Труды сотрудников ИВМ СО РАН

[Text] : статья / M.Desroche [et al.] // J. Geophys. Res-Space Phys. - 2013. - Vol. 118, Is. 6. - P3087-3095, DOI 10.1002/jgra.50294. - Cited References: 43. - The authors thank Chris Arridge for initially suggesting this project. The authors are thankful to Adam Masters, Bob Ergun, Jack Gosling, Martin Goldman, and Dmitri Uzdensky for helpful discussions and guidance. This work was supported by NASA's NESSF program. N.V. Erkaev acknowledges support by the RFBR grant No 12-05-00152-a. . - 9. - ISSN 2169-9380РУБ Astronomy & Astrophysics

Аннотация: Using idealized models of the magnetosheath and magnetospheric magnetic fields, plasma densities, and plasma flow, we test for the steady state viability of processes mediating the interaction between the solar wind and the magnetosphere of Saturn. The magnetopause is modeled as an asymmetric paraboloid with a standoff distance of approximate to 25R(S). We test where on the magnetopause surface largescale reconnection may be affected by either a shear flow or diamagnetic drift due to a pressure gradient across the magnetopause boundary. We also test for the onset of the KelvinHelmholtz instability. We find that, for the solar wind and magnetosphere states considered, reconnection is inhibited on the dawn flank due to the large shear flows in this region. Additionally, most of the dawn and dusk equatorial region of the magnetopause is KelvinHelmholtz unstable, due to the presence of the dense magnetospheric plasma sheet and weak magnetic fields on either side of the magnetopause. This study is a followup to a previously published study of the solar wind interaction with Jupiter's magnetosphere.


Доп.точки доступа:
Desroche, M.; Bagenal, F.; Delamere, P.A.; Erkaev, N.V.; Еркаев, Николай Васильевич; NASA's NESSF program; RFBR [12-05-00152-a]

[Text] / B.Harris [et al.] // Ann. Geophys. - 2013. - Vol. 31, Is. 10. - P1779-1789, DOI 10.5194/angeo-31-1779-2013. - Cited References: 26. - Work at UNH is supported by NASA Grants NNX10AQ29G and NNX13AP39G. N. V. Erkaev is supported by grant No. 12-05-00152-a from the Russian Foundation of Basic Research. . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Acceleration of magnetosheath plasma resulting from the draping of the interplanetary magnetic field (IMF) around the magnetosphere can give rise to flow speeds that exceed that of the solar wind (V-SW) by up to similar to 60%. Three case event studies out of 34 identified events are described. We then present a statistical study of draping-related accelerations in the magnetosheath. Further, we compare the results with the recent theory of Erkaev et al. (2011, 2012). We present a methodology to help distinguish draping-related accelerations from those caused by magnetic reconnection. To rule out magnetopause reconnection at low latitudes, we focus mainly on the positive B-z phase during the passage of interplanetary coronal mass ejections (ICMEs), as tabulated in Richardson and Cane (2010) for 1997-2009, and adding other events from 2010. To avoid effects of high-latitude reconnection poleward of the cusp, we also consider spacecraft observations made at low magnetic latitudes. We study the effect of upstream Alfven Mach number (M-A) and magnetic local time (MLT) on the speed ratio V/V-SW. The comparison with theory is good. Namely, (i) flow speed ratios above unity occur behind the dawn-dusk terminator, (ii) those below unity occur on the dayside magnetosheath, and (iii) there is a good general agreement in the dependence of the V ratio on M-A.


