Anomalous tropical planetary wave activity during 2015/2016 quasi biennial oscillation disruption

Abstract

In the present communication, a record breaking duration (23 months) of the eastward phase of the QBO at 20 hPa is reported and details of the tropical wave activity during the recent anomalous QBO event are discussed. Two-dimensional Fourier analysis revealed the presence of 30–40 and 10–15 day westward propagating wave number 1 structures at 40 hPa pressure level over the equator. A combination of the mid-latitude Rossby waves and the 30–40 day oscillations seems to be the most probable mechanism for the observed disruption of the QBO.