What would cause a wind pattern that held for at least
60 years to suddenly change?
Scientists are baffled and try to solve and understand
this new atmospheric enigma.
For the first time, scientists have observed a deviation
from the typical alternating pattern of easterly and
westerly winds in the equatorial stratosphere.
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
windsgradually weaken and descend inaltitude
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.
NASA.gov Video - A Strange Thing Happened in the Stratosphere.
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.
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.
Sources: NASA.gov | Strangesounds.org