Short-term upper-ocean variability in the central equatorial Indian Ocean during 2006 Indian Ocean Dipole event

Intensive observations, using an array of surface and subsurface moored buoys, are conducted around 80.5 degrees E in the equatorial Indian Ocean during October/November 2006. An intriguing data set of atmospheric and oceanic variables during a peak phase of a positive Indian Ocean Dipole is obtained. The ocean observation data shows relatively shallow thermocline, which intensifies with time during the one-month period, and eastward subsurface zonal flow under westward flowing surface current, generating unusually strong vertical shear above the thermocline. Intraseasonal meridional current variability is also observed. Upper-ocean volume budget analysis indicates that a strong upwelling event, larger than 10 m/day, and associated upward movement of the isotherms below the thermocline occur for a few days in early November. These observed data demonstrates unusual conditions of the upper ocean during boreal autumn in 2006.