ANNUAL CYCLE OF MIXED LAYER IN SOUTH CHINA SEA

Based on Levitus 94’ climatological temperature and salinity data, the temporal and spatial features of the mixed layer in the South China Sea (SCS) are derived, and the regular pattern of the mixed layer depth and temperature are analysed. Data analysis indicates that the monsoon has an obvious impact on the temporal and spatial features of the mixed layer in the SCS through the adjustment of the current field. The complicated effect of the wind includes not only influence on the mixed layer depth directly through sea surface Ekman process, but also divergence or convergence forced by the large scale circulation, which would favorite or suspend development of the mixed layer depth. The relationship between the mixed layer depth and temperature over the SCS is revealed. The formation of the maximum mixed layer depth in summer exhibits a process that the 28℃ isotherm line overlaps the bottom of the mixed layer, whereas the formation of the maximum mixed layer depth in winter is a process that the 28℃ warm water completely disappears and the isotherm lines intersect to the bottom of the mixed layer, and the seasonal thermocline is ventilated in the northern SCS.