Доп.точки доступа:
Harris, B.; Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Torbert, R.B.; NASA [NNX10AQ29G, NNX13AP39G]; Russian Foundation of Basic Research [12-05-00152-a]

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 1998. - Vol. 103, Is. A4. - P6703-6727DOI 10.1029/97JA03248. - Cited References: 39 . - РУБ Astronomy & Astrophysics

Аннотация: We present maximum growth rate charts of the Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities at the dayside magnetopause (MP), considering two orientations of the interplanetary magnetic field (IMF) (due north and 30 degrees west of north). We input parameters in the plasma depletion layer calculated from an MHD code. We study both a sharp MP transition and an MP with an attached boundary layer ("thin" and "thick" approximations, respectively). Our analysis applies to wavelengths (lambda) from similar to 2 x 10(3) km to less than or equal to 9 R-E. Thin model results are as follows: For a stationary MP and due north IMF, the off-noon, low-latitude MP is very low shear (less than or equal to 10 degrees) and is substantially KH active. With an IMF inclined to north, extremely low shear, KH-active regions are confined to two strips, one in each hemisphere, where short lambda perturbations are generated, which propagate as surface ripples on the high-latitude, duskside MP. For a sunward accelerating magnetopause and IMF north, a large part of the MP is unstable. With an inclined IMF, the KH+RT unstable strips are broader and growth rates are higher. Thick model results are as follows: For IMF due north and a stationary MP, the middle-to high-latitude MP is stable. At middle to low latitudes, the inner edge of the boundary layer (IEBL) is active, except fora 2-hour local time band on either side of noon. For the inclined IMF, the MP is stable for long lambda, with activity for short lambda confined to two strips, as before, with slightly reduced growth rates. For the IEBL, a clear dawn-dusk asymmetry in KH activity is evident. When the MP accelerates sunward and the IMF points north, we have to consider also the lambda of the perturbation. For short lambda, growth rates are enhanced with respect to stationarity at both the NIP and the IEBL. While there are extensive regions of negligible growth at the MP, the entire IEBL is RT + KH unstable. We give an example of a long lambda perturbation where both interfaces are coupled and oscillate together. Finally, for an inclined IMF, we have at the MP unstable strips which are wider and have higher growth rates. The IEBL, by contrast, is completely destabilized, with larger growth rates than under stationary conditions.

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Доп.точки доступа:
Farrugia, C.J.; Gratton, F.T.; Bender, L.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Quinn, J.M.; Torbert, R.B.; Denisenko, V.V.; Денисенко, Валерий Васильевич

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 1997. - Vol. 102, Is. A6. - P11315-11324DOI 10.1029/97JA00410. - Cited References: 29 . - РУБ Astronomy & Astrophysics

Аннотация: Together with the magnetic shear across the magnetopause, the solar wind Alfven Mach number, M-A infinity plays a central role in determining the structure of the magnetosheath. Recent theoretical modeling has shown, in particular, that as M-A infinity decreases, the region adjacent to the sunward side of the magnetopause where the interplanetary magnetic field (IMF) exerts a strong influence on the flow (i.e., the so-called ''plasma depletion layer''), is no longer confined to a thin layer similar to 0.3 Earth radii (R-E) thick but occupies an increasingly larger fraction of the magnetosheath. Furthermore, the model predicts the possibility of a plasma depletion layer for low M-A infinity, irrespective of the size of the magnetic shear at the magnetopause, In this paper we study three examples of low latitude ISEE 2 passes through the dayside magnetosheath near noon: December 3, 1979; October 5, 1979; and November 11, 1979, In all three examples, MA, was lower than normal. During the December 3 pass (which we treat qualitatively), we find evidence of a plasma depletion layer when the IMF was pointing south, On the other two passes (which we study quantitatively), the interplanetary magnetic field was strongly northward pointing, leading to low magnetic shear at the respective magnetopause crossings, The October 5 pass was under steady interplanetary conditions and we find good agreement between theory and data, Temporal variations of the interplanetary medium during the November 11 pass necessitated an extension of the steady state theory to encompass piecewise steady (on average) interplanetary conditions, Better agreement with the data results when the theory is extended further to correct the total pressure at the sunward side of the magnetopause by integrating the magnetic tension term across the layer. For wide plasma depletion layers, this correction can be substantial.


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

[Текст] / N. V. ERKAEV, A. V. STOLYAROV // Geomagn. Aeron. - 1994. - Vol. 34, Is. 1. - С. 30-35. - Cited References: 9 . - ISSN 0016-7940РУБ Geochemistry & Geophysics



Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; STOLYAROV, A.V.

