El Nino Southern Oscillation


The idea of the oscillation theory began with a group of fishermen in Peru in the 1800's that noticed a change in climate and currents. It started off being a weak, warm current that would throw off their fishing. The warmer water produced low fishing profits and it also affected the population of the Quano birds. This strange current always seemed to occur during Christmas time so they named it "the Christ child" or El Nino which means "male child" in Spanish. It occurs in the southern region of the globe in the Pacific Ocean, basically the South America region. Oscillation means to swing or move to and fro and in this case it is the see- saw pattern of reversing surface air pressure between the eastern and western Pacific. This, put together, tells us why it is called El Nino Southern Oscillation.


- No real outlying cause for this change, though there are some theories
- Global Warming is said to have an affect on the warming of surface waters and the amount of water to which is transfered as precipitation, it is said to affect El Nino more, but is also not proven yet
-The Atmosphere can give answers about ENSO, taking information from the local vicinity of the surface temperatures and putting it through the global climate system
Here you can see the on-going 'dialog' between the ocean and atmosphere in the tropical Pacific ocean.


 - The warmer surface temperature of the ocean leads to many problems
a) poor fishing conditions without the cold, nutrient rich upwellings that sustains a large fish population
b) with less fish, it is harder to sustain the Quano bird population of Peru that support the fetilizer industry
c) it creates opposite climates in many areas for example Australia becomes dry and more succeptible to fires and drought, Peru gets heavy rains and warm weather, North Africa is wetter and South Africa is dryer
d) the warmer surface temperature leads to large clouds with rain, or cumulonimbus clouds, that result in rains on dryer areas near the equator
- it produces significant economic and atmoshpheric consequences
- these changes in climate affect regions that are unused to the weather that occurs and don't know what to do
- in the 1997-1998 event, there were the most disastrous events that the history of El Nino has seen; in California wave heights reached 30 feet and major highways were washed out and blocked by mudslides
- on the coast of California in the first week of February alone, there was 22 inches of rain, homes crashed into the sea, and 3 feet of snow fell on the mountains; this lasted until early spring
- In Japan, the climate changed to severe drought during the winter and effected the Olympic Winter Games
- bad fires and droughts were a normal occurrence in Australia for this event.


El Nino is a sparratic event that does not come at a certain time every year, let alone come every year. Some aspects of El Nino show up every year with the increase of temperature in the surface, but there have only been a few cases where the difference in temperature was so immense, the climates were drastically changed. 1982-1983 was possibly the strongest event of this oscillation, next being 1997-1998. These two occurrences produced some devastation amongst regions because of the effected climate which then produced natural disasters that affected parts of the globe which are stated in "EFFECTS" . In 1982-1983, the largest flood of the Rillito River in Tucson, Arizona occurred. Residents from around the Tuscon Raquet and Fitness Club were evacuated and some homes along the river colapsed into it. When El Nino does occur, it usually lasts for 12-18 months.
Home along the Rillito River that is damaged from floods
Bridge along the Rillito River damaged from the flooding.


La Nina meaning "the little girl" has opposite effects of El Nino. It makes a regions usual climate more intense, but the effects are not as disastrous. For example, Arizona has a dry climate so during La Nina, it becomes a little drier, but is not so drastic because we are already used to the dry weather. In wetter climates like the rainforest, it rains a little more and it wetter, but again does not make conditions that are unbearable and hard to deal with.