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El
Niņo
is here!
Sometimes, the Pacific Ocean
near America warms. Normal ocean currents and winds change. The oceans
to the north-east of Australia cool. El Niņo is here! See the El
Niņo animation (size 350KB requires javascript enabled browser)
to get a better understanding of El Niņo.
The following link to the
El Niņo Table presents information on El
Niņo and rainfall for the years from 1947 to 1992. The rainfall column
of the table gives the total annual rainfall for Canary Island in northern
Victoria. (It's not actually an island but a place about 30 km south
of Kerang and 90 km north of Bendigo). Students are to use this information
to answer the set questions.
The "SOI", or Southern Oscillation
Index, is a measure that scientists use to establish whether El Niņo
is present and how strong it is. A negative SOI value indicates an El
Niņo. The lower the value of the SOI, the stronger the El Niņo event.
If the SOI value is positive, it means that there was no El Niņo event
in that year.
The Southern Oscillation
Index (SOI) is determined by the difference in barometric pressure between
Tahiti and Darwin. Pressure fluctuates between the two locations, but
in El Niņo years (SOI is negative), the pressure is higher in Darwin
than in Tahiti. See the SOI
graph for the current
values.
El Niņo's influence is usually
very extensive, with rainfall being affected throughout eastern Australia.
For more information about El Niņo go to:
Climate variability and El Niņo.
Scientists also study
sea surface temperatures to help them make predictions about the climate.
Have a look at what is happening to the current sea surface temperatures
by examining the following sea
surface temperature animation. Notice the shift in warmer and colder
water. During an El Niņo episode you'll see reddish colours in the animation
around the pacific near the top of South America.
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