Variations of electrical characteristics of near-surface atmosphere of the Earth during magnetic storm

<p>Temporal variations of the electric field in near-surface layer of the Earth are determined by many factors, among which strong disturbances of the magnetic field should be especially noted. Magnetic storms cause an increase in the ionospheric electric field, which leads to variations in the gradient of the electric field potential near the Earth's surface. We consider the effect of magnetic storms in variations in the electrical characteristics of the atmosphere at Geophysical observatory «Mikhnevo» of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences and at Center for geophysical monitoring of Moscow of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences. We used data from the continuous monitoring of three components of the magnetic field, vertical components of the atmospheric electric field and atmospheric current carried out in fair weather. Experimental data processing and analysis show that accompanying magnetic storms with geomagnetic K index more or equal 5 increased variations in the electric field and vertical atmospheric current are characterized by different morphological structures. It is currently difficult to interpret the data. Nevertheless, the research results can be of great help in the development and verification of theoretical and computational models for generating variations in the electric field as a result of strong geomagnetic disturbances.</p>

Geomagnetic effect of earthquakes

Based on the results of instrumental observations carried out at a number of mid-latitude observatories of the INTERMAGNET network and at the Mikhnevo Geophysical Observatory of Institute of Geosphere Dynamics of Russian Academy of Sciences, it is shown that strong earthquakes are accompanied by increased variations of Earth’s magnetic field. In this case, the short-period stage (period ~ 0.5-0.8 min) and long-period stage (period ~ 5-20 min) of increased geomagnetic variations are clearly distinguished. The maximum amplitude of induced geomagnetic variations is 1.5-2 nT and 2- 4 nT, respectively, for short-period and long-period variations. A similar in morphology and almost synchronous nature of the induced geomagnetic disturbances at the observatories located at significantly different distances from the earthquake source is noted.