| description abstract | To collect stratospheric air samples for greenhouse gas measurements, a compact cryogenic air sampler has been developed using a cooling device called the Joule?Thomson (J?T) minicooler. The J?T minicooler can produce liquefied neon within 5 s from high pressure neon gas precooled by liquid nitrogen. The sampler employs liquid neon as a refrigerant to solidify or liquefy sampled atmospheric constituents. Laboratory experiments showed that the sampler is capable of collecting about 3 and more than 7 L STP of air at 25 and 120 hPa, respectively, which corresponds to about 25 and 15 km above ground within 240 s, respectively. The new balloon-borne sampling system, which was set up for Antarctic experiments, consists of the compact sampler, a 2-L high pressure neon gas cylinder, pneumatic and solenoid valves, a controller with a GPS receiver, a telemetry transmitter, and batteries. The size of the sampling system is 300 mm width ? 300 mm depth ? 950 mm height and it weighs about 22 kg (including liquid nitrogen). Two of these compact sampling systems (configured for sampling at altitudes 18 and 25 km) were launched from Syowa Station (69.0°S, 39.5°E), Antarctica, in January 2008 using 1000 or 2000 m3 plastic balloons. They were launched successfully and recovered without any problem on sea ice on the same day as their launch. The collected stratospheric air samples showed reasonable concentrations of the stratospheric greenhouse gases over the Antarctic region. | |
