New research has found that a small area in the southwest Pacific Ocean, between New Zealand and Australia, can cause changes in temperatures that affect the entire southern hemisphere. Its discovery could explain historical climate changes
New research has found that a small area in the southwest Pacific Ocean, between New Zealand and Australia, can cause changes in temperatures that affect the entire southern hemisphere.
The new climate pattern, which has similar characteristics to El Niño, is called "Circular Pattern Number 4 of the Southern Hemisphere."
Unlike El Niño which starts in the tropics, this pattern starts in the middle latitudes. The study, published this month in the Journal of Geophysical Research: Oceans, highlights how important the interaction between the ocean and the atmosphere is for our climate.
Belji Sanpati of the University of Reading, lead author of the paper, said: "This discovery is like finding a new switch in the Earth's climate. It shows that a relatively small area of the ocean can widely influence global weather and climate patterns."
"Understanding this new system can greatly improve weather forecasting and climate prediction, especially in the Southern Hemisphere. The new pattern may help explain previously mysterious climate changes and improve our ability to predict extreme weather and climate events."
The researchers used advanced climate models to simulate 300 years of climate conditions. This model combines atmosphere, ocean and sea ice components to create a comprehensive representation of the Earth's climate system. Analyzing the data in the simulation, the team identified a recurring pattern of changes in sea surface temperature that surrounds the Southern Hemisphere.
The climate pattern works like a global chain reaction. This pattern creates four alternating warm and cold zones in the oceans, which form a complete circle in the Southern Hemisphere. It starts near the ocean near New Zealand and Australia. When the ocean temperature changes in this small area, it creates a wave effect in the atmosphere, which develops into a wave pattern that travels around the entire southern hemisphere, carried by strong westerly winds.
As this atmospheric wave moves, it affects ocean temperatures and creates the four warm and cold zones.
The ocean plays a big role in this process. When the atmospheric wave changes the wind patterns, it affects how heat moves between the ocean and the air. It changes the depth of the upper layer of warm ocean water, which can amplify or weaken changes in temperature.
This new pattern occurs independently of the other known weather systems in the tropics, such as the El Nino warming pattern of currents and trade winds, or its cooling phase, La Niña. This suggests that it has always been part of the Earth's climate, but has only just been noticed.
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