Труды сотрудников ИВМ СО РАН

[Text] / N. V. Erkaev, V. S. Semenov // PROCEEDINGS OF THE FIFTH INTERNATIONAL CONFERENCE ON SUBSTORMS. Ser. ESA SPECIAL PUBLICATIONS : ESA PUBLICATIONS DIVISION C/O ESTEC, 2000. - Vol. 443: 5th International Conference on Substorms (MAY 16-20, 2000, ST PETERSBURG, RUSSIA). - P161-164. - Cited References: 14 . - ISBN 0379-6566. - ISBN 92-9092-772-0РУБ Astronomy & Astrophysics

Аннотация: In the theory of magnetic reconnection there is the old problem: it is still unclear which conditions make Petschek-type reconnection to be possible and which are responsible for the Sweet-Parker regime. The fact is that numerical simulations were not able to reproduce solution of Petschek type but rather were in favor of Sweet-Parker solution unless the resistivity was localized in a small region. The problem of reconnection rate is connected with the matching of a solution for the diffusion region where dissipation is important, and solution for the convective zone where ideal MHD equations can be used. Using the nonsteady numerical MHD solution obtained for the diffusion region, we determine the reconnection rate as a function of time by matching of the outer Petschek solution and the internal diffusion region solution. The reconnection rate obtained naturally incorporates both Sweet-Parker and Petschek regimes, the latter seems to be possible only for the case with strongly localized resistivity.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.

[Text] / V. V. DENISENKO, S. S. ZAMAY // Planet Space Sci. - 1992. - Vol. 40, Is. 7. - P941-952, DOI 10.1016/0032-0633(92)90134-A. - Cited References: 47 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: A model of the ionosphere as a global conductor is used to examine synchronous variations of electric fields and currents at high and low latitudes. The special form of a boundary value problem and a multigrid numerical method permit investigation of auroral field penetration to the equator. A model of field-aligned currents and conductivities for expansion and recovery phases of a substorm are suggested, which are in accordance with empirical models and with theory of field-aligned current dynamics. Electric field distributions near the equator, which were obtained as a result of calculations, are in accordance with observations during substorms. It is shown that the contribution of high latitude sources to low latitude electric fields and currents during quiet-time periods is comparable with that given by dynamo fields. The nature of the post-sunset peak of the zonal electric field at the equator and seasonal variations of this peak are explained.


Доп.точки доступа:
ZAMAY, S.S.; Денисенко, Валерий Васильевич

[Text] / V. V. Denisenko, V. V. Bychkov, E. V. Pomozov // Geomagn. Aeron. - 2009. - Vol. 49, Is. 8. - P1275-1277, DOI 10.1134/S0016793209080489. - Cited References: 4. - This work was supported by the Russian Foundation for Basic Research (project no. 07-05-00135) and the Russian Academy of Sciences (program nos. 2.16 and 16.3). . - ISSN 0016-7932РУБ Geochemistry & Geophysics

Аннотация: The spatial distributions of electric fields and currents in the Earth's atmosphere are calculated. Electric potential distributions typical of substorms and quiet geomagnetic conditions are specified in the ionosphere. The Earth is treated as a perfect conductor. The atmosphere is considered as a spherical layer with a given height dependence of electrical conductivity. With the chosen conductivity model and an ionospheric potential of 300 kV with respect to the Earth, the electric field near the ground is vertical and reaches 110 Vm(-1). With the 60-kV potential difference in the polar cap of the ionosphere, the electric field disturbances with a vertical component of up to 13 V m(-1) can occur in the atmosphere. These disturbances are maximal near the ground. If the horizontal scales of field nonuniformity are over 100 km, the vertical component of the electric field near the ground can be calculated with the one-dimensional model. The field and current distributions in the upper atmosphere can be obtained only from the three-dimensional model. The numerical method for solving electrical conductivity problems makes it possible to take into account conductivity inhomogeneities and the ground relief.


Доп.точки доступа:
Denisenko, V.V.; Денисенко, Валерий Васильевич; Bychkov, V.V.; Pomozov, E.V.; Помозов, Егор Владимирович; Russian Foundation for Basic Research [07-05-00135]; Russian Academy of Sciences

