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This paper uses the plasma data from Cluster and TC-1 and geomagnetic data to study the geomagnetic signatures of current wedge produced by fast-flow braking in the plasma sheet. The three fast flows studied here occurred in a very quiet background and were accompanied by no (or weak) particle injections, thus avoiding the influences from other disturbances. All the geomagnetic signatures of a substorm current wedge can be found in geomagnetic signatures of a current system produced by the braking of fast flows, indicating that the fast flows can produce a complete current wedge which contains postmidnight downward and premidnight upward field-aligned currents, as well as a westward electrojet. The Pi2 precursors exist not only at high latitudes but also at midlatitudes. The starting times of midlatitude Pi2 precursors can be identified more precisely than those of high-latitude Pi2 precursors, providing a possible method to determine the starting time of fast flows in their source regions. The AL drop that a bursty bulk flow produces is proportional to its velocity and duration. In three cases, the AL drops are 200 nT, whether a substorm can be triggered depends mainly on the conditions of the braking regions before fast flows. The observations of solar wind before the three fast flows suggest that it is difficult for the fast flows to trigger a substorm when the interplanetary magnetic field Bz of solar wind is weakly southward.
Geomagnetic signatures of current wedge produced by fast flows in a plasma sheet / Jin-Bin Cao, Chunxiao Yan, Malcolm Dunlop, Henri Reme, Iannis Dandouras, Tielong Zhang, Dongmei Yang, Alexey Moiseyev, Stepan I. Solovyev, Z. Q. Wang, A. Leonoviche, N. Zolotukhina, and V. Mishin // Journal of Geophysical Research: Space Physics. – 1978. – 2010 (August), vol. 115, N 8. – P. A08205.
Analysis of the global magnetosphere-ionosphere response to solar wind dynamic pressure variations under the negative IMF Bz has been performed. It is shown that an increase in the dynamic pressure leads to a double response of the ionospheric currents and aurora, i.e. simultaneously (within the accuracy of 1 min) and ~5-7 min afterward. Thereby, the eastward and westward convective electrojets are enhanced in the evening and morning sectors respectively, followed by the intensification of the westward current in the near midnight and evening sectors. The intensification of the electrojets is followed by extension of the diffuse precipitation zone and its high latitude boundary movement to the pole and to the east in the midnight-to-morning sector. In our case, no poleward or westward extension of aurora before midnight is observed. The disturbance triggered by a dynamic pressure increase may be considered as a convection disturbance associated with reconstruction of the DP2 current system.
Magnetosphere-ionosphere response to magnetosphere compression by the solar wind / S. I. Solovyev, A. V. Moiseyev, K. Yumoto, M. Engebretson // Physics of auroral phenomena : proceedings of the 26th annual seminar, 25 - 28 February 2003. – 2003. – P. 41-44.
Moiseyev, A. V. Peculiarities of traveling convection vortices propagation: comparison with sudden geomagnetic impulse / A. V. Moiseyev, S. I. Solovyev, A. Du // Physics of auroral phenomena : proceedings of the 32nd annual seminar, Apatity, 3 – 6 March 2009. – 2010. – P. 75-78.
Evolution of geomagnetic perturbations and aurora dynamics during the strong magnetic storms events / S. I. Solovyev, R. N. Boroev, A. V. Moiseyev, A. Du, K. Yumoto // Physics of auroral phenomena : proceedings of the 32nd annual seminar, Apatity, 3 – 6 March 2009. – 2010. – P. 41-44.
The spatial evolution of vortex-like flow structures induced by a negative sudden impulse (SI-) is studied on the basis of SuperDARN King Salmon HF radar (KSR) with other ground and satellite data. A large dip in the solar wind density induced a fairly large SI- with a SYM-H amplitude of ~40 nT. The SI-induced ionospheric flow signatures in the evening sector (MLT ~ 19 h) were observed by KSR as a westward flow associated with the preliminary impulse (PI) followed by a more intense eastward flow with the main impulse (MI) in the sub-auroral region on the magnetic latitude ~60-70 deg, consistent with the local ground magnetic field observations. Following the first PI-MI flow sequence, KSR saw a second and possibly third sequence of flow variation which were much smaller in flow amplitude than the first pair but showed qualitatively very similar flow variations and latitudinal/longitudinal propagation characterististics/ These observations can be interpreted as aftershocks of the first PI-MI; the same sequence of vortices and field-aligned currents were generated and then drifted anti-sunward with the same mechanism, namely the pumping motion of dayside magnetosphere. These results are qualitatively consistent with predictions suggested by recent numerical simulations.
