Geophysical Research Letters | Dunkerton 
Over the last 9 months, the Quasi-Biennial Oscillation (QBO) of the equatorial lower stratosphere has deviated significantly from its normal behavior documented since 1953. Historically, the QBO has varied mainly in the duration of individual oscillation phases, or equivalently, the rate of azimuthal propagation in a 2D phase space; in contrast, the oscillation in recent months seems to have ceased. Other features such as the magnitude of wind extrema, east-west phase asymmetry, and seasonal modulation have been fairly regular over all cycles save for the current one and its closest analog in 1960. Our Comment on Newman et al. (2016, this issue) highlights features of the anomaly noted by them, contrasts this evolution with the standard QBO model, and draws attention to some unusual features of the 2015-16 ENSO warm event.
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