioned spheres. It would be necessary to take into account these trends in applied problems related to planning space vehicle orbits, propagation of radio waves, measurements at low-orbiting satellites, and so on. It is emphasized that the Helio–Geophysical Service of the State Committee of Hydrometeorology, which supplies customers with information on the state of the upper atmosphere, ionosphere, and near-Earth space, should develop information products related to possible changes in atmospheric and ionospheric parameters caused by the presence of the long-term trends.

Geomagnetism and Aeronomy. 2018;58(4):493-500
pages 493-500 views

Parameters of the Geomagnetic Activity, Thermosphere, and Ionosphere for the Ultimately Intense Magnetic Storm

Deminov M.G., Belov A.V., Nepomnyashchaya E.V., Obridko V.N.

Abstract

Equations of regression are derived for the intense magnetic storms of 1957−2016. They reflect the nonlinear relation between Dstmin and the effective index of geomagnetic activity Ap(τ) with a timeweighted factor τ. Based on this and on known estimations of the upper limit of the magnetic storm intensity (Dstmin =–2500 nT), the maximal possible value Ap(τ)max ~ 1000 nT is obtained. This makes it possible to obtain initial estimates of the upper limit of variations in some parameters of the thermosphere and ionosphere that are due to geomagnetic activity. It is found, in particular, that the upper limit of an increase in the thermospheric density is seven to eight times larger than for the storm in March 1989, which was the most intense for the entire space era. The maximum possible amplitude of the negative phase of the ionospheric storm in the number density of the F2-layer maximum at midlatitudes is nearly six times higher than for the March 1989 storm. The upper limit of the F2-layer rise in this phase of the ionospheric storm is also considerable. Based on qualitative analysis, it is found that the F2-layer maximum in daytime hours at midlatitudes for these limiting conditions is not pronounced and even may be unresolved in the experiment, i.e., above the F1-layer maximum, the electron number density may smoothly decrease with height up to the upper boundary of the plasmasphere.

Geomagnetism and Aeronomy. 2018;58(4):501-508
pages 501-508 views

Modeling the Effect of Mesospheric Internal Gravity Waves in the Thermosphere and Ionosphere During the 2009 Sudden Stratospheric Warming

Karpov I.V., Bessarab F.S., Borchevkina O.P., Artemenko K.A., Klopova A.I.

Abstract

The results of numerical experiments on the modeling of thermospheric and ionospheric disturbances under conditions of sudden stratospheric warming are presented to study the possible mechanisms of such disturbances. Local disturbances caused by a planetary wave with zonal wave number s = 1 and internal gravity waves (IGWs) propagating from the disturbed region in the stratosphere are taken into account as sources of disturbances. It is shown that the inclusion of an additional source of thermospheric disturbances caused by mesospheric variations of atmospheric parameters with IGW periods over the region of sudden stratospheric warming leads to significant changes in the parameters of the thermosphere and ionosphere, including a change in the global structure of the distributions of the gas components of the thermosphere and a shift in maximum concentrations of atomic oxygen to low latitudes of the Southern Hemisphere; there is an increase in the mean values, the diurnal and semidiurnal variations of the ion concentration in the F region of the ionosphere. These features of changes in the parameters of the thermosphere and ionosphere occurred with insignificant disturbances of tidal variations in the thermosphere.

Geomagnetism and Aeronomy. 2018;58(4):509-522
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Estimating the Frequency and Amplitude Parameters of the Serpentine-Emission Type of Geomagnetic Pulsations

Getmanov V.G., Dovbnya B.V., Kornilov A.S.

Abstract

Geomagnetic pulsations of the serpentine-emission (SE) type are considered. A method for estimating the frequency and amplitude parameters in the form of a time function for pulsations—SE and the accompanying spectral components—is suggested. An estimation algorithm is developed on the basis of local approximating polyharmonic models and weighted moving average filtration. Examples of the estimation of the frequency and amplitude parameters of SE pulsations are given. It is proposed that the procedure be used to calculate the estimation errors in SE pulsation frequency parameters and to choose the tuning parameters.

Geomagnetism and Aeronomy. 2018;58(4):523-532
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Motion of Ionospheric Plasma: Results of Observations above Kharkiv in Solar Cycle 24

Emel’yanov L.Y., Lyashenko M.V., Chernogor L.F., Domnin I.F.

