Atmospheric Sciences Research Spotlight

Mysterious Anomaly Interrupts Stratospheric Wind Pattern

For the first time, scientists have observed a deviation from the typical alternating pattern of easterly and westerly winds in the equatorial stratosphere.

Source: Geophysical Research Letters

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The weather we experience on Earth typically occurs in the troposphere, the lowest layer of the atmosphere. But the stratosphere, which envelops the planet just above the troposphere, is home to winds of its own. In a new study, Newman et al. report an anomalous interruption in an otherwise reliable stratospheric wind pattern known as the quasi-biennial oscillation.

Each cycle of the quasi-biennial oscillation begins with strong westerly winds that flow through the stratosphere in a belt around the equator. Over the course of about 1 year, these winds gradually weaken and descend in altitude to the lower stratosphere as easterly winds replace them. These easterly winds slowly sink and weaken, too, as westerly winds return. The cycle repeats roughly once every 28 months.

Since 1953, scientists have observed equatorial winds by instruments known as radiosondes, which are carried skyward by weather balloons. The quasi-biennial oscillation was discovered in the early 1960s. Although the timing of each cycle has sometimes varied by a few months, the pattern as a whole has remained uninterrupted—until now.

Using radiosonde data from several equatorial locations around the world, the scientists discovered that the quasi-biennial oscillation began to deviate from its usual pattern in late 2015. At that time, westerly winds were descending in altitude and should have continued to sink and weaken as easterlies replaced them.

Instead, the westerly winds shifted upward and seemed to cut off the descent of high-altitude easterlies before they could begin their usual dominance. Additional easterly winds developed at lower altitudes in the stratosphere, beneath the rising westerlies. However, by June, the westerlies appeared to have resumed their normal descent.

The researchers plan to continue analyzing wind and temperature data to determine what caused this anomaly and what its implications may be. Their investigation will include an exploration of possible connections with the 2015–2016 El Niño and climate change. (Geophysical Research Letters, doi:10.1002/2016GL070373, 2016)

—Sarah Stanley, Freelance Writer

Citation: Stanley, S. (2016), Mysterious anomaly interrupts stratospheric wind pattern, Eos, 97, doi:10.1029/2016EO058557. Published on 02 September 2016.
© 2016. The authors. CC BY-NC-ND 3.0
  • Howard Roark

    One could suggest a more turbelent stratosphere might create unusual weather conditions in a variety of locations. Historic agricultural patterns would be challenged and likely crop failures may become more numerous. Humanity may be stressed to feed everyone, and with a Trump energy program that ignors science a more turbelent atmosphere may become the norm more rapidly.

  • Cindy Burton

    Would the injection of stratospheric aerosols via geoengineering not be a possible cause?

  • Android

    Gospel According to Luke 21:10-11.

  • R.J.

    So will it it being be negative by Winter?