Generation and evolution of mode-two internal waves in the South China Sea

► We investigated the generation and evolution of mode-two solitons on the shelf break.
► Historical mooring and satellite data have been investigated for the detection of mode-two solitons in the ocean.
► The mode-two waves on the shelf are generated from the disintegration of mode-one solitons in the deep ocean.
► The soliton width of large mode-two waves is much wider than mode-one waves.

The objective of this study is to investigate the generation and evolution of mode-two internal waves on the shelf break. In this study, some historical mooring and satellite data have been investigated for the detection of mode-two solitons in the ocean. A recent field experiment in May 2009 near Dong-Sha Island in the South China Sea (SCS) is first described and analyzed. During the experiment, a small mode-two wave was observed following a huge mode-one soliton on the shelf. Then, the environmental conditions for the evolution of mode-two internal waves were assessed for parametric and sensitivity study based on the CTD data from previous experiment in SCS. The generation of mode-two waves on the shelf by disintegration of mode-one solitons in the deep ocean is proposed and analyzed based on the theory of modal-decomposition. For comparison, the soliton characteristics of mode-one and -two waves from environmental parameters have been estimated. It’s been shown that the soliton width of large mode-two waves is much wider than mode-one waves.