An automated system for the measurement of nitrogen oxides and ozone concentrations from a passenger aircraft: Instrumentation and first results of the NOXAR project

A fully automated system for measuring NO, NO2, and O-3 in the upper troposphere and lower stratosphere from a passenger aircraft is described. Detection limits (1 sigma) of 23, 45, and 500 pptv were achieved for NO, NO2, and O-3, respectively, for a 2 min integration time during flights. Continuous measurements were made during a 1 year period ending May 1996 on a total of 540 flights between Zurich and destinations in the United States and the Far East. The measurements represent about a 10-fold increase in the coverage of presently available NOx measurements in the tropopause region. The measurement hardware, based on commercially available instrumentation and specifically designed to meet the very stringent safety regulations normal in civil aviation, is described, and first results are briefly reported.