The magnetospheric response to 8‐minute period strong‐amplitude upstream pressure variations

Abstract

This paper documents a series of brief, strong (Δp/p = 1), dynamic pressure oscillations that occurred in the region upstream of the Earth's bow shock during a period of radial interplanetary magnetic field (IMF). The analyzed set of oscillations, which may be either intrinsic solar wind or bow shock‐related phenomena, recur approximately every 8–10 min, and their magnetic field signatures occur nearly simultaneously over great distances transverse to the Earth‐Sun line. The pressure oscillations appear to drive tailward‐moving magnetopause surface wavelets. In turn, the surface wavelets can be identified as hydromagnetic waves with strong compressional components in the outer magnetosphere and as quasi‐periodic variations in electron precipitation and high‐latitude ground pulsations. We use observations by spacecraft in the outer dayside magnetosphere to predict geosynchronous and subsolar magnetic field strengths, the location of the subsolar magnetopause, the solar wind dynamic pressure, and variations in the energetic magnetospheric ion flux.

Comprehensive study of the magnetospheric response to a hot flow anomaly

“…When the transient density and dynamic pressure increases and decreases strike the magnetopause, they launch fast compression and rarefaction waves deep into the magnetosphere [e.g., Sibeck et al, 1989]. We should be able to use geosynchronous GOES-8 spacecraft magnetic field observations [Singer et al, 1996] to identify these waves and confirm the magnetopause motion.…”

Motion of flux transfer events: a test of the Cooling model

“…Sibeck et al, 1989;Lanzerotti, 1989;Sibeck, 1990;Elphic, 1990;Sckopke, 1991;Lockwood, 1991;Sibeck, 1992;Smith and Owen, 1992;Kawano et al, 1992;Elphic et al, 1994;Song et al, 1994Song et al, , 1996Newell, 1995, 1996;Sanny et al, 1996). In the context of this debate, Kawano et al (1992) introduced a "characteristic time" (t char , defined as the time between the positive and negative peaks in the B N signature) to distinguish between longer events with bipolar B N signatures (t char >90 s) which were found to occur over a wide range of McIlwain L-shells and were not correlated to periods of reconnection as evidenced by AE index or southward interplanetary magnetic field (IMF), and shorter events (t char <90 s) which occurred nearer the magnetopause during periods of high AE index and southward IMF.…”

Investigation of ∼ 20–40 mHz ULF waves and their driving mechanisms in Mercury's dayside magnetosphere

“…Dungey (1954) introduced the idea that certain ULF waves detected in the terrestrial magnetosphere could be standing Alfvén waves on geomagnetic field lines referred to as field line resonances (FLRs). Different internal and external driving mechanisms, such as resonance with energetic particle populations (e.g., Southwood et al, 1969), pressure fluctuations in the solar wind (e.g., Sibeck et al, 1989) or the Kelvin-Helmholtz instability (KHI) (e.g., Dungey and Southwood, 1970), have been proposed. In particular, terrestrial toroidal-mode Pc 5 pulsations have been proposed to likely be driven by the KHI (e.g., Samson et al, 1971).…”