Toward the development of the SuperDARN receiver system with improved spatial and temporal resolution

The Super Dual Auroral Radar Network (SuperDARN) is a network of High-Frequency (HF) radars located at the high- and mid-latitude regions in both hemispheres. Among the total of 38 SuperDARN radars (as of July 2020), the Hokkaido Pair of (HOP) radars, consisting of Hokkaido East (2006-) and West (2014-) radars, are located at the lowest geomagnetic latitude and have been acquiring data with unique characteristics. After the operation of several years and data accumulation, it has been clear that sub-auroral and mid-latitude ionospheric phenomena, such as Sub-Auroral Polarization Streams (SPAS), sometimes have inner structures with a temporal scale of one to a few minutes, and that the standard temporal and spatial resolution of the present system is not sufficient to fully monitor two-dimensional characteristics of these phenomena. To solve the current difficulties, we have been developing a prototype (4-ch subset out of 20-ch array) of the SuperDARN imaging receiver system consisting mainly of USRP receiver units, which is attached to the SuperDARN Hokkaido East radar. Installation of the imaging receivers can significantly improve the spatial-temporal resolution of the radar data, and make it possible to monitor several phenomena such as SAPS wave structures, Pc3 pulsations and coseismic ionospheric disturbances, which have not been captured with sufficient spatial-temporal resolution with the preexisting receiver set. Details of the latest status of the development and scientific objectives are presented.