A Survey of large, rapid solar wind dynamic pressure changes observed by Interball-1 and IMP 8

P A Dalin,G N Zastenker,K I Paularena,J D Richardson

doi:10.5194/angeo-20-293-2002

P A Dalin, G N Zastenker + Show 2 more

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https://doi.org/10.5194/angeo-20-293-2002

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Journal: Annales Geophysicae	Publication Date: Mar 31, 2002
Citations: 30	License type: CC BY 3.0

Affiliation: Space Research Institute

Abstract

Abstract. The high time-resolution solar wind ion flux measurements from Interball-1 and IMP 8 show about one hundred large, rapid dynamic the pressure changes each year. We cataloged these events by the size and transition time of the pressure changes and present a statistical survey of these events. We find that the majority of the pressure changes of more than 1–2 nPa occur over a very short time period, on the order of a few minutes or less. Most of the large pressure changes not associated with shocks are due solely to density changes with speed remaining constant. We find that pressure balance between the thermal and magnetic pressures is not maintained across most of these events, so these events are still evolving.Key words. Interplanetary physics (solar wind plasma)

Highlights

Among the great variety of small-scale solar wind plasma structures, rapid and large increases and decreases in the plasma dynamic pressure are especially important because they can be very geoeffective.Several papers are devoted to observations of solar wind dynamic pressure pulses (Gosling et al, 1967; Shodhan et al, 1999) and their interaction with Earth’s magnetosphere (Sibeck et al, 1989; Borodkova et al, 1995; Sibeck et al, 1996)
For about two hundred selected events observed by Interball-1 and about one hundred events observed by IMP 8 we found the average pressure change was 4 nPa and the average value of the relative pressure change equaled 0.65
The most impressive feature of the large pressure changes is their short transition time; in about 50% of the studied events, the large change in the dynamic pressure takes less than 1 min In 10% of the cases, large changes in plasma pressure occurred in a few seconds

Summary

Introduction

Among the great variety of small-scale solar wind plasma structures, rapid and large increases and decreases in the plasma dynamic pressure are especially important because they can be very geoeffective.Several papers are devoted to observations of solar wind dynamic pressure pulses (Gosling et al, 1967; Shodhan et al, 1999) and their interaction with Earth’s magnetosphere (Sibeck et al, 1989; Borodkova et al, 1995; Sibeck et al, 1996). Dalin et al.: A Survey of large, rapid solar wind dynamic pressure changes observed by Interball-1 and IMP 8

Results

Conclusion