El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years. The Southern Oscillationrefers to variations in the temperature of the surface of the tropical eastern Pacific Ocean (warming and cooling known as El Niño and La Niña respectively) and in air surface pressure in the tropical western Pacific. The two variations are coupled: the warm oceanic phase, El Niño, accompanies high air surface pressure in the western Pacific, while the cold phase, La Niña, accompanies low air surface pressure in the eastern Pacific. Mechanisms that cause the oscillation remain under study.
The extremes of this climate pattern's oscillations, El Niño and La Niña, cause extreme weather (such as floods and droughts) in many regions of the world. Developing countries dependent upon agriculture and fishing, particularly those bordering the Pacific Ocean, are the most affected. In popular usage, the El Niño-Southern Oscillation is often called just "El Niño". El Niño is Spanish for "the little boy" and refers to the Christ child, because periodic warming in the Pacific near South America is usually noticed around Christmas.
El Niño is defined by prolonged differences in Pacific Ocean Sea surface temperatures when compared with the average value. The accepted definition is a warming or cooling of at least 0.5 °C (0.9 °F) averaged over the east-central tropical Pacific Ocean. Typically, this anomaly happens at irregular intervals of 3–7 years and lasts nine months to two years. The average period length is 5 years. When this warming or cooling occurs for only seven to nine months, it is classified as El Niño/La Niña "conditions"; when it occurs for more than that period, it is classified as El Niño/La Niña "episodes".
The first signs of an El Niño are:
- Rise in surface pressure over the Indian Ocean, Indonesia, and Australia
- Fall in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean
- Trade winds in the south Pacific weaken or head east
- Warm air rises near Peru, causing rain in the northern Peruvian deserts
- Warm water spreads from the west Pacific and the Indian Ocean to the east Pacific. It takes the rain with it, causing extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific.
El Niño's warm rush of nutrient-poor tropical water, heated by its eastward passage in the Equatorial Current, replaces the cold, nutrient-rich surface water of the Humboldt Current. When El Niño conditions last for many months, extensive ocean warming and the reduction in Easterly Trade winds limits upwelling of cold nutrient-rich deep water and its economic impact to local fishing for an international market can be serious.
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a.) Today I learned that El Niño is defined by prolonged differences in Pacific Ocean Sea surface temperatures when compared with the average value.
b.) I will apply my learnings about El Niño in my daily life. It can be useful for myself to easily classify what is happening in my surroundings. Like when it gets really hot, I might be able to deduce that it certainly is the time for this phenomenon.
c.) Learning about this topic is important because it have certain features that many does not know about. I can prevent myself from panicking about such a thing because I know that it happens naturally. But if it happens too quickly, I can help prevent it, or if I can't, make myself ready about what to happen next and inform anyone as I can.
d.) On a larger scale, I will share my learnings about this phenomena to others because, what if they don't have any idea bout this, and they panic because they think that this is very dangerous? What will happen t everyone. I thought about that and arrived at the conclusion that I should just make it clear to them that this happening is not as dangerous as they think, but it can be harmful at times too.
e.) I need to know more about how it happens. That's all. since I want to be scientifically aware about anything that happens around me. I want a logical explanation about everything. (Though I don't need one about Religion. I believe everything that is written in the bible.)
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And that's the end of it, see you next time!
famlei
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