3. Features of the Magnetic Storm

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[7]  Let us consider the character of the studied magnetic storm on 14-17 May 1997. From different sources of geophysical data available on through the Internet (SPIDR, SDAWeb, IDCE, Kyoto WDC C2, Sodankyla, etc.) one can find that the onset of the storm took place at 1600 UT on 14 May 1997 and it ended in the evening of 17 May 1997. So, by analyzing data of the IMP 8 satellite, a sharp increase of solar wind velocity (flow speed) from 300 km s^-1 to 500 km s^-1 occurs from 1600 UT (14 May 1997) till 0600 UT (15 May 1997), flux of protons with energy > 1 MeV for this period increases 5 times, and the average field magnitude of the IMF increases also 5 times (from 5 up to 25 nT). The Kp index grows from 1 to 7 for the considered period and the Dst index has a maximum at 1200 UT on 15 May 1997. In the evening of 17 May 1997 all mentioned parameters are near to the initial data before 1600 UT on 14 May 1997 again. One can see in Figures 1, 2, 3, 4, and 5 the corresponding variations of the parameters AE, B_z component and riometer absorption. For example, at 1700 UT on 14 May 1997 the B_z value (see Figure 1f) reaches the minimum negative value, the maximum of the AE index is reached at 1800 UT. Further, B_z minima are at 2000 UT on 14 May 1997; 0630 UT on 15 May 1997; 1100 UT on 15 May 1997; 1400 UT on 16 May 1997; 2300 UT on 16 May 1997 and approximately one hour later there are the AE maxima at: 2100 UT on 14 May 1997; 0730 UT on 15 May 1997; 1200 UT on 15 May 1997; 1500 UT on 16 May 1997 and 2400 UT on 16 May 1997. Such behavior of the B_z and AE indexes is classical [Rostoker et al., 1980]. From 0100 UT on 17 May 1997 B_z data are absent. Sharp growth of riometer absorption A (Figure 1d) occurs at 1700 UT on 14 May 1997. Further, absorption has moderate values (about A > 1 dB) till evening hours on 17 May 1997. The period from 0000 till 1600 UT for 14 May 1997 and the full day on 18 May 1997 (Figure 5) could be classified as slightly disturbed or nearly quiet because the AE indexes do not exceed 150-200 nT, values of the Kp indexes do not exceed 2 and the absorption A < 0.5 dB.