High spatial resolution radar observations of ultralow frequency waves in the southern polar cap. Issue 5 (5th May 2016)

• Record Type: Journal Article
• Authors: Bland, Emma C.; McDonald, Andrew J.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 5(2016:May)
• Page Start: 4005
• Page End: 4016
• Publication Date: 2016-05-05
• Subjects: MHD waves -- SuperDARN; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA022235
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We present an analysis of ultralow frequency (ULF) waves detected in the southern polar cap using the Super Dual Auroral Radar Network (SuperDARN). These waves manifest as quasi‐sinusoidal oscillations in the Doppler velocity, which arise due to the oscillating ULF wave electric field in the F region ionosphere. The event reported in this study occurred during the southern polar winter under quiet geomagnetic conditions. The 1.1–1.3 mHz oscillations were observed throughout the polar cap by the McMurdo, Dome C East, and South Pole Station SuperDARN radars and also by the Dome Concordia and Scott Base magnetometers at corrected geomagnetic latitudes of ∼89°S and ∼80°S, respectively. In contrast to large‐scale toroidal field line resonances observed at auroral latitudes, we find that the magnetic perturbation vector of the polar cap oscillations did not undergo a 90° rotation upon transmission from the ionosphere to the ground and was instead rotated by about 30°. The polar cap oscillations were also accompanied by simultaneous field line resonance (FLR) activity in the dayside auroral zone, in the field of view of the Zhongshan SuperDARN radar. This FLR occurred at the same frequency and exhibited a similar azimuthal phase velocity to the polar cap oscillations, indicating that they may have been driven by the same source mechanism. Key Points: ULF waves have been detected in the southern polar cap using three SuperDARN radars and two ground‐based magnetometers Rotation of wave disturbance vector from ionosphere to ground only 30 degrees ULF oscillations accompanied by a field line resonance event in the dayside auroral oval and may be driven by the same source mechanism