Variable temperature, salinity and water mass structures in the southwestern Taiwan Strait in summer

Using the CTD data from four successive summer cruises during 2004–2007, this paper studies the variable temperature, salinity and water mass structures in the southwestern Taiwan Strait in summer. By applying the fuzzy clustering method to the collected CTD data, we classify the hydrographical structure as mainly having five major water masses in the studied area in summer. The variable hydrographical structure is especially demonstrated by the coastal upwelling, which occurred in the sea area near Dongshan with different scales, locations and intensities during the observation period of each cruise. Evident coastal upwelling appeared in the southwestern Taiwan Strait during July of 2005 and 2007. Numerical simulations from a POM-based, high resolution and three-dimensional model explain the observed variable hydrographical structures and show that the variability is largely associated with local wind conditions.