We use a biogeochemical model to examine how particulate organic carbon (POC) is produced, transformed and transported to the deep ocean. Vertical flux attenuation arises from several interacting processes: export pathways, particle lability, temperature-dependent degradation, and zooplankton transformations, leading to strongest attenuation in the most productive region. Together with extensive comparison to observations, such a budgeting approach can help constrain model projections.