The southern oscillation index soi is a standardized index based on the observed sea level pressure differences between tahiti and darwin, australia. We have already seen an example of a natural mode of climate variability above in the amo. Originally described in 1893 as corriente del nino1 a warm regional ocean current. The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds. The southern oscillation index soi is a standardized index based on the observed. The southern oscillation index soi, which measures enso, is calculated from the difference between the standardised surface air pressures at tahiti and darwin. It is a large scale ocean atmosphere climate interaction that originates in the pacific ocean but spreads across the world. The soi is one measure of the largescale fluctuations in air pressure occurring between the western and eastern tropical pacific i. The southern oscillation is the accompanying atmospheric component. Observations of the tropical pacific ocean during a normal year the national oceanographic and atmospheric administration noaa maintains several laboratories around the country for specialized atmospheric and oceanic research. The various cold and warm patches of ocean water act to cool or heat the atmosphere, influencing global climate patterns. For example, when the pressure is low in the south pacific high pressure cell and high over indonesia and australia, the pacific trade winds weaken, upwelling of cool water on the pacific.
As the name suggests, enso consists of two components. It can be explained neither in strictly oceanographic nor strictly meteorological terms. Climate prediction center southern oscillation index links. The southern oscillation is a seesaw of atmospheric mass pressure between the pacific and indo australian areas. Diminished fisheries off south america, drought in western pacific, increased precipitation in southwestern north america, fewer atlantic hurricanes. Enso represents a coupled mode of the ocean and atmosphere, which is to say that the atmosphere influences the ocean. They are associated with widespread changes in the climate system that last several months, and can lead to significant socioeconomic impacts affecting infrastructure, agriculture.
Enso is a coupled oscillation in the tropical pacific ocean and atmosphere, characterized in the ocean by a shift in the position of the very warm water that makes up the tropical western pacific warm pool. It is a large scale oceanatmosphere climate interaction that originates in the pacific ocean but spreads across the world. Takahashi and mosqueratvasquezinstituto geofisico del peru. Again, fill in the data tables and use those data to make a plot of the. This type of climatology is fundamental because it teaches. This volume provides a brief history of the subject, summarizes the oceanographic and meteorological observations and theories, and discusses the recent.
This warmer water can affect fisheries and cause a persistent elevation of sea. Environmental investigations scientists warn of critical gaps in australias climate science capability. The future of the worlds climate second edition, 2012. National weather service weather forecast office bismarck, nd. Such events are a consequence of strong and extensive interactions between the ocean and atmosphere. Observations of the tropical pacific ocean during a normal year the national oceanographic and atmospheric administration noaa maintains several laboratories. The name enso is a reminder that close interaction between the atmosphere and ocean is an essential part of the. Since enso is one of the most prominent sources of interannual variations in regional patterns of precipitation and temperature, any uncertainty in how it will change implies a corresponding uncertainty in certain regional patterns of climate change. It occurs every 27 years, typically lasting 618 months. Climate prediction center southern oscillation index. It can be explained in neither strictly oceanographic nor strictly meteorological terms. The heat transfer controls weather over both land and sea.