What Is La Niña
Called so by presenting contrary to El Niño conditions, but is also known as " El Viejo " or " The Anti- child." Usually accompanied by the drop in temperatures and intense drought in the Pacific coastal areas .
" La Niña" began in 1903 and continued in 1906 , 1909 , 1916 , 1924 , 1928 , 1938, 1950 , 1954 , 1964 , 1970 , 1973, 1975 , 1988, and the more intense the 1995.Siendo of 1988/1989 .
The growing phenomenon of the Girl
This fenómenode develops when the positive phase of the Southern Oscillation , significant levels and lasts for several months such as in 1973 , 1988, 1998 , and is characterized among others by the following conditions , which are opposite to those of El Niño :
Decreases in sea level pressure in the Oceania region , and increased it in the tropical and subtropical Pacific off the coast of South America and Central America, causing increased pressure difference between both ends of the equatorial Pacific.
Alders winds increase , causing the relatively cooler along the equatorial Pacific deep water remain on the surface .
Abnormally strong trade winds have a greater effect on trawl the ocean surface , increasing the sea level difference between both ends of the equatorial Pacific. This decreases the sea level on the coast of Colombia
, Ecuador , Peru and northern Chile and increases in Oceania.
As a result of the emergence of relatively cool along the Ecuador waters , the sea surface temperature decreases below the mean climatological value . This constitutes the most direct evidence of the presence of
La Niña . However the maximum negative temperature anomalies are lower than those recorded during El Niño.
During La Niña events the warm waters in the equatorial Pacific , are concentrated in the Pacific region and is adjacent to this region, where the most intense cloudiness and precipitation develops.
Phases through which passes the La Niña
This phenomenon first appeared in scientific literature in late 1989 , is divided into four phases:
1. The Prelude to La Niña - . 's Termination of El Niño ( Southern Oscillation)
Two . The Home of La Niña is characterized by :
a) A strengthening of the trade winds found in the intertropical convergence zone , as well as a shift earlier this north of its usual position .
b ) Increase of the convention in the Pacific Ocean , west of the 180th meridian , where the temperature of the ocean surface rises usual temperature (28 and 29 ° C).
Three . Development phenomenon is identified by :
a) A weakening against equatorial current , causing the warm waters from the Asian coasts , little affect the waters of the Pacific to America.
b ) An expansion of marine outcrops , which occur as a consequence of the intensification of the trade winds.
c ) Strengthening the South Equatorial Current , especially near Ecuador , dragging colder water temperatures decrease the eastern and central tropical Pacific.
d ) A closer thermocline ( region where there is a rapid drop in temperature ) to the sea surface in the tropical Pacific , which favors the permanence of marine species that find their food for long periods .
April . Maturation - . 's The end of the La Niña event , occurring after the intensity of the trade winds have returned to normal.
Duration and frequency of the phenomenon of La Niña appears
The La Nina phenomenon may last from 9 months to 3 years, depending on its intensity is classified into weak, moderate and strong.
The La Nina phenomenon is stronger the smaller is its duration , and its greatest impact on the weather conditions observed in the first 6 months of life phenomenon.
It usually starts from mid- year, reaches its maximum intensity at the end and dissipates middle of next year.
This phenomenon occurs less frequently and the child is said to occur for a period of 3-7 years.
Detection of La Niña
The World Climate Research Programme WMO through the Program Tropical Ocean and Global Atmosphere, monitors the Tropical Pacific Ocean using fixed buoys , drifting buoys , Gauges , Beat thermographs and Satellites , which generate information for conditions this current , and power models for the prediction of future behavior and characteristics of the child.
Consequences of global climate La Niña
* In the tropics , the variations are radically opposed to those caused by El Niño.
* In the Americas , the air temperatures of the winter season , become warmer than normal in the Southeast and cooler than normal in the Northeast.
* In South America, predominantly drier and cooler than normal on the Ecuador and Peru conditions, and wetter than normal conditions in the Northeast of Brazil .
* In Central America, relatively wetter conditions than normal occur mainly on the coastal zones of the Caribbean.
* In Mexico , causes excessive rains in central and southern regions , droughts and rains in northern Mexico , and winters with marked absence of rains.
Whether this phenomenon La Niña El Niño , are normal variations in the temperatures of the sea surface , which have been around for thousands of years and will continue to exist, without which man can interfere .