The Particle Flux from the Convective Mixed Layer Simulated by large eddy simulation (LES)

The particle flux escaping from the convective mixed layer was investigated by analyzing the motion of a large number of Lagrangian particles from large eddy simulation (LES) with an aim to understand the seasonal variation of phytoplankton population in the mixed layer. It was found that the settling of particles from the mixed layer depends on the turbulence within the mixed layer, represented by w* (= (Q0h)1/3) as well as the terminal velocity of a particle ws and the entrainment of the mixed layer we, where Q0 is the surface buoyancy loss and h is the mixed layer depth. The percentage of particles surviving the wintertime mixed layer and the consequent particle concentration was predicted in terms of ws, Q0, and the background stratification N. The results were compared with the simple model predicting the phytoplankton concentration in the mixed layer and its oceanographic application was discussed.

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