Sudden stratospheric warming

An unusual warming event known as Sudden Stratospheric Warming (SSW) has been observed over Antarctica and Arctic which is also found to be linked with an ozone hole shrinking over the pole. SSW refers to this warming in the stratosphere, a rapid warming (up to about 50-°C in just a couple of days), between 10 km and 50 km above the earth’s surface. This is so high that we don’t feel the ‘warming’ ourselves.

Planetary waves have ridges and troughs like ocean waves, but span huge distances in the atmosphere. Just like waves crash at beaches, atmospheric waves can crash too both in horizontal and vertical directions. When a tropospheric wave crashes vertically into the stratosphere and slows into polar vortex, it transfers a huge amount of energy that energy can slows or even reverse the circulation of the polar vortex and cause rapid warming.

In this case both troposphere and stratosphere appear to have been involved. A tropospheric wave at the end of January gave the vortex a minor bump from below causing rapid but modest warming. This destabilizes the polar vortex that later triggered a full on disruption and sudden stratospheric event.

Impact on atmosphere and weather :-

1. In warmer temperatures fewer polar stratospheric clouds form and they don’t persist as long, thus limiting the ozone-depletion process.
2. The stratospheric sudden warming can sometimes cause the jet stream to snake more, and this tends to create a large area of blocking high pressure.
3. It influences the North Atlantic Oscillation in an negative way.
4. Dry and windy conditions are likely to increase the fire threat in a number of regions.
5. This can trigger hot, dry winds across Australia over the next three months, impact rainfall and worsen droughts.
6. This air temperatures increase suddenly, produces widespread effects on weather, air chemistry, and telecommunications.