Story: Climate

Southern Oscillation Index, 1955–2005

Southern Oscillation Index, 1955–2005

The most accurate way of identifying El Niño or La Niña weather phases is to measure the annual air-pressure variation across the Pacific (between Tahiti in the east and Darwin in the west). These measurements are known as the Southern Oscillation Index. A variation of below -1 indicates an El Niño weather pattern. When the variation is above +1, La Niña is active.

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Source: NIWA – National Institute of Water and Atmospheric Research

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How to cite this page:

Brett Mullan, Andrew Tait and Craig Thompson, 'Climate - New Zealand and global climate patterns', Te Ara - the Encyclopedia of New Zealand, (accessed 21 October 2021)

Story by Brett Mullan, Andrew Tait and Craig Thompson, published 12 Jun 2006