Upstream Wave Related Pc3 Pulsations Observed by the MM100 Meridional Magnetometer Array

The upstream waves (UWs) are typically 20-30 s magnetosonic waves generated in the Earth’s foreshock region. Under appropriate interplanetary conditions the UWs are able to enter the magnetosphere, propagate across field lines down to the ionosphere and reach the ground as Pc3 geomagnetic pulsations. In the past years, a semi-automated method was developed to monitor UW-related geomagnetic pulsation activity. The method was based on cross spectral density estimation of signals recorded at meridionally distributed stations or by satellites at LEO (CHAMP). The MM100 meridional array, including Finnish, Polish, Slovak and Hungarian observatories, was established in 2001. In the present pa