Journal of the Atmospheric Sciences · 1972 · 704 citations · 0 references
Upper AtmosphereQuasi-biennial CycleEngineeringAtmospheric SoundingAtmospheric ModelEarth System ScienceEarlier TheoryEarth ScienceGeophysicsAtmospheric ScienceUpdated TheoryClimate ChangeLower AtmosphereMeteorologyAtmospheric InteractionMesoscale MeteorologyTropical StratosphereSpace WeatherClimate SystemEarth's ClimateClimate DynamicsClimatologyAtmospheric RadiationCritical Level AbsorptionQuasi-biennial Oscillation
The quasi‑biennial oscillation theory is revisited using recent observations and theoretical advances. Short‑period waves are attenuated by infrared cooling, depositing momentum flux into the mean flow. The study shows that infrared cooling, not critical‑level absorption, attenuates short‑period waves, and the resulting momentum deposition can generate the quasi‑biennial oscillation with fewer assumptions.
The authors' earlier theory of the quasi-biennial oscillation is reevaluated in the light of more recent observational analyses and theoretical developments. The main contention of the earlier theory, that the stratospheric oscillation is driven by the vertically propagating, short-period (5–15 days) waves excited in the upper troposphere, is now well establued. However, the assumption that the waves interact with the mean flow through critical level absorption is now seen to be largely, if not entirely, incorrect. Instead it appears that the short-period waves are strongly attenuated primarily by infrared cooling. As they are attenuated, their mean momentum flux is deposited in the mean flow. It is shown that this mechanism leads to an oscillation in the mean flow as readily as the earlier critical-level mechanism, and with fewer assumptions.