El Niño – The Christ Child (in Spanish) What is El Niño? During El Niño winds across the Pacific change direction and blow from West to East. This changes the weather patterns around the Pacific. Occurs every 3 – 7 years although they appear to be getting more regular. El Nino happens in this area of the world in the Pacific Ocean

Normal Year compared to El Nino year The trade winds move warm surface water towards the western Pacific Cold water wells up along the west coast of S.America (near Peru) Upwelling important for fish stocks in Peru El Nino Year Air pressure over West coast of S. America becomes low and air over west Australia high pressure The normal east to west trade winds over pacific are disrupted and warm water ‘sloshes’ eastwards No upwelling on S.American coast

THEORIES ON THE CAUSE OF EL NINO Rossby wave – wave lowers thermocline in W. Pacific reducing the upwelling of water. Winds then blow towards warmer water and event starts. 2. Random occurrence 3. Tropical storms – if storms are strong enough they can blow water eastwards and start the event. 4. Heat from sea floor – warming by sea floor volcanoes (no evidence)

The following page shows the sea temperatures between 1997 and 1998 a strong El-Nino year! Be aware of the West to East Movement of warmer sea temperatures! http://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/index.html

With the movement of warm water back Eastwards it prevents any upwelling of cold nutrient-rich, water on which Plankton feed. Plankton is the main food of the anchovy which is one of the main fishing types in Peru!                                         Warm water also expands. So as the water piles back East towards Peru sea levels increase by 30cm! So what potential problems has this change in climate brought about so far?

Teleconnections – knock-on effects of El Niño world wide. DEFINITIONS El Niño – the appearance of warm surface water from time ot time in the Eastern Equatorial Pacific. La Niña – the appearance of colder than average sea surface temperatures in the Central and East Equatorial Pacific. ENSO – El Niño-Southern Oscillation. Term used to describe the full range of events triggered by the see-saw motion of atmospheric pressure over the Pacific. Teleconnections – knock-on effects of El Niño world wide. Thermocline – sharp boundary between cold deep water and warmer surface water.

Problems caused elsewhere! Due to the teleconnections of the earth’s climate problems are caused elsewhere! El-nino can disrupt passage of jet streams! What effects could events such as this have on the economy?

La-Nina Year! Occasionally as an El-Nino year dies out, a third weather condition arises!La-Nina Really simple!All it is, is an exaggerated version of normal conditions. Air pressure is unusually high over the west coast of S.America and low over eastern Australia As warm water is pushed westwards sea levels rise by up to 1m Around Indonesia and Philippines. Strong uplift of air leads to heavy Rain!

You Should Now Be Able to Answer These Questions: Name one country that El Nino effects? What is the Spanish meaning of El Nino? What is the direction of winds in an El Nino year? What does teleconnections mean? What is the name of the Ocean involved with El Nino? What is the reverse effect of El Nino called? Name a particularly bad year for El Niño? Name 2 countries that were effected by this event and what the effects were?