El Nino

We live on an incredibly large planet. Even broader than the size of the planet are the amount of changes and relationships between humans, animals, environment, weather, and the affects of each. Many times with busy schedules and modern lifestyles we forget the interaction that goes on between any number of concepts or idea's. We fail to realize that a specific weather occurrence in the Pacific Ocean can have an affect on every day life in the United States. El Nino is one of the largest scientific phenomenons that scientists have ever explored. The main concepts of El Nino are very simple and there are many variations, causes, affects, and relationships to study.

The main idea behind El Nino is that the wind changes direction across the Pacific Ocean. In a non El Nino year (normal), the trade winds blow from east to west across the ocean, from North and South America towards the tropical regions of the Pacific Ocean. In an El Nino year, the trade winds change direction and blow from Asia and the tropical Pacific towards North and South America (NOAA B, 2004). The changes in these winds, commonly called Southern Oscillation winds because the majority of activity happens in the southern parts of the Pacific, produce many other changes. In the final analysis, the winds are the root of this scheme. John Daly (2004) discussed how the winds produce major changes in the temperature of the ocean water. This is the second main concept of El Nino. In normal years, when the wind blows from east to west, the temperature at "Sea Surface" is about 8 degrees cooler in the west than in the east. During El Nino, the winds blow a certain amount of water towards the west, thus piling it up and making its depth approximately one half meter deeper. Because of the loss of water at either coast, the deeper ocean water rises to replace what is gone. The deeper/cooler water is the source of many incomes in North and South America; however, in an El Nino year, the warmer water sits on top of the ocean, which creates many tribulations relating to both income and weather. The last main point of El Nino is the weather that follows due to the changes in water temperature. Precipitation follows the warmer water, whichever direction it flows. During the normal wind patterns the rainfall in the southern Pacific islands is consistent and creates their tropical identity. When the wind shifts the other direction it creates droughts and heat waves in the western Pacific and often time's floods, or blizzards, in the eastern Pacific (NOAA A, 2004).

The theory of El Nino was originally explored and documented in the 1560's. Mayell (1997) discussed how fishermen from Peru wondered why in certain years the normally cold water would become warm and the flow would reverse in an opposite direction. The change in water temperature would kill the majority of the fish and thus cause major problems for fishermen and many others who relied on fish. The changes in the water temperature usually began near Christmas, therefore the fishermen called this phenomenon El Nino, which means The Christ Child in Spanish.

Scientists who studied El Nino stayed only on the South American coast until the early 1900's. British scientist Sir Gilbert Walker was stationed in India to study weather patterns after a monsoon in 1899 devastated the country. As he studied the monsoon's he noticed a connection between water temperature and rainfall. He also discovered that the barometer readings of eastern and western Pacific Ocean were almost always identically opposite. He noticed that when pressure rises in the east, it usually falls in the west, and vice versa. He coined the term Southern Oscillation to dramatize the ups and downs in this east-west seesaw effect. He also linked the affects of the wind and water temperatures to drought or rainfall, depending on which side of the ocean you studied. Sir Gilbert Walker took large amounts of grief for his bold statements, but the advances in technology in the future would prove he was correct (Mayell, 1997).

As technology advanced throughout the 1900's the ability to observe and research was increased. Originally a Norwegian meteorologist, then a professor at the University of California in the 1960's, Jacob Bjerknes, put together the connection of wind direction and Sir Gilberts discoveries of water temperature and barometer readings. With the readings of computers the phenomenon now seemed fairly simple. Bjerknes coined the term ENSO which stands for El Nino Southern Oscillation and is used by scientists today (Mayell, 1997).

After the discoveries and observations of El Nino scientists began to wonder if the opposite phenomenon were possible. If so, did it have any implications? Discoveries were made that there was a connection between unusually cold ocean water and changes around the globe. This separate phenomenon was called La Nina, which means the little girl in Spanish, and has been labeled as a temperature change in the entire Pacific Ocean, rather than the seesaw affect of El Nino. La Nina has been characterized to be not nearly as dramatic or have the implications that El Nino has. The impacts of La Nina are generally only seen during the winter time and as a temperature change, instead of an entire climate and lifestyle change. These changes, however, can result in more or less precipitation depending on the region and degree of change (Redmond, 1998).

Scientists soon began to wonder how often El Nino patterns would occur and if they could be predicted. After research and documentation of weather patterns dating all the way back to the 1870's, scientists discovered that the El Nino phenomenon occurred fairly irregularly, but there seemed to be some action at least once every two to seven years. The most recent El Nino years were 1982-1983, 1991-1992, 1994-1995, and 1997-2000. The longest recorded El Nino activities in the last 50 years occurred between June 1998 - May, 2000. Although sometimes being very mild, ENSO was still present. Every El Nino occurrence varies in some way such as the magnitude, duration, or measured causes around the globe (NOAA C, 2004).

The reason that ENSO is documented and measured in the Pacific Ocean instead of any other ocean seems to be for one main reason: the overall size of the Pacific as compared to the Atlantic or Indian Oceans (Daly, 2004). The size of the Pacific Ocean allows the water to swell in size and temperature as it moves in one direction or another. There are similar occurrences in the Atlantic and Indian Oceans, but there is not enough space for the water and wind to become large enough to make a significant impact.

There are several general environmental patterns that are dictated by El Nino and La Nina. The first is tropical storms and hurricanes. The National Oceanic