Ocean Surface Layer Response to Convectively Coupled Kelvin Waves in the Eastern Equatorial Indian Ocean

Abstract

Moored measurements between June 2011 and April 2012 at 0°, 90°E in the Indian Ocean are analyzed to assess the surface layer response to the passage of 15 convectively coupled Kelvin waves. During the suppressed phase of the Kelvin waves, intense downward net surface heat flux, weak winds, and a strong diurnal cycle were evident. The net surface heat flux was 3 times larger than turbulent cooling at the base of the surface layer, accounting for an increase of surface layer temperature by +0.2 °C on average. In contrast, strong winds, heavy rainfall, diminished diurnal variations, and air-sea heat loss marked the active phase, during which surface layer cooling from above by air-sea fluxes and from below by subsurface turbulent mixing led to a decrease in surface layer temperature by −0.3 °C. Strong salinity stratification formed a thick barrier layer during the active phase, inhibiting the downward diffusion of heat below the surface layer.