ON THE NONSTATIONARY PROCESSES IN GEOPHYSICAL MEDIA

In this methodological article we consider the effects that arise from the nonstationarity of the geospheres, namely, the magnetosphere, the atmosphere, and the lithosphere. The intensification of convection in the magnetosphere during the geomagnetic storm leads to the self-excitation of the electromagnetic ULF oscillations of the increasing frequency in the dusk sector. The paper gives a vivid example of observing oscillations of the increasing frequency at the mid-latitude Mondy station. It illustrates the exceptional complexity of nonstationary processes actually occurring in the magnetosphere. In the upper atmosphere (in the ionosphere), after the sunset, the source of ionization is turned off and the electron concentration begins to decrease. The nonstationarity of the medium consists in a monotonous decrease in the temperature of the atmosphere after the sunset, and it is manifested in the fact that the evolution of the electron density deviates noticeably from the prediction on the basis of a simple theory of recombination. This example is interesting in that it gives the key to understanding the known deviation of the aftershocks stream in the lithosphere from the simple Omori hyperbolic law. The marked analogy gives us an idea, firstly, to present the law in the form of a differential equation for the evolution of aftershocks and, secondly, gives us a non-trivial generalization of the Omori law, which takes into account the nonstationarity of the earthquake focus “cooling off” after the main shock. Methodologically, the above examples are supplemented by the hose MHD instability in the expanding solar corona, and the Jeans gravitational instability in the expanding Universe. The general conclusion is that it is necessary to carefully analyze the possible manifestations of the nonstationarity of the environment, even if the nonstationarity is smooth and, at first glance, is irrelevant.