Arctic Oscillation | Surface Temperatures | Stratospheric Temperatures | Clouds | Ocean

	Polar vortex. From the Discovery Channel.

The stratosphere is the upper middle part of the atmosphere, and is the level of the Jet Stream winds. Colder temperatures in the stratosphere over the Arctic are associated with the positive phase of the Arctic Oscillation, and are indicative of stronger polar winds.

The polar vortex is the pattern of winds around the North Pole, shown in the figure (right) from the Discovery Channel. Click to see a larger image.

The following figures are maps showing a northern polar view of stratospheric temperature anomalies in March for different years. The extensive region of colder dark blue temperatures are indicative of stronger polar vortex winds. An anomaly is the difference from a long term average for the same time of year.

Note the change in intensity and location of this cold polar vortex from year to year. It is thought that conditions in the stratosphere may influence conditions in the rest of the atmosphere. Six of the nine years in the 1990s had colder stratospheric temps and stronger vortex winds compared to the warmer conditions in the 1980s. After that, conditions were more variable. See the YouTube animation of the stratospheric temperature anomalies in March (1981 - 2016).

March stratospheric (200 hPa) temperature anomalies based on NCEP/NCAR reanalysis, shown from 1981 to 2016. The anomaly is the departure from its 1981-2010 averages for that month. This mean period is consistent with online NCEP/NCAR reanalysis plots. Download large images (zip file) or view the YouTube animation.

Find more information (references and websites):

• What are climate indices?
• Winds of Change - about the Polar Vortex, from the Discovery Channel
• The Polar Vortex - definition, from National Snow and Ice Data Center
• Phases of the Arctic Oscillation, the Polar Vortex and Arctic weather patterns - from National Snow and Ice Data Center
• The Arctic Oscillation and polar vortex - from the University of Washington
• The Arctic Oscillation's impact on northern climate - from the University of Washington