Abstract
Abstract. The mechanism of generation of 2-day photochemical oscillations in the mesopause region (80–90 km) has been studied analytically. The initial system of equations of chemical kinetics describing the temporal evolution of O, O3, H, OH and HO2 concentrations with allowance for diurnal variations of solar radiation has been simplified successively to a system of two nonlinear first-order time equations with sinusoidal external forcing. The obtained system has a minimum number of terms needed for generation of 2-day oscillations. Linearization of this system near the period-doubling threshold permits separating explicitly a particular case of the Mathieu equation ẍ + α · sin ω t · x = 0, in which the first sub-harmonic (ω/2) of the exciting force starts to grow exponentially when the amplitude of external forcing (α) exceeds its threshold value. Finally, a system of two simplest differential equations with power-law nonlinearity has been derived that allows analytical investigation of the effect of arising of reaction-diffusion waves in the mesospheric photochemical system.
Highlights
An intriguing photochemical property of the mesosphere is that this system can respond nonlinearly to diurnal variations of solar radiation. Sonnemann and Fichtelmann (1987, 1997), Fichtelmann and Sonnemann (1992), Feigin et al (1998), and Konovalov and Feigin (2000) used zerodimensional models to show that a wide spectrum of periodic and chaotic regimes of behavior of minor gas constituents may exist at the heights of the mesopause region (80–90 km)
The interest in nonlinear oscillations in the mesopause region is associated with the fact that they may influence the behavior of key characteristics of the mesosphere
The point is that exothermal reactions between the chemical constituents of the mesospheric photochemical system ensure the main photochemical heating of the mesospheric air reaches 1–2 K per day at the heights of the nonlinear-response region (Sonnemann et al, 1999)
Summary
An intriguing photochemical property of the mesosphere is that this system can respond nonlinearly to diurnal variations of solar radiation. Sonnemann and Fichtelmann (1987, 1997), Fichtelmann and Sonnemann (1992), Feigin et al (1998), and Konovalov and Feigin (2000) used zerodimensional models (without spatial transport) to show that a wide spectrum of periodic (subharmonic, with periods of 2, 3, 4, and more days) and chaotic regimes of behavior of minor gas constituents may exist at the heights of the mesopause region (80–90 km). Analysis within the framework of the zero-dimensional MPCS model revealed a wide spectrum of periodic (subharmonic) and chaotic modes of behavior of minor gas constituents of the mesosphere that are realized depending on the values of control parameters, such as H2O, Nonlin. The variation of the other control parameters (H2O and temperature) within the range of the values typical of the summer mesopause manifests itself into a slight shift of the height of the region where the 2-day oscillations may occur (Kulikov, 2007) O and H concentrations are dynamic variables (with characteristic times equal to 5 × 104–105 s) found from a system of two first-order differential equations:
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