[Text] / D. I. Kubyshkina [et al.] // J. Geophys. Res-Space Phys. - 2014. - Vol. 119, Is. 4. - P. 3002-3015, DOI 10.1002/2013JA019477. - Cited References: 32. - We thank C. W. Carlson and J. P. McFadden for use of THEMIS ESA data; K. H. Glassmeier, U. Auster, and W. Baumjohann for the use of FGM data provided under the lead of the Technical University of Braunschweig and with financial support through the German Ministry for Economy and Technology and the German Center for Aviation and Space (DLR) under contract 50 OC 0302. The work was partly supported by SPbU grant 11.38.84.12, by RFBR grants 12-05-00152-a and 12-05-00918-a, and by the grant for support of leading Scientific schools 2836.2014.5. The work of S. Dubyagin and N. Ganushkina was partly supported by the Academy of Finland. This work was supported by the Austrian Science Fund (FWF): I193-N16. N. V. E acknowledges the support by the International Space Science Institute (ISSI, Switzerland) and discussions within the ISSI Team 214 on Flow-Driven Instabilities of the Sun-Earth System. The research has received funding also from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 269198-Geoplasmas (Marie Curie International Research Staff Exchange Scheme) and 218816 (SOTERIA project). . - ISSN 2169-9380. - ISSN 2169-9402РУБ Astronomy & Astrophysics

Аннотация: Flapping waves are most noticeable large-scale perturbations of the magnetotail current sheet, whose nature is still under discussion. They represent rather slow (an order of magnitude less than typical Alfven speed) waves propagating from the center of the sheet to its flanks with a typical speed of 20-60 km/s, amplitude of 1-2 R-e and quasiperiod of 2-10 min. The double-gradient MHD model, which was elaborated in Erkaev et al. (2007) predicts two (kink and sausage) modes of the flapping waves with differences in their geometry and propagation velocity, but the mode structure is hard to resolve observationally. We investigate the possibility of mode identification by observing the rotation of magnetic field and plasma velocity vectors from a single spacecraft. We test theoretical results by analyzing the flapping oscillations observed by Time History of Events and Macroscale Interactions during Substorms spacecraft and confirm that character of observed rotation is consistent with kink mode determination made by using multispacecraft methods. Also, we checked how the existence of some obstructive conditions, such as noise, combined modes, and multiple sources of the flapping oscillations, can affect on the possibility of the modes separation with suggested method.

Полный текст (доступен только в локальной сети)

Держатели документа:
ИВМ СО РАН

Доп.точки доступа:
Kubyshkina, D.I.; Sormakov, D.A.; Sergeev, V.A.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kubyshkin, I.V.; Ganushkina, N.Y.; Dubyagin, S.V.; German Ministry for Economy and Technology; German Center for Aviation and Space (DLR) [50 OC 0302]; SPbU [11.38.84.12]; RFBR [12-05-00152-a, 12-05-00918-a]; grant for support of leading Scientific schools [2836.2014.5]; Academy of Finland; Austrian Science Fund (FWF) [I193-N16]; International Space Science Institute (ISSI, Switzerland); European Union [269198, 218816]

/ K. Yu. Slivka [et al.] // J. Geophys. Res. A. Space Phys. - 2015. - Vol. 120, Is. 11. - P9471-9483, DOI 10.1002/2015JA021250 . - ISSN 2169-9380
Аннотация: The magnetic barrier is a region which is formed in the course of the solar wind flow around the Earth's magnetosphere and is characterized by depleted plasma and an enhanced magnitude of the magnetic field. There is a general point of view that the magnetic barrier can persist only for the northward interplanetary magnetic field (IMF), whereas it is practically absent if the IMF is southward directed. We studied the presence of the magnetic barrier for low-shear (predominantly northward IMF) and high-shear (predominantly southward IMF) magnetopause conditions and analyzed 74 events of low-latitude dayside magnetopause crossings by the Time History of Events and Macroscale Interactions during Substorms satellites. We used the superposed epoch analysis to study variations of magnetic field and plasma parameters near the magnetopause. Results of Phan et al. (1994) that the magnetic barrier is well pronounced for low-shear magnetopauses and practically absent for high-shear events have been confirmed by our analysis. However, 5 from 49 high-shear events show clear signatures of a magnetic barrier. Hence, we conclude that the magnetic barrier is formed in the same manner for all direction of IMF but for high-shear events it is destroyed by reconnection much faster than it accumulates. Ratio of the events with and without magnetic barrier signatures (5/44) is approximately equal to the ratio of characteristic times of disruption due to reconnection (1-2 min) and the formation of a magnetic barrier (10 min). The reduction of the magnetic field due to reconnection can be used to estimate reconnection rate which turns out to be rather high of the order of 0.3 in 19 from 31 cases. ©2015. American Geophysical Union. All Rights Reserved.

Scopus,
WOS

Держатели документа:
Earth Physics Department, Saint Petersburg State University, Saint Petersburg, Russian Federation
Institute of Computational Modelling SB RAS, Krasnoyarsk, Russian Federation
Department of Applied Mechanics, Polytechnic Institute, Siberian Federal University, Krasnoyarsk, Russian Federation
Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Доп.точки доступа:
Slivka, K. Yu.; Semenov, V. S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Dmitrieva, N. P.; Kubyshkin, I. V.; Lammer, H.

