Труды сотрудников ИВМ СО РАН

/ C. J. Farrugia [et al.] // Sol. Phys. - 2012. - Vol. 281, Is. 1. - pp. 461-489, DOI 10.1007/s11207-012-0119-1. - Cited References: 53 . - 29. - ISSN 0038-0938РУБ Astronomy & Astrophysics

Аннотация: We discuss the temporal variations and frequency distributions of solar wind and interplanetary magnetic field parameters during the solar minimum of 2007-2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A. We find that the density and total field strength were significantly weaker than in the previous minimum. The Alfv,n Mach number was higher than typical. This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions. We then discuss two major aspects that this weak solar activity had on the magnetosphere, using data from Wind and ground-based observations: i) the dayside contribution to the cross-polar cap potential (CPCP), and ii) the shapes of the magnetopause and bow shock. For i) we find a low interplanetary electric field of 1.3 +/- 0.9 mV m(-1) and a CPCP of 37.3 +/- 20.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions. We suggest that the Alfven wave trains in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this three-year period. For ii) we determine 328 magnetopause and 271 bow shock crossings made by Geotail, Cluster 1, and the THEMIS B and C spacecraft during a three-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the three years under survey. We use the same numerical approach as in Fairfield's (J. Geophys. Res. 76, 7600, 1971) empirical model and compare our findings with three magnetopause models. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 R-E and 14.35 R-E, respectively. When comparing with Fairfield's (1971) classic result, we find that the subsolar magnetosheath is thinner by similar to 1 R-E. This is mainly due to the low dynamic pressure which results in a sunward shift of the magnetopause. The magnetopause is more flared than in Fairfield's model. By contrast the bow shock is less flared, and the latter is the result of weaker MHD forces.

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Доп.точки доступа:
Farrugia, C.J.; Harris, B.; Leitner, M.; Mostl, C.; Galvin, A.B.; Simunac, K.D.C.; Torbert, R.B.; Temmer, M.B.; Veronig, A.M.; Erkaev, N.V.; Еркаев, Николай Васильевич; Szabo, A.; Ogilvie, K.W.; Luhmann, J.G.; Osherovich, V.A.

/ N. V. Erkaev [et al.] // Geophys. Res. Lett. - 2012. - Vol. 39. - Ст. L01103, DOI 10.1029/2011GL050209. - Cited References: 16. - This work was done while NVE was on a research visit to the Space Science Center of UNH. This work is supported by RFBR grant N 09-05-91000-ANF_a, and also by the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. Work by CJF was supported by NASA grants NNX10AQ29G and NNX08AD11G. . - ISSN 0094-8276РУБ Geosciences, Multidisciplinary

Аннотация: In previous work we used a semi-analytical treatment to describe accelerated magnetosheath flows caused by the draping of interplanetary magnetic field (IMF) lines around the magnetosphere. Here, we use the same approach, i.e., modeling the magnetic field lines as elastic strings, to examine how the magnetic tension force, one of the two agents responsible for producing these flows, varies along field lines away from the equatorial plane. The bend in the field line caused by the draping mechanism propagates as two oppositely-directed waves to higher latitudes. For a due northward IMF - the case we consider here - these propagate symmetrically north/south of the equatorial plane. As a result, a two-peaked latitude velocity profile develops as we go further downtail and the velocity peaks migrate along the magnetic field line to higher latitudes. We examine this velocity-profile for two Alfven Mach numbers (M-A = 8 and 3), representative of conditions in the solar wind at 1 AU ("normal" solar wind and solar transients). Qualitatively, the picture is the same but quantitatively there are important differences: (i) the flows reach higher values for the lower M-A (maximum V/V-SW = 1.6) than for the higher M-A (V/V-SW = 1.3); (ii) asymptotic values are reached farther downstream of the dawn-dusk terminator for the lower M-A (similar to-50 R-E vs -15 R-E); (iii) For the lower M-A the highest speeds are reached away from the equatorial plane. We predict two channels of fast magnetosheath flow next to the magnetopause at off-equatorial latitudes that exceed the solar wind speed. Citation: Erkaev, N. V., C. J. Farrugia, A. V. Mezentsev, R. B. Torbert, and H. K. Biernat (2012), Accelerated magnetosheath flows caused by IMF draping: Dependence on latitude, Geophys. Res. Lett., 39, L01103, doi:10.1029/2011GL050209.

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Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Farrugia, C.J.; Mezentsev, A.V.; Torbert, R.B.; Biernat, H.K.

