Ocean Mixing's Role in Convectively Coupled Kelvin Waves

The role of turbulent mixing in regulating the upper ocean’s response to the convectively coupled Kelvin wave [CCKW] is assessed from measurements of surface forcing, acoustic, and microstructure between June 2011 - April 2012 at 0, 90E in the Indian Ocean. During the the CCKW passage, the heat content of the near surface layer was cooled from above by air-sea fluxes and from below by turbulent mixing, in roughly equal proportions. Sea surface temperature (SST), on average, decreased by 0.5^oC. Barrier layer thickness controlled the vertical divergence between surface and subsurface turbulent heat fluxes in the SST cooling. Despite heavy precipitation during the CCKW passage, subsurface mixing was sufficient to increase the upper ocean salinity by entraining salty Arabian Sea Water from the pycnocline. The turbulent salt flux across the base of the near surface layer was 2 times as large as the surface salt flux. These turbulent processes may account for systematic errors in numerical models of the evolution of the CCKW, an important component of the convective envelope of the Madden-Julian oscillation (MJO).