Decadal fluctuations in the western Pacific recorded by long precipitation records in Taiwan

A 110-year precipitation record in Taiwan, located at the western edge of the subtropical North Pacific, depicts a pronounced quasi-decadal oscillation (QDO). The QDO in Taiwan exhibits a fluctuating relationship with the similar decadal variations of sea surface temperature (SST) anomalies in the central equatorial Pacific, known as the Pacific QDO. A regime change was observed around 1960, such that the decadal variation of Taiwan’s precipitation became more synchronized with the Pacific QDO’s coupled evolutions of SST and atmospheric circulation than before, while the underlying pattern of the Pacific QOD did not change. Using long-term reanalysis data and CMIP5 single-forcing experiments, the presented analysis suggests that increased SST in the subtropical western Pacific and the strengthened western extension of the North Pacific subtropical anticyclone may have collectively enhanced the relationship between the Taiwan precipitation and the Pacific QDO. This finding provides possible clues to similar regime changes in quasi-decadal variability observed around the western Pacific rim.