Interpretation in terms of gyrotropic waves of Schumann-resonance-like line emissions observed at Nakatsugawa in possible association with nearby Japanese earthquakes

The observation of ULF/ELF electromagnetic waves in the frequency range below 50 Hz has been continued at Nakatsugawa (in the Gifu prefecture), Japan since 1998. This paper summarizes anomalous Schumann resonance (SR) phenomena and SR-like line emissions observed at Nakatsugawa in possible association with recent nearby earthquakes (EQs) (the 2004 Mid-Niigata prefecture and the 2007 Noto-Hanto (peninsula) EQs), which have been already described in detail by Ohta et al. (2009). The intensity of particular modes of SR increased before these large EQs and the excitation of other anomalous SR-like line emissions also existed at the frequency shifted by about 2 Hz from the typical SR modes. Since temporal changes of the anomalous SR modes and line emissions are synchronous in time, there might be a possibility that the line emission is a consequence of the anomalous SR. In this paper we propose an interpretation of those anomalous phenomena in terms of excitation of gyrotropic waves due to input wave from below with a band from 15 to 20 Hz as an exciter. The theoretical computational results seem to be generally consistent with the observational finding.     

A New Way of Automated Dust Control of the External Atmosphere of a Spacecraft During Thermal-Vacuum Testing

Solar System Research - During ground-based thermal vacuum tests of spacecraft, it is necessary to control and monitor the change in dust content in closed and semiclosed hollows of the spacecraft,...     

Generation of VHF radio emissions by electric discharges in the lower atmosphere over a seismic region

Observational data of the seismic related VHF radio emissions at 41 and 53 MHz obtained at the four stations of Create Island are presented. The epicenter of EQs is located at the distance more than 300 km behind the horizon. It was shown that VHF radiation is generated at the altitudes 1–10 km in the atmosphere over the epicenter of EQs. The theory of generation of electromagnetic radiation by random electric discharges was developed. These discharges are excited by DC electric field enhanced up to the breakdown value in the atmosphere. The field is connected with the electric current flowing in the atmosphere–ionosphere circuit, whose source is generated by convective transport of charged aerosols, which are injected in the atmosphere by soil gases during the enhancement of seismicity. Calculations of the spectrum of electromagnetic radiation are derived, and the theoretical results are confirmed by observation data.