CRYOGENIC AIR SAMPLING SYSTEM FOR MEASUREMENTS OF THE CONCENTRATIONS OF STRATOSPHERIC TRACE GASES AND THEIR ISOTOPIC-RATIOS OVER ANTARCTICA

In order to measure the concentrations of trace gases such as CO2, CH4 , N2O and halocarbons and the isotopic ratios of delta(13)C, delta(18) O and Delta(14)C 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 stratosp heric air over Japan since 1985. The sampler developed in this study i s capable of collecting air samples with volumes of 20-30 I-STP at 12 height levels. Special attention was paid to the sampler so that the c ollection 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 sampler was designed to l and on the sea or the ice field safely. We also simulated the flight t rajectories of the sampler using the wind data observed at Syowa Stati on (69 degrees 00' S, 39 degrees 35' E), Antarctica. The results sugge sted that the sampler may land within approximately 150 km from the st ation, if air sampling is made in the summer season. Indeed, the traje ctories, thus predicted, were confirmed to be valid by experiments mad e using a rubber balloon at Syowa Station on January 21 and February 6 , 1995.