Spectral width of F-region Syowa East SuperDARN echoes

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月15日（火） 国立極地研究所 2階大会議

Comparison of flow angle variations of E-region echo characteristics at VHF and HF

In this study, characteristics of the auroral E-region echoes at two significantly different radar frequencies of 12 and 50 MHz are compared. Considered observations were performed at the Syowa Antarctic station in March of 1997 using two HF and one VHF radars at various angles with respect to the magnetic L shells. The diurnal variation of echo occurrence was found to be similar at two frequencies and consistent with previous studies. On the other hand, variation of echo occurrence with L-shell angle φ was shown to be significantly different at two frequencies. 50-MHz echoes were detected preferentially along the L shell (dominating direction of the electrojet flow) while 12-MHz echoes were detected in a broad range of azimuths with the maximum in echo occurrence at φ=40-50°. By plotting the Doppler velocity versus L-shell angle, we demonstrate that 12-MHz echoes can be divided into two populations, the high- and low-velocity echoes. The high-velocity echoes were observed mostly along the L shells while the low-velocity echoes were observed at all directions. We also show that the echo populations exhibit different variation of the Doppler velocity with the L-shell angle. We argue that while the 50-MHz echoes are related to the Farley-Buneman and gradient drift plasma instabilities, the 12-MHz echoes can have additional sources, such as the thermo-diffusion instability and/or neutral wind-related plasma instabilities

Correction to: Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars (Progress in Earth and Planetary Science, (2019), 6, 1, (27), 10.1186/s40645-019-0270-5)

After publication of this article (Nishitani et al. 2019), it was brought to our attention that the figure 5 is incorrect, where the positions of DCE and SPS were misplaced. The correct figure 5 is as below, the original publication has been corrected