Fuzzy cluster analysis of water mass in the western Taiwan Strait in spring 2019

The classification of the springtime water mass has an important influence on the hydrography, regional climate change and fishery in the Taiwan Strait. Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019, we analyze the spatial distributions of temperature (T) and salinity (S) in the investigation area. Then by using the fuzzy cluster method combined with the T-S similarity number, we classify the investigation area into 5 water masses: the Minzhe Coastal Water (MZCW), the Taiwan Strait Mixed Water (TSMW), the South China Sea Surface Water (SCSSW), the South China Sea Subsurface Water (SCSUW) and the Kuroshio Branch Water (KBW). The MZCW appears in the near surface layer along the western coast of Taiwan Strait, showing low-salinity (<32.0) tongues near the Minjiang River Estuary and the Xiamen Bay mouth. The TSMW covers most upper layer of the investigation area. The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait, beneath which is the SCSUW. The KBW is a high temperature (core value of 26.36°C) and high salinity (core value of 34.62) water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.