Decadal variations of the subsurface and intermediate waters in the western tropical Pacific derived from Argo and historic data

The decadal variations of the subsurface and intermediate water masses in the western tropical Pacific Ocean are analyzed with the CTD data of World Ocean Database 2001 (WOD01) in 1980s-1990s and the Argo data after 2000.The results show that the general distributions and water properties of the subsurface water masses and the interm ediate water masses in the western tropical Pacific Ocean during periods of 1985-1994 and 2002-2005 are basically consistent.The slight decadal variation corresponds to the normal status of the global atmosphere-ocean coupling system during the two periods.By tracking the salinity maximum representing the character of the subsurface water masses, the northward diffusion of South Pacific Tropical Water is found to enhance with its edge moving from 5°N during 1985-1994 to 6°~7°N during 2002-2005, while the southward diffusion of North Pacific Tropical Water weakened with its edge moving from 2°N during 1985-1994 to 4°N during 2002-2005.The salinity minimum representing the character of the intermediate water masses show that the northward diffusion of Antarctic Intermediate Water streng thened with its edge moving from 11°N during 1985-1994 to 13°N during 2002-2005; simult aneously, the southward diffusion of North Pacific Intermediate Water weaken.The relationship between the foregoing decadal variations and the strength of global water cycle is worth studying in the future.