In order to measure the concentrations of trace gases such as C02, CH4, N20 and halocarbons and the isotopic ratios of 513C, 5180 and A14C of CO2 in the stratosphere over Antarctica in January 1998, a balloon-borne cryogenic air sampling system was developed on the basis of the sampler which has used for the collection of stratospheric air over Japan since 1985. The sampler developed in this study is capable of collecting air samples with volumes of 20-30 lsTp at 12 height levels. Special

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... ion was paid to the sampler so that the collection of a large amount of the stratospheric air can be completed in a short time, which is crucial for recovering the sampler near the station using a helicopter. In addition, the samplerwas designed to land on the sea or the ice field safely. W e also simulated the flight trajectories ofthe sampler using the wind data observed at Syowa Station (69'00'S, 39'35'E), Antarctica. The results suggested that the sampler may land within approximately 150 km from the station, if air sampling is made in the summer season. Indeed, the trajectories, thus predicted, were confirmed to be valid by experiments made using a rubber balloon at Syowa Station on January 21 and February 6, 1995.