Southern Oscillation Index
Quick Summary
The Southern Oscillation Index (SOI) measures the atmospheric component of the El Niño/Southern Oscillation (ENSO) phenomenon. It tracks interannual fluctuations in atmospheric pressure across the tropical Indo-Pacific region.1
The SOI compares pressure differences between Australia/Indonesia and the eastern South Pacific. A negative SOI indicates high pressure in the west and low pressure in the east, often coinciding with El Niño conditions. Conversely, a positive SOI signifies low pressure in the west and high pressure in the east, considered the "high phase".12
These pressure shifts influence global weather patterns, affecting rainfall and temperatures. The Southern Oscillation was first identified by Gilbert Walker in the early 20th century as he sought to predict monsoon behavior.12
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- Southern Oscillation
…may be understood using the Southern Oscillation Index (SOI), which compares the difference in atmospheric pressure over Australia and Indonesia with that of the eastern South Pacific.
Read More…may be understood using the Southern Oscillation Index (SOI), which compares the difference in atmospheric pressure over Australia and Indonesia with that of the eastern South Pacific.
Read More - climateThe Southern Oscillation
A Southern Oscillation Index (SOI), based on pressure differences between the two regions (east minus west), showed low, negative values at such times, which were termed the “low phase” of the SO. During more normal “high-phase” years, the pressures were low over Indonesia and high in…
Read MoreA Southern Oscillation Index (SOI), based on pressure differences between the two regions (east minus west), showed low, negative values at such times, which were termed the “low phase” of the SO. During more normal “high-phase” years, the pressures were low over Indonesia and high in…
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