El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the El Nino-Southern Oscillation (ENSO) cycle.
Theme : Important Geophysical Phenomena,Physical Geography
Paper:GS - 1
TABLE OF CONTENT
- Context
- El Nino
- La Nina
- Monitoring El Niño & La Nina
- Impacts of El Nino
- Impacts of La Nina
Context : El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the El Nino-Southern Oscillation (ENSO) cycle.
El Nino :
- El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
- It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).
- It occurs more frequently than La Nina.
La Nina :
- La Nina, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the tropical eastern Pacific.
- La Nina events may last between one and three years, unlike El Nino, which usually lasts no more than a year.
- Both phenomena tend to peak during the Northern Hemisphere winter.
Monitoring El Niño & La Nina :
- Scientists, governments, and non-governmental organizations (NGOs) collect data about El Nino using a number of technologies such as scientific buoys.
- A buoy is a type of an object that floats in water and is used in the middle of the seas as locators or as warning points for the ships. They are generally bright (fluorescent) in color.
- These buoys measure ocean and air temperatures, currents, winds, and humidity.
- The buoys transmit data daily to researchers and forecasters around the world enabling the scientists to more accurately predict El Nino and visualize its development and impact around the globe.
- The Oceanic Nino Index (ONI) is used to measure deviations from normal sea surface temperatures.
- The intensity of El Nino events varies from weak temperature increases (about 4-5° F) with only moderate local effects on weather and climate to very strong increases (14-18° F) associated with worldwide climatic changes.
Impacts of El Nino :
In order to understand the concept of El Nino, it’s important to be familiar with non-El Nino conditions in the Pacific Ocean.- Normally, strong trade winds blow westward across the tropical Pacific, the region of the Pacific Ocean located between the Tropic of Cancer and the Tropic of Capricorn.
- Impact on Ocean: El Nino also impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond.
- Increased Rainfall: Convection above warmer surface waters brings increased precipitation.Rainfall increases drastically in South America, contributing to coastal flooding and erosion.
- Diseases caused by Floods and Droughts: Diseases thrive in communities devastated by natural hazards such as flood or drought.
- El Nino-related flooding is associated with increases in cholera, dengue, and malaria in some parts of the world, while drought can lead to wildfires that create respiratory problems.
- Positive impact: It can sometimes have a positive impact too, for example, El Nino reduces the instances of hurricanes in the Atlantic.
- In South America: As El Nino brings rain to South America, it brings droughts to Indonesia and Australia.
- These droughts threaten the region’s water supplies, as reservoirs dry and rivers carry less water. Agriculture, which depends on water for irrigation, is also threatened.
- In Western Pacific: These winds push warm surface water towards the western Pacific, where it borders Asia and Australia.
- Due to the warm trade winds, the sea surface is normally about 0.5 meter higher and 4-5° F warmer in Indonesia than Ecuador.
- The westward movement of warmer waters causes cooler waters to rise up towards the surface on the coasts of Ecuador, Peru, and Chile. This process is known as upwelling.
Impacts of La Nina :
- Europe: In Europe, El Nino reduces the number of autumnal hurricanes.
- La Nina tends to lead to milder winters in Northern Europe (especially UK) and colder winters in southern/western Europe leading to snow in the Mediterranean region.
- North America: It is continental North America where most of these conditions are felt. The wider effects include:
- Stronger winds along the equatorial region, especially in the Pacific.
- Favorable conditions for hurricanes in the Caribbean and central Atlantic area.
- Greater instances of tornados in various states of the US.
- South America: La Nina causes drought in the South American countries of Peru and Ecuador.
- It usually has a positive impact on the fishing industry of western South America.
- Western Pacific: In the western Pacific, La Nina increases the potential for landfall in those areas most vulnerable to their effects, and especially into continental Asia and China.
- It also leads to heavy floods in Australia.
- There are increased temperatures in Western Pacific, Indian Ocean and off the Somalian coast.
FAQs :
-
What is El-Nino?
ANS.
- El Nino is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
- It is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).
- It occurs more frequently than La Nina.
-
What is La-Nina?
ANS.
- La Nina, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the tropical eastern Pacific.
- La Nina events may last between one and three years, unlike El Nino, which usually lasts no more than a year.
- Both phenomena tend to peak during the Northern Hemisphere winter.