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Using Antarctic rockets S-310JA-4 and S-310JA-6 launched respectively on August 18 and August 27 in 1978,plasma waves in the MF and HF frequency range, i.e., from 0.1MHz to 10MHz have been observed in the polar ionospheric level up to 230km. Four categories of the plasma wave emissions are identified in consideration of the correlation with the energetic particles data. The first is the subsidiary emissions that are enhanced in the form of the ESCH (electrostatic electron cyclotron harmonic) waves due to the energetic electron beams in 2keV range; the emissions are generated in a regime of the nonlinear wave particle interactions because of the effective growth rate of the ESCH waves. The second is the ESLEC mode waves. The electrostatic plasma waves in the frequency range lower than the electron cyclotron frequency are called ESLEC mode waves in this paper; the generation of ESLEC mode wave is caused by the loss-cone type velocity distribution of the particles without any significant relationship to the electron beams in auroras. The third is the wide-band emission that can be attributed to the continuum emission emanating from the upper side of the ionosphere located below the rocket position; there still remains a possibility of the celestial radio waves arriving from the outside of the earth. The fourth is the leaked auroral kilometric radiation (AKR), propagating down towards the ionosphere in the form of the whistler mode waves. The waves have no one-to-one correspondency to the in situ observations of the precipitating particles, but the source is located in the region of the auroral particle accelerations where the AKR is generated.

A high-sensitive VLF wave observation has been carried out using the stratospheric balloon (B_-4N) launched from Esrange in Sweden on December 9,1982. The VLF receiving system installed on the balloon has been equipped with a large one-turn loop antenna attached along the balloon surface. During the level flight at an altitude of 30km, power line harmonic radiations and periodic emissions with the repetition period of about 2.7s have been observed in connection with the development of an auroral substorm. In this paper, spectral characteristics of these emissions are examined based on the dynamic spectral analysis in order to clarify the feature of the wave-particle interactions relating to the generation of these emissions.

In July 1985 a joint Japanese-Danish-Norwegian balloon campaign for auroral zone conjugate observations (AZCO) was carried out. The campaign was complementing measurements at Japanese geophysical stations in Iceland and in Antarctica. The instrumentation on the ground included magnetometers, riometers, and VLF detectors in both conjugate areas and also back-scatter radar and auroral monitors in the South. The balloons were equipped with detectors for X rays, electric fields, and VLF electromagnetic emissions. This report is preliminary as the data have not been reduced thoroughly yet. Information has been obtained about particle injection during substorms and the connection between ionospheric electric and magnetic fields.

Balloon observations of auroral X-rays using different detector systems were carried out twice over Esrange, Sweden, in November and December 1982,in order to examine spatial and temporal characteristics of the energetic component of auroral electrons. One detector is a telescope system consisting of four scintillation counters whose fields of view are different with each other as well as with the viewing directions. It is shown from the first flight carrying the telescope system that a limited illuminating region of auroral X-rays coincides with that of visual aurora. The other is the so-called pinhole camera and a shot of X-ray image detected by a thin NaI (T1) crystal is viewed by a microchannel plate photomultiplier tube (MCP PMT) with 4×4 anodes. The second flight was made for simultaneous observations by three kinds of payloads of the MCP PMT system, a subsidiary X-ray energy counter and a VLF wave receiver. The balloon did not encounter good activity of aurora enough for X-ray image-formings by the MCP PMT system during the ceiling flight, but the other two detectors revealed the first on-board evidence of the auroral X-ray event well associated with abrupt absorption of VLF emissions.

A balloon observation of auroral X-rays has been carried out by using two kinds of X-ray imagers, i.e., a newly developed imager with 5×5 matrix array of Si(Li) semiconductor detectors (SSD's) and another one with one-dimen-sional array of 8 NaI (Tl) scintillation counters. Each of these two imagers has a pinhole collimator, which gives a resolution angle of 15°at the central detector (counter). The lower limits of X-ray energy measurable are 37 and 22keV for the SSD and NaI(Tl) imagers, respectively. The balloon carrying these imagers was launched from Abelver, Norway at 2117 UT on July 5,1985 and was flown toward lceland. An enhancement of auroral X-ray flux was observed in the location of L=5.2 at ∿ 2334 MLT near the geomagnetic midnight, during a geomagnetic substorm. Temporal variation of two-dimensional auroral X-ray images was derived with 3 s time resolution from SSD imager data. Also, another imager of NaI(Tl) counters confirmed the SSD results. It is shown that a sequence of auroral X-ray images obtained by two imagers are not like a stable arc structure but a localized structure with a rapid time variation. The present results suggest that localized intermittent precipitations of energetic electrons with several tens keV or greater are possible.

The outline of lidar measurements which were made at Syowa Station (69°00'S, 39°35'E), Antarctica since March 1983 is described. Interesting topic was the enhancement of the stratospheric aerosol layer in winter. Coordinate measurements by the lidar and balloons were successfully done to clarify the early stage of the winter enhancement of the stratospheric aerosol layer.