A 2-DIMENSIONAL MODEL STUDY OF THE QBO SIGNAL IN SAGE-II NO2 AND O3

Calculations of the QBO signal in SAGE II O3 and NO2 data between 1984 and 1991 are presented and have been investigated by using a two-dime nsional model. The isentropic 2D model is a fully interactive radiativ e-dynamical-chemical model in which the eddy fluxes of chemical specie s are calculated in a consistent manner. The QBO in the model has been forced by relaxing the equatorial zonal wind toward the observations at Singapore allowing the comparison of the model with observations fr om specific years. The model reproduces the observed vertical structur e of the equatorial ozone anomaly with the well-known transition from dynamical to photochemical control at around 28km. The model also repr oduces the observed vertical structure of the SAGE II observed NO2 ano maly. The model studies have shown that it is the QBO modulation of NO 2 which is the main cause of QBO signal in O3 above 30km. The model al so reproduces the observed latitudinal structure of the QBO signals in O3 and NO2. Due to the differing horizontal distribution of O3 and NO (y) the ozone signal shows a distinct phase change in the subtropics w hereas the NO2 anomaly gives a broader signal.