For our El Nino background report, we wanted to scrutiniize various websites and other information to learn about the El Nino phenomena itself. As a result, we have found plenty of information on the topic - the term "El Nino" itself and its meaning, why it appears intervally, and the global changes it causes.
The El Nino term -- translated as the Christ child in Spanish, was given by South American fishermen along the coast based on its occurence around Christmas time. El Nino was first noticed as an unusual warming of the oceanic waters off the coast of Peru. This warming brought with it many changes in the local weather and had an impact on the sea life and human activities in the area. As more has been learned about this phenomena, a much wider, even global impact has been associated with it. With a Child's unpredictablity and its "tantrums", it has presented scientists a real challenge to sort out exactly what is going on, and they are working overtime to comprehend it. Here is what those scientists have discovered:
El Nino occurs at an irregular rate - it could come again after two years or in a decade. Like snowflakes, no two events are alike. An example of that can be seen in the El Nino of 1982-83, when the El Nino changes, unlike others, were coming later than usual in the year, and were not predisposed by stronger normal easterlies periods. Many aspects of the weather change, including the sea surface temperature, ocean upwelling, the biology, and the winds, but scientists are recognizing patterns as seen here in the chart.
Well, here it is; a weather phenomena that may go way back
as long as a thousand years ago. Scientists are also questioning about the
original El Nino, whether it had begun recently or was here all
along..
El Nino, in a word, disorients the ocean-atmosphere system in the tropical Pacific with consequences for weather around the globe. Some of those consequences are increased rainfall across the southern part of the United States and in Peru, causing flooding and drought destruction in the west Pacific. To receive the necessary data for the prediction of El Nino, NOAA operates a network of buoys which measure temperature, water currents and winds. These buoys then transmit daily data on the internet which is available to researchers and forecasters around the globe.
The Tropical Atmosphere Ocean (TAO) Array is made up of about 70
buoy moorings across the Tropical Pacific Ocean. Buoys measure real-time
current, winds, sea surface temperature, and other data and send it by
radio transmission to computers around the world.
In the normal conditions as seen above, the trade winds blow toward the west across the tropical Pacific to pile up warm surface water in the west Pacific, so that the sea surface is about 1/2 meter higher at Indonesia than at Ecuador. The sea surface temperature is roughly 8 degrees Celsius lower in the east, with cooler temperatures off South America, due to an upwelling of cold water from deeper levels in the oceans. The cold water is composed of nutrient-rich bottom water, which supports various marine ecosystems. The rainfall is found in rising air over the warmest water, normally in the western Pacific.
During El Nino, the trade winds weaken in the central and western Pacific leading to a reduction of the thermocline in the eastern Pacific, and an increase of the thermocline in the west. This reduces the upwelling that had cooled normally the sea surface and as a result, the nutrient rich thermocline water supply is cut. Afterwards, there are increases in the sea surface temperatures and a drastic decline in primary productivity, affecting higher levels of the food chain, including the region's commercial fisheries. In an El Nino year, sea birds tend to abandon their young ones for food, causing a decline in the sea bird population. There also tends to be a decline in the fur seals population, as well as in sea lions, and several other varieties of fishes in the region.
Rainfall follows the warm water eastwardly, and the result is flooding in some areas like Peru. The eastward movement of warm air causes huge changes in the global atmospheric circulation which in turn forces changes in weather in the tropical pacific region.
Credit for discovering the links between these climatic effects in distant parts of the globe and El Nino is given to a certain man with a "rebellious" attitude. Despite the hardships and opinionated minds he faced, a British scientist Sir Gilbert Walker researched air pressure changes across the tropical Pacific during the 1920's, and as a result discovered El Nino. Walker was on an assignment in India -- attempting to find a method to predict the Asian monsoon, which was unpredictable seasons of heavy precipitation. As he sorted through world weather records, he discovered a connection between barometer readings at stations on the eastern side and western side of the Pacific. He noticed that when pressure rises in the east, it usually falls in the west, and vice versa. Walker formed the term Southern Oscillation to define the ups and downs in the east-west seesaw Southern Pacific barometer measurements. After the El Nino was discovered, meteorologists have increased their knowledge of the weather itself, and this kind of infomation will be useful in predicting both short term global weather changes and long term climate changes in the future.
by Vinny Riccobono Jr. and John Lawson V