Quasi-biennial oscillation

The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km (0.6 mi) per month until they are dissipated at the tropopause.

In 1908, data balloons launched above Lake Victoria in Africa recorded westerly winds in the stratospheric levels of the atmosphere.

In the 1970s it was recognized by Richard Lindzen and James Holton that the periodic wind reversal was driven by atmospheric waves emanating from the tropical troposphere that travel upwards and are dissipated in the stratosphere by radiative cooling.

Easterly phases of the QBO often coincide with more sudden stratospheric warmings, a weaker Atlantic jet stream, and cold winters in Northern Europe and the Eastern U.S.

[8] The Free University of Berlin supplies a QBO data set that comprises radiosonde observations from Canton Island, Gan, and Singapore.

Time–height plot of monthly-mean, zonal-mean equatorial zonal wind ( u ) in m/s between about 20 and 35 km (22 mi) altitude above sea level over a ten-year period. Positive values denote westerly winds and the contour line is at 0 m/s.