page_title: La Niña
section_title: Diversity
hierarchical_section_title: La Niña / Diversity
caption_attribution_description: English: Map of various index regions used to measure the strength of an ENSO; plotted over a background of the +2 and +3 °C contours of the 1997-8 DJF surface temperature anomaly. 1: [10S, 5S] and [90W, 80W] 2: [5S, Eq] and [90W, 80W] 3: [5S, 5N] and [90W, 150W] 4: [5S, 5N] and [150W, 160E] 3.4: [5S, 5N] and [170W, 120W] Each index captures different properties; nino3.4 is probably most commonly used. By William M. Connolley with enso-index-map.pro
context_page_description: La Niña is a coupled ocean-atmosphere phenomenon that is the colder counterpart of El Niño, as part of the broader El Niño–Southern Oscillation climate pattern. The name La Niña originates from Spanish, meaning "the girl", analogous to El Niño meaning "the boy". It has also in the past been called anti-El Niño, and El Viejo. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3 to 5 °C. An appearance of La Niña persists for at least five months. It has extensive effects on the weather across the globe, particularly in North America, even affecting the Atlantic and Pacific hurricane seasons, in which more tropical cyclones occur in the Atlantic basin due to low wind shear and warmer sea surface temperatures, while reducing tropical cyclogenesis in the Pacific Ocean.
context_section_description: The traditional La Niña, also called Eastern Pacific (EP) La Niña, involves temperature anomalies in the Eastern Pacific. However, in the last two decades, nontraditional La Niña were observed, in which the usual place of the temperature anomaly (Niño 1 and 2) is not affected, but an anomaly arises in the central Pacific (Niño 3.4). The phenomenon is called Central Pacific (CP) La Niña, "dateline" La Niña (because the anomaly arises near the dateline), or La Niña "Modoki" (Modoki is Japanese for "similar, but different"). There are flavors of ENSO additional to EP and CP types and some scientists argue that ENSO exists as a continuum often with hybrid types.
  The effects of the CP La Niña are different from those of the traditional EP La Niña—e.g., the recently discovered La Niña leads to a rainfall increase over northwestern Australia and northern Murray-Darling basin, rather than over the east as in a conventional La Niña. Also, La Niña Modoki increases the frequency of cyclonic storms over Bay of Bengal, but decreases the occurrence of severe storms in the Indian Ocean overall, with the Arabian Sea becoming severely non-conductive to tropical cyclone formation.
  The recent discovery of ENSO Modoki has some scientists believing it to be linked to global warming. However, comprehensive satellite data go back only to 1979. Generally, there is no scientific consensus on how/if climate change may affect ENSO.
  There is also a scientific debate on the very existence of this "new" ENSO. A number of studies dispute the reality of this statistical distinction or its increasing occurrence, or both, either arguing the reliable record is too short to detect such a distinction, finding no distinction or trend using other statistical approaches, or that other types should be distinguished, such as standard and extreme ENSO.
  Recent years when La Niña Modoki events occurred include 1973–74, 1975–76, 1983–84, 1988–89, 1998–99, 2000–01, 2008–09, 2010–11 and 2016–17.
caption: Map showing Niño3.4 and other index regions
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