Ocean variability North of New Guinea derived from TRITON buoy data

We investigated variability in the ocean surface-subsurface layer north of New Guinea using Triangle Trans-Ocean Buoy Network (TRITON) buoys at 2°N, 138°E and 0°N, 138°E during the period from October 1999 to July 2004. Both North and South Pacific waters were observed below the subsurface at these stations. The variability in the subsurface waters was particularly high at 2°N, 138°E. Clear interannual variability occurred near the surface; the water type differed before and after onset of the 2002–03 El Niño. Before summer 2001, water that appeared to be advected from the central equatorial Pacific occupied the near surface layer. After autumn 2001, waters advected by the New Guinea Coastal Current were observed near the surface. Intraseasonal and seasonal variations were also observed below the subsurface. With regard to seasonal variability, the salinity of the subsurface saline water, the South Pacific Tropical Water, was generally high during the boreal summer-autumn, when the New Guinea Coastal Undercurrent was strong. Intraseasonal fluctuations on a scale of 20 to 60 days were also seen and may have been associated with intrinsic oceanic variability, such as ocean eddies, near the stations. Ocean variability in the thermocline layer between 100 and 200 m greatly affects the surface dynamic height variability; water variability before 2001 and variability in the pycnocline depth after 2002 are important factors affecting the thermocline.