El Niño and La Niña
El Niño- Little Boy and La Niña- Little Girl come from Spanish word also known as the Christ child. The fishermen of South America mainly the Peruvian used this term around 1600s. El Niño is familiar as an unusual warm water (warm phase) of equatorial Pacific Ocean. The warm water event occurs around December-during Christmas (upcoming winter), when sea surface temperatures across central and east-central pacific is warming. La Niña is opposite of the El Niño is the cooler surface water (cold phase) of the equatorial pacific ocean. The event of El Niño, La Niña and neutral event combine called ENSO (El Niño Southern Oscillation).
During El Niño dry conditions exist in northern Australia and Southeast Asia, and wetter conditions occur in Pacific coastal South America. Reversely during La Niña the opposite things is happens as dry conditions in Pacific coastal South America and wetter condition in northern Australia and Southeast Asia.
El Niño and La Niña trend to occur every 2-7 years and last for 9-12 month sometimes 2 years in rare case. During El Niño sea surface temperature reaches 0.50C then normal temperature and during La Niña the sea surface temperature is lower than the normal temperature.
Historical El Niño and La Niña Events
History says there are three super El Niño events earth experienced and the recent strongest event occurred in 2015-2016. During Weaker event of El Niño the temperature anomaly is 0.50 to 0.90 c and the temperature anomaly reach ≥ 20c during very strong event. The recent 2018-19 El Niño we experienced is the weaker one.
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El Niño |
La Niña |
|||||
|
Weak |
Moderate |
Strong |
Very Strong |
Weak |
Moderate |
Strong |
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1952-53 1953-54 1958-59 1969-70 1976-77 1977-78 1979-80 2004-05 2006-07 2014-15 2018-19 |
1951-52 1963-64 1968-69 1986-87 1994-95 2002-03 2009-10
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1957-58 1965-66 1972-73 1987-88 1991-92
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1982-83 1997-98 2015-16
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1954-55 1964-65 1971-72 1974-75 1983-84 1984-85 2000-01 2005-06 2008-09 2016-17 2017-18 |
1955-56 1970-71 1995-96 2011-12 1955-56 1970-71 |
1973-74 1975-76 1988-89 1998-99 1999-00 2007-08 2010-11
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*Adopted from- https://ggweather.com/enso/oni.htm
El Niño, La Niña and Climate change
It is a tough question to answer that the El Niño is influenced by climate change. Some scientists believe that climate change is increasing the frequency of El Niño and La Niña events, but there have no strong evidence of intervention of climate change on increasing the frequency of El Niño and La Niña events. But El Niño and Climate Change have a combine effect that are more intense than individual one. Combine El Niño and Climate Change we already observed in the year of 2015 (the hottest year).
Effects of El Niño and La Niña
The effects of El Niño and La Niña are varying region to region; the effects include extreme weather condition as droughts, floods and storms. These extreme weather events have strong impacts on millions of people throughout the world by low rainfall, cyclone, dryness, salt water intrusion etc. These primary events provoke secondary catastrophic event as; water shortage, soil degradation, change in cropping season, forest fire, degrade the water quality and intrusion of different disease etc.
(Writer-Md. Ashraful Islam Chowdhury, B.Sc. &M.Sc. in Environmental Sciences, Jahangirnagar University, email: ashraful.yc@gmail.com)
BDST: 1317 HRS, SEP 9, 2019
RS/SMS
