Turbulence at the periphery of Sri Lanka dome

Measurements of kinetic energy dissipation rate ε and other oceanographic variables (temperature, salinity, density, and current profiles) were conducted at 20 stations along a 90 nautical mile section at the southwestern periphery of Sri Lanka Dome (SLD), which is a mesoscale cyclonic eddy that usually appears in Bay of Bengal to the east of Sri Lanka during summer monsoons. The broad aim was to document and interpret the structure of flow and turbulence in SLD and quantify turbulent mixing therein using parametric studies. A tendency of upward doming (upwelling) of the pycnocline toward the SLD center is observed, leading to substantial shallowing of the mixed layer therein, with the mixed layer depth decreasing from ~40 m outside the SLD to ~10–15 m inside the cyclonic eddy. The cumulative distribution of ε in the SLD pycnocline (below 40 m depth) is well approximated by the Burr probability distribution. A high level of ε in the pycnocline was observed at the inner periphery of SLD, concurrent with low values of gradient Richardson numberRi. A parameterization for eddy diffusivity in the SLD pycnocline as a function of Ri is suggested.