Energetic Electron Precipitation Occurrence Rates Determined Using the Syowa East SuperDARN Radar

• Main Authors: Bland, Emma C., Partamies, Noora, Heino, Erkka, Yukimatu, Akira Sessai, Miyaoka, Hiroshi
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2021
• Subjects: Space Physics physics.space-ph; FOS Physical sciences; Syowa Station; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.48550/arxiv.2107.03185; https://arxiv.org/abs/2107.03185

We demonstrate that the Super Dual Auroral Radar Network (SuperDARN) radar at Syowa station, Antarctica, can be used to detect high frequency radio wave attenuation in the D region ionosphere during energetic electron precipitation (EEP) events. EEP-related attenuation is identified in the radar data as a sudden reduction in the backscatter power and background noise parameters.We focus initially on EEP associated with pulsating aurora and use images from a colocated all-sky camera as a validation data set for the radar-based EEP event detection method. Our results show that high-frequency attenuation that commences during periods of optical pulsating aurora typically continues for 2-4 hr after the camera stops imaging at dawn.We then use the radar data to determine EEP occurrence rates as a function of magnetic local time (MLT) using a database of 555 events detected in 2011. EEP occurrence rates are highest in the early morning sector and lowest at around 15:00-18:00 MLT. The postmidnight and morning sector occurrence rates exhibit significant seasonal variations, reaching approximately 50% in the winter and 15% in the summer, whereas no seasonal variations were observed in other MLT sectors. The mean event lifetime determined from the radar data was 2.25 hr, and 10% of events had lifetimes exceeding 5 hr.