In order to obtain detailed crustal structures in a typical oceanic island arc system, we have been conducting multichannel seismic (MCS) reflection survey in the Izu-Ogasawara region, by using R/V Kairei of Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Swath-bathymetry, geomagnetic and gravity data are simultaneously observed during the cruises. In 2004 fiscal year, we collected a total of 2030.9 km of MCS data: 228.20 km in KR04-10, 384.70 km in KR04-13 and 1417.95 km in KR04-15 cruises. On-board processing results demonstrate clear seismic reflection images of the subducting Pacific plate, forearc tectonic features and backarc basin structures, showing that all of the MCS data collected are of good quality.

Multiple, gravity and piston cores were collected at four sites in the Chilean marginal area during the R/V MIRAI MR03-K04 cruise (leg.3, 15 October-2 November 2003). This cruise is a part of the BEAGLE (Blue Earth Global Ocean Experiment) program, a circumpolar cruise around the Southern Hemisphere, developed by JAMSTEC / POGO-IOCCG.

Here, we report the basic data on coring site locations and some geological data: visual core descriptions, color reflectance spectra, magnetic susceptibility, gamma ray attenuation density, and microfossil assemblage, which were determined on board the ship during the cruise.

The two post-processing procedures for the R/V Mirai Doppler radar data using dual-PRF technique are developed. One is to correct the Doppler velocity data which is falsely-unfolded by dual-PRF real-time unfolding. The correction amount is determined by comparing target data bin to neighbor data bins. Another is to reduce second-trip echo in the reflectivity data, by detecting characteristic alternate pattern in dual-PRF observation. The parameters for the procedures are tuned by statistical method using observed dataset for tropical cloud system. Both procedures demonstrate good performance on the observed dataset by using tuned parameters.

We have developed an automatic atmospheric observation system to measure CO₂ levels continuously in the stratosphere for the study of global warming and other environmental problems.

The system consists of two major parts: an automatic atmospheric air sampler and a sequential carbon dioxide (CO₂) gas level meter equipped with an NDIR analyzer. The system is controlled with a pre-programmed microcomputer and powered by a Li-ion battery pack. The system runs on a stand-alone mode or a remote control mode. In both modes, the data measured and the system status are monitored from a land station via radio wave. We had carried out stratospheric environment tests and reliability tests. The test results show that the system samples/compresses air into the bottles with pressure of 150 kPa and measures levels of CO₂ continuously with precision of about 0.2 ppm in the stratosphere up to 15,000 m.

In May, 2005, intensive single channel seismic surveys have been successfully completed in Sagami Bay area, central Japan, during the KY05-06 cruise using R/V KAIYO of JAMSTEC (Japan Agency for Marine-Earth Science and Technology). We obtained 22 SCS profiles in the overall Sagami Bay area, and 37 shallow and deep profiles around the Hatsushima cold seep communities in the western Sagami Bay. Very clear acoustic images were captured down to 1 sec. (TWT) after some editing, band-pass filtering and time migration. We present here the seismic profiles obtained during the KY05-06 cruise.