Entry of heated solar wind plasma into the magnetosphere is examined using electron distributions measured by AMPTE UKS and HEOS 2. In particular, the angular structure of the electron distributions is studied within the transition region separating the magnetosheath from the inner magnetosphere. The measurements suggest that electrons in the outer part of the transition region originate in the magnetosheath, whilst the population closer to the Earth consists of electrons from the magnetosphere combined with an energized magnetosheath component. This energized component contains “counterstreaming” electrons, which are confined to directions closely parallel and antiparallel to the magnetic field direction. The possibilities, that the energization of the counterstreaming electrons is cumulatively gained from either waves, electric fields perpendicular to the magnetic field, or quasi‐Fermi acceleration, are discussed. It is not possible to identify the topology of the magnetic fields of the outer part of the region, but there is strong evidence that the inner part is on closed magnetic field lines, which map to the day side auroral zone. The outer part of the transition region is a plasma depletion/magnetic field compression layer. The structure of the transition region is similar to that surrounding flux transfer events, which leads to the deduction that the plasma and field signatures of flux transfer events may be the result of displacement of the transition region earthward. Cases where the displacement is such that the field maximum of the depletion/compression region is encountered may well explain “crater” flux transfer event signatures.

Schumann resonance oscillation detection is a complex procedure which requires customized and high-quality measurement systems. The primary objective of this work was to design and implement a stand-alone, portable, and low-cost receiver able to measure as much Schumann resonance harmonics as possible. Design, as well as detailed analysis of the efficient induction coil magnetic antenna and the low-noise amplifying-filtering chain, is presented. The detection system includes two coils back to back, resulting in a total coil length of 60 cm. The filtering and amplification chain exhibits an experimentally measured total passband gain equal to 112 dB at 10 Hz and as low as 2.88 nV/√Hz equivalent input noise. In order to validate the new portable ELF Schumann resonance detection and monitoring system, we took measurements at various spots "relatively" free from man-made electromagnetic pollution. Results have shown very clear Schumann resonance peaks for the first six modes with 10-min acquisition time.

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Abstract-In this paper, a cost-effective prototype data acquisition system specifically designed for Schumann resonance measurements and an adequate signal processing method are described in detail. The implemented system captures the magnetic component of the Schumann resonance signal, using a magnetic antenna, at much higher sampling rates than the Nyquist rate for efficient signal improvement. In order to obtain the characteristics of the individual resonances of the SR spectrum a new and efficient software was developed. The processing techniques used in this software are analyzed thoroughly in the following. Evaluation of system's performance and operation is realized using preliminary measurements taken in the region of Northwest Greece.