Statistical characteristics of midlatitude ionospheric F-region
backscatter observed by the SuperDARN Jiamusi radar
Abstract
The Jiamusi (JME) radar is the first high-frequency coherent scatter
radar independently developed in China. In this study, we investigate
the statistical characteristics of the occurrence rate of F-region
ionospheric irregularities between 40°N and 65°N geomagnetic latitude by
using the Jiamusi radar data from March 2018 to November 2019. Diurnal
and seasonal variations in scattering echoes and their dependence on
geomagnetic conditions are statistically investigated. It is shown that
the local time of the peak echo occurrence rate varies depending on the
season, i.e., approximately 20-22.5 magnetic local time (MLT) in summer,
17.5-20.5 MLT in equinox, and 16-17.5 MLT in winter, which is closely
associated with the time of sunset. The echo occurrence rate also
increases with the enhancement of the geomagnetic index. To further
understand the mechanism of these features, we simulate the distribution
of the gradient drift instability indicator (∇n • V E /n) by using the
Thermosphere-Ionosphere-Electrodynamics General Circulation Model
(TIEGCM). The analysis results indicate that the gradient drift
instability is an important mechanism for irregularities in this region.
Key points: 1. Diurnal and seasonal variations in the scatter occurrence
rate and their dependence on Kp conditions are statistically analyzed.
2. The distribution of the gradient drift instability indicator (∇n • V
E /n) is simulated by using the TIEGCM. 3. The gradient drift
instability is an important mechanism for the high occurrence rate of
echoes in the midlatitude region.