Abstract
An ethylene-ozone Chemiluminescent instrument has been modified so that it can control the sample and ethylene flow rates irrespective of the ambient pressure and temperature. Through detailed laboratory tests the following characteristics have been found.
(1) The sensitivity of the instrument is highly dependent on the sample mass flow rate as ex- pected from the chemiluminescent reaction scheme. (2) The change in sensitivity as a function of the ethylene mass flow rate is much less. (3) The error associated with the stability of the zero level and the standard deviation from a linear relationship is less than 1 ppbv. (4) The change in the sensitivity for pressures between 1000 and 500mb is insignificant. A larger reduction in sensitivity at lower pressures necessitates corrections based on the calibration curve obtained. It amounts to about 10% at 400mb under optimum flow conditions.
Aircraft observations of ozone up to the altitude of 6km have been made. The flow control system has proved to maintain the flow rates constant to within 3% on board the aircraft. Ozone mixing ratios obtained by this experiment are also reported.
