Editing Quasi-biennial oscillation (section)

== Theory ==
In 1883, the [[1883 eruption of Krakatoa|eruption of Krakatoa]] led to visual tracking of subsequent volcanic ash in the stratosphere.  This visual tracking led to the discovery of easterly winds between 25 and 30&nbsp;km above the surface. The winds were then called the Krakatau easterlies.  In 1908, data balloons launched above [[Lake Victoria]] in Africa recorded westerly winds in the stratospheric levels of the [[atmosphere]].  These findings, at the time, were thought to contradict the 1883 findings.<ref>{{cite book |title=Climatology |page=229 |year=2012 |url=https://books.google.com/books?id=WvuCyjEPxr4C&q=qbo+1800s&pg=PA229|isbn=9781449655914 |last1=Rohli |first1=Robert V. |last2=Vega |first2=Anthony J. |publisher=Jones & Bartlett Publishers }}</ref>  However, the winds that would become known as the QBO were discovered to oscillate between westerly and easterly in the 1950s by researchers at the UK [[Meteorological Office]].<ref>{{cite journal |first=P. |last=Graystone |title=Meteorological office discussion on tropical meteorology |journal=Met. Mag. |volume=88 |pages=117 |year=1959 }}</ref>  The cause of these QBO winds remained unclear for some time.   [[Radiosonde]] soundings showed that its phase was not related to the [[annual cycle]], as is the case for many other stratospheric circulation patterns.  In the 1970s it was recognized by [[Richard Lindzen]] and [[James Holton]] that the periodic wind reversal was driven by [[atmospheric wave]]s emanating from the tropical [[troposphere]] that travel upwards and are dissipated in the [[stratosphere]] by [[radiative cooling]]. The precise nature of the waves responsible for this effect was heavily debated; in recent years, however, [[gravity wave]]s have come to be seen as a major contributor and the QBO is now simulated in a growing number of climate models.<ref>{{cite journal |first=M. |last=Takahashi |title=Simulation of the stratospheric Quasi-Biennial Oscillation using a general circulation model |journal=Geophys. Res. Lett. |volume=23 |issue=6 |pages=661–4 |year=1996 |doi=10.1029/95GL03413 |bibcode=1996GeoRL..23..661T}}</ref><ref>{{cite journal |first1=A.A. |last1=Scaife |last2=Butchart |first2=N. |last3=Warner |first3=C.D. |last4=Stainforth |first4=D. |last5=Norton |first5=W. |last6=Austin |first6=J. |title=Realistic quasi-biennial oscillations in a simulation of the global climate |journal=Geophys. Res. Lett. |volume=27 |issue=21 |pages=3481–4 |year=2000 |doi=10.1029/2000GL011625 |bibcode=2000GeoRL..27.3481S|s2cid=129296437 }}</ref><ref>{{cite journal |first1=M. |last1=Giorgetta |last2=Manzini |first2=E. |last3=Roeckner |first3=E. |title=Forcing of the quasi-biennial oscillation from a broad spectrum of atmospheric waves |journal=Geophys. Res. Lett. |volume=29 |issue=8 |pages=861–4 |year=2002 |doi=10.1029/2002GL014756 |bibcode=2002GeoRL..29.1245G|hdl=11858/00-001M-0000-0012-027C-1 |s2cid=28289267 |hdl-access=free }}</ref>