Space Weather in Magnetic Observatory Noise

Space weather impacts human activity by degrading satellite operation or disrupting electrical power grids. By exploiting small differences in the time stamp between magnetometer pairs to facilitate data filtering, we find that ground-based magnetic observatories are well suited to measure space weather phenomena, and in particular, high frequency fluctuations known as pulsations. Several of the world's consortium of INTERMAGNET observatories are used in the analyses. They show that pulsation amplitudes attain a maximum near local noon over diurnal periods. Long-term trends in pulsation amplitude correlate well with the solar cycle, with the greatest effect occurring during the waning part of the cycle when the derivative of the number of sunspots attains a maximum rate of decrease. Seasonal variability and total amplitude of the diurnal expression of pulsations depends on latitude. Our study highlights the utility of ground-based observatories to understand solar phenomena and suggests how INTERMAGNET data and protocol could be better tuned to monitor space weather.