2-day oscillation in mesosphere
The photochemical system of the mesosphere represents a nonlinear enforced chemical oscillator driven by the diurnally periodic insolation. This system is able to produce chemical resonances if the characteristic chemical response time ranges on the order of one day, period doubling cascades and other subharmonics or chaos. This is precisely true in the mesopause region. It was shown in the joint paper by Sonnemann that this system is able to create subharmonic oscillations of period-2, period-3 and chaos depending on the period of an artificial day of insolation. Such phenomena are called nonlinear effects. The period of a subharmonic oscillation in short subharmonics is a multiple of the fundamental period amounting to a day, in the case of the chemistry of the earth’s atmosphere, which is driven by the diurnally periodic solar insolation.
A trajectory describes the movement of a phase point within a sub-phase space and an attractor reflects the motion in case of a limit cycle. Attractors are indicative for the nonlinear response of the system. Figure display the examples of quasi attractor for ozone-atomic oxygen phase space at 83 km height and 42.5° N for a permanent 1st July. The data from calculations were stored every 1.5 h and therefore the curves appear to be very angular. In reality they are smoothed. Although the calculations based on a permanent date the figures do not represent an ideal limit cycle because the long-living constituents still change slowly during the time period considered. Both of the different diurnal variations can be clearly recognized as separate loops.
The result presented here clearly shows that two-day oscilation in the chemistry of the mesopause region can occur under favorable conditions but also that the two-day variation is not a general feature of the dynamics. In order to use certain conditions, the system was integrated under the conditions of a continuously repeating date.