Study of polar ionosphere and magnetosphere dynamics based on SuperDARN time series analysis technique

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In this study we upgraded the SuperDARN time series analysis technique [Yukimatu and Tsutsumi, 2002] by adding new capabilities to improve spatial resolutions, and also developed techniques to observe new targets such as meteors and polar mesosphere summer echoes.1.Two techniques to improve the range resolution were newly added to the SuperDARN operating software; frequency domain interferometer(FDI) and oversampling. These techniques were first applied to meteor echo observations and proved to be useful for the study of polar mesosphere dynamics. It is notable that this meteor observation can be conducted together with the existing SuperDARN F-region observation and does not affect it at all. Network observation of polar mesosphere region is now being sought. The FDI technique was further applied to CUTLASS SuperDARN radars (Iceland and Finland) to study the minute spatial and time characteristics of irregularities which were generated by the ionosphere heating facility located at Tromso.2.We started to develop a multi receiver imaging technique using Syowa station SuperDARN radars. A digital receiver was newly added to each of the 20 antenna outputs. Softwares to control these receivers are being developed to study fine structures of ionospheric echoes.3.Polar mesosphere summer echoes (PMSEs) were studied by developing algorithms to detect them from near range data. Using 15 SuperDARN radars in Arctic and Antarctic regions, the occurrence rates of PMSEs were found to be different between Arctic and Antarctic and also show higher values with increasing latitudes.