CAREER: Modeling Ocean Particle Export Flux by Combining Particle Aggregation and Biogeochemical Models

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OCE-0645485An important component of net ecosystem production in the surface ocean sinks to depth where it can be remineralized to carbon dioxide or transit to the bottom. Some of these sinking particles are formed via a number of processes that create rapidly sinking particles that have the potential to transport carbon to the benthos without remineralization. However, currently, very few biogeochemical models explicitly represent the flux of sinking of particles, relying instead on empirical or semi-empirical relationships to distribute material vertically in the water column.In this integrated research and education CAREER proposal, a researcher from the University of Georgia will focus on the development of numerical models of particle export flux from the surface ocean that can be incorporated into regional and global biogeochemical models. The novel aspect of these models is that they will concentrate on the physical and biological processes (coagulation and fecal pellet production) that transform individual, slowly sinking particles into large, rapidly sinking ones. Naively incorporating coagulation models into these models is computationally prohibitive, so new algorithms and parameterizations will have to be developed that represent the salient features of particle coagulation (e.g., particle settling velocities) and the interaction between particle dynamics, ecosystem dynamics and the physical properties of the water column (such as density). This will be accomplished using physical and biogeochemical models of increasing complexity (such as simple mixed layer models and the JGOFS Regional Test Bed Models), with new parameterizations and algorithms being developed at each stage and influencing the next one.The educational component of this proposal is integrated with the research component and aims at enhancing quantitative problem solving skills at all levels using real world, oceanographic data sets. High-school and middle-school teachers will be involved in workshops in which they will develop teaching materials for students involving quantitative analysis from publicly available oceanographic data sets. The PI will further develop undergraduate and graduate level courses that will include the construction and analysis of models from large-scale data sets. The work will be of considerable interest to researchers in biogeochemical cycling and global climate change as well as policy makers and the general public by increasing our ability to make more accurate predictions of the effect the ocean has on the planet's climate. The broader impacts also include increased exposure of teachers and students to the development and analysis of models and their use in understanding and solving real-world oceanographic problems.