Explanation of nouns in southern oscillation

The southern oscillation nouns are explained as follows:

Meteorologists used to express the difference of pressure field between Tahiti Island in the east of the South Pacific and Darwin, Australia in the west, and named this oscillation as the Southern Oscillation Index.

Brief introduction of southern oscillation index

According to Walker's southern oscillation theory, scientists chose Tahiti Station to represent the southeast Pacific Ocean and Darwin Station to represent the Indian Ocean and the western Pacific Ocean. After the mathematical statistics of the sea level pressure difference between the two stations, an index to measure the intensity of the Southern Oscillation, called the Southern Oscillation Index, is obtained, which is expressed by SOI.

The index effectively reflects the evolution of pressure increase and decrease on the east and west sides of the Pacific Ocean. When this index is positive, it means that the pressure in Tahiti is higher than that in Darwin, that is, the pressure difference between the eastern and western Pacific Ocean increases; When the index is negative, it shows that the pressure difference between the eastern and western Pacific Ocean decreases. When the negative value is extremely low, the air pressure between the two places may be reversed, that is, the actual air pressure at Darwin Station exceeds that at Tahiti Station.

Relationship between Walker Circulation and Southern Oscillation

The Southern Oscillation refers to the large-scale pressure fluctuation between the Pacific Ocean and the Indian Ocean.

The Southern Oscillation (SOO) is formed by the sea surface temperature in the equatorial region of the eastern Pacific Ocean (El Ni? o warming and La Ni? a cooling) and the sea surface pressure change in the equatorial region of the western Pacific Ocean. These two changes are interrelated: the warm ocean stage in the eastern Pacific, namely El Nino, is accompanied by the high sea surface pressure in the western Pacific; The cooling stage of the eastern Pacific, La Nina, is accompanied by the low sea surface pressure in the western Pacific.

Extended data:

Reasons for the formation of El Nino phenomenon:

Weakening of southeast wind

When the southeast wind blowing near the equator in the southern hemisphere weakens, the cold water flooding in the Pacific will be reduced or stopped, which will lead to the abnormal warming of seawater temperature in a large range, and the traditional equatorial ocean current and atmospheric circulation will also be abnormal, resulting in abnormal precipitation in some areas along the Pacific coast and severe drought in some areas.

earth rotation

It is found that the occurrence of El Nino event is related to the change of the earth's rotation speed. Since the 1950s, the average acceleration distribution in the past 10 years has been destroyed by the earth's rotation speed, which fluctuated for 4-5 years. Some strong El Nino events occurred in the year when the earth's rotation speed had a major turning point, especially in the year when the rotation slowed down.