EVALUATION OF MODELED O-3 USING MEASUREMENT OF OZONE BY AIRBUS IN-SERVICE AIRCRAFT (MOZAIC) DATA

The O-3 distribution calculated by a global three-dimensional chemistr y transport model, TOMCAT, is compared to O-3 data collected on Airbus A340 passenger aircraft as part of the Measurement of Ozone by Airbus In-Service Aircraft (MOZAIC) project. The model results are compared to seasonally averaged data at cruise altitudes in the upper troposphe re and lower stratosphere and to individual vertical profiles collecte d over particular cities during takeoff and landing. In many regions, the model shows good agreement with these data, given the large variab ility encountered, particularly around the tropopause. There are also significant day to day variations in ozone, which, in the vertical pro file data, TOMCAT captures well over northern midlatitude cities, espe cially in the upper troposphere and also in the winter lower troposphe re. In the tropics, the MOZAIC data often shows a lot of structure, wi th thin layers of high O-3 which are sometimes captured in the model. Possible reasons for this and other discrepancies are discussed.