Something Stranged Happened in the Stratosphere.

High above Earth's tropics, a pattern of winds changed recently in a way that scientists had never seen in more than 60 years of consistent measurements.

A disruption to the wind pattern called the quasi-biennial oscillation raised a few interesting questions for the NASA scientists earlier this year. Raising questions such as: If a pattern holds for six decades and then suddenly changes, what caused this to happen? Will it happen again? What effects might it have? The quasi-biennial oscillation is a quasiperiodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months. Winds in the tropical stratosphere, an atmospheric layer that extends from about 10 to 30 miles above Earth's surface, circulate the planet in alternating easterly and westerly directions over roughly a two-year period. Westerly winds develop at the top of the stratosphere, and gradually descend to the bottom, about 10 miles above the surface while at the same time being replaced by a layer of easterly winds above them. In turn, the easterlies descend and are replaced by westerlies. This pattern repeats every 28 months.  This pattern continually stayed the same until late 2015. This new pattern held for nearly half a year, and by July 2016 the old regime seemed to resume. The quasi-biennial oscillation has a wide influence on stratospheric conditions. The amount of ozone at the equator changes by 10 percent between the peaks of the easterly and westerly phases, while the oscillation also has an impact on levels of polar ozone depletion. With this disruption now documented, scientists are currently focused on studying both its causes and potential implications. They have two hypotheses for what could have triggered it. The particularly strong El Niño in 2015-16 or the long-term trend of rising global temperatures. The scientists are conducting further research now to figure out if the event was a black swan, a once-in-a-generation event, or a "canary in the coal mine", a shift with unforeseen circumstances, caused by climate change.

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https://www.sciencedaily.com/releases/2016/09/160902142132.htm