[Text] / C.J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 2010. - Vol. 115. - Ст. A08227, DOI 10.1029/2009JA015128. - Cited References: 34. - The authors would like to thank David Burgess for helpful discussions. Part of this work was done when NVE was on a research visit to the Space Science Center of the University of New Hampshire, USA. This work is supported by NASA grants NNX08AD11G and NNG06GD41G, and also by RFBR grants 07-05-00135, 09-05-91000-ANF_a and by Program 16 of RAS. R. P. Lin has been supported in part by NASA grant NNX08AE34G at UC Berkeley, and the WCU grant (R31-10016) funded by the Korean Ministry of Education, Science and Technology. We thank D. J. McComas and H. J. Singer for the ACE plasma data and GOES magnetic field data, respectively, obtained through NASA cdaweb site. . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: While there are many approximations describing the flow of the solar wind past the magnetosphere in the magnetosheath, the case of perfectly aligned (parallel or antiparallel) interplanetary magnetic field (IMF) and solar wind flow vectors can be treated exactly in a magnetohydrodynamic (MHD) approach. In this work we examine a case of nearly-opposed (to within 15) interplanetary field and flow vectors, which occurred on October 24-25, 2001 during passage of the last interplanetary coronal mass ejection in an ejecta merger. Interplanetary data are from the ACE spacecraft. Simultaneously Wind was crossing the near-Earth (X similar to -13 Re) geomagnetic tail and subsequently made an approximately 5-hour-long magnetosheath crossing close to the ecliptic plane (Z = -0.7 Re). Geomagnetic activity was returning steadily to quiet, "ground" conditions. We first compare the predictions of the Spreiter and Rizzi theory with the Wind magnetosheath observations and find fair agreement, in particular as regards the proportionality of the magnetic field strength and the product of the plasma density and bulk speed. We then carry out a small-perturbation analysis of the Spreiter and Rizzi solution to account for the small IMF components perpendicular to the flow vector. The resulting expression is compared to the time series of the observations and satisfactory agreement is obtained. We also present and discuss observations in the dawnside boundary layer of pulsed, high-speed (v similar to 600 km/s) flows exceeding the solar wind flow speeds. We examine various generating mechanisms and suggest that the most likely cause is a wave of frequency 3.2 mHz excited at the inner edge of the boundary layer by the Kelvin-Helmholtz instability.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Torbert, R.B.; Biernat, H.K.; Gratton, F.T.; Szabo, A.; Kucharek, H.; Matsui, H.; Lin, R.P.; Ogilvie, K.W.; Lepping, R.P.; Smith, C.W.

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 2008. - Vol. 113. - Ст. A00B01, DOI 10.1029/2007JA012953. - Cited References: 38 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: We identify a planar, pressure-balanced structure bounded by sharp changes in the dynamic pressure plastered against the front boundary of the magnetic cloud which passed Earth on 20 November 2003. The front boundary of the magnetic cloud (MC) is particularly well-defined in this case, being located where the He(++)/H(+) number density ratio jumps from 4 to 10% for the first time and the proton plasma beta decreases sharply from similar to 1 to similar to 0.001. The feature, estimated to have a length scale similar to 50 RE in the Sun-Earth direction, bears close resemblance to a slow mode transition region in that the magnetic pressure decreases, the plasma pressure increases, and their temporal variations are anticorrelated. Using a 2-D MHD simulation, we hypothesize that a pressure-balanced structure was encountered by the MC en route to Earth. Our calculations reproduce qualitatively the major features of the observations. Using a simplified geometry suggested by the observations, we find that the lateral deflection speed of the plasma is less than the lateral expansion speed of the MC. We infer that the structure traversed the MC sheath in similar to 20 h, consistent with its crossing of the MC's shock at 0.6-0.7 AU. The finding is consistent with the recent paradigm according to which solar wind plasma and magnetic field tend to pile up in front of interplanetary ejecta because the expansion of the ejecta hinders the shocked solar wind plasma from deflecting effectively around the object. Also, the inferred "age'' of the layer contiguous to the surface of the MC, the earliest relic of its passage through the inner heliosphere, is in agreement with general estimates.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Taubenschuss, U.; Shaidurov, V.A.; Smith, C.W.; Biernat, H.K.

