Polar Geophysical Institute

Apatity, Russia

Polar Geophysical Institute

Apatity, Russia
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Tereshchenko E.D.,Polar Geophysical Institute | Tereshchenko P.E.,Russian Academy of Sciences
Technical Physics | Year: 2017

Electric field excitation by a horizontal flooded source placed at the interface between two media has been considered. A solution to the problem has been represented in the form of integrals that contain a quickly oscillating Bessel function. Under the quasi-static approximation, general functions that describe a field in water have been represented using the Watson integrals through the well-studied modified Bessel functions. It has been shown that, in the region at a distance more than a skin-layer from the antenna, the vertical component is determined by the field that propagates exclusively in the lower medium, and components perpendicular to the antenna have the form of the waves that propagate in the upper medium without absorption and then penetrate deeply, changing by the exponential law. © 2017, Pleiades Publishing, Ltd.

Germanenko A.V.,Polar Geophysical Institute | Balabin J.V.,Polar Geophysical Institute
Bulletin of the Russian Academy of Sciences: Physics | Year: 2017

The Polar Geophysical Institute continuously monitors different components of secondary cosmic rays (soft gamma radiation in the range of 20–5000 keV, charged particles of 5–7 MeV, and the neutron component) at two stations: Apatity (Murmansk oblast) and Barentsburg (Spitsbergen Archipelago). The relation between annual variations in the registered secondary components of cosmic rays and seasonal meteorological cconditions, and the thickness of the ice cover in particular, is considered in this work. There is a clear correlation between the thickness of the ice cover and the soft gamma radiation flow received by the detector from the upper hemisphere. A mechanism that qualitatively explains these variations is proposed. © 2017, Allerton Press, Inc.

Balabin J.V.,Polar Geophysical Institute
Bulletin of the Russian Academy of Sciences: Physics | Year: 2017

Neutron monitors at the Baksan, Moscow, Apatity, and Barentsburg stations are equipped with a unique high-speed registration system that registers the arrival of a pulse with an error of about 1 μs. Analysis of data obtained using the neutron monitors reveals the presence of isolated particle clusters in the flux of high-energy (above tens of GeV) cosmic ray particles. The clusters are known as transients. The neutron monitors detect brief surges of density in the high-energy particle flux. Each surge lasts 20–40 s. The flux density inside the transients is about twice the average level. The transients are isolated by dips that are brief 200–300% drops in the particle flux density, observed in front of and behind each one. It is assumed that a transient is a brief local surge in particle flux density during cosmic ray diffusion and scattering in the interplanetary magnetic field. © 2017, Allerton Press, Inc.

Barabash V.,Lulea University of Technology | Osepian A.,Polar Geophysical Institute | Dalin P.,Swedish Institute of Space Physics | Kirkwood S.,Swedish Institute of Space Physics
Annales Geophysicae | Year: 2012

The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80° and larger than 99° under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F10.7 have been incorporated into the model. Influence of minor neutral species (NO, H2O, O, O3) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73-85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km.

Model responses to changes of the solar zenith angle, solar activity (low-high) and season (summer-winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere. © Author(s) 2012. CC Attribution 3.0 License.

Kozelov B.V.,Polar Geophysical Institute | Golovchanskaya I.V.,Polar Geophysical Institute
Journal of Geophysical Research: Space Physics | Year: 2010

In the study of scaling properties of auroral luminosity variations by ground-based imaging observations, a problem arises that the actual scaling characteristics are distorted because of contributions to images from extension of auroral structures along the geomagnetic field. The field-aligned trends come into play for whatever small deviations from the magnetic zenith, making questionable the appropriateness of ground imaging data for investigation of turbulence signatures in aurora. In order to clear up how to correct for this effect, we have modeled the distortions, stemming from aspect angle broadening, for synthesized self-similar fluctuations with known scaling characteristics in the plane perpendicular to the magnetic field. Both narrow and wide field-aligned profiles of luminosity were considered. Three estimators for deriving scaling parameters were applied, including the wavelet estimator, dyadic filter estimator, and standard deviation statistical estimator, of which the wavelet estimator is shown to be most robust. The formulas are presented that relate the observed scaling characteristics with the true ones for the case of aurora being observed near magnetic zenith. Copyright 2010 by the American Geophysical Union.

