Buoy drift trajectory and numerical simulation in Pingtan coastal waters

Pingtan coast in Fujian Province is an accident-prone area due to its irregular coastline,serried islets and complex topography.This paper develops a trajectory forecast system for accidental drifts.The target is tracked with Lagrange method under given ocean conditions which are obtained via atmosphere and ocean numerical models.The ocean model used here is regional ocean modelling system(ROMS) with wet-dry mode.The horizontal spatial resolution is 100 meters and vertical resolution is 16 layers,which is fine enough to resolve the complex topography.Validation analysis shows that,the model's mean absolute errors for tide elevation,flow velocity and flow direction are 0.20 m,0.12 m/s and 26 degrees,respectively.Two floats were released in seawater 3 km offshore to further verify model's applicability in Pingtan waters.The analysis of float trajectories and velocities show that drifts are mainly affected by the tide and the local terrain.The simulation of float trajectories are consistent with the observation on a maximum spatial deviation of 2.8 km.The trajectory forecast system is proved to be reliable in predicting path information of drifts in Pingtan coastal waters.