A simple approach is presented to model the effect that turbulence has on the sedimentation loss of pelagic particles from the mixed layer. The approach consists in determining how turbulence affects their vertical distribution by splitting the solution of the advection-diffusion equation into two functions, one for the concentration of particles in the mixed layer and the other one reflecting the shape of the profile of particle concentration. The results of the paper indicate that the sedimentation flux is seriously underestimated if a uniform distribution of particles is assumed in the mixed layer when turbulence levels are low. A correction to this underestimation is possible in many situations without resolving the vertical scale in the mixed layer. The cases in which the correction cannot be applied are delimited in the paper in terms of dimensionless numbers. The results also demonstrate the importance of resolving the vertical scale in models of particle dynamics and add further support to the hypothesis of turbulence as the mechanism responsible for daily cycles of aggregates in the sea.
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