In this study, we first investigate the Multi-variate ENSO Index (MEI) and the Pacific Decadal Oscillation (PDO) index as climate data if a multi-decadal fluctuation of climate exists or not by using a relatively new method, Hilbert-Huang Transform (HHT). Then, the tropical cyclone activities using Best Track data from the Joint Typhoon Warning Center (JTWC) were analyzed also using HHT to find out the relation between the multi-decadal fluctuation of climate and tropical cyclones in the western North Pacific (WNP). The results showed a certain relation between them in about 15 to 30 years timescales. Finally, we investigated past records of typhoon and storm surge events in Japan and found the effects of multi-decadal fluctuation of climate on related coastal hazards in similar multi-decadal timescales. Based on the results, adaptive measures for future storm surge and coastal hazards under changing climate which takes into account "multi-decadal fluctuations" of climates as well as the global warming trend is proposed.
There is a concern that extreme meteorological events such as heat waves, drought, flood, and tropical cyclones (TCs) will increase in intensity and frequency due to global warming (Trenberth et al., 2007). The general features derived from reanalysis datasets include a poleward shift in storm track location and increased storm intensity but a decrease in the total number of storms in the Southern Hemisphere (SH) (Simmonds and Keay, 2000) and in the Northern Hemisphere (NH) (Gulev et al., 2001; McCabe et al., 2001; Simmonds and Keay, 2000). In the NH, McCabe et al. (2001) found that there has been a significant decrease in mid-latitude cyclone activity and an increase in high-latitude cyclone frequency, suggesting a northward shift of the storm track, with storm intensity increasing over the North Pacific and North Atlantic.