Abstract

The equipment and methodical characteristics of determining the vertical component of the ionospheric plasma motion velocity Vz based on an incoherent scatter radar of Institute of Ionosphere, National Academy of Sciences and Ministry of Education and Science of Ukraine (Kharkiv), which is the only radar of such type in Central Europe, are described. Based on the radar data, the patterns of altitude and diurnal variations in Vz near the maximum of solar cycle 24 for the typical geophysical conditions (around the summer and winter solstices, the spring and fall equinoxes) at low geomagnetic activity and the specifics of these changes during ionospheric storms are presented. The results of modeling of the dynamic processes in ionospheric plasma under the conditions of the undisturbed ionosphere, including the determination of altitudetime variations in the thermospheric wind velocity, are presented. It has been established that this velocity can significantly differ from the thermospheric wind velocity calculated by the known empirical global models. This difference is likely related to the regional features of thermospheric wind that are not shown in the global models.

Geomagnetism and Aeronomy. 2018;58(4):533-547
pages 533-547 views

Features of the Atmospheric Temperature Variations Prior to Strong Earthquakes in Kamchatka and Their Relation to the Fluxes of Outgoing Infrared Radiation

Mikhailova G.A., Kapustina O.V., Mikhailov Y.M., Smirnov S.E.

Abstract

The temperature variations of the near-surface atmosphere in Kamchatka at Paratunka observatory and fluxes of outgoing infrared radiation prior to strong Kuril earthquakes (November 15, 2006, M = 8.3; January 13, 2007, M = 8.1) have been analyzed. It is shown that the radiation fluxes at ground level, as measured on satellites above the epicenter of earthquakes and above a remote observatory, coincide with each other, both in magnitude and in the feature of their time variations. The temperature measured directly at the observatory and the temperature at surface level estimated from satellite observations differ in magnitude, but they coincide in the feature of their time variations. The detected temperature increase (despite the negative regular trend at this time of year) is caused by the appearance of an additional heat source entering in the nearsurface atmosphere. This result, together with the studies of variations of various geophysical data before strong earthquakes performed earlier in Kamchatka, led to the conclusion that the additional heat source is in the Earth’s crust.

Geomagnetism and Aeronomy. 2018;58(4):548-553
pages 548-553 views

Dynamics of the Development of Aluminum Monoxide Clouds in the Upper Atmosphere During the Launch of Solid-Propellant Rockets

Platov Y.V., Nikolaishvili S.S.

Abstract

Various mechanisms of the formation of AlO molecules during the operation of solid-propellant rocket engines in the upper atmosphere and processes of AlO glow decay are considered. The main contribution to AlO formation at altitudes of 120–200 km is made by the interaction of metallic aluminum contained in products of solid propellant combustion with atmospheric oxygen. The decrease in the brightness of AlO clouds is caused by a decrease in the AlO concentration as a result of cloud expansion due to diffusion processes and AlO oxidation with atomic oxygen.

Geomagnetism and Aeronomy. 2018;58(4):554-558
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The Nocturnal Positive Ionospheric Anomaly of Electron Density as a Short-Term Earthquake Precursor and the Possible Physical Mechanism of Its Formation

Pulinets S.A., Davidenko D.V.

Abstract

This paper summarizes the years of studies devoted to the self-similarity of anomalies originating in the ionosphere above the regions of the preparation of strong earthquakes. Using statistical processing of data on electron density variations obtained by methods of vertical sounding and measurements of the total electronic content, we have formed a pattern of similar variations observed at midlatitudes before strong earthquakes; we call it a precursor mask for earthquakes. It was found that the positive anomaly in the ionosphere formed at nighttime after sunset and ended at sunrise. In the case of strong earthquakes, the anomaly can last 12 h and emerge within a few days at the same local time. We propose a physical mechanism of anomaly formation in the ionosphere bound with the diurnal dynamics of the atmospheric boundary layer, which regulates the height distribution of cluster ions.

Geomagnetism and Aeronomy. 2018;58(4):559-570
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Evolution of Dimensionless Numbers in Geodynamo Models

Reshetnyak M.Y.

Abstract

The evolution of the dimensionless Ekman, Rossby, and Rayleigh numbers in the model of composite convection in the Earth’s, which that determine the force balance and magnetic field evolution, is considered on the basis of known estimates of the rate of solid core growth and variations in the day length. Various scenarios of this evolution, both in the past and future, are presented over time intervals comparable with the age of the core. It is shown, in particular, that the current intensity of convection in the fluid core continues to increase. This fact corresponds to the increase in the frequency of geomagnetic field inversions and the transition from a dipole field to a multipole one. A decrease in the volume of the liquid core leads to a decrease in the magnetic field strength.

Geomagnetism and Aeronomy. 2018;58(4):571-575
pages 571-575 views