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

TL;DR

This study uses the Syowa East SuperDARN radar to detect energetic electron precipitation events via radio wave attenuation, analyzing their occurrence rates, seasonal variations, and durations in Antarctica.

Contribution

It introduces a radar-based method for detecting EEP events and provides the first statistical analysis of their occurrence rates and seasonal patterns in the Antarctic region.

Findings

EEP occurrence rates are highest in early morning MLT

Seasonal variation shows higher rates in winter

Mean EEP event lifetime is approximately 2.25 hours

Abstract

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.