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

Abstract

Intensive observations, using an array of surface and subsurface moored buoys, are conducted around 80.5°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.