The zonal wind effect on the photochemistry within the mesosphere/mesopause region Original Research Article

The solar radiation periodically excites the chemistry of the earthʹs atmosphere diurnally. The photochemical system of the mesosphere represents a driven chemical oscillator which shows a resonance-like response to the radiative forcing if the characteristic chemical system time ranges in the order of 1 day. This is the case in the upper mesosphere and mesopause region. An air parcel moves along a parallel according to the direction and velocity of the zonal wind. In compliance with the wind direction this air parcel is subjected to an insolation period longer or shorter than 1 day. The changed period can be described by a modified Doppler formula. For real zonal wind speeds in the domain under investigation, the shift of the Doppler period amounts to more than +4 and −7 hours. As a consequence the diurnal variation of the acting minor constituents and some important parameters, such as the diurnal amplitude or the occurring time of the maximum concentration, change with the zonal wind. We investigate this behavior on the basis of a realistic 3D-model of the dynamics and chemistry of the middle atmosphere. We briefly discuss some results.