DESCARTES: A novel lightweight balloon-borne instrument for measurement ofhalocarbons

A new, lightweight balloon-borne instrument (DESCARTES) has been developed to make measurements of long-lived trace gases in the stratosphere. DESCART ES is designed to be simple to operate and to fly on small balloons or to " piggyback" on larger payloads. To collect samples, a measured volume of air is passed through a sample tube containing a Carboxen adsorbent. Atmospher ic halocarbons are adsorbed and the sample tube is then isolated under an i nert nitrogen atmosphere. A number of sample tubes are filled at different altitudes during the flight. After recovery of the instrument the halocarbo ns are thermally desorbed and quantified using a gas chromatograph with an electron capture detector. In this article we present the design, test, and operation of the instrument with particular emphasis on CFC-11 (CFCl3), th e gas for which operation has been optimized. (C) 2000 American Institute o f Physics. [S0034-6748(99)01712-8].