Golovchanskaya I.V.,Polar Geophysical Institute | Kozelov B.V.,Polar Geophysical Institute
Journal of Geophysical Research: Space Physics | Year: 2010

We compare scaling properties of electric fields measured by the low-altitude polar-orbiting Dynamics Explorer 2 satellite in the auroral zone and the polar cap under interplanetary magnetic field (IMF) southward conditions. The techniques of logscale diagrams (LDs) and probability density function (PDF) are applied to demonstrate the scale-free structure of electric fluctuations on scales from 0.5 km to 256 km in both regions. It is shown that while the amplitudes of electric field fluctuations are much smaller in the polar cap than in the auroral zone, the scaling characteristics of the fluctuations in the two domains are basically the same. To examine the possibility that electric turbulence in the polar cap may be driven directly by turbulent solar wind variations, we searched for the relationship between the RMS values of the electric fluctuations in the polar cap and solar wind variability and did not find a clear relationship. We also demonstrate that the Poynting flux associated with electric and magnetic fluctuations in the polar cap tends to subside from the flanks toward the center of the polar cap. These findings are more consistent with plasma shear flow on open field lines being the driver of turbulence in the polar cap ionosphere. Copyright 2010 by the American Geophysical Union.

Kornilova T.A.,Polar Geophysical Institute | Kornilov I.A.,Polar Geophysical Institute
Journal of Geophysical Research: Space Physics | Year: 2012

Using of high-quality keograms constructed by filtered and averaged images from the Lovozero all-sky imager (ASI) station and THEMIS all-sky imager array allowed us to investigate in detail optical signatures of poleward forms propagating equatorward and getting involved in the auroral pattern in the course of substorm expansion. We found that weak, nearly east-west oriented auroral arcs often penetrate into poleward expanding regions of active auroras from preceding breakup activations in the south. In total, 40 such events have been analyzed. The major point that we aimed to clarify is whether these weak forms fade, disperse, or keep moving equatorward in such occasions. We were able to trace their fate and demonstrate that they keep their equatorward motion against the background of bright, poleward expanding auroras, forming a counterstreaming auroral pattern at substorm expansion. Copyright 2012 by the American Geophysical Union.

The paper presents a model of the kinetics of electronically excited O 2(c 1Σ u -,v), O 2(A′ 3Δ u,v), O 2(A 3Σ u +,v) molecules at heights of the lower thermosphere and mesosphere with allowance for electronic excitation transfer processes during molecular collisions. The model is used to calculate the relative O 2(A 3Σ u +,v) and O 2(A′ 3Δ u,v) populations at heights of 80-110 km. The calculated populations are compared with the available literature results on experimental estimates, and good agreement is obtained. It is shown how the increase in the quenching rates of the considered states by oxygen atoms affects the calculation results. © 2012 Pleiades Publishing, Ltd.

Vorobjev V.G.,Polar Geophysical Institute | Yagodkina O.I.,Polar Geophysical Institute | Katkalov Y.,Polar Geophysical Institute
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2013

Based on statistical treatment of DMSP F6 and F7 spacecraft observations, an interactive Auroral Precipitation Model (APM) parameterized by magnetic activity has been created (available at http://apm.pgia.ru/). For a given level of magnetic activity the model yields a global distribution of electron precipitation and planetary patterns of both average electron energy and electron energy flux in different precipitation zones. Outputs of the model were used to determine the basic variables of the magnetosphere, such as boundary location and the area of the polar cap, magnetic flux transferred from the dayside magnetosphere into the tail, global precipitation power realized by different types of precipitation and others. The model predicts an increase in the polar cap area from about 6.3×106km2 to 2.0×107km2, in the magnetic flux from 390MWb to 1200MWb, and in the global precipitation power from 3.4GW to 188.0GW, when the magnetic activity changes from silence (null AL and Dst) to significant disturbance (AL=-1000nT, Dst=-200nT). The use of dayside auroral observations as an input for APM provides an opportunity for continuous monitoring of magnetospheric conditions. Two time intervals on Dec. 27, 2000, and Dec. 12, 2004, of dayside auroral observations with the meridian scanning photometer at Barentsburg (Spitsbergen) were selected to demonstrate derivation of magnetospheric variables with APM. It is shown that the values of the AL index derived from optical observation appear in a reasonable agreement with those published by WDC. © 2013 Elsevier Ltd.

Golovchanskaya I.V.,Polar Geophysical Institute | Kozelov B.V.,Polar Geophysical Institute | Mingalev O.V.,Polar Geophysical Institute | Fedorenko Y.V.,Polar Geophysical Institute | Melnik M.N.,Polar Geophysical Institute
Geophysical Research Letters | Year: 2011

Magnetic perturbations in the topside auroral ionosphere observed by the FAST satellite in the events of broadband extra low frequency (BB ELF) turbulence are investigated at frequencies 0.5-8 Hz (scales from 14 km down to 0.9 km). The power-law scaling and peculiar polarization patterns of the perturbations are highlighted. By comparing with the magnetic fields simulated according to the Chang et al. (2004) scenario of coarse-graining process development, we demonstrate that the magnetic perturbations observed in the events of the BB ELF turbulence can be reasonably understood in terms of non-linearly interacting multiscale field-aligned currents traversed by the spacecraft. Copyright 2011 by the American Geophysical Union.

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