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The Tropical Indian Ocean

Using the Seasat altimeter crossover differences, Perigaud and Minster [1988] investigated the movement of the ``Great Whirl'' formed in the Somali Current and found fair agreement between altimetry data and in-situ data. Variability of the Somali Current was studied by Perigaud and Delecluse [1989] using the Seasat altimeter data and scatterometer data and numerical models. They found that nonlinearity is crucial in explaining the observations. A large anticyclonic eddy formed in the eastern Arabian Sea during the northeast monsoon was studied by Bruce et al. [1994] using the Geosat data with a numerical model. Perigaud and Delecluse [1992] investigated the annual sea level variations using the Geosat altimeter data and a shallow-water model. Significant correlation was found between the first complex empirical orthogonal functions of both the observation and the model simulation. This annual signal was interpreted in terms of Rossby waves with the maximum amplitude located near 12 S and 90 E. Using four years' worth of the Geosat data, Perigaud and Delecluse [1993] investigated the interannual sea level variations and compared the observation to the simulation by a shallow-water model. Averaged over the basin studied (north of 20 S), the observation and the simulation were highly correlated (0.92). The signal was characterized by a sea level rise during the 1986--87 El Niño with the maximum amplitude (5 cm) occurring in the southern domain (10 S--20 S). They also used the Geosat data to test the quality of the wind driving the model.



U.S. National Report to IUGG, 1991-1994
Rev. Geophys. Vol. 33 Suppl., © 1995 American Geophysical Union