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UBC Theses and Dissertations

The effect of multicomponent diffusion on the chemical composition of seawater Simantiris, Nikolaos


Double-diffusive convection or Double Diffusion is an interaction within a fluid whose density is governed by two constituents of different molecular diffusivities. Double diffusion in the ocean appears to create unique structures that look like staircases in vertical profiles of temperature and salinity. Many oceanographers believe that double diffusion can affect the water masses and the circulation of the ocean. However, in the current literature the detailed physics behind the formation of this staircase are still unclear. In sea salt each ion has different diffusion rate and because of that modelling salt diffusion is actually more complicated since there is no single ”salt diffusivity”. Therefore in order to describe the effects of double diffusion in seawater we have to consider a multicomponent system where each ion is reacting differently than the other ones. To simulate this system we use MIN3P a multicomponent diffusion model. Our approach is primarily numerical, but in order to test the conclusions of our model we compare against observations in Powell Lake. We see that Multicomponent Diffusion can change the chemical composition of seawater and should be considered an important transport mechanism in the ocean.

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