Theoretical validation of ground-based microwave ozone observations

• Main Authors: P. Ricaud, G. Brasseur, J. Brillet, J. de La Noë, J.-P. Parisot, M. Pirre
• Format: Article
• Language: English
• Published: Copernicus Publications
• Series: Annales Geophysicae
• Online Access: http://www.ann-geophys.net/12/664/1994/angeo-12-664-1994.html
• ISSN: 0992-7689; 1432-0576

Ground-based microwave measurements of the diurnal and seasonal variations of ozoneat 42±4.5 and 55±8 km are validated by comparing with results from a zero-dimensional photochemical model and a two-dimensional (2D) chemical/radiative/dynamical model, respectively. O<sub>3</sub> diurnal amplitudes measured in Bordeaux are shown to be in agreement with theory to within 5%. For the seasonal analysis of O<sub>3</sub> variation, at 42±4.5 km, the 2D model underestimates the yearly averaged ozone concentration compared with the measurements. A double maximum oscillation (~3.5%) is measured in Bordeaux with an extended maximum in September and a maximum in February, whilst the 2D model predicts only a single large maximum (17%) in August and a pronounced minimum in January. Evidence suggests that dynamical transport causes the winter O<sub>3</sub> maximum by propagation of planetary waves, phenomena which are not explicitly reproduced by the 2D model. At 55±8 km, the modeled yearly averaged O<sub>3</sub> concentration is in very good agreement with the measured yearly average. A strong annual oscillation is both measured and modeled with differences in the amplitude shown to be exclusively linked to temperature fields.