Accumulation of particles with different characteristics in the global ocean*

Assessing the distribution of plastic debris in the ocean has proven to be important. Previous research, utilizing Lagrangian models, has confirmed the influence of convergent surface flows on tracer accumulation and identified five major garbage patches within subtropical ocean gyres. However, to understand the distribution of particles with different characteristics, an Eulerian model is preferred for its enhanced ability to incorporate parametrizations and fragmentation. For this purpose, we present an Eulerian microplastic transport model using MITgcm. This model incorporates ECCOv4r4 climate data and includes a 25-year simulation of seasonal cycles.

Following the other two existing Eulerian works by Mountford and Peng & Wu, we explored the behaviors of positively and negatively buoyant particles of sizes ranging from 1 micrometer to 1 millimeter. Particularly, regarding the distribution, only large enough plastics form five patches in subtropical gyres, while small plastics, known as microplastics, only form three gyres in the resulting accumulation pattern.