New Application of Wavelet Transform for Internal Wave Detection SAR and Optical Image: A Case Study in Japan Waters

Abstract

We observed the internal wave features in ERS1/2 SAR and ASTER images data over Japan waters, during 1993-2004 period. The internal wave features were shown in the Tsushima Strait, coast of Izu Peninsula, coast of Ibaraki in east of Honshu, coast of Sado Island in west of Honshu, and southwest and south of Hokkaido. The internal wave feature characteristics in image suggest tidal generation source. At these places, packets of non-linier internal waves were formed over shelf break areas such as ridge and sill. Various wavelet transform, e.g. Haar, Daubechies, Symlet, Coif, Biorthogonal, and Meyer wavelet, are tested comparably to study the internal wave detection in image using multi resolution analysis. Though all of wavelet families can be used for internal wave packet detection, the decomposed feature tends to follow the wavelet function, which compress the first wave crest. To solve this problem, we propose new wavelet function constructed from Damped Oscillation Function. So far this method show good result. Finally, we show the application of KdV model to calculate the nonlinear speed of the internal wave, which can be use to predict the generation of strong current when internal waves occur.