Calibration of a marine floating litter transport model

ABSTRACT Predicting the transport of marine floating litter requires a detailed understanding of the processes involved in the dispersion of floating materials in the ocean. The restraining effect of a near-coastal boundary or shallow bottom topography may affect the drift response to local wind forcing. The aim of this work is to develop a particle-tracking model for the north-west Iberian waters that allows for spatial variations in the effect of winds on the transport of marine floating litter. Observational data from 23 drifters were used, in conjunction with wind and ocean current data from atmospheric and ocean models. The drifter locations were grouped into three separate zones based on the bathymetry and the orientation of the coastline. Response matrices for each of these areas were computed using a 2-D vector regression approach. The maximum drift response to local wind forcing is alongshore in inner shelf waters, whereas an isotropic drift response to winds is observed in outer shelf waters. The wind drag coefficient ranges from 0.5 × 10−2 to 1.2 × 10−2, depending both on the wind direction and the drifter position.