Abstract. High-velocity magnetotail flow bursts measured by the Geotail Low Energy Plasma experiment in the premidnight equatorial region between 10 and 15 RE have been compared with other magnetospheric phenomena. These bursts, typically characterized by earthward velocities approaching 1000 km/s and lasting for times of the order of 1 min, are associated with magnetotail dipolarizations and large magnetic field fluctuations. Using supporting measurements of the International Solar Terrestrial Physics program it is found that the flow bursts are closely associated with auroral brightenings, AKR onsets, geosynchronous particle injections, and ground magnetic activity. Flow bursts for which Polar UVI images are available showed auroral brightenings that developed near the footpoint Geotail field line. AKR intensifications usually accompanied the flow bursts in close time coincidence, whereas dispersionless geosynchronous particle injections tended to be delayed by 1-3 min. Since flow bursts often exhibit the earliest onsets of these various phenomena, it seems likely that this chain of events is initiated in the tail beyond 15 RE, presumably by magnetic reconnection. It is concluded that flow bursts are a fundamental magnetotail process of limited spacial extent that are important in energy and magnetic flux transport in the magnetosphere. Magnetotail flow bursts are intimately connected to auroral acceleration processes and AKR generation at several thousand kilometer altitude and a full explanation of substorms will have to explain this relationship.

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Abstract. A new kind of terrestrial continuum that appears to be generated inside the Earth's plasmasphere has been detected by the Geotail satellite at an orbital distance of 10 to 30 R E in the dayside and evening sectors of the magnetosphere. This previously undetected emission, which will be called "kilometric continuum," is found to consist of slowly drifting narrowband signals at a frequency of 100 to 800 kHz, corresponding to the plasma frequency inside the plasmasphere at an altitude extending down to only a few thousand kilometers in the topside equatorial region of the Earth's ionosphere. Unlike normal continuum, kilometric continuum is found to occur only near the magnetic equator, where it appears to be unrelated to magnetic activity and is emitted within a well-defined beam within only -10 ø of the magnetic equator.

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The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural 146 T. Ono et al. radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.