Long-Term (1982-2012) Summertime Sea Surface Temperature Variability in the Taiwan Strait

Long-term (1982 - 2012) advanced very-high-resolution radiometer (AVHRR) data collected at a resolution of 0.04 degrees clearly indicated sea surface temperature (SST) warming and variations associated with El Nino and Southern Oscillation (ENSO) in the Taiwan Strait (TS) during the summer. From 1982 - 2012 the spatially averaged warming trend in the TS was 0.057 degrees C y(-1). However, during the last 10 years the warming phenomenon appears to have halted and a slight cooling rate (0.03 degrees C y(-1)) was observed. The monthly SST transition from June - July became increasingly sharp. The first mode (70%) of the empirical orthogonal function (EOF) analysis indicated an SST warming trend. The warming occurred primarily in the eastern strait. The warming slowed down and considerable inter-annual variation occurred in the period after 1994. EOF results applied to the data between 1994 - 2012 showed that the first EOF mode (55%) revealed a warming pattern, whereas the second EOF mode (12%) revealed a pattern that explained the inter-annual variation in the SST, which was strongly correlated with the wind speed. Strong winds enhanced the upwelling along the China coast, eastern Taiwan Banks (TWB) and southern Peng-Hu Islands, whereas the SST in eastern TS increased because of increased warm water transport from the South China Sea. The inter-annual variation in the southwesterly wind could be affected by both ENSO and the background Pacific Decadal Oscillation (PDO) phase. The strongest upwelling in the TS tended to occur when ENSO and PDO were in phase associated with the southwesterly wind.