Comparison of in situ stratospheric ozone measurements obtained during the MAP/GLOBUS 1983 campaign

An instrumented gondola, carrying five types of in situ ozone sensors, was flown twice as part of the MAP/GLOBUS 1983 campaign. It is shown that when the individual sondes are carefully prepared and preflight calibrated, they produce data that agree to within a 5% uncertainty throughout the middle stratosphere. The individual measurement techniques are described and the error budgets given as well as the possible reasons for discrepancies in the ozone values at higher and lower altitudes. The techniques used include two electrochemical sondes (ECC and Brewer-Mast), ultraviolet absorption photometry, olefin chemiluminescence and indigo decolorization. ECC sonde precision (about 1%) demonstrated by two instruments was slightly better than that indicated with three Brewer sondes. Results from both electrochemical techniques reveal differences with u.v. photometry measurements that are similar to systematic errors identified by Barnes et al. (1985, J. geophys. Res.90, 7881) from laboratory calibrations. Compared to u.v. photometry values, electrochemical results were greater in the lower stratosphere (100 to about 50 mb), within a few percent in the middle stratosphere, and decreased to values lower than those from u.v. photometry in the upper stratosphere. Although the Brewer sondes operate only to the triple point (5.8mb) of the potassium iodide solution used, ECC sondes demonstrated the ability to measure ozone to a pressure of 3 mb. Olefin chemiluminescence measurements were generally within 8% of u.v. photometry results. The indigo decolorization technique results were compared with the mean values of measurements from the other techniques for two altitude regions of about 6 km; ozone column contents were greater by 52% and 17%.