Meaning – La Nina The little girl El Viejo – Old Man A cold event A cold episode
What is La Nina? Cold phase of ENSO Unusually cold ocean temperatures in the eastern equatorial Pacific. Winds move warm water allowing cold underwater to rise to the surface
Why La Nina Occurs Changes in tropical Pacific and large modulations of the jet stream Shifting of the point where the stream normally crosses North America Overall changes in atmosphere result in temp and precipitation abnormalities over North America
Where La Nina Occurs South America Coast of Peru Coast of Chile Northern Brazil North America North Midwest Northern Rockies Northern California Pacific Northwest’s southern and eastern regions
When La Nina Occurred Previously La Nina has occurred in: 1904 1908 1910 1916 1924 1928 1938 1950 1955 1964 1970 1973 1975 1988 1995
Characteristics Unusually cold ocean temperatures in the eastern equatorial pacific Below average precipitation in the south- western and south eastern states Above average precipitation in the North- west Drought in the coastal regions of Peru and Chile Wetter than normal in northern Brazil between December and Fabruary
Discoveries The head of the Indian Meteorological Service, Sir Gilbert Walker, recognized patterns in the rainfall in South America, in the 1920’s Further study led to the realization that monsoons in Asia, under certain conditions where linked to droughts in some areas of the world. The connection between the changes of weather from La Nina was not noticed until the late 1960’s by Norwegian meteorologist, Jacob Bjerknes.
Meaning – El Nino In the 1500’s, fishermen in South America wondered about a current of unusually warm water that came to shore ever few years around Christmas. They believed in the birth of Jesus Christ celebrated at Christmas and decided to name the hot water El Nino, meaning ‘the infant’ in Spanish.
What is El Nino Warm phase of ENSO Warm wind and water that drift toward land Unusually warm air and water temperatures along the South American and North American coast
Why El Nino Occurs Causes are still being investigated
Where El Nino Occurs South America Peru Ecuador Chile Brazil Argentina North America Western Canada Eastern Canada Northwest Mexico Southwest United States Northwest United States Northmidwest United States Northmideast United States
When El Nino Occurs Previously El Nino has occurred in: 1986 1991-92 1994-95 2002-03 2004-05 2009-10
Characteristics Rise in surface pressure over the Indian Ocean, Indonesia, and Australia. Fall of pressure over the central and eastern pacific ocean Trade winds in the south pacific weaken or head east Warm air rises near Peru Warm water spreads for west Pacific and the Indian Ocean to the east Pacific Drought in western Pacific More rainfall in eastern Pacific