Sea surface salinity (SSS) measurements from the Aquarius/SAC‐D satellite during September–December 2011 provide the first satellite observations of the salinity structure of tropical instability waves (TIWs) in the Pacific. The related SSS anomaly has a magnitude of approximately ±0.5 PSU. Different from sea surface temperature (SST) and sea surface height anomaly (SSHA) where TIW‐related propagating signals are stronger a few degrees away from the equator, the SSS signature of TIWs is largest near the equator in the eastern equatorial Pacific where salty South Pacific water meets the fresher Inter‐tropical Convergence Zone water. The dominant westward propagation speed of SSS near the equator is approximately 1 m/s. This is twice as fast as the 0.5 m/s TIW speed widely reported in the literature, typically from SST and SSHA away from the equator. This difference is attributed to the more dominant 17‐day TIWs near the equator that have a 1 m/s dominant phase speed and the stronger 33‐day TIWs away from the equator that have a 0.5 m/s dominant phase speed. The results demonstrate the important value of Aquarius in studying TIWs.

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Using two nonintrusive visualization methods, laboratory experiments are performed to examine the internal wave field underlying a turbulent region generated by a vertically oscillating grid. The first method uses dye-lines to mark the vertical motions of isopycnal layers and the second uses ''synthetic schlieren'' to visualize the entire wave field. In a range of experiments, the strength of the stratification is varied so that the buoyancy frequency Nϭ0.33-1.40 s Ϫ1. In all cases, large tank-scale standing wave modes are established which last throughout the experiment. The amplitudes of the isopycnal lines, A , follow a power law relation A ϳN Ϫ1.5. The synthetic schlieren technique allows us to visualize turbulent eddy-scale waves and to isolate the properties of the strongest downward propagating waves at the base of the turbulent layer. These waves have a surprisingly narrow range of frequencies and vertical wavenumbers. The angles of wave propagation from the vertical for the dominant waves lie in the range ⌰ϭ42°-55°. The amplitudes in the wave field follow a relation A ϳN Ϫ1.68. These waves are of large amplitude: their vertical displacement is from 2% to 4% of their horizontal wavelength, a significant fraction of the breaking amplitude.