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The 40th Japanese Antarctic Research Expedition (JARE-40) wintering party, with 40 members, has successfully conducted the third-year project of the Vth five-year JARE program, over the period from 1st February 1999 to 31st January 2000, at Syowa Station, Antarctica.The framework of the JARE-40 wintering party program was the same as those of JARE-38 and JARE-39, comprising three routine observation programs and project/monitoring research observation programs in upper atmospheric physics, atmospheric sciences and glaciology, geophysics, and biology. In addition to many continuing projects, several new observations were started: 50MHz/112MHz aurora radars and a VLF wave receiver as part of the ionosphere program, aerosol sonde observations of Polar Stratospheric Clouds (PSCs) as part of the meteorological program, HF/MF radars as part of the upper atmospheric physics program, frequent VLBI experiments as part of the geophysics program, and biological field surveys (including two dives), including monitoring of the undersea behavior of Weddell seals using bio-logging devices.In terms of inland field surveys, two parties were organized: fuel transportation and glaciological/meteorological observations along the route to Mizuho Station in August-September and to Dome Fuji/Yamato air-basecamp in November-January. These surveys involved snow sampling, precise GPS positioning, and sub-glacial surveys using three types of ice radar.Logistical activities, conducted in cooperation with the JARE-40 summer party, included the construction of a second summer lodge, the startup of a second 300 kVA generator and co-generator system, the development of a sewage plant, solar power panels, an access road to the A-heliport, and the cleanup of disused buildings. During the wintering period, efforts were directed towards the maintenance of all facilities at Syowa Station, safety management, and practical support for field operations.The Antarctic Environmental Protection Law came into force in January 1998. Since this time, the outdoor burning of all packaging materials has been restricted at Syowa Station; consequently, we sent a large amount of waste (136t, including 98t of large-size material) back to Japan onboard the RV Shirase.

The activities in the 2006-2007 austral summer of the 48th Japanese Antarctic Research Expedition (JARE-48) are reported. JARE-48 consisted of 62 personnel including 27 summer personnel and 35 wintering personnel. In addition, several observers joined to the voyage of Icebreaker Shirase (four Japanese), operation at Dome Fuji Station (two foreigners), Japan-Germany Collaborative Airborne Survey (eleven foreigners), and terrestrial observation around Syowa Station (three foreigners). Icebreaker Shirase arrived at the ice edge on 16 December 2006. She anchored at Syowa Station on 23 December and unloaded ca. 1000 t of cargo and fuel by mid-January 2007. Because weather in this season was extremely good, transportation and construction works at Syowa Station were going well. Biological, geodetic and geological field investigations and geophysical field station observations were carried out in the Ltzow-Holm Bay region. The JARE-48 summer party and JARE-47 wintering party on board Shirase left Syowa Station on 16 February. On the return voyage, oceanographic and marine biological observations, geomagnetism and other studies were carried out. All personnel disembarked at the Port of Sydney on 21 March. A 7-person special team (five summer and two wintering personnel) for the deep ice-drilling project took air transportation from Cape Town via Novolazarevskaya Station. The team met the traverse party of JARE-47 wintering team at ARP2 point on 3 December. They carried out ice drilling to a depth of 3025.22 m at Dome Fuji Station. The summer members of the drilling team arrived in Tokyo on 20 February. One summer personnel, who conducted the Japan-Germany Collaborative Airborne Survey, arrived to Neumayer Station on 8 December. He conducted the airbone survey in the vicinity of Neumayer Station, and moved to S17 on 6 January. The airbone survey was conducted above Ltzow-Holm Bay region. He arrived to Japan on 8 February.

To analyze characteristics of solar ultraviolet irradiance in the ozone hole region, solar ultraviolet-B (UV-B : 280-315nm) and ultraviolet-A (UV-A : 315-400nm) irradiance at noon were measured from October 4,1999 to January 31,2000 at Syowa Station in Antarctica (69°00′S, 39°35′E). UV-B irradiance measured at Syowa was compared with UV-B irradiance measured at Tokai University, in Hiratsuka, Kanagawa, Japan (35°21′N, 139°16′E). Maximum irradiance of the UV-B at Syowa was measured early in December 1999. It is equal to the maximum irradiance of UV-B measured in the middle of June 1999 and/or early in September 1999 at Hiratsuka. UV-B and UV-A irradiance at Syowa showed less scatter than that at Hiratsuka. This implies that the difference of scatter between irradiance at Syowa and at Hiratsuka may be attributed to the cloud types which appeared over both observation sites, providing different shielding effects of cloud types for UV irradiance. By eliminating the cloud effect by dividing UV-B irradiance by UV-A irradiance (UV-B/UV-A), a high negative correlation was obtained between UV-B/UV-A and the effective ozone amount. By applying this correlation, total ozone amount can be estimated by use of the values of UV-B/UV-A and air mass

