ENSO and PDO-related interannual and interdecadal variations in the wintertime sea surface temperature in a typical subtropical strait

The Taiwan Strait has the largest temporal variability in the wintertime sea surface temperature (SST) along the China coast. The warming and cooling trends reach about ± 1 °C per decade in winter during 1982–1999 and 1999–2014, respectively, which are about 4 times larger than neighboring coastal area and open ocean. Previous studies have noted these opposite trends, but the cause remains unclear due to insufficient study on teleconnections of this local signals to large-scale climate signals (e.g., Pacific Decadal Oscillation, PDO; El Niño–Southern Oscillation, ENSO). Using different period filters, wintertime SST anomaly in the Taiwan Strait (TS-SSTa) of different timescales were separated and connected to the large-scale climate signals. Besides the impact of global warming, we also found that the interdecadal signal of PDO contribute significantly to the warming and cooling trends of the wintertime TS-SSTa during 1982–2014 (mostly the positive PDO phase). During the positive PDO phase, a sea level pressure (SLP) dipole develops at the North Pacific, leading to a northeasterly wind jet along the Eurasian eastern coast, and affecting the interdecadal wintertime TS-SSTa through the East Asia Winter Monsoon (EAWM) and North Pacific Subtropical Gyre. During the negative PDO phase, the influence from North Pacific weakens, and the tropical Pacific has a greater influence on the interannual wintertime TS-SSTa through the northward movement of the ENSO-related cyclone/anticyclone anomaly over East Asia. Thus, the influence from North Pacific (PDO) and tropical Pacific (ENSO) alternately control the TS-SSTa variation during the positive and negative PDO phases.