Abstrakt
In this study, the influence of interplanetary (IP) shocks detected by the Wind spacecraft on the wave intensity in the frequency range up to 20 kHz measured by the DEMETER spacecraft at altitudes of about 700 km is analyzed. Altogether, the analysis of 225 (87 fast forward, 31 fast reverse, 59 slow forward, and 48 slow reverse) shocks detected during 6.5 years of the DEMETER mission is presented.
At first, the variation of an overall geomagnetic activity around the time of the shock arrival is investigated using the superposed epoch analysis. The results demonstrate increase of the geomagnetic activity related to the shock occurrence.
The variation of wave intensity around the shock detection was investigated by two different techniques: i) using moving averages of the measured wave intensity, and ii) using principal component analysis. The obtained results indicate that the wave intensity variation depends strongly on the type of the shock, but it is typically limited to frequencies below about 10 kHz.