The ocean fine spray

TL;DR

This paper presents a theoretical model explaining the origin and distribution of ocean spray aerosols, emphasizing the role of tiny bubble bursting events that produce nanometer-scale droplets with high velocities.

Contribution

It introduces a one-parameter model that accurately predicts the size distribution of ocean spray aerosols across a wide range, based on bubble bursting physics.

Findings

Model fits experimental data over five orders of magnitude in spray size.

Small bubble bursts produce high-velocity, nanometer-scale droplets.

Most atmospheric aerosols originate from nano-sized bubbles on the ocean surface.

Abstract

A major fraction of the atmospheric aerosols come from the ocean spray originated by the bursting of bubbles from breaking waves. A theoretical framework that incorporates the latest knowledge on film and jet droplets from bubble bursting is proposed. Assuming that their relics constitute the ultimate origin of primary and secondary sea aerosols through a diversity of physicochemical routes, the model can be reduced to a single controlling parameter to predict the global probability density distribution (pdf) of the ocean spray. The bursting and collapse of small bubbles on the sea surface from about 10 to 100 microns produces an extreme energy focusing and the ejection of a rapid liquid spout whose size reaches the free molecular regime of the gaseous environment. In these rarefied conditions, simulations show that this spout yields a jet of sub-micrometer and nanometric scale droplets whose number and speed can be far beyond any previous estimation, overcoming by orders of magnitude alternative mechanisms recently proposed. The one-parameter model fits remarkably well published experimental measurements along five orders of magnitude of spray size, from about 5 nm to about 0.5 mm. According to this proposal, the majority of aerosols determining the life on our planet would have their extremely elusive birth in the uterus-like nano-shape of small bursting bubbles on the ocean surface at the very latest instants of collapse.