COMPARISON OF OZONE PROFILES OBTAINED WITH BREWER-MAST AND Z-ECC SENSORS DURING SIMULTANEOUS ASCENTS

Uccle is a European station with a long tradition in measuring ozone p rofiles with Brewer-Mast (BM) ozone sensors. In :1996 the use of model Z electrochemical concentration cell (Z-ECC) ozonesondes, manufacture d by EN-SCI Corporation, was considered. To document the changeover fr om BM to Z-ECC ozonesondes, a program of double soundings was started in October 1996. With the use of an appropriate correction procedure, accounting for the loss of pump efficiency with decreasing pressure an d temperature, it is possible to reduce the mean difference between oz one profiles obtained with both types of sondes below 3%, which is sta tistically insignificant over nearly the whole operational altitude ra nge (from the ground to 32km). It is concluded that with this new meth od the uncertainty, introduced in trend analyses by the changeover, is less than the internal uncertainty within the BM time series. The req uired corrections are discussed according to measurements of the pump efficiencies at different pressures and temperatures in a vacuum chamb er.