Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

V. D. Tereshchenko et al. 3. Results of measurements and analysis As the source of disturbances at the circumterrestrial environment the explosion on the nuclear submarine (NS) "Kursk" was considered. According to seismic data of the network of stations on 12 August 2000 there were two seismic events in Barents sea with coordinates 69.604°N and 37.160°E [Koper et al., 2001]. The first event was fixed at 7:28:27 UT with magnitude ML=2.2, the second was at 7:30:42 UT with magnitude ML = 4.2. The nature of the first event it was not possible to determine, but according to all attributes, the second event was a typical underwater explosion. By various estimations energy of the second explosion corresponded to 3-7 tons of trinitrotoluene (TNT). In Figure 1 altitude-temporal dependences of the amplitude of reflections of the ordinary wave and the electron concentration are shown during the explosion on the NS "Kursk". The radar of PGIKSC RAS was situated about 70 km from the place of the explosion. 7.00 7.25 7.50 7.75 8.00 UT.hrs Fig. 1. Amplitudes of radio echo and the electron concentration as functions of time and heights (vertical lines are the moments of seismic events). In the Figure wavy changes of considered parameters in the course of time are visible. Observable quasi-periodic processes can be caused by influence of a shock-acoustic wave (SAW). Time of distribution of the SAW up to the D region of the ionosphere is approximately equal to 4 minutes, and up to the E region it is about 6 minutes. Splashes in the amplitude of reflections are usually connected to amplification of intensity of heterogeneous structure of the electron density and increasing in the electron concentration. It is necessary to note, that there is a conformity of intensive reflections of the ordinary wave with a) the region of lower electron density (at 7:19-7:31 UT) and b) the region of increased electron concentration (at 7:45+7:48 UT). The prominent feature of the observable events was that they occurred during a strong magnetic storm with Kp = 7.7 and Dst = 197 nT (Figure 2). The analysis of time variations of the horizontal component of the geomagnetic field has shown, that, for 8 minutes before the first event, on the background of smooth reduction of the geomagnetic field two sharp increase of its amplitude by 70 and by 30 nT have taken place which have duration about 3 minutes each. The values of quasi­ periods of disturbances were 3-6 minutes. In Figure 3 the spectrograms received from the data of partial reflections for the concrete heights of 47.5 and 83.0 km are submitted. It can be seen, that ionospheric disturbances which have occurred before explosion are visible the most clearly at the height of 83 km. Interpretation of the signals is complicated, but the considered event, to all attributes, is typical one for starts of rockets or charged particles penetrations. For the model of the isothermal atmosphere of the Earth the border between sound and internal gravity waves (IGW) lays in the field of the periods about 5 minutes [Gossard and Hooke, 1978]. From results of observations (Figure 3) follows, that the explosion generated in the lower ionosphere the infrasonic fluctuations with the period about 3 minutes and the IGW with the period of 6 minutes. In Figure 4 variations of the total electron content (TEC) at the heights of 70-90 km in the mesosphere (the D region of the ionosphere) before considered events are shown. With the purpose of revelation of ionospheric response of the SAW, time series of the TEC were subjected to procedure of removal of a linear trend. It turned out, that the obtained pulse ionospheric disturbance could be characterized by the A'-shaped wave (compression with the subsequent exhaustion) with the periods of 8 and 16 minutes (Figures 4a, b). 120