Popular Science Let Me Tell You丨Who Determines the Direction of a Typhoon?

Spread scientific ideas and promote scientific spirit

The 2024 Hainan Province Science Popularization Explanation Competition came to a successful conclusion a few days ago. "Science Popularization Hainan" broadcast the speeches of the contestants who entered the finals to spread the voice of science popularization more widely.

Today, let us follow Yang Dan from the Hainan Provincial Meteorological Service Center to learn about "Where the Typhoon Goes, We Have No Control".

In summer and autumn, the movement of typhoons attracts much attention. This year's typhoons: Makai went all the way west; Shantuoer took a "U" shape; Prasang turned east at nearly 90 degrees on land; and when Gemi was about to land in Taiwan, it suddenly turned around and circled, just after landing in Fujian, it retreated to the sea, made a detour, and landed again in Fujian... This casual pace was jokingly called "street drifter" by netizens.

It is said that typhoons are willful, but can they really go wherever they want? In fact, the direction of a typhoon is often "out of their control"! The strength of the typhoon itself and the deflection of the earth's rotation are factors that affect the direction of a typhoon, but the greatest influence is the atmospheric circulation.

So, who is behind the typhoon's direction?

In the Northern Hemisphere, typhoons rotate counterclockwise, while subtropical high pressure rotates clockwise. The two often meet in the subtropical region.

When a powerful subtropical high pressure forms an east-west belt and firmly blocks the north side of a typhoon, the strong easterly airflow on its south side will push the typhoon and move westward; when the typhoon moves to its southwest, it will have a chance to turn north under the guidance of its outer airflow; when it weakens and breaks into a ring shape, the typhoon can pass through its gaps and take a shortcut to the north or turn.

It can be said that the subtropical high pressure is the operator of typhoons !

However, in the complex and changeable atmospheric circulation, there are other weather systems that appear one after another or in groups, secretly competing for command, making the typhoon complex and changeable.

For example, Typhoon Wayne in 1986 was affected by a series of factors, including the eastward movement of the cold front, the containment and then the pulling of Typhoon Vina, and the strengthening of the airflow guidance on the southwest side of the westward extending subtropical high. It repeatedly turned and circled back and forth, forming a unique "twisted" path.

Therefore, the direction of a typhoon is the result of the competition and influence of multiple factors and multiple weather systems ! In particular, it is closely related to the position movement, intensity change, and distance between the surrounding weather systems. This increases the difficulty of forecasting, but scientific and technological personnel rise to the challenge.

First, we will establish an integrated Chinese meteorological monitoring network covering land, sea, air and space, covering comprehensive observations from satellites, radars, ground and ocean buoys; second, we will make breakthroughs in key technologies and apply the assimilation of satellite radar data to the initial field of typhoon numerical forecasts; third, we will develop new methods of typhoon forecasting technology that combine AI technology and ensemble forecasting, and put them into operational applications.

Nowadays, the average error of typhoon path forecast in my country is decreasing. Among them, the 24-hour error is reduced from 227 kilometers to 62 kilometers. For a single typhoon landing, a reduction of 1 kilometer in the forecast error can reduce direct economic losses by about 100 million yuan. I believe that in the near future, with the development of science and technology, typhoon path forecasts will be more accurate!

Source: Text comes from the 2024 Hainan Province Science Popularization Explanation Competition, pictures come from the Internet, unauthorized reproduction is strictly prohibited!

Note: The cover image is a copyrighted image. Reprinting it may cause copyright disputes.