Shibalova A.S.,Moscow State University |
Obridko V.N.,IZMIRAN |
Sokoloff D.D.,Moscow State University
Solar Physics | Year: 2017
Small-scale solar magnetic fields demonstrate features of fractal intermittent behavior, which requires quantification. For this purpose we investigate how the observational estimate of the solar magnetic flux density B depends on resolution D in order to obtain the scaling ln BD= − kln D+ a in a reasonably wide range. The quantity k demonstrates cyclic variations typical of a solar activity cycle. In addition, k depends on the magnetic flux density, i.e. the ratio of the magnetic flux to the area over which the flux is calculated, at a given instant. The quantity a demonstrates some cyclic variation, but it is much weaker than in the case of k. The scaling obtained generalizes previous scalings found for the particular cycle phases. The scaling is typical of fractal structures. In our opinion, the results obtained trace small-scale action in the solar convective zone and its coexistence with the conventional large-scale solar dynamo based on differential rotation and mirror-asymmetric convection. © 2017, Springer Science+Business Media Dordrecht.
Devi M.,Guwahati University |
Barbara A.K.,Guwahati University |
Ruzhin Y.Y.,IZMIRAN |
Hayakawa M.,University of Electro - Communications
Surveys in Geophysics | Year: 2012
The purpose of this paper is to review current activities for the identification of earthquake (EQ) precursors and their epicentres. Starting with a brief description on the background to approaches using ultra-low (ULF), extremely low (ELF), very low/low (VLF/LF), medium (MF), high (HF), very high frequency (VHF) etc. radio waves for short-term EQ prediction, the paper concentrates on those characteristics of anomalous VHF reception from frequency-modulation (FM) radio transmissions and broadcast television (TV) signals in relation to EQ precursors. The possible ways to identify an impending EQ and its epicentre position as defined and observed by workers from a variety of studies fall within the purview of the paper. In attempts to find pre-EQ energy exchange and coupling processes between the lithosphere and atmosphere, the paper highlights some relevant observations of surface latent heat flux, sonic detection and ranging (SODAR) echograms and LF propagation. Explanations on possible causes leading to such anomalous reception are reviewed with reported results in association with pre-seismic induced modifications to tropospheric and ionospheric parameters. © 2012 Springer Science+Business Media B.V.
Cliver E.W.,Air Force Research Lab |
Ling A.G.,Atmospheric Environmental Research |
Belov A.,IZMIRAN |
Yashiro S.,NASA |
Yashiro S.,Catholic University of America
Astrophysical Journal Letters | Year: 2012
We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (≥1000kms-1) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (α values) of power-law size distributions of the peak 1-8 Å fluxes of SXR flares associated with (a) >10MeV SEP events (with peak fluxes ≥1prcm-2s-1sr-1) and (b) fast CMEs were 1.3-1.4 compared to 1.2 for the peak proton fluxes of >10MeV SEP events and 2 for the peak 1-8 Å fluxes of all SXR flares. The difference of 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux. © 2012 The American Astronomical Society. All rights reserved.
Gulyaeva T.L.,IZMIRAN |
Veselovsky I.S.,Moscow State University
Advances in Space Research | Year: 2014
The Global Electron Content, GEC, represents the total number of electrons in the spherical layer over the Earth restricted by orbit of Global Positioning Satellite system (20,200 km). GEC is produced from Global Ionospheric Map of Total Electron Content, GIM-TEC, transformed to the electron density varying with height using the International Reference Ionosphere and Plasmasphere model, IRI-Plas. The climatologic GEC model is developed from GIM-TEC maps for a period 1999-2012 including the solar activity, annual and semiannual cycles as the most important factors affecting daily GEC variation. The proxy R zp of the international sunspot numbers, Ri, is used as a measure of solar activity composed of 3 day smoothed Ri, 7 day and 81 day backwards mean of Ri scaled to the range of 1-40 proxy units, p.u. The root mean square error of the GEC climatologic model is found to vary from 8% to 13% of GEC. Taking advantage of a long history of sunspot numbers, the climatologic GEC model is applied for GEC reconstruction backwards in time for more than 160 years ago since 1850. The extended set of GEC values provides the numerical representation of the ionosphere and plasmasphere electron content coherent with variations of solar activity as a potential proxy index driving the ionosphere models. © 2013 COSPAR.
Vernova E.S.,IZMIRAN |
Tyasto M.I.,IZMIRAN |
Baranov D.G.,RAS Ioffe Physical - Technical Institute
Solar Physics | Year: 2014
Photospheric magnetic fields were studied using the Kitt Peak synoptic maps for 1976 - 2003. Only strong magnetic fields (B>100 G) of the equatorial region were taken into account. The north-south asymmetry of the magnetic fluxes was considered as well as the imbalance between positive and negative fluxes. The north-south asymmetry displays a regular alternation of the dominant hemisphere during the solar cycle: the northern hemisphere dominated in the ascending phase, the southern one in the descending phase during Solar Cycles 21 - 23. The sign of the imbalance did not change during the 11 years from one polar-field reversal to the next and always coincided with the sign of the Sun's polar magnetic field in the northern hemisphere. The dominant sign of leading sunspots in one of the hemispheres determines the sign of the magnetic-flux imbalance. The sign of the north-south asymmetry of the magnetic fluxes and the sign of the imbalance of the positive and the negative fluxes are related to the quarter of the 22-year magnetic cycle where the magnetic configuration of the Sun remains constant (from the minimum where the sunspot sign changes according to Hale's law to the magnetic-field reversal and from the reversal to the minimum). The sign of the north-south asymmetry for the time interval considered was determined by the phase of the 11-year cycle (before or after the reversal); the sign of the imbalance of the positive and the negative fluxes depends on both the phase of the 11-year cycle and on the parity of the solar cycle. The results obtained demonstrate the connection of the magnetic fields in active regions with the Sun's polar magnetic field in the northern hemisphere. © 2014 Springer Science+Business Media Dordrecht.
