Jan 07, 2016 southern oscillation, in oceanography and climatology, is a coherent interannual fluctuation of atmospheric pressure over the tropical indopacific region. Southern oscillation index soi teleconnections national. The southern oscillation index soi is a measure of the intensity or strength of the walker circulation. Most global climate models do simulate enso, although. From december 1997, this image shows the change of sea surface temperature from normal. The southern oscillation entails a largescale pressure seesaw, on a time scale of 210 years, and with dipoles over the eastern south pacific and the greater indonesianaustralasian region, but spanning the global tropics. Year djf jfm fma mam amj mjj jja jas aso son ond ndj. The connection between earths oceans and atmosphere has a direct impact on the weather and climate conditions we experience. Oceanatmosphere coupled anomaly in the tropical pacific. The low phase of the so can be defined by anomalously lowhigh surface pressure at. The southern oscillation is an eastwest balancing movement of air masses between the pacific and the indoaustralian areas. The soi measures the difference in surface air pressure between tahiti and darwin. The complete table going back to djf 1950 can be found here. The southern oscillation index soi is a standardized index based on the observed sea level pressure differences between tahiti and darwin, australia.
The soi is one measure of the largescale fluctuations in air pressure occurring between the western and eastern tropical pacific i. At intervals that vary from 2 to 10 yr seasurface temperatures and rainfall are unusually high and the tradewinds are unusually weak over the tropical pacific ocean. Historical background on enso and its societal consequences. Enso is the anomalous and recurring pattern of cold and warm patches of water periodically developing off the western coast of south america. Any strong change in enso statistics will therefore have serious climatic and ecological consequences. The southern oscillation is the accompanying atmospheric component, coupled with the.
Abstract a 116yrsouthern oscillation index record was used in conjunction with environmental data and. Here we provide a synopsis of our current understanding of the spatiotemporal complexity of this important climate mode and its influence on the earth system. Ensoneutral is favored for the northern hemisphere summer 2020 60% chance. Ocean dynamics alter seasurface temperature, changing the atmospheric heating. We analyzed fossil coral reconstructions of enso spanning the past 7000 years from the northern line islands, located in the center of action for enso. Southern oscillation an overview sciencedirect topics. The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds. Ke trenberth, national center for atmospheric research, boulder, co, usa a 20 elsevier inc. The southern oscillation index used for the figure is a composite number derived from observations of air pressure at sea level for cape.
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