Unveiling three-dimensional sea surface signatures caused by internal solitary waves: insights from the surface water ocean topography mission

Internal solitary waves (ISW), characterized by large amplitude and long propagation distance, are widespread in global oceans. While remote sensing images have played an essential role in studying ISWs, they mainly exploit two-dimensional image information. However, with the launch of the surface water ocean topography (SWOT) satellite on December 16, 2022, a unique opportunity has emerged to capture wide-swath three-dimensional ISW-induced sea surface information. In this study, we examine ISWs in the Andaman Sea using data from the Ka-band Radar Interferometer (KaRIN), a crucial sensor onboard SWOT. KaRIN not only provides backscattering satellite images but also employs synthetic aperture interferometry techniques to retrieve wide-swath two-dimensional sea surface height measurements. Our observations in the Andaman Sea revealed the presence of ISWs characterized by dark-bright strips and surface elevation solitons. The surface soliton has an amplitude of 0.32 m, resulting in an estimation of ISW amplitude of approximately 60 m. In contrast to traditional two-dimensional satellite images or nadir-looking altimetry data, the SWOT mission's capability to capture three-dimensional sea surface information represents a significant advancement. This breakthrough holds substantial promise for ISW studies, particularly in the context of ISW amplitude inversion.