a see-saw of atmospheric pressure anomalies between the Indonesian region and the eastern tropical Pacific Ocean.
Climatic variation, particularly rainfall, caused by changes in air pressure and sea pressure in the Pacific Ocean; also known as El Niño-La Nina
is the periodic change (i.e., oscillation) of sea level pressure differences across the tropical Pacific that have been found to correlate with El iño and La iña events. First recognized by British scientist Sir Gilbert Walker in the 1920s by observing pressure differences between Darwin, Australia and Tahiti while stationed in India studying the monsoon.
shifting patterns of air pressure at sea level, between eastern and western edges of the Pacific Ocean.
Episodic strengthening and weakening of the contrast in sea-level barometric pressure between the eastern and western sides of the Pacific. Normally, the pressure is higher on the eastern side, driving the easterly tradewinds in the equatorial belt. The Southern Oscillation causes the pressure contrast and the strength of the easterlies to fluctuate between high-index (strong tradewind) and low-index (weak tradewind) conditions.
A periodic, large scale atmospheric oscillation of the large scale distribution of sea level pressure, and air and water temperature that originates over the southern hemisphere. Consequently, there is an associated change in the surface winds, and some storms become stronger than normal. This oscillation is on the scale of a year or a few years, and has global implications such as widespread drought or flooding. Oceanic fishing is also disrupted.
The oscillating of atmospheric pressure cells back and forth across the Pacific Ocean, in association with El Ni96o.
a large-scale atmospheric and hydrospheric fluctuation centered in the equatorial Pacific Ocean; exhibits a nearly annual pressure anomaly, alternatively high over the Indian Ocean and high over the South Pacific; its period is slightly variable, averaging 2.33 years; the variation in pressure is accompanied by variations in wind strengths, ocean currents, sea- surface temperatures, and precipitation in the surrounding areas
a fluctuation in the atmospheric circulation, in particular over the tropical areas of the Pacific and Indian oceans; in general, when atmospheric pressures are high over the eastern Pacific Ocean they tend to be low in the eastern Indian Ocean and vice versa; the fluctuation between the two produces a marked variation in parameters such as the sea surface temperature and rainfall over a wide area of the Pacific and has a cycle of two to seven years; the phenomenon is strongly linked to the El Niño
the reversal of typical surface air pressure patterns across the tropical Pacific that occurs during a major El Niño event
Shifting of pressure zones in the Pacific during an El Niño event.
A periodic reversal of the pressure pattern across the tropical Pacific Ocean during El Nino events.
The Southern Oscillation Index (SOI), defined as the normalized difference in surface pressure between Tahiti, French Polynesia and Darwin, Australia is a measure of the strength of the trade winds, which have a component of flow from regions of high to low pressure. High SOI (large pressure difference) is associated with stronger than normal trade winds and La Niña conditions, and low SOI (smaller pressure difference) is associated with weaker than normal trade winds and El Niño conditions. The terms ENSO and ENSO cycle are used to describe the full range of variability observed in the Southern Oscillation Index, including both El Niño and La Niña events.
The Southern Oscillation is a see saw of atmospheric mass (pressure) between the Pacific and Indo Australian areas. The pressure difference can be associated with planetary-scale circulation changes.
Originally defined in 1924 by Gilbert Walker as a low-latitude, planetary- scale "seesaw" in sea level pressure, with one pole in the eastern Pacific and the other in the western Pacific–Indian Ocean region. The pressure seesaw is associated with a global pattern of atmospheric anomalies in circulation, temperature, and precipitation. The primary timescale of the oscillation is interannual–multiyear, and it is now recognized to be primarily a response to basin-scale sea surface temperature variations in the equatorial Pacific arising from coupled ocean–atmosphere interactions, the opposite extremes of which are the El Niño and La Niña warm and cold events. See also ENSO. Philander, S. George, 1990: El Niño, La Niña, and the Southern Oscillation, Academic Press, International Geophysics Series, Vol. 46 Walker, G. T., 1924: Correlation of seasonal variations in weather IX: A further study of world weather. Mem. Indian Meteor. Dep., 24, 275–332.
The Southern Oscillation refers to an oscillation in air pressure between the southeastern and southwestern Pacific waters. When the eastern Pacific waters increase in temperature (an El Niño event), atmospheric pressure rises in the western Pacific and drops in the east. This pressure drop is accompanied by a weakening of the easterly Trade Winds.