Eulerian modeling of neutrally buoyant tracers in global oceans

Evaluating the distribution of plastic debris in the ocean has been an intriguing but challenging task. Previous studies using Lagrangian models have identified the effect of convergent surface flow to tracer accumulation, and have revealed the presence of five garbage patches in subtropical ocean gyres. In this work, aiming to eventually enable assimilation of remote-sensing data, we developed an Eulerian model for plastic transport in the global ocean. The model was built for neutrally buoyant tracers, in our case microplastic, in the framework of MITgcm. It incorporates the ECCOv4r4 climate data, which was obtained in a data-constraint global ocean simulation, and is integrated for 24-years from 1992 to 2017. Comparison with previous model and measurement data, and sensitivity test of the result to configuration of sources/sinks of plastics will be presented.