By combining all of these observations with the high resolution maps made from the TOPEX/Poseidon data, one can begin to see how the Indian Ocean warming is related to El Niño.
The October wind burst in the Pacific forced a Kelvin wave in the eastern Pacific, which caused sea-level to peak for a second time off the coast of South America. The wind burst in the Indian Ocean created Rossby waves which moved westward in the Indian Ocean. By December, sea-level in the southwestern Indian Ocean was as high as sea-level in the eastern Pacific, and was a near mirror-image of El Niño in the Pacific. Similar variations have been observed during the 1994 El Niño. Based on the altimeter observations, it is beginning to look like El Niño has a very similar mode in the Indian Ocean.
Although these results are preliminary, they show that there is still a lot about El Niño that we do not understand. Continued data from satellite altimeters, space-borne AVHRR, and moored buoys will all contribute to improving our knowledge. Numerical models will also play an important part in testing our theories, as I am sure Professor O’Brien will discuss next week. Understanding this apparent El Niño mode in the Indian Ocean may help us explain teleconnections between El Niño and weather patterns in Asia, Africa, Europe, and other sites that are far removed from the Pacific.