Airborne gas chromatograph for in situ measurements of long-lived species in the upper troposphere and lower stratosphere

A new instrument, the Airborne Chromatograph for Atmospheric Trace Species IV (ACATS-IV), for measuring long-lived species in the upper troposphere and lower stratosphere is described. Using an advanced approach to gas chromatography and electron capture detection, the instrument can detect low levels of CFC-II (CCl3F), CFC-12 (CCl2F2), CFC-113 (CCl2F-CClF2), methyl chloroform (CH3CCl3), carbon tetrachloride (CCl4), nitrous oxide (N2O), sulfur hexafluoride (SF6), Halon-1211 (CBrClF2), hydrogen (H-2), and methane (CH4) acquired in ambient samples every 180 or 360 a. The instrument operates fully-automated onboard the NASA ER-2 high-altitude aircraft on flights lasting up to 8 hours or more in duration. Recent measurements include 24 successful flights covering a broad latitude range (70 degrees S-61 degrees N) during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) campaign in 1994.