High-Frequency Geomagnetic Fluctuations at Auroral Oval and Polar Cap

Rapid magnetic fluctuations are known to be closely linked to the high-latitude geomagnetic activity, in particular, to geomagnetic pulsations and subtorms. Increasing amount of commercial activity in the arctic regions requires better monitoring capability and improved understanding on the effects of geomagnetic hazards to infrastructure. In this study, we analyze rapid, 1-s fluctuations in Greenland. To measure high-frequency geomagnetic fluctuations in the auroral oval and polar cap, we use high time resolution data of 1 s from 12 stations covering a large latitudinal range of 64 to 84 quasi-dipole geomagnetic latitude (QDGMlat). We found out that the large magnetic field fluctuations exceeding 0.2 nT/s are observed 10–30% of the time in auroral oval latitudes, depending on the solar cycle phase and station location. The latitudinal differences are much larger in fluctuation coverage (fractional derivative rate, FDR) than in fluctuations amplitude (dH/dt). The highest |dH/dt| and FDRs at noon are observed at the northern stations from 72 to 84 QDGMlat, while in south Greenland from 72 to 65 QDGMlat, the highest |dH/dt| and FDRs are recorded at midnight. The largest differences in seasonal variation between noon and midnight are observed in the polar cap, where a summer increase is seen at noon and almost flat seasonal profile at midnight.