Evolution of negative SI-induced ionospheric flows observed by SuperDARN King Salmon HF radar / T. Hori, A. Shinbori, N. Nishitani, T. Kikuchi, S. Fujita, T. Nagatsuma, O. Troshichev, K. Yumoto, A. Moiseyev, and K. Seki // Journal of Geophysical Research: Space Physics. – 1978. – 2012 (December), vol. 117, N 12. – P. A12223. DOI: 10.1029/2012JA018093
By global geomagnetic observation data the variations of intensity and dynamics of auroral electrojets, low-latitude disturbances at latitudes ~10-55°, SYM-H and studied. It is shown that positive values of SYM-H and Dst or the decrease of their negative values correspond to the growth period of Pd. The enhancement of magnetic field depression at latitudes Ф'~10-30° with the maximum ∆H in the evening sector is observed at negative values of IMF Bz and is accompanied by the enhancement of auroral electrojets in all temporal sectors and their southward shift. The maximum values of Dst ~-400 nT correspondent to the most intensity of western (eastern) electrojet in the midnight (evening) sector with a current center at the lowest latitudes. The possible sources of Dst and SYM-H variations are discussed.
Dependence of High-Latitude and Low-Latitude Geomagnetic Disturbances on Solar Wind Parameters during the Magnetic Storm of November 7-8, 2004 / S. I. Solovyev, R. N. Boroyev, A. V. Moiseyev, A. Du, K. Yumoto // Solar Extreme Events Fundamental Science and Applied Aspects Nor-Amberd, Armenia 26-30 September 2005 : proceedings of the Second International Symposium / edited by A. Chilingarian and G. Karapetyan. − Erevan : Cosmic Ray Division, Alikhanyan Physics Institute, 2006. − P. 104-106.
The geomagnetic manifestation of sudden impulse (SI) caused by a sharp decrease of the solar wind dynamic pressure due to the plasma density reduction is considered. The observational data of the magnetometer world network have been analysed. The propagation velocities of the SI signal in the meridional direction by using data of the horizontal component of geomagnetic field in the high-latitude region have been calculated. It is found that at a sharp decrease of the solar wind density the meridional propagation of the SI signal is in the northern direction. In this case, on the day side the propagation velocity is constant but there is a tendency of its increasing in the MLT morning sector. It has been established that the meridional propagation velocity of the SI signal at a sharp decrease of the solar wind density depends on the geomagnetic latitude, i.e. with the rise of latitude the velocity in the auroral zone decreases and in the polar cap it increases.
High-latitude peculiarities of the geomagnetic SI impulse propagation meridional velocity during sharp decrease of solar wind density / G. A. Makarov, D. G. Baishev, A. V. Moiseyev, S. I. Solovyev, V. A. Pilipenko, M. J. Engebretson, K. Yumoto // Proceedings of the Fifth International Conference on Substorms : 16-20 May 2000 Congress Centre of the Arctic and Antarctic Research Institute, St. Petersburg, Russia. − Noordwijk, Netherlands : European Space Agency, 2000. − P. 523-526.
Specific features and development of Pi and Pm impulses at latitudes from the equator to the polar cap are studied. It is shown that formation of Pi and Pm impulses at high latitudes (Ф'=70°) is related to simultaneous intensifications of the westward and eastward currents on the dayside of the magnetosphere with a consequent shift of the eastward current to the pole. It leads to an increase of duration of Pi impulse with the growth of latitude. Inversion of Pi and Pm signs relative to the noon meridian takes place only at Ф'≈36-60°. At these latitudes the duration of Pi impulse also increases with growth of latitude, but the increase velocity is one order of magnitude larger than at Ф'=63-83°. The current system of SI impulse and possible reasons of Pi and Pm formation at different latitudes are discussed.
Moiseyev, A. V. Relation between the formation of preliminary and main SI impulses during a sharp compression of the magnetosphere by solar wind / A. V. Moiseyev, S. I. Solovyev, K. Yumoto // Physics of auroral phenomena : proceedings of the 25th annual seminar, Apatity, 26 February – 1 March 2002. – 2002. – P. 51-54.
Moiseyev, A. V. Characteristics of substorms stimulated by variations of the dynamic solar wind pressure and magnetospheric convection electric field / A. V. Moiseyev, S. I. Solovyev, K. Yumoto // Physics of auroral phenomena : proceedings of the 25th annual seminar, Apatity, 26 February – 1 March 2002. – 2002. – P. 29-32.
Geomagnetic sudden impulse characteristics in dependence of the IMF orientation / S. I. Solovyev, A. V. Moiseyev, M. Engebretson, K. Yumoto, A. Du // Physics of auroral phenomena : proceedings of the 29th annual seminar, Apatity, 27 February – 3 March 2006. – 2007. – P. 116-119.