Geomagnetism and Aeronomy | Year: 2014
Scaling laws for hydromagnetic dynamo in planets initially express the characteristic strength of the magnetic field through the primary values, such as the size of the conductive core of the planet, the angular rotation rate, electrical conductivity and energy flows. Most of the earlier proposed scaling laws based only on observations and assumptions about force balances. Recent and my new approaches to fully take into account the energy and induction balance has additionally expressed here in terms of primary values such important characteristics as forces, magnitudes, energies, scales and orientations of hydromagnetic fields. The direct numerical simulation of the hydromagnetic dynamo and modeling ability in a fairly wide range of parameters for the first time allowed direct test such laws. The obtained numerical geodynamo-like results for the Earth, Jupiter and partially Saturn postulated previously not identified analytically simplest law that predicts the field strength is only depended on the specific energy density of convection and the size of the dynamo area. This simplest and already widely used law was original way analytically grounded here along with other previously known and new laws. This analytic identifies the physics determining geomagnetic periodicities for jerk, secular variations and inversions. Mean period between the inversions is found to be roughly proportional to the intensity of the geomagnetic field that is confirmed by some paleomagnetic researches. Possible dynamos in Mercury, Ganymede, Uranus and Neptune are also discussed. © Pleiades Publishing, Ltd., 2014.
Gudoshnikov S.A.,Magnetic and Cryoelectronic Systems Ltd. |
Liubimov B.Ya.,IZMIRAN |
Usov N.A.,Magnetic and Cryoelectronic Systems Ltd.
AIP Advances | Year: 2012
The hysteresis losses of a dense assembly of magnetite nanoparticles with an average diameter D = 25 nm are measured in the frequency range f = 10 - 200 kHz for magnetic field amplitudes up to H0 = 400 Oe. The low frequency hysteresis loops of the assembly are obtained by means of integration of the electro-motive force signal arising in a small pick-up coil wrapped around a sample which contains 1 - 5 mg of a magnetite powder. It is proved experimentally that the specific absorption rate diminishes approximately 4.5 times when the sample aspect ratio decreases from 11.4 to 1. Theoretical estimate shows that experimentally measured hysteresis loops can be approximately described only by taking into account appreciable contributions of magnetic nanoparticles of both very small, D < 10 - 12 nm, and rather large, D > 30 nm, diameters. Thus the wide particle size distribution has to be assumed. © 2012 Author(s).
Journal of Physics: Conference Series | Year: 2014
We investigate combinatorial properties of a higher invariant of magnetic lines, which is defined in the paper Akhmet'ev-1 (2013). Assume that a 3-component link L is modeled by a magnetic field B, which is represented by 3 closed magnetic lines. Main Theorem relates the integral invariant M(B) and a combinatorial invariant , defined from the Conway polynomial. As a corollary of Main Theorem, asymptotic properties for combinatorial links are proposed. The combinatorial invariant satisfies these asymptotic properties. © Published under licence by IOP Publishing Ltd.
Journal of Geometry and Physics | Year: 2013
A particular result towards a positive solution of a problem by V.I. Arnol'd about a higher analog of the ergodic asymptotic invariant of magnetic fields is presented. © 2013 Elsevier B.V.
Gulyaeva T.L.,IZMIRAN |
Arikan F.,Hacettepe University |
Hernandez-Pajares M.,Polytechnic University of Catalonia |
Stanislawska I.,Polish Academy of Sciences
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2013
The Ionospheric Weather Assessment and Forecast (IWAF) system is a computer software package designed to assess and predict the world-wide representation of 3-D electron density profiles from the Global Ionospheric Maps of Total Electron Content (GIM-TEC). The unique system products include daily-hourly numerical global maps of the F2 layer critical frequency (foF2) and the peak height (hmF2) generated with the International Reference Ionosphere extended to the plasmasphere, IRI-Plas, upgraded by importing the daily-hourly GIM-TEC as a new model driving parameter. Since GIM-TEC maps are provided with 1- or 2-days latency, the global maps forecast for 1 day and 2 days ahead are derived using an harmonic analysis applied to the temporal changes of TEC, foF2 and hmF2 at 5112 grid points of a map encapsulated in IONEX format (-87.5°:2.5°:87.5°N in latitude, -180°:5°:180°E in longitude). The system provides online the ionospheric disturbance warnings in the global W-index map establishing categories of the ionospheric weather from the quiet state (W=±1) to intense storm (W=±4) according to the thresholds set for instant TEC perturbations regarding quiet reference median for the preceding 7 days. The accuracy of IWAF system predictions of TEC, foF2 and hmF2 maps is superior to the standard persistence model with prediction equal to the most recent 'true' map. The paper presents outcomes of the new service expressed by the global ionospheric foF2, hmF2 and W-index maps demonstrating the process of origin and propagation of positive and negative ionosphere disturbances in space and time and their forecast under different scenarios. © 2013 Elsevier Ltd.