[Text] / U. V. Amerstorfer [et al.] // Planet Space Sci. - 2007. - Vol. 55, Is. 12. - P1811-1816, DOI 10.1016/j.pss.2007.01.015. - Cited References: 20 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: In this paper, the Kelvin-Helmholtz instability is studied by solving the ideal MHD equations for a compressible plasma. A transition layer of finite thickness between two plasmas, across which the magnitude of the velocity and the density change, is assumed. Growth rates are presented for the transverse case, i.e., the flow velocity is perpendicular to the magnetic field. If only the velocity changes across the boundary layer and the density is kept constant, an important quantity affecting the growth of the Kelvin-Helmholtz instability is the magnetosonic Mach number, which characterizes compressibility. The growth rates for the case when both, the velocity and the density, change are very sensitive to the ratio of the upper plasma density to the lower plasma density: a decrease of the density ratio yields a decrease of the growth rate. Including a density profile is very important for the application of the Kelvin-Helmholtz instability to the solar wind flow around unmagnetized planets, e.g., Venus, where the plasma density increases from the magnetosheath to the ionosphere. (C) 2007 Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Amerstorfer, U.V.; Erkaev, N.V.; Еркаев, Николай Васильевич; Langmayr, D.; Biernat, H.K.

[Text] / T. Penz [et al.] // Planet Space Sci. - 2004. - Vol. 52, Is. 13. - P1157-1167, DOI 10.1016/j.pss.2004.06.001. - Cited References: 53 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: Mars Global Surveyor detected cold electrons above the Martian ionopause, which can be interpreted as detached ionospheric plasma clouds. Similar observations by the Pioneer Venus Orbiter electron temperature probe showed also extreme spatial irregularities of electrons in the form of plasma clouds on Venus, which were explained by the occurrence of the Kelvin-Helmholtz instability. Therefore, we suggest that the Kelvin-Helmholtz instability may also detach ionospheric plasma clouds on Mars. We investigate the instability growth rate at the Martian ionopause resulting from the flow of the solar wind for the case where the interplanetary magnetic field is oriented normal to the flow direction. Since the velocity shear near the subsolar point is very small, this area is stable with respect to the Kelvin-Helmholtz instability. We found that the highest flow velocities are reached at the equatorial flanks near the terminator plane, while the maximum plasma density in the terminator plane appears at the polar areas. By comparing the instability growth rate with the magnetic barrier formation time, we found that the instability can evolve into a non-linear stage at the whole terminator plane but preferably at the equatorial flanks. Escape rates of O+ ions due to detached plasma clouds in the order of about 2 x 10(23)-3 x 10(24) s(-1) are found. Thus, atmospheric loss caused by the Kelvin-Helmholtz instability should be comparable with other non-thermal loss processes. Further, we discuss our results in view of the expected observations of heavy ion loss rates by ASPERA-3 on board of Mars Express. (C) 2004 Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Penz, T.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Lammer, H.; Amerstorfer, U.V.; Gunell, H.; Kallio, E.; Barabash, S.; Orsini, S.; Milillo, A.; Baumjohann, W.

[Text] / S. Muhlbachler [et al.] // COMPARATIVE RECONNECTION STUDIES AT THE SUN AND IN PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2002. - Vol. 29: D0 1-E3 1 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assmbly (JUL, 2000, WARSAW, POLAND), Is. 7. - P1113-1118, DOI 10.1016/S0273-1177(02)00033-9. - Cited References: 14 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Magnetic reconnection is a process which allows topological different magnetic fields to interconnect. Thus, in magnetospheric context, reconnection is strongly associated with substorm phenomena. Because many observations show a difference between the pressure parallel and perpendicular to the magnetic field, it is reasonable to study the reconnection mechanism for the set of equations, involving a pressure tensor. Existing theoretical work for isotropic weak reconnection is extended for anisotropic theory. In particular, the reconnection associated discontinuities as the Alfven discontinuity, the slow shock, and the contact discontinuity are generalized for anisotropic pressure. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Muhlbachler, S.; Biernat, H.K.; Semenov, V.S.; Farrugia, C.J.; Vogl, D.F.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / D. F. Vogl [et al.] // PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE BV, 2001. - Vol. 28: D3 1/C3 3 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assembly (JUL, 2000, WARSAW, POLAND), Is. 6. - P851-856, DOI 10.1016/S0273-1177(01)00503-8. - Cited References: 12 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: In this paper we report on the variations of the magnetic field strength and the plasma parameters across a fast shock as functions of upstream Alfven Mach numbers and pressure anisotropy downstream of the shock. In our study we consider an oblique shock where the angle between the magnetic field vector and the normal vector upstream of the shock is chosen to be 45degrees. We further use two threshold conditions of plasma instabilities as additional equations to bound the range of the pressure anisotropy, p(perpendicular to)/p(\\), i.e., the criterion of the mirror instability and that of the fire-hose instability. We found that the variations of the parallel pressure, the parallel temperature, as well as the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock, whereas the variations of the plasma density, the normal velocity, the magnetic field strength, and perpendicular pressure and temperature with respect to the magnetic field show much less pronounced dependence on the anisotropy. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Vogl, D.F.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Muhlbachler, S.; Farrugia, C.J.

