28 Mar 2022
28 Mar 2022
Status: this preprint is open for discussion.

The ocean fine spray

Alfonso M. Gañán-Calvo1,2 Alfonso M. Gañán-Calvo
  • 1Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos, ETSI, Universidad de Sevilla, Camino de los Descubrimientos, 41092 Sevilla, Spain
  • 2Laboratory of Engineering for Energy and Environmental Sustainability, Universidad de Sevilla, Camino de los Descubrimientos, 41092 Sevilla, Spain

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.

Alfonso M. Gañán-Calvo

Status: open (until 09 May 2022)

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Alfonso M. Gañán-Calvo

Alfonso M. Gañán-Calvo

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Short summary
The bursting of bubbles from breaking waves produce vital ocean aerosols for our planet. After a thorough analysis of the physics and statistics of the film and jet droplets from bursting bubbles, a global model describing the overall statistics of the ocean spray is proposed. The remarkable agreement of this model with a large number of experimental measurements suggests that the contribution of jet droplets from very small bubbles to the submicrometer oceanic spray is of crucial importance.