/ S. A. Kiehas [et al.] // J. Geophys. Res-Space Phys. - 2017. - Vol. 122, Is. 3. - P3212-3231, DOI 10.1002/2016JA023169. - Cited References:48. - This work is supported by the Austrian Science Fund (FWF) J3041-N16 and P27012-N27 and by grants 16-05-00470, and 15-05-00879-a from the Russian Foundation of Basic Research. No data were used. . - ISSN 2169-9380. - ISSN 2169-9402РУБ Astronomy & Astrophysics

Аннотация: We evaluate the large-scale energy budget of magnetic reconnection utilizing an analytical time-dependent impulsive reconnection model and a numerical 2-D MHD simulation. With the generalization to compressible plasma, we can investigate changes in the thermal, kinetic, and magnetic energies. We study these changes in three different regions: (a) the region defined by the outflowing plasma (outflow region, OR), (b) the region of compressed magnetic fields above/below the OR (traveling compression region, TCR), and (c) the region trailing the OR and TCR (wake). For incompressible plasma, we find that the decrease inside the OR is compensated by the increase in kinetic energy. However, for the general compressible case, the decrease in magnetic energy inside the OR is not sufficient to explain the increase in thermal and kinetic energy. Hence, energy from other regions needs to be considered. We find that the decrease in thermal and magnetic energy in the wake, together with the decrease in magnetic energy inside the OR, is sufficient to feed the increase in kinetic and thermal energies in the OR and the increase in magnetic and thermal energies inside the TCR. That way, the energy budget is balanced, but consequently, not all magnetic energy is converted into kinetic and thermal energies of the OR. Instead, a certain fraction gets transfered into the TCR. As an upper limit of the efficiency of reconnection (magnetic energy kinetic energy) we find eta(eff)=1/2. A numerical simulation is used to include a finite thickness of the current sheet, which shows the importance of the pressure gradient inside the OR for the conversion of kinetic energy into thermal energy.

WOS,
Смотреть статью,
Полный текст (доступен только в ЛВС)

Держатели документа:
Austrian Acad Sci, Space Res Inst, Graz, Austria.
St Petersburg State Univ, Inst Phys, St Petersburg, Russia.
Russian Acad Sci, Inst Computat Modelling, Siberian Branch, Krasnoyarsk, Russia.
Siberian Fed Univ, Dept Computat Phys, Krasnoyarsk, Russia.

Доп.точки доступа:
Kiehas, S. A.; Volkonskaya, N. N.; Semenov, V. S.; Erkaev, N.V.; Бекежанова, Виктория Бахытовна; Kubyshkin, I. V.; Zaitsev, I. V.; Austrian Science Fund (FWF) [J3041-N16, P27012-N27]; Russian Foundation of Basic Research [16-05-00470, 15-05-00879-a]

/ M. Kubyshkina [et al.] // Geophys. Res. Lett. - 2018. - Vol. 45, Is. 9. - P3760-3767, DOI 10.1002/2017GL076268 . - ISSN 0094-8276
Аннотация: We analyze two substorm onset lists, produced by different methods, and show that the (Bx·vz) product of the solar wind (SW) velocity and interplanetary magnetic field (IMF) components for two thirds of all substorm onsets has the same sign as IMF Bz. The explanation we suggest is the efficient displacement of the magnetospheric plasma sheet due to IMF Bx and SW flow vz, which both force the plasma sheet moving in one direction if the sign of (Bx·vz) correlates with the sign Bz. The displacement of the current sheet, in its turn, increases the asymmetry of the magnetotail and can alter the threshold of substorm instabilities. We study the SW and IMF data for the 15-year period (which comprises two substorm lists periods and the whole solar cycle) and reveal the similar asymmetry in the SW, so that the sign of (Bx·vz) coincides with the sign of IMF Bz during about two thirds of all the time. This disproportion can be explained if we admit that about 66% of IMF Bz component is transported to the Earth's orbit by the Alfven waves with antisunward velocities. ©2018. American Geophysical Union. All Rights Reserved.

Scopus,
Смотреть статью,
WOS

Держатели документа:
Earth Physics Department, Saint Petersburg State University, Saint Petersburg, Russian Federation
Institute of Computational Modelling, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Akademgorodok, Russian Federation
Department of Applied Mechanics, Siberian Federal University, Krasnoyarsk, Russian Federation
Finnish Meteorological Institute, Helsinki, Finland
Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, United States

Доп.точки доступа:
Kubyshkina, M.; Semenov, V.; Erkaev, N.; Gordeev, E.; Dubyagin, S.; Ganushkina, N.; Shukhtina, M.