Interannual wave climate variability in the Taiwan Strait and its relationship to ENSO events

Abstract

This study investigated the interannual wave climate variability in the Taiwan Strait (TS) and its relationship to the El Nino-Southern Oscillation (ENSO) phenomenon using a high-resolution numerical wave model. The results showed the interannual variability of significant wave height (SWH) in the TS, which exhibits significant spatial and seasonal variations, is typically weaker than the seasonal variability. The standard deviation of the interannual SWH anomaly (SWHA) showed similar spatial variations in the TS throughout the year, being largest in the middle of the strait and decreasing shoreward, except in summer, when there was no local maximum in the middle of the TS. Further analyses proved the interannual wave climate variability in the TS is controlled predominantly by tropical cyclone activities in summer and by the northeasterly monsoon winds in winter. Furthermore, the interannual SWHA in the TS was found correlated highly negatively with the ENSO phenomenon. This relationship mainly derives from that during the northeasterly monsoon seasons. During the northeasterly monsoon seasons in El Nino (La Nina) years, the negative (positive) SWHA in the TS derives from weakened (strengthened) northeasterly monsoon winds induced by a lower-tropospheric anomalous anticyclone (cyclone) over the western Pacific Ocean and the South China Sea. During the southwesterly monsoon season in El Nino (La Nina) years, however, the SWH in the TS tends to increase (decrease) anomalously because of intensified (weakened) TC activities over the western North Pacific Ocean and adjacent seas.