Solar Cycle Effects in Occurrence of SuperDARN Echoes at Various Latitudes

Abstract:

Frequent occurrence of ionospheric F region echoes is a critical factor for successful plasma flow monitoring with the SuperDARN HF radars. Several publications demonstrated that the rates of SuperDARN echo detection, both ionospheric echoes and ground scatter, changes as the solar cycle progresses. This study is a systematic investigation of echo occurrence rates for SuperDARN radars, from the midlatitude Hokkaido radar at the lowest geomagnetic latitude to the Dome-C East radar at the highest geomagnetic latitude, in the center of the southern polar cap. All available data collected by key radars between 1996 and 2019 are considered. Daytime and nighttime observations are considered separately. Differences and similarities between revealed long-term trends are emphasized. The extent to which the electron density in the ionosphere controls the solar cycle variations of both ionospheric echoes and ground scatter is discussed.