Analysis of Typhoon-Induced Waves along Typhoon Tracks in the Western North Pacific Ocean, 1998-2017

In this study, Version 5.16 of the WAVEWATCH-III (WW3) model is used to simulate parameters of typhoon-generated wave fields in the Western North Pacific Ocean during the period 1998-2017. From a database of more than 300 typhoons, typhoon tracks are partitioned into six groups by their direction of motion and longitude of recurvature track. For typhoons that recurve east of 140 degrees E, or track toward mainland Asia, regions of high significant wave height (SWH) values are separated by a minimum in SWH near 30 degrees N. Partitioning SWH into wind sea and swell components demonstrates that variations in typhoon tracks produce a much stronger signal in the wind sea component of the wave system. Empirical orthogonal function (EOF) analysis is used to compute the four leading modes of variation in average SWH simulated by the WW3 model. The first EOF mode contributes to 17.3% of the total variance; all other modes contribute less than 10%. The first EOF mode also oscillates on an approximately 1-year cycle during the period 1998-2017. Overall, typhoon-induced wave energy dominates north of 30 degrees N. Temporal analysis of the leading principal component of SWH indicates that (a) the intensity of the wave pattern produced by westward-tracking typhoons decreased during the last 20 years, and (b) typhoons that recurve east of 140 degrees E and those that track westward toward southeast Asia are largely responsible for the decadal variability of typhoon-induced wave distribution.