Measurements of carbon monoxide concentrations and isotopic ratios from the atmosphere via equipment aboard supply aircrafts operating between Christchurch, New Zealand and McMurdo Sound

Carbon monoxide (CO) is a trace gas in the atmosphere. The use of the radioactive isotope 14C in carbon monoxide is useful for determining the oxidative capacity via oxidation by hydroxyl (OH). Large whole air samples (1000-1400 litres) were collected from compressor system aboard the supply aircrafts operating between Christchurch and McMurdo (Hercules – C130, Starlifter – C141 and the Globemaster - C17). Samples were analysed for CO concentrations and the isotopic content of 14C. CO is extracted as CO2 by selective combustion techniques and the 13C/12C and 18O/16O isotopic ratios are determined. The use of different aircrafts offers the ability to measure the vertical distribution of carbon monoxide and the isotopic ratios within the troposphere and stratosphere along a latitudinal transect. Because of the low concentrations of CO in the Southern hemisphere very large samples were collected for 14CO measurements.