Magnetic Schumann Resonances in Swarm ASM Burst Mode, VFM HF and e-POP Data?

The Schumann Resonances (SR) consist of a series of peaks in spectral power in the magnetic and electric field at frequencies of around 8, 14, 22 and 27 Hz. They arise from the continuous occurrence of equatorial lightning strikes [1]. The broadband electromagnetic emission from each lightning strike is contained within a waveguide, bounded by the Earth’s surface and the ionosphere at around 80 km in altitude. The SR are detectable on the ground using sensitive search-coil magnetometers. They have a large Q-factor (i.e. broad peaks) and an obvious diurnal and seasonal variation due to the location of landmasses. Although, the electric field SR have been detected in space using the C/NOFS satellite in 2010/11 at altitudes of 600 km [2], there have been no confirmed measurements using magnetic field instruments. There are theoretical arguments that the ionosphere acts to fully shield the magnetic signal from penetrating out of the atmosphere to Swarm altitudes, though other models suggest some secondary signals occur [3].We examine data from the Swarm Absolute Scalar Magnetometer Burst Mode (250 Hz), the Swarm Vector Field Magnetometer High Resolution (50Hz) and enhanced Polar Outflow Probe (e-POP) Magnetic Field (160 Hz) instruments collected on the 19-Jan-2014 during the commissioning phase of the mission to look for SR signals.