To observe auroral X-ray images, the horizontal two-dimensional array of the Lithium-drifted Silicon Si(Li) detectors has been developed. The auroral X-ray imager has 5×5 pixels. The sensor element of one pixel is the 18×18mm area and 5mm thick Si(Li) detector. The Si(Li) detectors have such large noises at room temperature as to be unsuitable for X-ray measurements, but the noises become much smaller at -20℃. Then, X-ray measurements are fully possible at this low temperature. In observations by a stratospheric balloon, cooling of the semiconductor detectors is made by dissipating of heat to low temperature environment. The heat pipe has been used to cool the chamber containing the Si(Li) detectors. The energy range of auroral X-rays to be observed is from 37 to 200keV. The horizontal two-dimensional array of Si(Li) detectors is placed in a pinhole collimator. The angular resolution of the auroral X-ray imager is 15° at the center pixel. The full field of view of the imager is 62°. In July 1985,the balloon flight with this auroral X-ray imager has been performed in the northern auroral region.

Since 1984 the National Institute of Polar Research, the Institute of Space and Astronautical Science and collaborative scientists have conducted the long-term circumpolar balloon program that is called Polar Patrol Balloon (PPB) project, and they also have developed ballooning technologies for this program. This project aims at establishing a station network in the stratosphere over the Antarctic region for geophysical and astrophysical observations. Two test flight experiments that were performed by the 28th Japanese Antarctic Research Expedition (JARE) in 1987 have convinced us that PPB would come back to the launching area with a good possibility. During 1991 and 1993 (JARE-32-34) at Syowa Station. The PPB experiments will consequently be done for scientific researches. This brief paper reports unique advantages of PPB, specifications and expected trajectories of PPB, and planned scientific researches with PPB.

An observation of the plasma wave spectrum in a high frequency range from 0.1 to 10 MHz has been made using the ionospheric sounding rocket S-210JA-21, launched on July 26, 1976 from Syowa Station in Antarctica. Plasma wave emissions were observed in two frequency ranges ; the first range is from the UHR frequency to the Z-mode cut ofr frequency, and the second is a range lower than the electron cyclotron frequency. The center frequency of the first kind emissions indicates a variation corresponding to the local upper hybrid and to the electron plasma frequencies along the flight path of S-210JA-21, indicating an evidence that the emissions are produced in the ionosphere as a result of the wave-particle interaction due to the auroral precipitation particles. The intensity of the second type emissions has been changed in correlation with the electron flux in the 40-60 keV range that is observed by ESH simultaneously. It has been clarified that the second kind emissions are plasma waves of the electrostatic origin which are also excited at the lower ionospheric level by the electrons precipitating along the auroral field line.

Observations of the plasma wave emissions in a high frequency range from 01 to 10 MHz have been made using the lonospheric sounding rockets S-310JA-1, and 2, launched on February 13, 1976 and on February 10,1977, respectively, from Syowa Station in Antarctica The observed HF plasma waves are characterized by the electrostatic electron cyclotron harmonic waves generated by the beam-wave interaction in the ionosphere The flight of S-310JA-1 rocket was carried out after the termination of a substorm effect, where the drifting electrons were making enhanced precpitation near the rocket path ; enhancement of the HF plasma waves was remarkable at UHR (upper hybrid resonance) frequency and in a frequency range lower than the electron cyclotron frequency associated with nonlinear wave-particle interactions. The S-310JA-2 flight was made during the particle precipitation of a diffuse aurora where the HF emissions were weaker than the case of S-310JA-1, due to soft precipitation of particles

Multiwavelength laser radar system was installed at Syowa Station in 1983 by the 24th Japanese Antarctic Research Expedition for measurement of the middle atmospheric phenomena in cooperation with International Middle Atmosphere Program (MAP). The laser radar can simultaneously shoot two kinds of laser pulses (0.6943μm : the fundamental wave, 0.3471μm : the second harmonic wave) by means of ruby laser with regulated repetition frequencies (maximum : 1Hz) and receive scattered light by a telescope with the 50 cmφ-lens in efficient diameter. The measurement can be done by using a photon counter for each wave and A-scope for the fundamental wave. The test observation had been successfully made in Japan and it showed the remarkable increases of the strato-spheric aerosol due to the volcanic eruption of Mt. El Chichon. It was also inferred that the size distribution of the particles in the aerozol layer is inhomogeneous.