Daily technouns | the stratosphere to warm explosively

The stratospheric warms explosively

stratospheric sudden warming

Also known as: sudden stratospheric warming

Definition: A sudden increase in temperature of 40 to 50 K in the stratosphere within a few days. It generally appears in polar regions.

Discipline: Atmospheric Sciences_Dynamic Meteorology

Related terms: atmospheric circulation stratosphere

【Further reading】

Stratospheric explosive warming is a sudden warming phenomenon in the stratospheric atmospheric circulation in winter, and the stratospheric atmospheric temperature can increase sharply in winter and spring, even as high as 50 ° C within a few days. This phenomenon was first discovered by German scientists in 1952.

The seasonal variations of the stratospheric atmospheric circulation are obvious, with westerly winds prevailing in the northern hemisphere in winter and easterly winds prevailing in summer. The stratospheric polar region is polar vortex in winter and controlled by a giant anticyclone in summer. Before the stratospheric eruption of warming, westerly winds prevailed in the polar region, and strong cold polar vortexes dominated the stratospheric circulation, occupying most of the middle and high latitudes of the Northern Hemisphere. When the stratospheric explosive warming occurs, the polar stratospheric temperature suddenly increases, and the stratospheric circulation associated with the temperature change also undergoes a sharp adjustment, the latitude westward circulation around the pole becomes the east wind circulation, and the polar vortex undergoes strong disturbance and deviates from the polar region, or even collapses completely, establishing a polar symmetrical two-wave flow pattern. Explosive stratospheric warming occurs mostly in the northern hemisphere, while there is rarely explosive warming in the southern hemisphere.

According to the heating intensity, stratospheric explosive warming can be divided into two categories: strong warming and weak warming. In the stratosphere and its atmosphere, the average temperature of the latitude increases from 60° north latitude to the polar region and the associated circulation reverses, the polar vortex collapses, and the westerly circulation becomes the eastward circulation, which is called a strong warming process. Although the weak warming process can also achieve similar warming values, there is no panicle collapse. If the warming in late winter and early spring causes the winter circulation to be destroyed and no longer recovers and develops into a summer circulation, it is called the last warming.

The explosive warming of the stratosphere not only directly affects the changes in the stratospheric atmospheric circulation, but also greatly affects the winter tropospheric atmosphere. The occurrence of explosive stratospheric warming destroys the polar vortex, hinders the formation of polar stratospheric clouds, and cuts off the mechanism of ozone depletion. After the end of the warming, the polar vortex gradually recovers, and sometimes severe ozone depletion events occur. In addition, when stratospheric anabolic warming occurs, the stratospheric annular mode often presents a negative phase, which can be transmitted down to the troposphere in subsequent weeks, affecting the weather and climate of the troposphere. Therefore, the study of stratospheric explosive warming has very important practical significance for extended weather forecasting.