[Text] / C. J. Farrugia, N. V. Erkaev, H. K. Biernat // J. Geophys. Res-Space Phys. - 2000. - Vol. 105, Is. A1. - P115-127, DOI 10.1029/1999JA900350. - Cited References: 26 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: We apply our recent three-dimensional anisotropic MHD model of magnetosheath flow [Erkaev et al., 1999] to study quantitatively effects of solar wind dynamic pressure (P-d infinity) and Alfven Mach number (M-a infinity) on the anisotropic magnetosheath and the plasma depletion layer (PDL) in the subsolar region. Given the wide range over which these two parameters vary, their influence on the magnetosheath structure may be significant. Our analysis is applicable to quasisteady changes in the interplanetary medium. Following our earlier work; and in general agreement with the data, we define the sunward edge of the PDL by beta(parallel to) = 1, where pll is the proton beta parallel to the magnetic field. We first discuss changes in P-d infinity occurring under constant M-a infinity. In this case, a rescaling of the parameters yields the effects on the magnetosheath. We then study quantitatively a changing dynamic pressure through a varying Alfven Mach number. We obtain profiles of key magnetosheath parameters and the width of the PDL for Alfven Mach numbers representative of the solar wind at Earth orbit. Gradients in parameter profiles become steeper and shift toward the magnetopause as M-a infinity increases. We find that PDL width varies as 1/M-a infinity(2) even in the anisotropic magnetosheath. Using our model to study the magnetosheath location where the electromagnetic ion cyclotron wave (EICW) instability dominates over the mirror instability, we find that this location occurs well inside the PDL. In addition, we estimated the fraction of the PDL width occupied by the EICWs as a function of solar wind Alfven Mach number. We conclude that the EICW regime is contained in, but is not co-extensive with, the PDL. Examining critically this issue by changing the PDL identification criterion to others based on a density decrease relative to the bow shock value and a systematic drop toward the magnetopause, we find that this result still holds, but the region where EICWs are destabilized occupies a different fraction of the PDL thus defined. Some model results are compared with documented data from an inbound crossing of the magnetosheath made on December 24, 1994. Good agreement with model predictions are obtained.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.

[Text] / C. J. FARRUGIA [et al.] ; ed. H. K. BIERNAT // MAGNETOSHEATH. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON PRESS LTD, 1994. - Vol. 14: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission D of the COSPAR 29th Plenary Meeting (AUG 28-SEP 05, 1992, WASHINGTON, DC), Is. 7. - P105-110, DOI 10.1016/0273-1177(94)90055-8. - Cited References: 15 . - ISBN 0273-1177. - ISBN 0-08-042484-8РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We present magnetic field and particle (protons and electrons) observations in the sheath region behind an interplanetary shock driven by a magnetic cloud, and in the magnetic cloud itself. We also discuss observations in the dayside terrestrial magnetosheath during cloud passage. We find that the region ahead of the cloud is in pressure balance. Further, throughout its extent ( 0.06 AU), the magnetic field strength is anticorrelated with the plasma density, with the latter decreasing steadily as the cloud is approached. This behaviour is indicative of magnetic forces influencing the Row topology and highlights a large-scale breakdown of predictions based solely on gas dynamical considerations. We also study density stuctures inside the cloud which result in an undulating dynamic pressure being applied to the magnetopause causing it to oscillate with amplitudes of similar to 1 similar to 3 Re and period similar to 2h.


Доп.точки доступа:
FARRUGIA, C.J.; FITZENREITER, R.J.; BURLAGA, L.F.; Erkaev, N.V.; Еркаев, Николай Васильевич; OSHEROVICH, V.A.; BIERNAT, H.K.; FAZAKERLEY, A.; BIERNAT, H.K. \ed.\

[Текст] / V. S. SEMENOV, N. V. ERKAEV, M. F. HEYN // Geomagn. Aeron. - 1991. - Vol. 31, Is. 2. - С. 233-239. - Cited References: 11 . - ISSN 0016-7940РУБ Geochemistry & Geophysics



Доп.точки доступа:
SEMENOV, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; HEYN, M.F.

