Water exchange in the Luzon Strait during monsoon transition periods

In situ observation data obtained from six cruises spanning 1998 and 2005 to 2008 combined with remote sensing sea surface wind and sea surface high data are used to investigate the water exchange characteristics in the Luzon Strait during monsoon transition periods. Temperature and salinity feather analysis results show that the interannual variability of the Kuroshio intrusion is strong in the upper 200 m layer. The weakest intrusion is found in August 2008, and the strongest intrusion is in June 1998. The intermediate and lower layer waters show a strong property of the South China Sea water mass, the intrusion of Kuroshio is weak. Dynamic calculation results show that the synoptic scale variability of geostrophic current in the sections is very strong. The meridional mean Luzon Strait transport (LST) of the sections in six cruises are -3.2, -4.29, -3.80, -3.65, -5.25 and 0.09 Sv respectively (1 Sv = 106 m3/s. Negative values denote westward transport). Direct relationship between wind fields and upper layer transports can not be found in these in situ observations. Eddy induced transport due to instability of Kuroshio may be the key factor regulating the upper layer transport of the Luzon Strait.