Simultaneous Observations of a Polar Cap Sporadic-E Layer by Twin Incoherent Scatter Radars at Resolute

At high latitudes, the Sporadic-E layer (Es layer) is a common phenomenon but is still poorly understood due to sparse measurements and the difficulty of conventional mechanisms to operate. In this study, an interesting case of polar cap Es layer is first studied by using the twin incoherent scatter radars (northward-looking face of Resolute Incoherent-Scatter Radar and Resolute Incoherent-Scatter Radar-Canada), a Canadian Advanced Digital Ionosonde, and a Magnetometer, all at Resolute, Canada. From several electron density profiles of the twin radars, the horizontal scale of the polar cap Es layer is found to be greater than 350 km. Moreover, the polar cap Es layer is determined to be drifting from the bottom F region (>150 km) to the lower E region. Furthermore, a unique appearance of double polar cap Es layers is observed. As a result, these peculiar signatures inspire a newly proposed process that involves the combination of localized electric fields and gravity waves.