Generation of internal solitary waves in the Sulu Sea and their refraction by bottom topography studied by ERS SAR imagery and a numerical model

ERS-2 SAR images acquired over the Sulu Sea reveal that there are at least three areas where internal solitary waves are generated: (1) at the sill between Dok Kan Island and Pearl Bank; (2) at the sill between Pearl Bank and Talantam Shoal; and (3) at the sill between Talantam Shoal and Sentry Bank. It is observed that the internal solitary waves generated at different source regions merge into a single solitary wave system. When the solitary waves propagate into shallow water, the distance between the solitary waves in a wave packet decreases. Furthermore, when the water depth decreases in the direction of the soliton's crest line, the crest line is bent towards the shallow water region. These observational facts are explained by a wave refraction model which is based on the Korteweg-de Vries equation which is also valid for large amplitude internal solitary waves provided the pycnocline is sufficiently broad.