  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.
