Modeling the dynamical sinking of biogenic particles in oceanic flow

TL;DR

This study models the sinking behavior of biogenic particles in oceanic flows, showing that their motion is primarily passive with minor effects from inertia and Coriolis force, and reveals inhomogeneities similar to real ocean observations.

Contribution

It unifies theoretical models with oceanographic applications by analyzing particle sinking in mesoscale flow simulations, highlighting dominant physical processes.

Findings

Inertia and Coriolis effects are negligible for particle sinking.

Passive motion with gravity dominates particle dynamics.

Two-dimensional projections show realistic inhomogeneities.

Abstract

We study the problem of sinking particles in a realistic oceanic flow, with major energetic structures in the mesoscale, focussing in the range of particle sizes and densities appropriate for marine biogenic particles. Our aim is to unify the theoretical investigations with its applications in the oceanographic context and considering a mesoscale simulation of the oceanic velocity field. By using the equation of motion of small particles in a fluid flow, we assess the influence of physical processes such as the Coriolis force and the inertia of the particles, and we conclude that they represent negligible corrections to the most important terms, which are passive motion with the velocity of the flow, and a constant added vertical velocity due to gravity. Even if within this approximation three-dimensional clustering of particles can not occur, two-dimensional cuts or projections of the evolving three-dimensional density can display inhomogeneities similar to the ones observed in sinking ocean particles.