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What is La Niņa?
Quick Facts
El Niņo

La Niņa is characterized by unusually cold ocean temperatures in the equatorial Pacific. 

At the turn of this century, a connection between La Niņa, El Niņo, and other weather patterns had yet to be established.  During the 1920s, the head of the Indian Meteorological Service, Sir Gilbert Walker, recognized patterns to the rainfall in South America. His discovery led him to theorize additional associations with the change in the ocean temperatures, and with atmospheric pressure changes measured at stations at different parts of the Pacific (Darwin, Australia, and Tahiti).

Noticing that as pressure rises in the east, there is typically an accompanying decrease in the west, with the reverse also true, he coined the term Southern Oscillation to categorize his find.

Further study led to the realization that Asian monsoon seasons under certain barometric conditions were often linked to drought in Australia, Indonesia, India and parts of Africa, and to mild winters in western Canada.

Not until the late 1960s did a Norwegian meteorologist, Jacob Bjerknes, a professor at the University of California, establish the connection between the changes in sea surface temperatures and the weak winds from the east and heavy rainfall that accompany low pressure conditions.

Ultimately, Bjerknes' discovery led to the recognition that the warm waters of El Niņo (with the often cool waters of La Niņa) and the pressure variance of Walker's Southern Oscillation are interrelated, leading to the full naming of the phenomenon as : "El Niņo Southern Oscillation (ENSO)".

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Reference: Green Lane Environment Canada

  • The Phrase "La Niņa" is Spanish for "the girl" and sometimes called "El Viejo" (old man).  It is characterized by unusually cold ocean temperatures in the equatorial Pacific. 

  • La Niņas appear approximately every 4-5 years.  They typically last 1-2 years.

  • Global climate abnormalities of La Niņa are less pronounced and sometimes tend to be different than the El Niņo - however, the effects are not always the opposite of each other.

  • It is believed that La Niņa's cooling of the equatorial Pacific tend to favor hurricane formation in the western Atlantic.

  • La Niņa usually brings colder winters to the Canadian west and Alaska, and drier, warmer weather to the American Southeast.
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Reference: Green Lane Environment Canada


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