Yuri I. Yermolaev

Magnetopause motion driven by interplanetary magnetic field variations

We use previously reported observations of hot flow anomalies (HFAs) and foreshock cavities to predict the characteristics of corresponding features in the dayside magnetosheath, at the magnetopause, and in the outer dayside magnetosphere. We compare these predictions with Interball 1, Magion 4, and GOES 8/GOES 9 observations of magneto-pause motion on the dusk flank of the magnetosphere from 1800 UT on January 17 to 0200 UT on January 18, 1996. As the model predicts, strong (factor of 2 or more) density enhancements bound regions of depressed magnetosheath densities and/or outward magnetopause displacements. During the most prominent event, the geosynchronous spacecraft observe an interval of depressed magnetospheric magnetic field strength bounded by two enhancements. Simultaneous Wind observations indicate that the intervals of depressed magnetosheath densities and outward magnetopause displacements correspond to periods in which the east/west (By) component of the interplanetary magnetic field (IMF) decreases to values near zero rather than to variations in the solar wind dynamic pressure, the north/south component of the IMF, or the IMF cone angle.

Large‐scale solar wind structures: occurrence rate and geoeffectiveness

Large‐scale phenomena in the solar wind are important elements of heliospheric physics and space weather. On the basis of the OMNI database of interplanetary measurements we identified large‐scale structures of solar wind (SW types) for all time intervals during 1976–2000. Our classification includes quasi—steady types: (1) Heliospheric current sheet (HCS), (2) Slow and (3) Fast SW streams, respectively, from closed and open magnetic field structures in the solar corona, and disturbed types: (4) Corotating interaction regions (CIR—compressed regions between slow and fast SW streams), (5) SHEATH (compressed regions ahead of MC/EJECTA) and (6) Magnetic cloud (MC) and (7) EJECTA as well as (8) direct and (9) reverse interplanetary shocks (see catalog on site ftp://ftp.iki.rssi.ru/pub/omni/ and paper [1] ). We discuss several preliminary results obtained with our catalog (see more details in http://www.iki.rssi.ru./people/yyermol_inf.html) including effects on the Space Weather.

Plasma populations in the magnetosphere during the passage of magnetic cloud on January 10–11, 1997: INTERBALL/tail probe observations

The INTERBALL/Tail Probe observations of several unusual features of the plasma populations in the Earths magnetosphere during the passage of the magnetic cloud on January 6–11, 1997 are presented. Interaction of high-pressure pulses on leading and trailing edges of the cloud with the magnetosphere resulted in its strong compression and large-scale motions of the geomagnetic tail. Several important consequences of this interaction were: (1) observations of the magnetopause position 6RE nearer to the Earth than on average; (2) a huge increase in the magnetosheath plasma density and temperature; and (3) oscillation of magnetospheric tail structures past the satellite. These observations are discussed and compared with several models.

Where are medium-scale solar-wind variations formed?

The locations are discussed where periodic variations in the solar-wind density are formed taking into account the observed antiphase variations in the proton and alpha-particle densities (Viall et al., 2009). Taking into consideration that alpha particles move faster than protons, we can state that the observed variations should be formed at distances larger than 0.02 AU from the observation point.Location of formation of periodic solar wind number density structures is discussed. Observation of proton and alpha anticorrelation in these structures [Viall et al., 2009] indicates that taking into account that bulk velocity of aplha-particles is higher than that of proton the place of formation for these structures should be located at distance less 0.002 AU from place of observation.