Mindanao Current/Undercurrent measured by a subsurface mooring

The mean structure and variability of the currents east of Mindanao are investigated through 2 year mooring observations at about 8°N, 127°3'E from December 2010 to December 2012. The strong southward Mindanao Current (MC) exists in the upper 600 m with a maximum mean velocity of 73 cm/s and a standard deviation of 17 cm/s at 100 m. A northward mean flow is observed below 600 m to the depth deeper than 1000 m, which has been called the Mindanao Undercurrent (MUC) with a maximum mean velocity of about 10 cm/s at 950 m and a standard deviation of 19 cm/s. Further analysis with hydrographic data and an eddy‐resolving model outputs also suggests this northward mean current to be the MUC. Intraseasonal variability with a period of 60–80 days is revealed through the whole water column from 200 m down to about 900 m. This intraseasonal variability appears to be closely related to subthermocline eddies, which translate westward and intensify near the Mindanao coast.