Studies of Filtering Effect on Internal Solitary Wave Flow Field Data in the South China Sea Using EMD

Based on the scheme of Empirical Mode Decomposition(EMD), different low pass filtering algorithms were derived from Intrinsic Mode Function (IMF), then the rules to select superior filtering algorithms were established by minimum noise energy principles and filtering flatness indicators. The superior filtering algorithms proved to be theoretically effective and reasonable. The study finally revealed the filtering algorithm without the first four IMFs was the best. Utilizing the internal waves flow field data observed in the South China Sea, the filtering effect on the waves’ velocity propagating eastward was analyzed. The results obtained using the superior filtering algorithms could depict internal solitary waves phenomenon more clearly as compared with other algorithms. It was proved that the results were practical, and filtering algorithms and effects were appropriate.