FY 1997

Solitary waves in the western Equatorial Pacific Ocean

Pinkel, R., M. Merrifield, M. McPhaden, J. Picaut, S. Rutledge, D. Siegel, and L. Washburn

Geophys. Res. Lett., 24(13), 1603–1606, doi: 10.1029/97GL01610 (1997)

During the spring tides of early January and February 1993, groups of solitary internal waves were observed propagating through the Intensive Flux Array of the TOGA COARE experiment. The waves appear to originate near the islands of Nugarba (3° 30′S-154° 30′E). They travel northeastward at 2.5-3 m s^–1, closely coupled with the semidiurnal baroclinic tide. Peak amplitudes exceed 60 m. Velocities are in excess of .8 m s^–1. Sea surface vertical displacements of order .3 m can be inferred directly from the lateral acceleration of surface waters. The Equatorial Undercurrent is displaced by soliton passage but apparently is unaffected otherwise. The intrinsic shear of the solitary crests is small compared to ambient equatorial shears. The crests, while not themselves unstable, are effective at triggering instabilities on the background flow. The motions potentially contribute 10-15 Watts/m² to the flux of heat into the mixed layer.