We have continued investigation of waves in the regions of undisturbed solar wind, foreshock and magnetosheath. The analysis of ion flux and magnetic field variations with the time interval 1–240s was performed in the regions above. Very large variation in such a time interval can be considered the common feature of the foreshock and magnetosheath. The results of case and statistical studies showed that the level of relative variations of ion flux and magnetic field magnitude in foreshock is about 3 times larger than in undisturbed solar wind. Variations of these parameters in the magnetosheath topologically connected with the quasi-parallel bow shock are about two times larger than those behind the quasi-perpendicular. We also compared the results from Interball-1 data analysis with those from statistical analysis of cluster magnetic field measurements. The magnetic field variations obtained from the different satellite data coincide with each other very well not only in quality but also in quantity.

The results of comparison of the characteristics of sharp boundaries of small-scale and medium-scale solar wind structures in the case of their simultaneous observation on widely spaced spacecraft are described. It is shown that even very sharp boundaries, with duration of several seconds or fractions of a second, retain their amplitude and remain very sharp during solar wind propagation to distances of up to a million kilometers.

We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996–2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.

Solar wind parameters in the magnetosheath and foreshock fluctuate over time scales from less than one second to hours with amplitudes as high as 100%. We investigate such variations using ion flux and magnetic field measurements with 1 s time resolution from the Interball-1 spacecraft. WIND and Geotail spacecraft were used to monitor the unperturbed solar wind. Fast magnetosonic waves dominate in the foreshock region with correlation coefficients between the ion flux and magnetic field magnitude r(F/B) > 0.7. In the magnetosheath, the plasma flow is mainly turbulent and the character of the turbulence is strongly controlled by the angle ΘBn between the bow shock normal and the interplanetary magnetic field direction. Behind quasi-parallel bow shocks (ΘBn

This work reviews the characteristics of sharp (less than 10 min) and large (>0.5 × 108 cm−2 s−1) solar wind ion flux changes which are not due to shocks. These changes are boundaries of small‐ and middle‐scale solar wind plasma structures. We present examples and statistical results from simultaneous plasma and magnetic field measurements by Interball‐1 and Wind from 1996 to 1999. The behavior of the solar wind bulk velocity, temperature, and interplanetary magnetic field (IMF) during these changes is described. We show that in many cases pressure balance is not maintained across these structures and discuss possible implications. In 50% of the events the sharp boundaries are pressure balanced structures; these events are probably tangential discontinuities. We use multipoint measurements of the sharp discontinuities to determine the orientation of the plasma fronts; many fronts are at large angles to the solar wind flow direction. We show that these events can be geoeffective and produce sharp changes in the magnetic field at geosynchronous orbit and on the ground.

High time resolution data obtained by VDP and FM-31 instruments onboard INTERBALL-1 spacecraft were used to study the small-scale correlation between solar wind ion flux and magnetic field magnitude in the Earth's foreshock. Correlated quasi-harmonic structures were found simultaneously in ion flux and magnetic field data. Statistical analysis of these structures was done and a summary of obtained results is presented. Multipoint observations by INTERBALL-1 and MAGION-4 were used to estimate spatial correlation of small quasi-harmonic structures.

Based on simultaneous measurements of ion fluxes made onboard the closely separated satellites Interball-1and Magion-4, the propagation velocity of middle-scale plasma structures in the Earth's foreshock relative to the solar wind flow is estimated. The derived value of this velocity allows these structures to be identified as a fast magnetosonic wave propagating upstream of the solar wind inflowing the Earth's bow shock. An evaluation is also made of the correlation length of these disturbances in the plane perpendicular to the Sun–Earth line. This length is approximately equal to 2RE.

The velocity and correlation length of middle-scale (tens of seconds) plasma structures were estimated using the solar wind ion flux data obtained it the Earth's foreshock region by the pair of two closely separated spacecraft - INTERBAL-1 and MAGION-4. The velocity estimate allows us to identify these structures as fast magnetosonic waves propagating upstream from the Earth's bow shock, Middle-scale plasma structure correlation length in the plane perpendicular to the Sun-Earth line was also estimated to be approximately equal to 2 R-E.

Two points measurements of solar wind ion flux and interplanetary magnetic field obtained by INTERBALL-1 and MAGION-4 spacecraft in the Earth's foreshock on May 25, 1997 was used to estimate the propagation velocity and propagation direction of the small-scale quasi-harmonic structures.

Joint analysis of the data obtained by INTERBALL-1, its subsatellite Magion-4, IMP-8, WIND and GEOTAIL in solar wind, vicinity of bow shock, magnetosheath and magnetopause revealed a number of important features of the structures and variability of plasma in these regions (INTERBALL cusp studies are presented in paper by Sandahl. et al., in this volume). Different elements of the multiscale hierarchical chain of dynamical effects have been analyzed using the fortunate multispacecraft constellations at various separations. Experience gained from the examples of INTERBALL multiprobe studies might be useful for the more advanced CLUSTER-II 4-point measurements.

Based on the measurement data with a time resolution of 1/16 s conducted on the satellites Interball-1 and Magion-4, the problem of the existence in the region of the foreshock, in front of the Earth's bow shock, of correlated small-scale quasi-harmonic wave packets in the flux of the solar wind ions and in the interplanetary magnetic field is studied. We present the data of observations of a number of such structures and some results of their analysis.

High time resolution solar wind ion flux and interplanetary magnetic field measurements made by INTERBALL-1 satellite are used for the investigation of solar wind modifications in the foreshock region. High positive correlation (correlation coefficient is about 0.8) between ion flux and magnetic field fast variations with large amplitude inside the foreshock are found. Simultaneous observations by INTERBALL-1, GEOTAIL, IMP 8 and WIND near Earth’s bow shock allow us to estimate the motion of outer foreshock boundary. VOYAGER-1 data obtained during flyby near Jupiter are studied to compare Jupiter’s foreshock characteristics with near Earth’s ones.

We analyze solar wind mass flux data measured with the PROGNOZ 8 satellite. The temporal resolution of the data reaches 0.02 sec, such that also the range is probed where finite Larmor radius effects become increasingly important. We find a general tendency for steepening of the power spectra towards higher frequencies, similar to what is observed in spectra of magnetic field fluctuations. A significant peak is found near f=3.2 Hz in a high-resolution spectrum. Possible causes for this feature are discussed. Using the same data we also study the practical applicability of the wavelet transform as a tool for the analysis of non-stationary data with the emphasis on the search for transient spatial structures which are often not easily resolved using spectral analysis.