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| TOPEX/POSEIDON Satellite
Data for El Niņo Helping predict future El Niņo events [View our exciting DHTML animation showing the TOPEX/Poseidon satellite. Microsoft's Internet Explorer 4.0+ required.] Thanks
to NASA/JPL/Caltech for this image. |
In a normal year, the strong trade winds to the west push warm surface water against the western boundary of the Pacific Ocean near Australia and Indonesia, while nutrient rich cold water wells up along the west coast of South America, helping fish thrive. TOPEX/POSEIDON has tracked this building up of warm water in the western Pacific Ocean, which can be as much as 1 meter higher than the eastern Pacific. The trade winds are controlled by an air/sea interaction in which SST (Sea Surface Temperature) plays a huge part. In an El Niņo year, these trade winds weaken causing upwelling to decrease which in turn suppresses the upwelling of cold water. Thus, the thermocline deepens as a result of the Kelvin and Rossby Waves. [If you do not fully understand this succession of events, please go back to our overview and after reading those sections, come back here.]
All of this has been measured by TOPEX/POSEIDON during El Niņo events since 1992. The image at the bottom is an actual image of TOPEX/POSEIDON satellite data. The image on top is a computer simulation. These both represent images taken during December 1994. The colors show the sea level relative to a two-year mean (average) over 1993-1994. The color magenta indicates 15 centimeters lower, and red 15 centimeters higher, than average. El Niņo caused the excessive heat associated with the high sea levels (red and yellow) in the central equatorial Pacific Ocean. The associated rise of tropical air and formation of rain clouds contributed to the severe weather and heavy reains in California during winter 1995.
Thanks to NASA/JPL/Caltech for this image. Thus, the top image would be used in dynamical forecasts whereas the image on the bottom would be used for statistical forecasts. This comparision shows that the model underestimated the magnitude of oceanic features during an El Niņo event.
Using TOPEX/POSEIDON data, scientists are working to improve the performance of such models, with the goal of reliably predicting climatic many events, not just the dreaded El Niņo.
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