On the Aleatory and Epistemic Uncertainty of the Wave Resource Assessment in the North West Pacific

Abstract

This paper presents the results of quantifying uncertainty associated with the wave resource assessment in the North West Pacific. This study classifies uncertainty into 2 types: aleatory uncertainty and epistemic uncertainty. We defined the source of aleatory uncertainty as inter-annual variability of wave power and the source of epistemic uncertainty as difference between a model and an observation. Spectral analysis of inter-annual variability and correlation coefficient analysis between inter-annual variability and climate index such as Arctic Oscillation are conducted to quantify aleatory uncertainty. The results revealed that aleatory uncertainty in North West Pacific differs from that in North Atlantic. Regarding the cause of inter-annual variability, seas surrounding Japan can be classified into 4 regions: the sea of Okhotsk and Eastern Japan with high correlation with the North Pacific Index, the Japan Sea with Arctic Oscillation and Southern Japan with the typhoon frequency. These results provide the characteristic of uncertainty in wave power assessment in the North West Pacific, and they are helpful to establish standards of wave resource assessment in Japan.