[Текст] / N. V. ERKAEV // Geomagn. Aeron. - 1991. - Vol. 31, Is. 3. - С. 528-531. - Cited References: 15 . - ISSN 0016-7940РУБ Geochemistry & Geophysics



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

[Text] / N. V. Erkaev [et al.] // J. Geophys. Res-Space Phys. - 2009. - Vol. 114. - Ст. A03206, DOI 10.1029/2008JA013728. - Cited References: 24. - We thank V. Sergeev for fruitful discussions and help in the preparation of the manuscript. This work is supported by RFBR grants N 07-05-00776-a, N 07-05-00135, by programs 2.16 and 16.3 of RAS, and by project P20341-N16 from the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung,'' and also by project I.2/04 from "Osterreichischer Austauschdienst.'' . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: A new kind of magnetohydrodynamic waves is analyzed for a current sheet in the presence of a small normal magnetic field component (B-z) varying along the sheet. For the initial undisturbed state, a simplified model of the current sheet is considered with a Harris-like current density distribution across the sheet. Within the framework of this model, an analytical solution is obtained for the flapping-type wave oscillations and instability, related to the gradient of the normal magnetic field component along the current sheet. The flapping wave frequency is found to be a function of the wave number, which has an asymptotic saturation for large wave numbers. This frequency is pure real in a stable situation for the magnetotail current sheet, when the Bz component increases toward Earth. The current sheet becomes unstable in some regions, where the Bz component decreases locally toward Earth. In the stable region, the "kink''-like wave oscillations are calculated for an initial Gaussian perturbation localized to the center of the current sheet. The flapping wave propagations are analyzed for two cases: (1) the initial perturbation is fixed, and (2) the source is moving toward Earth. In the last case, the Mach cone is obtained for the propagating flapping waves. The source for the flapping waves is associated with the fast plasma flow originated from the reconnection region.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Kubyshkin, I.V.; Kubyshkina, M.V.; Biernat, H.K.; RFBR [N 07-05-00776-a, N 07-05-00135]; Austrian "Fonds zur Forderung der wissenschaftlichen Forschung,'' [P20341-N16]

[Text] / N. V. Erkaev [et al.] // Ann. Geophys. - 2009. - Vol. 27, Is. 1. - P417-425. - Cited References: 24. - We thank V. Sergeev for fruitful discussions and help in preparation of the manuscript. This work is supported by RFBR grants N07-05-00776-a, N 07-05-00135, by SFU grant N 10, by Programs 2.16 and 16.3 of RAS, and by project P20341-N16 from the Austrian " Fonds zur Forderung der wissenschaftlichen Forschung", and also by project I.2/04 from "Osterreichischer Austauschdienst". . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: One-fluid ideal MHD model is applied for description of current sheet flapping disturbances appearing due to a gradient of the normal magnetic field component. The wave modes are studied which are associated to the flapping waves observed in the Earth's magnetotail current sheet. In a linear approximation, solutions are obtained for model profiles of the electric current and plasma densities across the current sheet, which are described by hyperbolic functions. The flapping eigenfrequency is found as a function of wave number. For the Earth's magnetotail conditions, the estimated wave group speed is of the order of a few tens kilometers per second. The current sheet can be stable or unstable in dependence on the direction of the gradient of the normal magnetic field component. The obtained dispersion function is used for calculation of the flapping wave disturbances, which are produced by the given initial Gaussian perturbation at the center of the current sheet and propagating towards the flanks. The propagating flapping pulse has a smooth leading front, and a small scale oscillating trailing front, because the short wave oscillations propagate much slower than the long wave ones.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Kubyshkin, I.V.; Kubyshkina, M.V.; Biernat, H.K.; RFBR [N07-05-00776-a, N 07-05-00135]; SFU [N 10]; RAS [2.16, 16.3]; Austrian " Fonds zur Forderung der wissenschaftlichen Forschung" [P20341-N16]; Osterreichischer Austauschdienst [I.2/04]