SuperDARN observation of ionospheric plasma flows associated with low-latitude auroras in Hokkaido, Japan

During periods of severe geomagnetic activity, auroras can be observed at much lower geomagnetic latitudes than the average auroral oval, e.g., lower than 40 degrees. Although several papers discussed the possible generation mechanisms for these auroras, their relationship with the ionospheric plasma convection pattern or the electric field distribution is not well understood, mainly because there are few observation data available.

The SuperDARN (SD) Hokkaido East and West radars, located at the lowest geomagnetic latitude among the SD radars at present, have been operating since 2006 and 2014, respectively, and observed ionospheric plasma convection patterns for three storm events in March 2015, November 2023, and December 2023, when low-latitude aurora was observed in Rikubetsu, Hokkaido, Japan (geomagnetic latitude: 37 degrees). Generally, the low-latitude auroral precipitation regions are accompanied by a shear of east-west ionospheric flows, although the detailed flow structure differs for each event. Some discussions and interpretations of these plasma flow patterns associated with the low-latitude auroras will be presented.