The Proper Orthogonal Decomposition (POD) analysis method, which is one of principal component analysis techniques, was applied to time series tidal current vector data of Kagoshima Bay. Numerical simulation was applied to semidiurnal tidal conditions only. POD analysis has the advantage of revealing the dominant component with coherence and for visualizing as pattern recognition.
The result of POD analysis for velocity component of the fluctuating current which didn't contain residual current components shows that the upper two modes were the dominant current structures. The eigen vector fields in modes 1 and 2 correspond to the characteristics of oscillating current and crossing current, respectively. However, the major axis of eigen vectors of each mode is not necessarily in agreement with the major axis of current ellipses. This is in accordance to lags of the tide of the original current data which shows the different values at some places. Therefore, the POD method has qualitative potential and needs further improvement for pre-quantitative evaluation.