PRELIMINARY STUDY OF INTERNAL SOLITARY WAVE AMPLITUDE OFF THE EAST COAST OF KOREA BASED ON SYNTHETIC APERTURE RADAR DATA

Abstract

This paper presents a method of retrieving the amplitude of oceanic internal solitary wave (ISW), from synthetic aperture radar (SAR) data, and preliminary results obtained in the East/Japan Sea off the east coast of Korean Peninsula. The retrieval algorithms include the small perturbation method (SPM) for microwave backscatter, the action balance equation (ABE) for describing the interaction between wind-generated ocean waves and varying surface current, and also the Korteweg-deVries (KdV) (non-linear partial differential) equation for describing the surface current variation induced by an internal soliton. The radar cross section (RCS) was computed, and the ISW amplitude was estimated by fitting the RCS ratio to the SAR image of ISWs acquired by RADARSAT-1 through the ABE and KdV. Assuming that ISWs propagate along an isotherm between 5 degrees C and 10 degrees C as a boundary between upper and lower layers, ISW amplitude was estimated in the range of 12.5 m similar to 52.5 m. Although no in-situ data are available to validate the results, this study is the first of its kind to obtain the underwater information by SAR in the east coast of Korea.