Atmospheric temperature quasi-biennial oscillation and its tendencies for change

Tendencies in the variations of the characteristics of the quasi-biennial oscillation (QBO) of surface air temperature are analyzed from various data obtained for the Northern and Southern hemispheres within the last more than one hundred years. These tendencies are compared to those in the evolution of the characteristics of the annual cycle in surface air temperature. The corresponding tendencies are also evaluated from temperature data obtained for various layers of different latitudinal belts of the troposphere and stratosphere in the last few decades. It is revealed that the quasi-biennial oscillation of temperature in the troposphere (stratosphere) becomes weaker (stronger) as a whole during surface and tropospheric warmings. The tendencies revealed are associated with the general tendency of the amplitude of tropospheric (stratospheric) temperature annual cycle to decrease (increase). The results obtained are in qualitative agreement, in particular, with the fact that the mechanism of parametric resonance in the atmosphere may be responsible for the generation of the quasi-biennial oscillation.