Forecast an El Nino or La Nina! 

Who hasn't heard of El Nino and la Nina?  Almost no one!  But who can tell if one of these events that change our weather and climate is coming.  Scientists are working to forecast El Nino and La Nina events but as yet our best way to tell what is coming is to look at satellite ocean data and watch for these features as they travel across the ocean.  And you can do that!

First let's think about what an El Nino or La Nina is and how it affects us.  The simple explantion is that they are hot and cold ocean events that start in the tropical Pacific Ocean. These 'hot and cold' events cover large areas of the tropics, move from weat to east, and can spread north and south along the coasts of the Pacific ocean. The events are so large that they affect the local weather and change the jet stream which affects global weather.  For more information read further!
 

Let's take a look at the ocean!!

This picture was made from data taken from a satellite that measures the height of the ocean.  By measuring the height of the ocean surface we can make a map that gives us information about the amount of heat in the ocean.  The 'bottom line' is that hot water expands and is higher and cold water takes up less space so it is lower. Think about designing an experiment to prove this? (Hint!)

Check out this image taken from our TOPEX/Poseidon satellite

Time to do some thinking! - Why are there stripes on this image?  Hint! - What color is shows a  'normal' sea surface height and temperature? Hint! - Where in the ocean are the high areas indicating warm water? - What areas of the world (countries) are near high (warm) or low (cool) water?

Now for another view .....
 

Time to do some thinking! - Let's look at a recent image that uses 10 days of data which gives a more global coverage.(Why's that? Hint!) Check out where TOPEX/Poseidon is now! - In this image green shows areas that are a normal height, blue and purple are lower (cooler) than average and yellow, red and white are areas that are higher (warmer) than average. - How much is 14 cm?  - Where are the high areas indicating warm water? - What areas of the world are near high (warm) or low (cool) water?

 

Let's compare and forecast!

 

The image to the left is taken at the height of the '97-'98 El Nino.  Note the area of higher and warmer than average water (white) in the east. To see just how this moved, check out the whole series  or have a look an animation.

The image to the left is the '98-'99 La Nina.  Note the area of lower and cooler water in the tropical Pacific, this later moved to the east To see just how this moved, check out the whole series  or have a look an animation.

How does the ocean make a difference in the weather?

The ocean affects the temperature and the amount of moisture in the air.  How could you do an experiment to test this?  Hint!
With more moisture in the air, it is more likely to rain if the air is cooled.  How could you do an experiment to test this?  Hint!
With less moisture in the air, even as the air cools going over mountains there will be little rain.
Check out these graphics and write your own captions!
 

Your captions:	Your captions:

So why do we need to know what's coming next?

The El Nino and La Nina conditions are not necessarily bad, its just that we and the landscape adapt  to average or 'normal' conditions, so when the weather is not normal, it often causes problems.

•  For instance, if an area of steep hillslopes get twice the average rainfall, it is likely that a lot of erosion will occur.  If we know more rain is expected, then we can take precautions and clear flood chanels and clear out debris dams, that way the mud, water and debris will do less damage.
• If a farmer plants a crop that needs 30 inches of rain a year, but there is only 10 inches of rain, the crop will die. But if the farmer knows that there is likely to be less rain he or she can plant a more drought tolerant crop.

Drought

Drought is when there is not enough rainfall to support activities that usually occur on a piece of land.  These activites include growth of natural vegetation, use of the land for grazing or support of a city.  In the case of the latter, the affects of the drought can often be lessened, but in natural areas the affects often result in dramatic natural population changes.
 

Time for thinking! -What is your average rainfall? - What would happen to the area that you live in if you had half your annual rainfall? - If you knew that you would be getting half the average rainfall what could people do so it would matter less?

 

Wildfires

Drought affected many areas and in some regions such as Indonesia where burning tropical forest for agriculture is part of the traditional way of clearing land and introducing nutrients to the soil, the fires got out of control, burning thousands of acres and contributing to the crash of a jet.  (Photo: Courtesy of Someone Else)
 

Time to do some more thinking! -When are fires 'good' and when are they 'bad'

 

Mudslides

With up to four times the average rainfall in some locations in Peru, mud flows and water caused loss of life, damaged agricultural land and infrastructure such as roads and bridges.  This particular photo (Courtesy: Someone Else) was taken in the Honduras following Hurricane Mitch, a hurricane that some people attribute in part to the El Nino.
 

Satellite view of Hurricane Mitch (Courtesy:Same old Someone Else)

 

Ice storms

Ice storms are caused when moist air is overlaid by cold air (????forgotten which way this works). Rain falls through the cold air and freezes on contact with the ground, trees, power lines and all surface objects (including people!).  For people it is not a problem because they can m ove and shake the ice off, but if freezing rain continues for many hours, wires can be coated with a 2 inch thick layer of ice which is very heavy. The weight of ice on trees and wires can cause breakage.  In the spring of 1998, New England and Maine in the US and Quebec and Ontario in Canada had a severe ice storm (see image below from Maine, source unlisted), and some areas were without power for up to a month.
 

What would be affected in your life if you were without power for a week? How would a farmer be affected? How would a city be affected?