Combined Effect of Climatic Variations and Groundwater Movement on Observed Heat Flow

In most practical situations, the upper part of a geological section consists of loose sediments, in which heat transfer cannot be described as a purely conductive process. To investigate such situations a one-dimensional numerical model of terrestrial temperature field formation under the combined influence of vertical groundwater filtration and ground surface temperature changes has been developed. The model allows one to consider the perturbation of heat flow interval values resulting from short- and long-period temperature waves propagating into permeable rocks under conditions of advective heat transfer, caused by vertical groundwater filtration. The results show that temperature profiles and interval heat flow values are sensitive to both the paleoclimatic history and the rate of groundwater filtration. The latter plays the prevailing role in the variations of geothermal field parameters, especially within the uppermost part of the loose sediments in unconfined aquifers. The problem was solved for a permeable layer, underlaid by an impermeable layer. This schematisation of water exchange is the typically accepted for hydrogeological analysis. Even at very low rates of filtration the intensity of this effect is enhanced substantially for long-period variations. In the extreme case (for periods of temperature variations of the order of 100,000 years) at typical rates of filtration within the permeable layer, an almost gradient-free zone can be formed down to depths of a few hundred metres. For the case of upward filtration, on the contrary, the influence of climatic variations on the terrestrial temperature field becomes substantially attenuated.     

The role of solar wind pressure jumps in the initiation and control processes of magnetospheric substorms

By the example of commencement and development of two successive substorms on August 1, 1998, the mechanism resulting in the initiation of auroral processes (substorms) is discussed. These events were chosen due to the favorable position of satellites in the solar wind, magnetosphere, and plasma sheet, as well as due to the availability of satellite and ground-based observation data.     

Long-period geomagnetic pulsations caused by the solar wind negative pressure impulse on 22 March 1979 (CDAW-6)

An analysis is made of the long-period geomagnetic pulsations as recorded at seven Norilsk meridian stations ( = 162°, latitudinal range: 61°–71°N) following abrupt magnetospheric expansion during the storm of 22 March 1979 caused by a rapid decrease in solar wind density. As with the time interval following an abrupt contraction at the time of sudden storm commencement, there exist two types of pulsations in the pulsation spectra: latitude-independent (T>400 s) and latitude-dependent (T<200 s) pulsations. The first pulsation type is interpreted in terms of forced pulsations associated with magnetopause oscillations. The oscillation period is determined by plasma density in the boundary layer and by the radius of the magnetosphere (T ^1/2R⁴). The latitudinal dependence of the period, amplitude and polarization of the second-type pulsations is in agreement with the resonance mechanism of their origin.     

Spatial features of current systems of SFE-flares accompanied by gamma radiation

Based on statistical data and a detailed analysis of geomagnetic response to the hard electromagnetic radiation of the X17 solar flare of September 7, 2005, we considered spatial features of current systems producing the geomagnetic solar flare effect (SFE). During flares accompanied by intensive X-rays and gamma rays, SFEs are shown to be observed globally, including the night hemisphere and high latitudes. Cause-effect relations of phenomena under consideration are discussed.