[Text] / N. V. Erkaev [et al.] // Geophys. Res. Lett. - 2011. - Vol. 38. - Ст. L01104, DOI 10.1029/2010GL045998. - Cited References: 20. - This work was done while N.V.E. was on a research visit to the Space Science Center of UNH. This work is supported by RFBR grant N 09-05-91000-ANF_a and also by the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under project I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. Work by C.J.F. was supported by NASA grants NNX10AQ29G and NNX08AD11G. . - ISSN 0094-8276РУБ Geosciences, Multidisciplinary

Аннотация: We study the acceleration of magnetosheath plasma using a semi-analytical magnetic string approach for a range of solar wind Alfven Mach numbers, M-A, between 2 and 20. We work with an IMF vector perpendicular to the solar wind velocity, V-sw, and pointing north. We do not invoke magnetic reconnection. Our results indicate that magnetosheath speeds can exceed the solar wind speed, and the ratio V/V-sw increases with decreasing M-A. Analyzing the dependence of this ratio on M-A, we find that for M-A = 2, maximum V/V-sw approximate to 1.6, and for M-A = 10-20, maximum V/V-sw varies from 1.21 to 1.13. Maximum speeds occur a few Earth radii (R-E) tailward of the dawn-dusk terminator. The thickness of the accelerated flow layer varies as M-A(-2). Taking the magnetopause subsolar distance as 10 R-E, we find typical values for the thickness of similar to 4 R-E for M-A = 3 and 0.35 R-E for M-A = 10. The physical mechanism is that of draping of the magnetic field lines around the magnetosphere, and the associated magnetic tension and total pressure gradient forces acting on the flow. For lower M-A the plasma depletion is stronger, and thus the acceleration produced by the pressure gradient is larger. An additional acceleration is produced by the magnetic tension, which is stronger for smaller M-A. At the dayside the pressure gradient and magnetic tension forces both act in the same direction. But tailward of the terminator the magnetic tension starts to act in the opposite direction to the pressure gradient. When the resulting force vanishes, the highest speed is attained. Citation: Erkaev, N. V., C. J. Farrugia, B. Harris, and H. K. Biernat (2011), On accelerated magnetosheath flows under northward IMF, Geophys. Res. Lett., 38, L01104, doi: 10.1029/2010GL045998.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Farrugia, C.J.; Harris, B.; Biernat, H.K.

[Text] / N. V. Erkaev [et al.] // J. Geophys. Res-Space Phys. - 2014. - Vol. 119, Is. 2. - P. 1121-1128, DOI 10.1002/2013JA019514. - Cited References: 23. - This work was done while NVE was on a research visit to the Space Science Center of UNH. This work is supported by RFBR grant N 12-05-00152-a and also by the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. Work by CJF was supported by NASA grants NNX10AQ29G and NNX13AP39G. NVE and CJF acknowledge 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. . - ISSN 2169-9380. - ISSN 2169-9402РУБ Astronomy & Astrophysics

Аннотация: We apply a semianalytic magnetohydrodynamic approach to describe effects in the nightside magnetosheath related to accelerated magnetosheath flows caused by the draping of interplanetary magnetic field (IMF). Assuming a northward IMF direction, we show the development of slow mode fronts in the far tail (tailward of approximately -60 RmE). We find that accelerated flows north and south of the equator start to converge toward lower latitudes. The ensuing plasma compression gives rise to slow mode waves in the equatorial region which, further down the tail, evolve into slow mode shocks. These fronts propagating along the magnetic field lines are characterized by sharp increases of plasma density, pressure, and temperature and a decrease in the magnetic field strength. The magnetic pressure exhibits an anticorrelation with the plasma pressure, but the total pressure is fairly constant across the fronts. The field-aligned plasma velocity component anticorrelates with the plasma density, while the perpendicular velocity component does not have sharp variations at the fronts. For northward IMF, these fronts appear near the equatorial region and then propagate to higher latitudes. This effect is not very sensitive to the particular shape of the magnetopause. Lowering the upstream Alfven Mach number increases the strength of the slow mode waves, which also develop closer to Earth. We predict that this effect can be observed by space probes skimming the far tail. Key Points Magnetic field lines drape around the magnetosphere The field line bend makes the flows converge in the far tail We show that these give rise to slow mode waves

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Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Farrugia, C.J.; Mezentsev, A.V.; Torbert, R.B.; Biernat, H.K.; RFBR [N 12-05-00152-a]; Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" [I 193-N16]; "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences; NASA [NNX10AQ29G, NNX13AP39G]; International Space Science Institute (ISSI, Switzerland)