Seasonal and diurnal dependences of Pc3 and Pc4 geomagnetic pulsation power at very high latitudes

Introduction In our studies [Chugunova et al., 2002,03,04] we found the occurrence of ULF waves in the nominal Рс3-4 band in the polar cap. About 15% of this ULF activity is constituted by quasi-monochromatic waves. Though the mechanism of these waves in the region with open field lines has not been found yet [e.g., Pilipenko et al., 2004], inthis study we try to examine statistically the seasonal and yearly variations of signals and noise in the Рс3 and Рс4range. The data of observations in Antarctica have been used, where there is practically no industrial electromagnetic interference