Abstract:

In eddy-resolving hydrodynamic models, first-mode baroclinic Rossby waves linked to El Nino/Southern Oscillation are the dominant features which change basin-wide temperatures below the seasonal thermocline in the northeast Pacific at periods less than a decade. Realistic simulations are carried out in which Rossby waves are mapped using acoustic tomography. Based on the model which propagated these waves, a Kalman filter is used to map temperature signals for a year. At 300-m depth, 80% of the model variance is accounted for with tomography when the navigational errors of the sources and receivers are as poor as 1 km. Consequently, it may be unnecessary to accurately navigate actual tomographic instruments to map climate change [Spiesberger et al., IEEE Ocean. Eng. 22 (1997)]. [Work supported by SERDP and ONR.]